Horns, Tusks, and Flippers: The Evolution of Hoofed Mammals

Horns, Tusks, and Flippers

HORNS, TUSKS, AND FLIPPERS: THE EVOLUTION OF HOOFED MAMMALS

Donald R. Prothero Occidental College Los Angeles, California and

Robert M. Schoch Boston University Boston, Massachusetts

The Johns Hopkins University Press Baltimore and London

© 2002 The Johns Hopkins University Press All rights reserved. Published 2002 Printed in the United States of America on acid-free paper. 9876543 2

The Johns HopkinsUniversity Press 2715 North Charles Street Baltimore, Maryland 21218-4363 www.press.jhu.edu

Library of Congress Cataloging-in-Publication Data Prothero, Donald R. Horns, tusks, and flippers: the evolution of hoofed mammals / Donald R. Prothero and. Robert M. Schoch. p. cm. Includes bibliographical references (p. ) and index. ISBN 0-8018-7135-2 (alk. paper) 1. Ungulates-Evolution. 2. Ungulates, Fossil. 3. Elephants-Evolution. 4. Cetacea-Evolution. I. Schoch, Robert M. II. Title. QL737.U4 P76 2002 599.6138-dc21

2002069394

A catalog record for this book is available from the British Library.

Dedicated to our wives and sons Teresa LeVelIe and Erik Prothero Cynthia, Nicholas and Edward Schoch

and to the future of the animals described herein

Contents

Preface and Acknowledgments

Xl

1. Introduction American savanna . Names and dates Hoofed mammals Uinta beasts and the Cope-Marsh wars The lost world

1 2 6 9 13

2. Cloven hooves The kingdom of cloven hooves . Gut reactions "Bunny deer" Phosphate and fossils Pseudopigs Sui generis . "Nebraska man" and javelinas The "river horse"

19 19 19 23 25 26 27 35 39

3. Tylopods Camels without humps Ships of the desert "Mountain tooth"

45 45 53 56

4. Where the deer and the antelope play Graveyard of the Amazons Horns and antlers "Mouse deer" The "forest donkey" .. The camelopard Deer perfume AII-American-but not an antelope Deer to us all Abbe David and his deer

61 61 63 65 66 67 72 74 76 84

5. Hollow horns A world of bovids .. Bovines Aurochs and wisent Where the buffalo roam Cattle call Diving bucks "Bright eyes" Mountain monarchs

1

87 87 90 92 94 97 99 100 107

viii

6. A whale's tale Dr. Koch's "sea serpent" Walking whales? Andrews' giant "bear" The pedigree of Leviathan Life of a Leviathan "So long, and thanks for all the fish" Moby Dick, Flipper, and their kin Filter-feeding monsters Save the whales!

~................................................................................................

115 115 117 118 120 121 124 127 133 135

7. Out of Africa The tethytheres Mermaids The "feeble folk"

141 141 143 149

8. The origin of Jumbo Giants in the earth Early tuskers The "Great Missoul-ium" Shovel-tuskers and gomphotheres Elephant grinders Woolly wanderers The mystery of the missing mammoths

157 157 159 163 166 169 170 176

9. Kingdom of ivory Behold the behemoth Behemoth biology..... The sisterhood God and slave Blood and ivory

179 179 182 185 190 191

10. A horse of a different color (and shape) The origin of perissodactyIs The "hyrax beast" Cuvier's "ancient beast" Halfway horses Browsing anchitheres Grazing horses The hipparion controversy .

197 197 198 203 204 205 207 209

~.........................................................................................

11. Equus One-toed horses Stripes do not a zebra make Wild asses Wild and domesticated horses

213 216 221 223

12. Thunder beasts The legend of the Thunder Beasts Bone rush Osborn, Asia, and orthogenesis The biology of brontotheres

229 229 230 233 235

213

IX

13. Proboscises and claws Dragons' teeth Hall of the mountain cow.... Chalicotheres don't obey Cuvier's Law Just what are chalicotheres? Moropomorphs .

241 241 242 247 250 252

14. Rhinoceroses without horns "Ancient Dacians" and Siberian mummies . American rhinos The amphibious amynodonts Running rhinos and rhino ·giants True rhinoceroses Miocene invasions Rhinoceros Pompeii Hairy rhinos and giant "unicorns"

255 255 256 257 258 262 264 268 271

15. Thundering to extinction Unicorn, monoceros, and rhinoceros Black and white One-homed rhinos Horns of doom

277 277 280 284 287

Epilogue

293

References

297

Index

~.......................................................................................................

309

Preface and Acknowledgments

During the period 1983-1985 Schoch set about organizing a gathering of scientists that specialize in the evolution of perissodactyls (horses, rhinos, tapirs and their close living and extinct relatives). This culminated in a workshop on the evolution of perissodactyls (organized by Schoch and Jens Lorenz Franzen of the Forschunginstitut Senckenberg, Germany) which was held as part of the Fourth International Theriological Congress in Edmonton, Canada, in August 1985. Both of us played major roles in this workshop, and we found that so many new discoveries and ideas were presented at the workshop that it would be a shame to have no permanent record of its proceedings. Consequently, we invited the contributors to the workshop, plus other selected scientists who were not able to attend the meeting, to write updated articles on their work. These technical articles were then collected in a volume entitled The Evolution of Perissodactyls (edited by D. R. Prothero and R. M. Schoch, Oxford University Press, New York, 1989, 537 pages). After The Evolution of Perissodactyls was published we felt that the new ideas expressed in it should be made more readily accessible to a general audience. The evolution of horses in particular, as well as the evolution of other types of perissodactyls (such as brontotheres, see chapter 12 of this book) and their close relatives, the elephants, continue-to provide classic examples of evolution in both textbooks and popular books on evolution and prehistoric life. Yet much of what is put forth in these popular books is badly outdated, or simply wrong. We find this appalling, yet it is understandable in that many authors of popular books are not scientific experts in all of the fields they address. Out of enthusiasm for our subj'ect-we want scientifically up-to-date ideas about hoofed mammal evolution disseminated to the public-we decided to write this book. Initially we focused on the perissodactyls, but as the work progressed, the need for a book on all hoofed mammals and their close relatives (including whales and dolphins) became apparent. Eventually the book expanded to the present document. S·uch a book is timely, not only because of all the updated information, but also because most living hoofed mammals are now threatened by extinction. We find these animals to be intrinsically fascinating, and we hope that the reader will too. If more people come to appreciate these wonders of nature, perhaps their doom can be averted. Although no one is an expert on all the hoofed mammals, we have taken on this project because we have learned from the best. We thank Earl Manning for his many insights about ungulates, especially rhinos, Rich Cifelli for his ideas on ungulate relationships, Jens Franzen for his work on the Perissodactyl Workshop, Spencer Lucas and Margery Coombs for their enthusiasm for large mammals, Bruce MacFadden for his untiring work on horses, and Christine Janis and Elisabeth Vrba for their insights on ruminants. We thank our graduate advisers, Malcolm McKenna and John Ostrom, for their guidance and inspiration over the years. The entire book was reviewed by the late Herb Brauer, Colin Groves, Teresa LeVelIe, and the late Bob Savage. Individual chapters were reviewed by Larry Barnes, Rich Cifelli, Margery Coombs, Daryl Domning, Ewan Fordyce, William Franklin, John Harris, Christine Janis, Spencer Lucas, Tab Rasmussen, Hezy Shoshani, Lisa Spoon, Pascal Tassy, and Elisabeth Vrba. We are grateful to them all, and take complete responsibility, of course, for any errors of fact or interpretation. This book would never have been completed without the patience and understanding of our families, Teresa LeVelIe and Erik Prothero, and Cynthia, Nicholas, and Edward Schoch. Much of Prothero's portions of the book were written during a sabbatical in 1991, supported by grant EAR91-17819 from the National Science Foundation. The entire book was prepared by Prothero as camera-ready copy on a Macintosh PowerMac G4 computer, using Microsoft Word 8.0 and QuarkXpress 4.1 to layout the book for the printer. We thank Edward Tenner of Princeton University Press for originally suggesting this book, and Trevor Lipscombe of the Johns Hopkins University Press for handling the final editorial details.

Horns, Tusks, and Flippers

Figure 1.1. Artist's conception of the American savanna of the Great Plains during the late Miocene (about 710 million years ago). A great variety of hoofed mammals lived in the region then, and many resembled their counterparts in the modern East African savanna-except that they were the ecological equivalents of those living in Africa today, not closely related to them. For example, in Africa there is a great diversity of antelopes (members of the cattle family Bovidae). In the North American Miocene, there were three-toed horses (center right background), protoceratids (with "slingshot" horns on noses, left center), dromomerycids (with three horns, extreme left), and pronghorns (kneeling lower left). Instead of elephants, North America had mastodonts (left background). Instead of giraffes, North America had giraffe-like camels (extreme right). Instead of warthogs and other true pigs, North America had peccaries (center foreground). Instead of hippos, North America had hippo-like rhinos (center and left background), as well as more normally proportioned rhinos like the aceratherine Aphelops (center background) instead of black rhinos found in Africa today. (Painting by J. Matternes, courtesy Smithsonian Institution).

1. Introduction

AMERICAN SAVANNA If you took a time machine back to Nebraska or Kansas or South Dakota seven million years ago, at first you might not notice a remarkable difference. Everywhere you looked, there would be grass as far as the eye could see. However, there would be numerous stands of trees, much denser than you'd find in the Great Plains of North America today. As you gazed around, the landscape would begin to remind you not of the modern Plains, but the African savanna, so familiar from countless nature documentaries (Fig. 1.1). Dense stands of trees, and areas of deep underbrush punctuate the mostly grassy landscape. Looking again, the similarity to the modern African savanna would be fUlther reinforced by the cast of characters that lived on the landscape. Tall giraffe-like animals stretched their necks to reach leaves in the high tree canopy. Elephant-like beasts push aside the undergrowth to strip leaves away from the greenest branches. Large herds of striped horses resembling zebras and hundreds of antelopelike animals move slowly along, grazing the tender green shoots in the open grasslands. Pig-like beasts scuttle out of the dense brush, and occasionally you catch a glimpse of impala-like creatures which live in the dense undergrowth as well. In the nearby waterhole, huge barrel-chested animals wallow in the deep end, much like living hippos. Lurking nearby are the predators and scavengers, including packs of wild dogs, cat-like beasts with saber teeth, and even skulking hyaena-like animals with bone-crushing teeth, waiting to move in on a carcass once the predators have finished. But a closer look at these animals (especially if you could study their skeletons and teeth) would reveal that this similarity to animals of the modern African savanna is only superficial. Everyone of the beasts we've just noticed is in reality unrelated to its modern counterpart in Africa. Take, for example, the hippo-like beasts wallowing in the water hole. They may have the barrel chest and short legs of a hippo, and live in the same habitat, but on the tip of their nose is a small horn-they are the hippo-like rhinoceros known as Teleoceras, not actual hippos. Further inspection would show that they have the three-toed feet of rhinos, not the four-toed feet of hippos, and details of their skull, teeth, skeleton, muscles, and other soft tissues would further confirm that their similarities to hippos are strictly convergence:

an unrelated group of animals evol ves into a similar body form to occupy a specific niche. True hippos never came to North America, so a group of rhinos developed the same body form and ecological habitats to exploit this important niche of a semi-aquatic grazer. Indeed, if you were to watch Teleoceras feed, you would see even more similarities. Like hippos, Teleoceras did not eat water plants, but strolled around on the grassy meadows near their water holes (probably at night) eating grasses. Today, African rhinos are strictly land-dwelling, largebodied creatures who feed on either grasses (the white rhino) or green shoots and leaves in the bushes (the black rhino). North America also had a more normally proportioned rhinoceros known as Aphelops, which lived side-byside with the hippo-like Teleoceras. Like the living black rhino, it probably spent most of its time browsing leaves in the undergrowth. What about the giraffe-like beast browsing leaves from the tops of the trees? A closer inspection would show that the head lacks the two knob-like horns, and is all wrong for a giraffe. Instead, it has the distinctive face, eyes, and nostrils of a camel. Unlike any camel in the Old World, however, it lacks a hump (but so do the living South American camels, the llama, alpaca, guanaco, and vicuna), and it has an incredibly long neck (reaching over 22 feet, or 7 m, above the ground) and legs (some over 6 feet, or 2 m, in length). Once again, the niche for a long-necked treetop browser in North America had no occupant (since giraffes never reached this continent), so a native group (the camels) evolved a form to occupy it. As you gaze at the herds of animals on the plains, you find more examples of this trend. The delicate, gazelle-like creatures with extremely long, thin legs can run as fast as any living antelope, but they're not antelopes. Not only do they lack horns that almost all antelopes have-but once again, you realize that you're looking at another kind of camel. In fact, looking around, you would find over a dozen different species of camels, some adapted for giraffe-like or gazelle-like existences, but others of the size and proportions of the South American camels. And none had humps. The rest of the herd is also composed of mimics. Those horned beasts that resemble African antelopes? They're actually related to the American pronghorn, which is mis-

2

HORNS, TUSKS, AND FLIPPERS

takenly called "antelope" but is unrelated to the true antelopes of Africa and Eurasia. In North America seven million years ago, there were over a dozen species of pronghorns in over eight genera, all with distinctively different horns (see Fig. 4.12). And those zebra-like beasts are indeed related to zebras and other horses-but most of them are far more primitive than the Ii ving zebra. Most are rnuch smaller, with simpler teeth, and they almost all have three toes on their feet. In some places, there are as many as a dozen different species of horses living side-by-side. Some hide in the underbrush, using their robust side toes on marshy ground~ their simple, low-crowned teeth are only suited for soft leafy vegetation. Others are clearly plains dwellers, with greatly reduced side toes, longer more slender limbs, and ever-growing cheek teeth that allow them to eat gritty grasses without wearing their teeth down to the gums and starving to death. What about the elephant-like animal breaking off branches from the trees? It does have a trunk and simple tusks, but it is smaller than any living elephant, with a long jaw and flat forehead~and it has four straight tusks, not the two long curved upper tusks of a living elephant. Instead, it's a primitive mastodont, from which the living elephants and mammoths would one day evolve. Like the three-toed horses and zebras, this animal is indeed related to its living counterpart, but it is a much more primitive relative than the beast that lives in Africa today. Here we have a partial substitution of a remote ancestor in the role of its descendant, rather than the complete replacement of rhinos for hippos, camels for giraffes and antelopes, and pronghorns for antelopes that we saw earlier. And the impala-like beast hiding in the bushes near the water? In Africa, we'd expect a true antelope like the impala or bushbuck, but in ancient North America that role is occupied by Synthetoceras, a member of an extinct group known as the protoceratids. Instead of paired spiral horns on their heads like impala, Synthetoceras has a slingshot-like hom on its nose, and a pair of unbranched horns curving upward and inward from above its ears. Synthetoceras has no living descendants, but is distantly related to the camels. Nearby is another extinct beast, Cranioceras, with short straight horns pointing straight up above its eyes, and a thick blunt hom curving up and forward from the back of its head. This animal also has no close living relatives, since it is a member of the extinct family, the dromomerycids, which are only distantly related to deer. Scuttling in and out of the underbrush are pig-like beasts that might remind you of African hogs like the warthog or forest hog. But they are not true pigs at all, but peccaries, which live today in Central and South America, and even in the southwestern deserts of the United States. Peccaries resemble pigs in many superficial ways, but they are an entirely different family, restricted to North America, while true pigs and hippos were restricted to the Old World. But these extinct peccaries are much larger than the living javelinas of Mexico. They had longer snouts and flatter

heads, and much more prominent, dangerous-looking tusks. This list of similarities could go on and on. The hyaena-like animals feeding on carcasses are not true hyaenas, but bone-crushing borophagine dogs. Some of the "sabertooth cats" are not true members of the cat family, but an extinct group known as nimravids, which were related to dogs but had extremely cat-like bodies and teeth. Even the "bear" role is performed not by a bear, but by an extinct group of "beardogs," or amphicyonids. And this story is not restricted to the American savanna of seven million years ago. In Eurasia, there were similar savannas with ecological counterparts of the modern African savanna fauna, but with many substitutions. Indeed, this is a typical occurrence in the evolution of life: ecological niches are often occupied by unrelated groups of animals when the opportunity arrives, and the modern group was not present to occupy the niche. Throughout this book, this will be a common theme. Hoofed mammals have dominated the large bodied herbivorous niches on this planet for the past 65 million years, but many different, unrelated groups of hoofed mammals have evolved on many different continents. Frequently they develop body forms that converge on living animals when the same niche is available. And more often, they develop body forms which have no n\odern analog, making it very hard for the paleontologist to describe their lifestyle and ecology in terms of anything we're familiar with in the living world. NAMES AND DATES Paleontologists work in a world with a time frame completely different from ordinary human life. From various methods, we now know that Earth is about 4.5 billion years old. That's 4,500 million years, a number that is staggering in human terms. It is such an immense amount of time that some sort of analogy is necessary to make it comprehensible. Suppose we were to compress all 4.5 billion years of Earth history into a single calendar year. On this scale, each of the 365 "calendar days" equals twelve million years, and each minute of the "calendar" is 8561 years long! The formation of Earth would then take place on New Year's Day in this "calendar." The first recognizable life would not appear until February 21, and it would consist of tiny, single-celled blue-green bacteria. Complex, multicellular life, such as jellyfish, trilobites, and corals do not appear until November 12. The first amphibians crawled out on land on November 28. The first tiny mammals, and the first bird Archaeopteryx, appear during the peak of the age of dinosaurs, on December 17. The final extinction of the dinosaurs and the beginning of the age of mammals occur on the day after Christmas. The first ape-like primates that are members of our own family, the hominids, do not appear until eight hours before New Year's Eve. Neanderthal man, the classic Stone Age "cave man," appears ten minutes before New Year's Eve, as the countdown begins in parties everywhere. Recorded history began less than one minute before New Year's Eve, as the conductor raises his baton to

3

INTRODUCTION

Ma

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PERIOD

PleIstocene

( )119t

2

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Pliocene

Q

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34

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55

BARSTOVIAN HEMINGFORDIAN

ARIKAREEAN

-= = ~

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CLARENDONlM'

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ORELLAN CHADRONIAN DUCHESNEAN

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UINTAN BRIDGERIAN

~

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WmTNEYAN

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Figure 1.2. Cenozoic time scale. "Quat." = Quaternary; "IRV./RLB" = Irvingtonian/Rancholabrean land mammal ages; "Ma" = million years before present; "NALMA" = North American land mammal ages.

start Auld Lang Syne. Within a second before midnight, Charles Darwin's On the Origin of Species was published, and the American Civil War was fought. Virtually all of human history, especially the last few millennia, is drowned out by the drunks who blew their noisemakers a fraction of a second too early! On the scale of geologic time, human affairs appear pretty insignificant. The geologist is accustomed to dealing with such large amounts of time, and routinely deals with thousands and millions of years. For most geologic problems, events of less than thousands of years in duration cannot even be distinguished in the layers of sedimentary rocks. When dealing with events that occurred hundreds of millions or billions of years ago, even a million years here or there is negligible. A sense of "deep time" (as John McPhee labeled it) is very important to all of us, and not just to the geologists. Most geologists, however, find it practical to

deal with time not in absolute millions of years, but in relative time terms. Just as historians use "Elizabethan" or "Edwardian" to refer to periods in English history, so geologists use "Cambrian" and "Cretaceous" to refer to distinct episodes in Earth history. For the purposes of this book, most of these time terms will not be necessary. The evolution of rhinos, horses, elephants and their relatives has taken place in the last 65 million years, known as the Cenozoic Era (Fig. 1.2). The Cenozoic is divided into a number of epochs, which began with the Paleocene approximately 65 million years ago and run to the present. The Paleocene, which lasted from 65 to 54 million years ago, is followed by the Eocene (54-34 million years ago), the Oligocene (34-24 million years ago), the Miocene (24-5 million years ago), the Pliocene (5-1.8 million years ago), and the Pleistocene or Ice Ages (1.8 million years ago to 10,000 years ago). The period since the last

HORNS, TUSKS, AND FLIPPERS

4

retreat of the glaciers and present interglacial warming is called the Holocene, or Recent (10,000 years ago to present). Although these terms may seem intimidating at first, they are much easier to use than trying to estimate the age of an event in millions of years. Paleontologists and biologists must also use different names for the animals, as well as for their ages. Most living mammals today have common names which are widely understood, so that we know a white rhino from a black rhino from an Indian rhino. Yet in many parts of the Englishspeaking world, the same common name can have different meanings. In most of the United States, for example, a "gopher" is a digging rodent. In the southeastern states, a "gopher" can be a tortoise. Many animals have different common names in different parts of the country. In countries which do not speak English, the animals have names in the local language. To get around this problem, biologists have long ago adopted a series of scientific names which is universal, regardless of region or native language. In 1758 when the system was ~irst widely adopted, Latin was the universal language of scholars, so all scientific names are Latin in form, or Latinized words from Greek or some other language. A scientist will always understand Geomys to mean the rodent gopher, and Gopherus to mean the gopher tortoise. By convention, each species name is a compound of two words, always found together. These names are always italicized in print or underlined elsewhere. The first word is the genus name (plural: genera), which is always capitalized. The second word is the trivial name for the species, which is never capitalized. Four example, the correct scientific name of our species is Homo (genus) sapiens (species), which means "thinking man." Another related species in our genus is Homo erectus ("erect man"), our probable ancestor. Similarly, the Indian and Javan rhinoceros are in the same genus (Rhinoceros), but in different species. The Indian rhino is Rhinoceros unicornis, and the Javan rhino is Rhinoceros sondaicus. The black rhino is in a different genus Diceros, which has only one living species, Diceros bicornis. An example of the hierarchical classification of humans and Indian rhinos is shown below:

KINGDOM PHYLUM CLASS ORDER FAMILY SUBFAMILY TRIBE GENUS SPECIES

For most fossil mammals discussed in this book there are no popular names. The fossils are known only by their scientific names, and are always italicized in this book. At first, these long scientific names may seem hard to pronounce and remember. If you break them down syllable by syllable, however, they are not so intimidating. Generic and specific (species) names are not the only names used to identify and classify an organism. Every genus belongs to a larger subdivision of life called a family. For example, humans belong in the Family Hominidae, and true rhinos in the Family Rhinocerotidae. All zoological family names can be recognized by the "-idae" ending. All the families, in turn, can be included in orders. Thus, the Hominidae can be grouped with the other families of apes, monkeys, lemurs, and tarsiers in the Order Primates. Rhinos belong with the tapirs, horses, and various extinct groups in the Order Perissodactyla, or the odd-toed hoofed mammals. Orders are subdivisions of a larger group, the class. Both perissodactyls and primates are mammals, or members of Class Mammalia. Classes are grouped into even larger groups, the phylum. For example, mammals, birds, amphibians, reptiles, and fishes are all members of the Phylum Chordata, which includes all animals with a spinal cord. Finally, the major phyla are grouped into the great k%jngdoms of life: the Kingdom Animalia, the Kingdom Plantae, the Kingdom Fungi, and so on. This hierarchical arrangement of classification not only serves as a useful tool, but also indicates closeness of evolutionary relationship. Animals in the same genus are more closely related to each other than they are to animals in any other genus, and so on. The division of kingdoms into phyla, and phyla into classes, and so on, is actually a reflection of the branching tree of life. Of the mammals living today, most can be clustered into distinct, well defined groups that even a child can recognize. In most classifications of the mammals, these groups are ranked as orders. Many of the orders are obvious to the average zoo visitor. The bats comprise one order, the rodents another, the primates a third, and so on. Most of these orders have been recognized since the formalization of modern classification in 1758. Yet until recently, little was known about how these orders were related to one another, or from

Animalia Chordata Mammalia Primates Hominidae Homininae Hominini Homo sapiens

C

Animalia Chordata Mammalia Perissodactyla Rhinocerotidae Rhinocerotinae Rhinocerotini Rhinoceros unicornis

INTRODUCTION what kind of mammal they evolved. For over a century paleontologists tried to trace the ancestry of the major orders of mammals back to a common ancestor, but the quality of the fossil record was not good enough to do this. Most of the mammals of the late Cretaceous and Paleocene, when most of the orders must have differentiated, are not members of Ii ving orders, nor ancestral to them. Thus, mammal classifications have treated all orders as if they were independent and unrelated, when we know that there must be some orders which are close relatives of one another. In the last decade, however, new approaches have made major advances in deciphering mammal relationships. Scientists have begun to look at the complete anatomy of the animal, not just the teeth (the most commonly preserved part for most fossil mammals). They looked in detail at other parts of the skeleton, particularly the details of the bones and canals in the skull and ear region. They also looked at the muscles and other soft tissues of the living mammals. Finally, they began to look at the various molecules found in mammal tissues, and discovered that the similarity of molecules can also give clues to relationships. All of this emphasis on complete anatomical analysis is not completely new. In fact, most of it was first done by German anatomists in the late nineteenth century, and much recent work has begun to rediscover how careful and perceptive those early German anatomists were. However, the method of analyzing the data has changed. The traditional methods concentrated primarily on teeth and tried to find progressively more primitive teeth in older rock units. The new methods instead concentrate on shared specializations, or evolutionary novelties, that indicate close relationship. For example, there were many evolutionary novelties that appeared when mammals evolved. Some of these include the presence of hair (instead of scales or· feathers), and mammary glands to nurse their young. These features are called shared derived characters, and are among those used to define the Class Mammalia. Other shared specializations can be used to define orders within the Mammalia. For example, the bats can be defined by their complex wing .structure, formed by highly modified hands and fingers. The primates can be defined by a number of features, including their grasping hands and feet with opposable thumbs, nails instead of claws, or their forward-facing eyes with binocular color vision. Within the Order Primates, still smaller groups can be defined by their own evolutionary novelties. For example, the great apes (orangutan, gorilla, chimpanzee) and humans share a number of specializations, including the loss ofa tail, complex nasal sinuses, five or six vertebrae in the hip, an elongated middle finger, and over two dozen other features in the skeleton alone. Thus, the emphasis has shifted from seeking ancestral forms with their shared primitive similarity (which does nothing to indicate relationships-animals which share primitive characteristics mayor may not be closely related) to seeking out only shared derived similarity. For example, hair and mammary glands are good indicators distinguish-

5

ing mammals from other animals, but are of no use in determining relationships within mammals (since all mammals have them, they are primitive characters within the mammals). In traditional mammal classifications, some orders were based on nothing but these shared primitive similarities. For example, the old definition of the order Insectivora (which properly includes moles, shrews, and hedgehogs) was broadened to include a wide variety of primitive insecteating mammals unrelated to moles, shrews, or hedgehogs. To expand the meaning of "insectivore," the group was defined on characters such as having five toes on hand and foot (primitive not only for mammals, but even for their reptilian ancestors) or having 42 teeth, which is also primitive for all placental mammals. By doing this, the Insectivora became a "wastebasket" group. All primitive placental mammals that retained the ancestral insectivorous ecology were thrown into this "wastebasket," even though they were not closely related. Usually, this was done because there was no better place for these problematic animals, and people like to have their classifications tidy. Everything in its place, and every mammal in its proper order! Unfortunately, these wastebasket groups had a negative effect as well. For those not familiar with the animals, it created the impression that all the problems were solved (which they were not), and that these problematic animals were closely related to moles, shrews, and hedgehogs (which they were not). In many cases, scientists could not find a particular fossil that was the perfect ancestor for later animals, and would construct a "hypothetical ancestor" based on a wastebasket assemblage of animals. In doing this, they would ignore the fact that each of the members of the wastebasket group had its own anatomical specializations that prevented it from being the actual ancestor. In short, the use of these "wastebasket" groups created concepts in people's minds of animals that never really existed. Insectivores were not the only group to be made into a wastebasket. One of the worst wastebaskets was the archaic animals related to the hoofed mammals, or ungulates. Today, the living ungulates (Fig. 1.3) can be divided into at least six major groups of mammals, including the even-toed artiodactyIs (pigs, camels, sheep, deer, antelope, cattle), the odd-toed perissodactyls (horses, rhinos, tapirs), the elephants, and three other groups (hyraxes, whales, and sea cows) we will discuss later. However, there are a number of extinct animals which have hooves and all the other hallmarks of ungulates. These could not be assigned to any of the living orders, mostly because their bodies were built on a very archaic plan. They shared no specializations with any living order, and so they were placed in the ultimate "wastebasket" group, the order "Condylarthra." The only thing that "condylarths" had in common was that they were archaic hoofed mammals that didn't belong somewhere else. As in the case of other wastebasket groups, the "Condylarthra" made the classification appear neat and tidy, but it obscured all the problems and areas needing work.

HORNS, TUSKS, AND FLIPPERS

w z w

o

o

w

55

zw o

o

...w

6& a. 4(

Protungulatum

Figure 1.3. Relationships of the living and extinct ungulates. PLI Prothero, based on Prothero, Manning, and Fischer, 1988). Scientists would suggest that one or more of the Ii ving ungulate orders evolved from a "condyla11h ancestor," a hypothetical creature with no basis in reality. Others would generalize about the ecology, or behavior, or extinction of "condylarths," when in fact each of the "condylarth" groups had completely different ecologies and probably different behavioral patterns as well. Even worse, it misled anyone who did not know the fossils and got the mistaken impression that "Condylarthra" was as real a group as the order of bats or of whales. These people would make comparisons between "condylarths" and real groups, and the features they analyzed in the "condylarths" would not be true of most of its members. The "Order Condylarthra" obstructed the understanding of mammalian relationships for over a century, and finally it is being abandoned. Indeed, once the living and extinct ungulate groups were analyzed, using only shared specializations to cluster groups together, it became apparent that the ungulates have a very rich, interesting history. This story, however, remained unknown for over a century because of the

= Pliocene; Q = Quaternary.

(Drawn by C.R.

"condylarth" veil. In this book, we will present the new ideas about hoofed mammals. HOOFED MAMMALS The hoofed mammals, or ungulates, are the largest, most anatomically diverse, and ecologically dominant group of mammals alive today. One need only to look at the huge variety of elephants, rhinos, hippos, antelopes, wildebeest, zebras, giraffes, and buffalo on the African savannah to realize that all of the large plant-eating mammals are ungulates. Ungulates make up about a third of the genera and families of living mammals, outnumbering even the abundant and diverse rodents. Since many ungulates feed on large quantities of low-quality vegetation, they can get big. Indeed, the largest mammals (both on land or sea) that ever Ii ved, or are alive today, are all ungulates. Even when housecat-sized ungulates first appeared at the end of the reign of the dinosaurs, they were larger than most of their rat-sized contemporaries among the mammals. The earliest ungulates are a group of extremely primitive

INTRODUCTION

7

Figure 1.4. Restoration of the archaic ungulate Chriacus, an arctocyonid, emphasizing its superficial resemblance to the living coatimundis or raccoons. (Drawn by E. Kasmer, courtesy K. Rose). forms known as the zhelestids, recently described by David Archibald and the late Lev Nessov from Late Cretaceous rocks almost 90 million years old from Uzbekistan, central Asia. Although these animals are known only from a few jaws, they already show that the hallmarks of ungulate teeth were well established at an extremely ancient time-about as far back as any of the recognized orders of placental mammals is known to have lived. Clearly, the ungulate branch of the Mammalia is one that goes back to the very beginning of the radiation of the placental mammals, some 30 million years earlier than they were once thought to have originated. By the latest Cretaceous and earliest Paleocene, the zhelestids were replaced by the arctocyonids. The most complete skeletons known of these archaic ungulates (once called "condylarths") from the Paleocene reveal an animal that had a body much like a raccoon or coatimundi (Fig. 1.4). The skeleton was not specialized for running, like most Ii ving ungulates. Instead, it is a very generalized mammal body, with flexible limbs and long fingers, suitable for both climbing and walking. The tail is also quite long, probably

for balance. The head had a long snout, much like a raccoon. In most cases, the teeth were unspecialized, suitable for an omnivorous diet. However, there are a few features that tell us this animal is not related to raccoons. First, the relatively unspecialized teeth have a few advanced ungulate features compared to the other primitive mammals of the time. The cusps of the teeth are more bulbous than those of its insectivorous contemporaries, with low relief between cusps. These teeth were suited for a more grinding type of chewing, appropriate to an omnivorous diet of plants, seeds, and tubers, with some meat, eggs, fish or carrion. By contrast, most early mammals were insectivorous, with sharp, slicing crests on their teeth and very high relief between cusps. This kind of tooth pattern is suitable for chopping up the tough skins of insects, and shredding small prey animals. In addition to the teeth, there are several specializations of the skull openings for the arteries in the head, and in the bones that make up the ear region, which show that these arctocyonids are indeed ungulates. Finally, the ankle bones in even the most archaic ungulates are already adapted for

8

HORNS, TUSKS, AND FLIPPERS

Figure 1.5. A. Restoration of the Paleocene periptychid Ectoconus (painting by R. Bruce Horsfall, from Scott, 1913). B. Reconstruction of dachshundlike Eocene archaic ungulate Hyopsodus (After Gazin, 1968).

B

walking and bearing greater weight. Although the ankle is flexible, it is not as adapted for tree climbing as the ankle of primates or primitive carnivores. Hooves, the feature most characteristic of ungulates, have not yet appeared. The most primitive ungulates still had claws, although they were relatively short and blunt. When hooves finally develop, they do so independently in several different groups. This can be seen by looking at the details of the anatomy of the hoof. It is constructed very differently in horses than in deer, for example. There must be a great evolutionary advantage to developing hooves in large animals which are adapted for running (as most living ungulates are). Clearly, hooves are valuable protection for running across hard ground without cutting the foot and bleeding profusely (as can happen to cats or dogs when they run, and certainly to humans!). Recent research suggests that the first group to branch off from these earliest ungulates were the artiodactyIs, or the even-toed hoofed mammals (Fig. 1.3). Today, the artiodactyls are the most abundant ungulates, with over 190 living species. They include pigs, peccaries, hippos, camels and llamas, deer, pronghorns, giraffes, sheep, goats, and dozens of species of antelopes and cattle. We will discuss the artiodactyls in greater detail in the next four chapters.

After the artiodactyIs branched off from the ungulate common ancestor, the next groups were certain archaic ungulates (once called "condylarths") such as the extinct hyopsodonts and periptychids (Fig. 1.5). Periptychids became big, almost bear-like forms, with few anatomical specializations except in their teeth, which have highly wrinkled enamel surfaces. Hyopsodonts, on the other hand, developed a body form much like a weasel or dachshund. Although their skulls and teeth were primitive, they had very short limbs and a long trunk and tail. Many people have speculated about how hyopsodonts lived. Some think they may have burrowed, since they have strong digging limbs with claws. Others suggest that they were slinking along in the lower vegetation. Whatever they were doing, they were very successful archaic ungulates. While most archaic ungulates were dominant in the Paleocene and declined by the Eocene, hyopsodonts were some of the most common animals in the Eocene. They were also among the last archaic ungulates to die out at the end of the Eocene, long after all the others had gone extinct. In the older books, some scientists speculated that hyopsodonts were ancestral to artiodactyls. There are no shared specializations to support this idea, however, so it is no longer believed by paleontologists. After the divergence of artiodactyls, and of the peripty-

INTRODUCTION

9

Figure 1.6. Restoration of the archaic Eocene ungulate Phenacodus, once thought to be related to . .: perissodactyls (painting by R. Bruce Horsfall, from Scott, 1913).

chid-hyopsodont group, the next step is a surprising one. A wide variety of evidence, both from fossils, and from anatomy and molecular biology, clearly indicates that whales are also ungulates (Fig. 1.3). "What?" you say, "whales don't have hooves!" This is true, but remember that hooves are not the most important character that defines ungulates. When we trace whales back into the fossil record, we find progressively less specialized forms that look less like whales and more like other archaic ungulates. We will discuss the evidence for this surprising conclusion in Chapter 6. Once the whale lineage had split off in the Paleocene, the next groups to diverge are archaic ungulates formerly lumped with the periptychids and hyopsodonts in the "condylarth" wastebasket. The best known of these are the phenacodonts (Fig. 1.6). Phenacodonts evolved into sheepsized animals, with long faces and tails. However, their limbs are still unspecialized, along with the rest of their skull and skeleton. In the past, several scientists tried to show that phenacodonts were directly ancestral to the perissodactyls (horses, rhinos, and their relatives). However, as we shall see in Chapter 10, new discoveries suggest that phenacodonts are only distantly related to perissodactyls. Finally, we come to the last major grouping of ungulates, the higher ungulates (the Altungulata). This includes not only the traditional perissodactyls (horses, rhinos, tapirs, and their relatives), but also the hyraxes (or conies), and the tethytheres (elephants, manatees, and their relatives), as well as a number of extinct forms. These animals are the subject of the latter half of the book. UINTA BEASTS AND THE COPE-MARSH WARS One group often considered to be related to ungulates includes the bizarre animals known as the uintatheres (Fig. 1.7). Their name comes from the middle Eocene beds of the Uinta Basin of Utah, where they were first discovered. These animals reached elephantine size, yet they are not elephants. Their most distinctive features are the six knob-like

horns on the top of the head, and the huge protruding canine teeth protected by a flange on the lower jaw. It was a face only a mother could love! During the middle Eocene, they were the largest land mammals in both Asia and North America. By the late Eocene, they were extinct. T~eir role as a large, heavy-limbed herbivore was then taken over in North America by a succession of mammals: brontotheres in the late Eocene, rhinos in the Oligocene, and mastodonts in the middle Miocene. Some of the Mongolian uintatheres lack the knobs and canines; instead, Gobiatherium had a huge inflated bulb on its nose. What this structure was used for is anyone's guess. Some have suggested that it was functionally similar to the bulbous nose of the saiga antelope, which uses it for warming cold air as it inhales. However, uintatheres were found mostly during the tropical climates of the Eocene, which rules out any need for warming inhaled air. Uintatheres were large-bodied beasts that seem to have many specialized similarities to ungulates. For this reason, they have long been placed in ungulates, or in their own special order. In 1977, Earl Manning and Malcolm McKenna argued that uintatheres were ungulates related to the higher ungulate group, which incl udes perissodacty Is and tethytheres. However, in 1982 Tong Yongsheng and Spencer Lucas proposed that uintatheres were related to a bizarre group of Chinese Paleocene mammals known as anagalids, which are distantly related to rodents and rabbits. This suggestion is rather startling, since uintatheres are rhino-sized, and anagalids are much like rabbits in size and skeleton. Most of this argument is based on uintathere teeth, which are abnormally small for the size of the beast, and have a peculiar V-shaped crest pattern seen in a lot of primitive mammals. We are not convinced that uintatheres are "giant bunnies," but we admit that the evidence for their relationships to ungulates is also slim. Whatever uintatheres are related to, they are certainly among the most spectacular mammals in the middle Eocene of North America and Asia.

10

HORNS, TUSKS, AND FLIPPERS

B

Figure 1.7. A. The rhino-sized uintatheres had six knobby horns on top of their skulls, and huge tusks. Whether or not they were truly ungulates, they were the largest land mammals during the middle Eocene in North America and Asia (painting by R. Bruce Horsfall, from Scott, 1913). B. Cope's reconstruction of uintatheres with elephant ears and trunks. (From Penn Monthly, August, 1873).

INTRODUCTION

11

Figure 1.8. A. A typically pugnacious photograph of Edward Drinker Cope, the most brilliant paleontologist and herpetologist of his time. (Courtesy Academy of Natural Sciences, Philadelphia). B. Othniel Charles Marsh (back row, center) and the Yale field party of 1872, posing for a rough season in the Bridger Basin of Wyoming. The guns were no props, since the area was stil' controlled by hostile tribes. (Courtesy Yale Peabody Museum). Uintatheres were such spectacular fossils that they became the focus of a major war between America's dominant late nineteenth-century paleontologists, Edward Drinker Cope and Othniel Charles Marsh (Fig. 1.8). Cope (1840-1897) was a brilliant, intense academic and political outsider of Pennsylvania Quaker heritage who never had a steady, respectable position until late in his life (from 1889 until his death he was a professor at the University of Pennsylvania). Often in need of money, Cope either lived off money he inherited or raised funds for his paleontological work as opportunity arose. In spite of these limitations, he had true paleontological genius, and managed to publish some 1,400 scientific papers during the course of his life. Cope married and had a single daughter. His personality was complex and often difficult. In particular, he held and expressed his opinions very adamantly and did not take orders from anyone, be it a college administrator, the council of a learned society, or an army officer or government official on a geological survey. Although his immediate family was of a relatively humble New England background, Marsh (1831-1899) had the good fortune to be a nephew of the wealthy philanthropist George Peabody. Through his uncle's generosity (later inheritance), Marsh attended Yale University both as an undergraduate and graduate student, saw money donated to Yale for the Peabody Museum of Natural History, and from 1866 until his death was professor of paleontology at Yale. For most of his tenure he received no salary from Yale, but only an allowance from his uncle. Marsh remained a bachelor all of his life. He was alternately amicable and sociable,

or formal and aloof (more often the latter). He also had a secretive and suspicious nature, and could suffer from bouts of jealousy (such as when Cope beat him to the naming of new fossil species). Marsh was in no way as prolific as Cope; he published only 270 scientific papers in his lifetime. Unlike Cope, however, he was part of the establishment. Besides his position at Yale, Marsh often served as an officer of learned societies, such as holding the presidency of the National Academy of Sciences for a number of years. In the late 1860s Cope and Marsh each decided separately to aspire to the position of being the foremost vertebrate paleontologist in America. Until then, this title was held by Joseph Leidy, whom we will discuss more in the next chapter. Initially on friendly terms, Cope and Marsh began to compete with each other for specimens and information as the vast fossil beds of the American West were opened up. Each wanted the best specimens for his own collection, and the recognition that came with being the first to describe and name the fantastic extinct animals that were being newly discovered by science. To these ends, both men organized and unde1100k personal expeditions to the West. At various times they associated themselves with various official government geological and paleontological surveys, and bought (and some say stole) fossil specimens, the rights to collect on certain lands, and the services of local collectors (the alliances of collectors often changed quickly as the rivals outbid each other). The feud began in the summer of 1872 when Leidy, Cope, and Marsh were independently collecting fossils in the Bridger Basin and Washakie Basin of Wyoming. The

12

HORNS, TUSKS, AND FLIPPERS

largest and most spectacular specimens they found were skulls of the bizarre uintatheres, which impressed all three scientists with their weird horns and tusks. Naturally, they rushed to describe their new finds before they left the field. Since all three men were in remote parts of the country, with limited access to civilization, they had to leave camp to send news east by way of telegraph. In those days, it was common practice to publish a short note of only a few paragraphs naming a new animal, so that one could get credit for being its discoverer and namer. Today, such slapdash methods are frowned upon, but they were common in 1872especially when trying to beat a rival to press. Leidy was the first to publish, when a short note he had sent east, dated August 1, 1872, described Uintatherium robustum (this is now the correct name for most of the spec~ imens). On August 17 Cope sent a telegram from the Black Buttes in the Washakie Basin of Wyoming which was badly garbled when it was published two days later. His intended name for the beast, Loxolophodon, was misspelled Lefalaphodon. The nexr day, another notice that had actually been sent before the first telegram was published for Cope, naming the same beast Eobasileus cornutus. Today, this is the valid name for the largest of the uintatheres. On August 22 he corrected the garbled name back to Loxolophodon, although it was not available since he had already recklessly used it for another animal. Meanwhile, Marsh sent a note on August 20 naming his specimens Dinoceras and Tinoceras (they are now considered the same thing as Leidy's Uintatherium). All three were aware of the others nearby, and disputed their rivals' right to collect in "their" fossil field. Soon, this bitter rivalry drove Leidy into retirement from vertebrate paleontology as a field no longer fit for gentlemen. When Cope and Marsh returned east and began to publish longer descriptions, they became convinced that they both had the same animal and that their own name for it was correct. Actually, Cope had an Eobasileus, and Marsh had a specimen of Leidy's Uintatherium, but at the time they considered the differences slight, or the result of their rivals' mistakes. In 1873, Cope compounded his errors by suggesting that uintatheres were related to elephants, even putting elephant ears and trunk on them (Fig. 1.7). Marsh disputed this, and instead placed them in their own order, the Dinocerata (a name still used today, even if his name of Dinoceras was invalid). Between August 1872 and June 1873 Cope and Marsh each published 16 articles on uintatheres, each ignoring his rival's names, and both ignoring Leidy's work. As a result, uintathere names reached a state of chaos, with multiple names for the same species. Marsh grew so bitter at Cope's actions that he lashed out in print: "Cope has endeavored to secure priority by sharp practice, and failed. For this kind of sharp practice in science, Prof. Cope is almost as well known as he is for the number and magnitude of his blunders ... Prof. Cope's errors will continue to invite correction, but these, like his blunders, are hydra-headed, and life is really too short to spend valuable

time in such an ungracious task, especially as in the present case Prof. Cope has not even returned thanks for the correction of nearly half a hundred errors ... he repeats his statements, as though the Uintatherium were a Rosinante, and the ninth commandment a windmill" (Marsh 1873). Eventually, the uintathere wars died down as the rivals moved into conflicts over the naming of other beasts, such as the brontotheres discussed in Chapter 12. Fourteen years later, in 1884 Marsh finally published his huge scientific monograph on uintatheres, a 237-page volume entitled Dinocerata: a monograph of an extinct order of gigantic mammals, with giant folio pages and lavish plates. Meanwhile, Cope was losing ground politically. In the 1870s he had served under Ferdinand Hayden (see Chapter 12) on the U.S. Geological and Geographical Survey of the Territories, and from his collections made on those surveys, he had written a giant 1,009-page, 134-plate monograph for the Survey, now known as "Cope's Bible." However, in 1879 the Hayden Survey was merged with several other government surveys to form the present U.S. Geological Survey. The first directors were Clarence King and John Wesley Powell, both good friends of Marsh, and Cope found himself out in the cold. On December 16, 1889, Cope was ordered to turn his collections over to the Smithsonian, even though he had made most of them from private expenditures, not on government surveys. Cope was so outraged that he lashed out and called a reporter, William Hosea Ballou of The New York Herald, and filled his ear with grievances against Marsh and his cronies King and Powell. He charged that they were "partners in incompetence, ignorance, and plagiarism," and that the Survey was a "gigantic politico-scientific monopoly next in importance to Tammany Hall." He leveled charges of every kind at Marsh, including scientific blunders, keeping the salaries of his employees, and that most of his work (especially the Dinocerata monograph) was actually the work of assistants. This accusation was later supported by some of Marsh's former assistants, including the famous paleontologist Samuel Wendell Williston. Marsh defended himself by taking the train to Philadelphia and visiting the president and trustees of the University of Pennsylvania. He consoled them about "the shame that has befallen you," suggesting that "poor Cope" had cracked up and that Marsh would help locate "a more substantial scientist" to replace him. In the January 19, 1890 issue of the Herald, Marsh replied to Cope's accusations, charging that Cope had stolen his specimens, and that he had spied on Marsh's work when he was visiting Yale, and tried to publish it later. Ballou continued to play the feud out for several more columns, quoting and misquoting a number of paleontologists about the scientific competence and personal character of the two rivals. Eventually, this particular battle died down, leaving Cope and Marsh with egg on their faces. Cope retained his position and his fossils, as did Marsh and Powell.

INTRODUCTION Eventually, though, public scandals did hurt Marsh. When the budget of the U.S. Geological Survey came up before a House committee in 1892, fundamentalist congressman Hilary Herbert of Alabama discovered Marsh's recently published monograph, entitled Odontornithes, on toothed birds from the Cretaceous seas of Kansas. Waving it on the House floor, he shouted, "Birds with teeth! That's where your hard-earned money goes, folks-on some professor's silly birds with teeth." In terms similar to the recent science-bashing of William Proxmire and John Dingell, he stampeded Congress into cutting off funds from such "Godless" activities as monographs about impossibilities such as birds with teeth, and other creatures not mentioned in the Bible. Powell was finally forced to send Marsh a telegram: "Appropriations cut off. Please send your resignation at once." By this point both Cope and Marsh were broken men, and the field soon moved on to a new generation: Osborn, Scott, Hatcher, and others discussed elsewhere in this book. Cope continued to teach at the University of Pennsylvania for five more years, visiting the Dakota badlands in 1892 and 1893, and died on a cot in his study amidst all his unfinished projects and unpublished specimens on April 12, 1897. Marsh had spent all Uncle George Peabody's legacy on his expeditions and lavish publications, so he was forced to live on a modest salary from Yale in a brownstone near the Peabody Museum. In 1896 he published his greatest work, The Dinosaurs of North America. Early in 1899, he caught pneumonia, and died on March 18, with less than $100 to his name. Although the Cope-Marsh feud generated a lot of bad blood, it catalyzed the collection of literally tens of thousands of vertebrate fossils and inspired a number of younger geologists and biologists to pursue this field. Even if done in a sometimes less than gentlemanly fashion (Cope and Marsh criticized and insulted each other in otherwise "objective" scientific papers), an amazing amount of research was accomplished during these years. Modem American vertebrate paleotonlogy grew out of their work. THE LOST WORLD In his novel The Lost World, Sir Arthur Conan Doyle (creator of Sherlock Holmes) describes a plateau in the Amazon jungle which was a haven for dinosaurs still survi ving today. Although this is science fiction, South America was a "lost world" in a very different sense. It was isolated from all the other continents during most of the Age of Dinosaurs, and during the first sixty million years of the Age of Malumals. Almost no mammals or birds from the Old World managed to penetrate this island continent during this entire time. Consequently, the few mammals and birds that originally colonized it had the entire continent to themselves for millions of years. As we saw at the beginning of this chapter, ecological niches occupied by typical Old World or North American animals on other continents had to be filled by South American substitutes. There were no cats,

13

dogs, or bears, so carnivorous marsupials and gigantic, flightless, predatory birds were the main flesh eaters. In some cases this led to remarkable cases of evolutionary convergence. One South American marsupial, Thylacosmilus, had the same saber-like canines as the saber-toothed cat, even though it was a pouched mammal like a kangaroo. Others, known as borhyaenids, did a remarkable job of mimicking the wolves, bears, and hyaenas we have today, even though they too were pouched mammals. South America had three "old timer" groups inherited from the age of dinosaurs. The first include the marsupials, or pouched mammals, mentioned above. The second was the xenarthrans, or edentates (including the living tree sloths, armadillos, and anteaters), which eventually led to the giant ground sloths, and huge armadillo-:-like glyptodonts that were so characteristic of the Ice Ages. The third was hoofed mammals unique to South America, which evolved into the most amazing creatures of all. These South American experiments in evolution demonstrate just how stereotyped certain ecological niches are. For example, native South American ungulates evolved into beasts which converged on the body shape of horses, hippos, camels, elephants, and many other familiar beasts (Fig. 1.9). Yet none of these were related to their ecological counterparts-the resemblances are strictly due to evolutionary convergence, just as fish and dolphins have the same streamlined body shape even though they are unrelated in an evolutionary sense. The origin of these South American ungulate groups is still controversial. Only a few scraps of mammals are known from the age of dinosaurs in South America, and they include no hoofed mammals. The earliest Paleocene Tiupampa fauna includes a diverse assemblage of extremely primitive ungulates. The most familiar of these is called Perutherium. It is difficult to say what this animal is, other than that the teeth look much like those of typical archaic ungulates from other continents. We next pick up the South American record in the late Paleocene, but by then mammal diversity had blossomed. There are a great variety of bizalTe and unique forms whose relationships to mammals from the rest of the world are controversial. One group, the didolodonts, has long been placed in the "condylarth" wastebasket, but appears to be related to North American hyopsodonts. If so, then there was some sort of communication between North and South America during the Paleocene after all. Didolodonts flourished in the Eocene, but are not definitely known thereafter. Another group which appear to be related to hyopsodonts were the litopterns. They evolved into a variety of body forms throughout the Cenozoic, with their greatest diversity during the Miocene, when South America had savannas similar to the rest of the world at that time. Some litopterns were truly amazing. The proterotheriids, for example, paralleled the trend toward limb elongation and side-toe reduction that we see in horses on other continents at the same time. Diadaphorus, from the early Miocene, had

14

HORNS, TUSKS, AND FLIPPERS

D

Figure 1.9. Reconstructions of typical South American ungulates. A. The camel-like litoptern Macrauchenia. B. The hippo-like notoungulate Toxodon. C. The tapir-like Astrapotherium. D. The mastodont-like Pyrotherium. (Paintings by R. Bruce Horsfall, from Scott, 1913). a very horse-like build, but still retained three toes on each foot. Thoatherium, however, outdid even true horses-it had a single toe on each foot, with no vestiges of side toes like modern horses (Fig. 11.3)! As horse-like as their limbs and skeletons were, these animals were truly litopterns and not horses. Their teeth and skulls are completely unlike any mammal, horse or otherwise, from North America or the Old World. One of the most unusual of the litopterns was a beast known as Macrauchenia (Fig. 1.9A). Darwin first discovered it during the voyage of the Beagle, and wrote of it: "At Port St. Julian, in some red mud capping the gravel on the ninety-feet plain, I found half the skeleton of the Macrauchenia Patachonica, a remarkable quadruped, fully as large as a camel. It belongs to the same division of the Pachydermata with the rhinoceros, tapir, and

palaeotherium; but in structure of the bones of its long neck it shows a clear relation to the camel, or rather to the guanaco and llama" (Darwin 1839: 173).

Macrauchenia indeed had a camel-like neck, and primitive, heavy, rhinoceros-like feet, but its weirdest feature is the head. Unlike most advanced hoofed mammals, it still had all 44 teeth, with no gap between the front nipping teeth and the grinders, like horses and cattle have. To top it off, the nasal opening is up over the forehead, indicating that Macrauchenia had a long proboscis like a tapir or elephant. A "camel" with the feet of a rhino and the trunk of an elephant sounds like something out of Dr. Doolittle, but it was real and thrived during the Ice Ages in South America! The dominant group of hoofed mammals was the notoungulates, literally "southern hoofed mammals." They were by far the most diverse, with at least thirteen families

INTRODUCTION and well over 100 genera represented over their sixty million year history. They include peculiar beasts such as typotheres, which culminated in the beaver-like Mesotherium during the Pleistocene, and the hegetotheres, which converged on rabbits. The archaeohyracids, as their name implies, closely resembled the living hyraxes (which we will discuss in Chapter 7). The most diverse of notoungulates, however, were the toxodonts. Some toxodonts, like Thomashuxleya, looked much like warthogs; others, like Rhynchippus, converged on horses; still others resembled the primitive·homless rhinoceroses discussed in Chapter 14. Homalodotherium had robust limbs with claws on the toes, much like the chalicotheres we will discuss in Chapter 13. One of the most remarkable was Toxodon itself (Fig. 1.9B), which was also found by Darwin during the Beagle voyage: "Toxodon [is] perhaps one of the strangest animals ever discovered. In size it equalled an elephant or megatherium; but the structure of the teeth, as Mr. Owen states, proves indisputably that it was intimately related to the Gnawers, the order which at the present day includes most of the smaller quadrupeds. In many details it is allied to the Pachydermata. Judging from the position of its eyes, ears, and nostrils, it was probably aquatic, like the dugong and manatee, to which it is also allied. How wonderfully are the different orders, at the present time so well separated, blended together in different points of the structure of the toxodon!" (Darwin 1839: 83). Although Darwin was puzzled, we now know that Toxodon was not related to rodents, "pachyderms," manatees, or anything else outside South America; it is a native notoungulate. Its body form most closely converges on a hippopotamus, although its front teeth are chisels like those of gnawing rodents. Other toxodonts, such as Trigodon, had a single small horn in the center of the forehead, like one of the extinct rhinos; the sheep-sized Adinotherium also had a small hom on the forehead. Despite their great diversity and abundance of excellent fossils, the affinities of notoungulates are still a mystery. In 1913 William Stein was collecting Paleocene mammals for the American Museum of Natural History in the Bighorn Basin of Wyoming. When his collections were sent to New York for study, the great paleontologist William Diller Matthew was startled to find a primitive notoungulate he named Arctostylops. At first, he thought there had been a mistake. Stein had recently been collecting in Patagoniahad the specimen gotten trapped in a pant cuff and then accidentally added to the Wyoming collections? Stein assured him that it was from Wyoming, and in subsequent years, more Arctostylops fossils have been found in· the Bighorn Basin. Did the presence of a primitive notoungulate from the Paleocene of Wyoming indicate that these beasts had

15

escaped South America, or that they originated in North America and then spread south? The discovery of more arctostylopids from the Paleocene of China further complicated the story. Did they originate in Asia, pass through Wyoming, and then reach South America? Or was it the other way around? Philip Gingerich argues for the latter. The appearance of arctostylopids, along with edentate-like epoicotheres and the uintathere-like forms (discussed below) is clear evidence to him of a migration from South America through Wyoming to China in the late Paleocene. More recently, Richard Cifelli, an expert on notoungulates, has become less convinced that arctostylopids are notoungulates. He suggests that the Wyoming arctostylopids may be immigrants from China, but he sees no concrete evidence that either is truly part of the great South American notoungulate radiation. Besides the didolodont-litoptern-hyopsodont group, and the notoungulates, there were two other important kinds of native South American hoofed mammals. One of the most puzzling are the "lightning beasts," or astrapotheres (Fig. 19.C), typical of the Miocene, and their primitive Eocene relatives, the trigonostylopids. Astrapotherium itself was rhino-sized, but had short feeble legs and small feet for so large an animal. It had large flaring tusks in both the upper and lower jaws, which closely mimic those seen in living hippopotamuses. The forehead was domed and full of air sinuses. Its most outlandish feature was a deep retraction of the nasal notch in the skull, indicating that it also had a tapirlike or elephantine trunk or proboscis (even more developed than the one seen in Macrauchenia). A weak-footed hippo with a trunk? The animals most similar to astrapotheres were the hippo-like amynodont rhinoceroses discussed in Chapter 14, which had stout aquatic bodies and well developed tusks, and heavy molar teeth. The relationships of astrapotheres and trigonostylopids are still a mystery. Their teeth bear some resemblance to those of notoungulates, but recent work by Richard Cifelli has shown that there are no true shared specializations. The fourth odd South American ungulate group was the "fire beasts," or pyrotheres and their relatives (Fig. 1.9D). Pyrotherium itself comes from the late Oligocene of Patagonia and Bolivia, and is a truly amazing animal. The size of a small elephant, it had short upper and lower tusks and simple cheek teeth with cross-crests like primitive mastodonts. Like astrapotheres, its nasal bones are deeply notched to receive the muscles of a well-developed trunk. This animal is one of the best imaginable examples of convergence with mastodonts, since there is no question that it is not actually related to elephants or mastodonts. For a long time, it was said to have specializations of notoungulates, but recently this has been discounted. Although its teeth are highly specialized and stereotyped into tapir-like leaf-eating cross-crests, there is some evidence from more primitive beasts. Weird Eocene animals known as Carolozittelia, Proticia and Columbitherium have last molars like Pyrotherium, but their other teeth resemble the curious ani-

16

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HORNS, TUSKS, AND FLIPPERS

B

IS

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.

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Figure 1.10. Although not related to ungulates, the pantodonts were the largest herbivores of the Paleocene and early Eocene. A. Barylambda, a sheep-sized beast of the late Paleocene. B. Coryphodon, one of the last of the pantodonts, and the largest beast of the northern continents in the early Eocene (From Fenton and Fenton, 1958). mal called Carodnia, from the Paleocene of Brazil. ing discovery of all. In 1992, Henk Godthelp, Mike Archer, Carodnia was a mystery for so long that it was placed in its and others reported an early Eocene fauna from Australia. own order, the Xenungulata ("strange ungulates"). However, Prior to this report, there were no fossil mammals known a number of scientists have recently argued that Carodnia is from Australia earlier than the early Miocene (about 23 milvery similar to primitive uintatheres, implying that the lion years ago), and they were all pouched marsupials (like pyrothere-Carodnia group is part of the Dinocerata. If this is the kangaroo and koala), or egg-laying monotremes (like the the case, then once again the question arises: did a uin- platypus). For years, scientists have used this fact to argue tathere-pyrothere group arise in Asia and spread to South that Australia was isolated from the rest of the wofId back in America (passing through North America in the late the Cretaceous, when marsupials and placental mammals Paleocene), or vice versa? As in the case of arctostylopids were just differentiating. According to this hypothesis, plaand epoicotheres discussed above, some would argue that all centals never reached Australia (until the Ice Ages), allowthree groups originated in South America and ultimately ing the "island continent" to evolve marsupials in great reached China. However, if uintatheres are related to the abundance without placental competition for most of the higher ungulates (which began in Asia in the late Paleocene, Cenozoic. But this dogma came crashing down, since the as we shall see in Chapter 7), or to rabbits (as Tong and early Eocene Tinga Marra fauna included not only primitive Lucas argue), then perhaps it was the other way around. marsupials, but also a tooth of what appeared to be an archaic ungulate! Clearly, we need more fossils to test these hypotheses. It now appears that in the late Cretaceous (about 70 milRecently, another group of animals has been found in South America that suggest a northern connection. They are lion years ago), very archaic ungulates were present not only known as pantodonts, big galumphing mammals common in in North America and Asia, but also in South America and the Paleocene of Asia and North America (Fig. 1.10). Australia (and probably in Europe and Africa, if we had fosAlthough they were primitive in most skeletal features, they sils of the right age). For reasons not yet understood, they had very distinctive teeth, with molars which had distinctive did not persist in Australia, ceding the dominance to marsu"V"-shaped crests on the crowns. The last and largest of the pials. Ungulates flourished in the Northern Hemisphere, as pantodonts occurred in the Eocene, where the sheep-sized detailed in the rest of the book. As we have seen, in South Coryphodon is the largest mammal in the early Eocene beds America they evolved in isolation to produce extraordinary of North America and Europe (Fig. 1.10B), and the cow- ecological parallels with Northern Hemisphere ecological sized Hypercoryphodon lived on until the middle Eocene of equivalents. Returning to South America, these four bizarre groups China. Pantodonts were long thought to be a strictly Northern of endemic hoofed mammals remain a great puzzle. Two Hemisphere group, until 1987, when Christian de Muizon groups seem traceable to animals found outside South and Larry Marshall reported an extremely primitive America: didolodonts-litopterns to hyopsodonts, and pantodont they named Alcidedorbignya from the early pyrotheres-Carodnia to uintatheres. Arctostylopids may be Paleocene of Bolivia. Although it is the earliest pantodont notoungulates, giving us a third instance of exchange known, it is less primitive than some later Paleocene between South American ungulates and the rest of the world. pantodonts from China. Once again, this discovery poses a However, all of these possible cases are restricted to the puzzle. Did pantodonts originate in China (where the most Paleocene. By the Eocene, there is no further evidence that primitive species are found), then migrate through North South America's native ungulates ever traveled to other conAmerica to South America, or vice versa? tinents, and they continued to flourish for almost 50 million This puzzle is further complicated by the most surpris- years unmolested by outsiders. Secure on their island conti-

INTRODUCTION nent, they evolved startling examples of parallelism with horses, camels, rhinos, hippos, and elephants. Sometime in the late Oligocene, between 30 and 24 million years ago, rodents and primates arrived, possibly on rafts of floating vegetation or by island hopping. The rodents soon diversified into the great South American caviomorph radiation, producing everything from giant capybaras to agoutis to chinchillas and Guinea pigs. The primates became the prehensile-tailed New World monkeys, including the spider monkeys, howler monkeys and their kin. Raccoons and their relatives arrived sometime in the late Miocene, between 6 and 9 million years ago. However, none of these later arrivals seriously impacted the large ungulates, which continued to dominate the forests and grasslands. The isolation of South America was finally broken in the Pliocene, about 3.5 million years ago. Continental collisions lifted up sea floor and triggered volcanic eruptions,

17

building the Central American land bridge. As it did so, nature began one of its greatest experiments, the "Great American Interchange." Waves of invaders swept down from the north and competed for the first time with their southern equivalents. These included horses, sabertooth cats, pumas and jaguars, wolves and dogs, bears, mastodonts and mammoths, camels, tapirs, and deer. Some of these northern predators were undoubtedly more efficient than the native marsupial predators and giant predatory birds that had been there for millions of years. The native South American fauna was overwhelmed not only by the new predators, but also by competition from their ecological equivalents from the north. Most went extinct in a few thousand years, although some managed to survive well into the Ice Ages before finally disappearing, possibly due to hunting by the first humans to reach South America.

Figure 2.1. Two bull hippos battling for dominance with their sharp tusks. (Photo from IMSI Master Photo Collection).

2. Cloven Hooves

THE KINGDOM OF CLOVEN HOOVES When you hear "hoofed mammals," the animals that immediately come to mind are artiodactyls. Most domesticated ungulates, including cows, water buffalo, yaks, sheep, goats, camels, llamas, and even pigs, are artiodactyIs. Virtually all meat (whether beef, pork, or more exotic fare such as goat or venison) comes from artiodactyls. In addition, artiodactyls produce all our milk (whether from a cow, goat, or camel), and all of our wool. In the natural world, artiodactyls are equally dominant. Just think of the common large mammals found in North America. Deer, moose, elk, bison, bighorn sheep, mountain goats, peccaries, pronghorns-they are all artiodactyls. But North America is now depleted in large mammals-during the Ice Ages, there were camels, tapirs, horses, mammoths, and mastodonts here as well. A more typical natural setting is the East African savanna. On your average safari, every large herbivorous mammal you would encounter (except the zebra, rhino, and elephant) would be an artiodactyl. These include the treetopbrowsing giraffes, the huge hippos in the river (Fig. 2.1), the ugly warthogs, the dangerous Cape buffalo, and a tremendous diversity of antelopes-wildebeest (or gnus), impalas, gazelles, bushbucks, elands, sable antelopes, hartebeests, kudus, gerenuks, and even tiny klipspringers and dik diks. Today, the artiodactyls are the most abundant ungulates, with over 190 living species. They include pigs, peccaries, hippos, camels and llamas, deer, pronghorns, giraffes, sheep, goats, and dozens of species of antelopes and cattle (Fig. 2.2). Artiodactyls share many specializations, but the most obvious one is in their feet (Fig. 2.3). All artiodactyls are "cloven hoofed" in the Biblical sense. Their feet are di vided into an even number of toes (usually two or four), since the axis of the foot runs between the third and fourth fingers and toes (equivalent to your big finger and ring finger). The first digit (thumb or big toe equivalent) is lost completely. As they become more specialized for running, the finger and toe bones lengthen, giving their limbs an extra segment. The side toes (digits 2 and 5, equivalent to your index finger and pinky) become shorter than digits 3 and 4, and in many specialized artiodactyls, the side toes nearly disappear. The most specialized artiodactyIs run on two elongate toes, digits 3 and 4, as you can see by examining any camel, deer, antelope, or cow. These two toe bones

are usually fused together into a single bone, the "cannon bone," which makes them less likely to break while running. Along with toes developed for running, artiodactyls develop other limb specializations. The upper limb segments (upper arm and thigh) become short relative to the middle leg segment (lower arm and shin). With the addition of elongated toes, this lengthens the total stride and greatly increases running efficiency. The most diagnostic feature of artiodactyIs is in the ankle. The main pivot bone of the ankle, the astragalus, is highly specialized (Fig. 2.3). It has well-developed hinges on both the shin side and toe side, so that the limb can move rapidly back and forth in a front-to-back plane. This makes running more efficient, but it prevents other kinds of motion. Unlike you (or cats, opossums, rodents or many other mammals),artiodactyls cannot rotate their feet out of the front-to-back plane. This prevents grasping, or climbing, or other motions that such rotations allow. Another feature characteristic of many artiodactyls is antlers and horns. Antlers are found mainly in deer and elk, and are formed and shed once each year by the males. Horns, on the other hand, have a permanent bony core that is capped by a horny sheath. This is rarely shed, and the bony core is not lost at all. True horns are found on antelopes, goats, and cattle. (Rhino horns are made of matted hair-like fibers with no bony core.) These horns and antlers are very important, not only as defense against predators, but also in combat between males for females and territory, and for recognition of species. GUT REACTIONS Artiodactyls develop other specializations that are related to feeding. Their teeth become more and more specialized for grinding, and the front teeth that were once specialized for biting or stabbing are lost, or reduced to simple nippers. Many have taken to eating grass, which is an abundant but poor-quality source of food. To do so, their teeth have to develop very tall crowns that grow almost continuously because grass is full of gritty material that grinds teeth down very fast. All mammals have some kind of gut bacteria to handle the digestion since they do not have the necessary enzymes for most food. Humans have the all-purpose digestive bacterium, Escherischia coli, which breaks down food not pre-

HORNS, TUSKS, AND FLIPPERS

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= Quaternary (drawn by C.R. Prothero; from

ChevrOlai n (even· toed)

Figure 2.3. The contrast between even-toed ungulates (artiodactyls) and odd-toed ungulates (perissodactyls). Although the number of toes is important, the primary distinction is the axis of symmetry of the foot. In artiodactyl feet, the axis of the foot runs between the third and fourth digits. In perissodactyl feet, the axis runs through the central (third) digit; side toes (the second and fourth digits) are present in most perissodactyls except forthe one-toed horses. (After Colbert 1991).

,...

Rhinoceros (odd-toed)

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CLOVEN HOOVES

Esophagus

21

Small intestine

Omasum

Figure 2.4. The ungulates employ different digestive strategies. Most mammals (including perissodactyls, elephants, and primitive artiodactyls on the left) are hindgut fermenters. Bacterial breakdown of the food takes place in the cecum and colon, which decreases the efficiency of digestion, but allows the food to move through the gut faster. Ruminant artiodactyls (right), however, are foregut fermenters, with a four-chambered stomach, which allows immediate fermentation of the cellulose. In addition, the food can be regurgitated from the rumen and chewed again ("chewing the cud"), allowing further digestion. By the time the food has reached the digestive surfaces of the intestines and cecum, it has been broken down by gut bacteria, so it is more efficiently used. It also passes through the gut much more slowly. (After Pough et aI., 2002) viously digested and renders it digestible in our large intestines. Indeed, over 80% of our feces are actually coliform bacteria. In essence, we get many of our nutrients indirectly by digesting the byproducts of bacterial metabolism. This works pretty well for most proteins and carbohydrates in our diet, or the diets of most omnivores and carnivores. However, the hardest material to digest is cellulose, which is a complex carbohydrate that takes much longer to break down into soluble sugars. Since it is one of the major parts of most plant matter, we digest this inefficiently, adding to the fiber or "roughage" in our diet. In a microscope slide of a human stool most of the undigested material is cellulose fibers. Herbivorous animals, which must get all their proteins and carbohydrates from plants, have a more difficult problem. Termites have solved it by having a large colony of cellulose-digesting bacteria in their gut so they can digest raw wood. Most herbivorous mammals minimize the problem by eating the greenest and newest vegetation, which has not yet developed too much woody cellulose fiber. This "high-qual-

ity" vegetation is relatively rare and requires much selective feeding to obtain enough nutrition. Another strategy is to substitute quantity for quality. Most grazers (grass-eaters) eat large quantities of high-fiber, low-quality grass in an effort to get enough nutrition; most of the cellulose is left undigested and then excreted. In either case, a herbivore must have a chamber in its gastrointestinal tract where the digestive bacteria can operate. Most mammals have such a bacterial flora in their intestines, and a blind pouch between the large and small intestines, called the cecum, for fermentation by gut bacteria (Fig. 2.4). The cecum of some herbivores, such as the rabbit, is immense. Longer than the rest of the digestive tract, it winds around the abdominal cavity. However, since the cecum opens after the digestive area in the small intestine, most of the material that was broken down in the cecum is not digested, but simply passes out as feces. To compensate, rabbits are well known for eating their own feces to digest the material broken down during the first pass through their gut.

22

HORNS, TUSKS, AND FLIPPERS

Most herbivorous ungulates use a similar system of fermentation in the cecum. Because their bacterial breakdown takes place after the stomach and small intestine, this is known as "hindgut fermentation." Hindgut fermenters include perissodactyIs, elephants, and other non-ruminating ungulates. By contrast, some artiodactyls have "foregut fermentation" in their stomach. Camels, deer, pronghorns, giraffes, goats, sheep, antelopes and cattle have a stomach with multiple chambers. This allows them to crop their food quickly and swallow it immediately without chewing. The undigested food is stored in the first chamber of the stomach, called the rumen. Although only partly chewed, the bacteria in the rumen begin to ferment the food. Then, when the animal is resting, it regurgitates the food to its mouth and chews at its leisure. We call this rumination, or "chewing the cud." After this chewing, the food passes through the rest of the digestive tract, where further bacterial fermentation occurs. These bacteria are essential to breaking down the indigestible cellulose, which is the bulk of the material in their low-quality food., In addition to the ability to crop food quickly, the ruminating stomach gives its owner several other advantages. By having bacteria in their stomach to aid digestion, they are much more efficient at using all the nutrients in their food. In contrast to the foregut-fermenting ruminants, most herbivorous mammals must ferment their food in the cecum and colon of their intestinal tract. Since the tough cellulose is only partially digested by the cecum or colon of a hindgut fermenter, much of the nutrient value is excreted without being digested. A typical hindgut fermenter utilizes only 450/0 of the cellulose in its food, while a ruminating foregut fermenter typically digests 60%. The tradeoff, however, is digestion speed. A ruminant takes much longer (typically 80 hours) to digest the same amount of food that a horse would take (typically 48 hours). This difference between hindgut and foregut fermentation makes a big difference in ecology. Living hindgut fermenters, such as horses, rhinos, elephants, and hippos, must eat large quantities of low-quality vegetation in order to compensate for their low digestion efficiency. This works well for large-bodied animals, such as elephants, rhinos, and hippos, but not as well for smaller herbivores. By contrast, ruminants are so much more efficient in digestion that they must be selective about what they eat, and concentrate on smaller amounts of higher-quality vegetation (such as tender green leaves and shoots, with relatively little cellulose). In Africa, for example, the great diversity of savanna antelopes is ecologically stable because they do not compete directly; each feeds on a different type of vegetation, or at a different level in the vegetation. For example, giraffes feed on the tops of trees, gerenuks and impalas on the tops of bushes-, and other smaller antelopes feed on the middle or lower level bushes, or on grasses. In summary, hindgut fermenters (especially perissodactyls and elephants) have an advantage where there are large quantities of low-quality, high-fiber foods, such as

grass. Ruminants, on the other hand, can cope with almost any kind of food, even in limited quantities. In fact, ruminants do well even in deserts or tundra where the food is scarce. Where hindgut and foregut fermenters compete directly, they specialize on different parts of the plant. In the East African savanna, for example, hindgut-fermenting zebras eat the poor quality dry grass tops, while ruminating gazelles and wildebeest eat the higher-quality young green grass uncovered by zebras. Ruminants have other advantages as well. Unlike hindgut fermenters, ruminants do not have to excrete urea, which is normally eliminated through the urine. Instead, this nitrogenous waste product goes to feed the microorganisms, which the ruminant later digests. For desert artiodactyls, this means that they need to drink less water to balance the urea in their urine. A wild ass in the desert must drink daily, while the camel or oryx can go days without drinking. The ability to digest the protein-rich microorganisms efficiently means that ruminants get all the essential amino acids in their diets, and can eat a much narrower range of plant materials than can hindgut fermenters. There are a few disadvantages to ruminating stomachs. Foods with high caloric value and little fiber, such as fruits or extremely rich fodder, are too easy to digest. If a cow eats vegetation that is too rich, for example, it can become bloated with a huge gas-filled rumen. The gut bacteria are working so fast that they produce more carbon dioxide and methane than the cow can get rid of. If the cow cannot belch, it may die. The rancher may have to slash the rumen of the cow, or punch a hole in it and place a tube through the hole, to relieve the pressure. Although a slimy green mass of partially digested fodder pours out, the cow may have a chance of surviving. Hindgut fermenters, on the other hand, don't have that problem, since fruits are absorbed in the small intestine before the region of fermentation is reached. Another problem with the fermentation process is that it generates a lot of heat. Anyone who has ever had a compost heap in their garden knows that the fermentation process is very rapid, and can generate temperatures of over 160°F (70°C). The blood vessels that drain the gut region are not suited to dumping heat through the blood circulation. Instead, ruminants have arranged their stomach (particularly the rumen, where the fermentation takes place) into a wide, flattened external chamber which lies just under their skin along the left side and belly of the animal. It spreads out over 70% of the body wall! In hindgut fermenters, such as horses, where fermentation takes place in the cecum and large intestine, these organs are arranged around the entire surface of the abdominal cavity. In both cases, the heat-generating organs are located so they have maximum surface area to disperse the heat, and they are near the surface where the heat can diffuse out through the skin. As an animal gets larger, its body mass increases at a power of three (volume = length 3 ), as does the volume of its stomach, but its surface area for losing heat only increases by a power of two (area = length2). Jim Mellett suggests that

CLOVEN HOOVES the main reason herbivorous mammals don't get any larger is this problem of heat loss. Foregut fermenters, such as ruminants, seldom get larger than a giraffe (4200 pounds, or 1900 kg in body weight). Hindgut fermenters pass the food through much quicker with less heat generation, so they can be larger. The largest living hindgut fermenter, the elephant, reaches about 16,500 pounds (7500 kg). Paraceratherium, the gigantic hornless rhino, was the largest land herbivore, and must certainly have been a hindgut fermenter at 40,00060,000 pounds (20,000-30,000 kg) body weight. Mellett suggests that this is the upper limit for herbivorous land mammals. If so, then what about herbivorous dinosaurs, which were even larger? Mellett points out that those dinosaurs with complex shearing teeth for chopping food finely (such as duckbills and ceratopsians) did not exceed the elephant in size. Only the sauropod dinosaurs, with their simple peg-like teeth, were larger, and they must have passed their vast volumes of food through their guts quickly to prevent too much heat. The evolution of the ruminating stomach was a great advance in the evolution of herbivorous mammals. During the middle and late Eocene both perissodactyls and artiodactyls roamed the forests, browsing on large quantities of different kinds of leaves. When the world became drier and grassier in the Oligocene, however, specialized hindgut-fermenting browsers (including the great variety of tapirs, rhinos, and brontotheres discussed later in this book) were at a disadvantage. In North America, ruminating camels, pronghorns, and a variety of deer-like forms eventually came to dominate the Miocene grasslands of the midcontinent, pushing the perissodactyls into high-volume grazing (especially among the horses and rhinos). In Eurasia and Africa, ruminants were even more dominant, and today these continents have a great variety of deer, antelope, and cattle, but only a few horses or rhinos. Clearly, artiodactyls have come a long way from relatively unimportant animals to the dominant group of land herbivores. But where did they come from? To understand their story, we must look at some of their earliest fossils.

23

"BUNNY DEER" At the end of the Paleocene and beginning of the Eocene, the world was a very different place from what it is today. The climate was temperate to subtropical, with no polar ice caps or cold oceans. It was so warm and unseasonal that even the regions above the Arctic Circle were warm enough for alligators and a broadleaf, warm-climate vegetation. The thick, forest vegetation was found from pole to equator, and most of the animals were small and adapted to browsing on leaves or fruits in forests. There were no significant grasslands; indeed, modem grasses had not yet evolved. The tree cover was so thick that the most common animals were lemur-like primates, and a tree-dwelling extinct group of mammals called multituberculates. The largest mammal was about the size of a sheep, and most were much smaller. The main ground dwellers were small archaic ungulates, and the main predator was a large flightless carnivorous bird almost 7 feet (2 m) tall! In fact, very few of the mammals belonged to groups alive today, and those that did (like horses) looked nothing like their descendants. The beginning of the Eocene was unusual in another way. There were great migrations of mammals between Europe, eastern Asia, and North America. Malcolm McKenna has shown that many of these migrations took place across the connection between Greenland and northern Europe, since the Atlantic Ocean had still not opened very wide. There are great similarities between the archaic ungulates, the carnivorous mammals, the primates, and many other typical animals inhabiting Europe and those living in North America. This immigration event represents not only the first appearance in North America of even-toed artiodactyIs, but also the first appearance of the odd-toed perissodactyls, and the rodents. Since the closest relatives of all three of these are known from the Paleocene of Asia, they were probably all migrating across the precursor of the Bering land bridge. The early Eocene was one of the greatest periods of migration in the last 65 million years. Not until the Ice Age opening of the Bering land bridge and the Isthmus of Panama did so much exchange take place

Figure 2.5. Restoration of the archaic early Eocene artiodactyl Oiacodexis. (Courtesy K. Rose).

24

HORNS, TUSKS, AND FLIPPERS

between the animals of different continents. By the middle Eocene, however, this great exchange was nearly over. Asia and North America continued to exchange some kinds of mammals, but to a lesser degree than previously. The connection across Greenland and Scandinavia was severed as the Atlantic Ocean began to spread even further. Since Europe was separated from Asia by a shallow inland sea running along the present Ural Mountains, and from Africa by the Tethys seaway, it was truly isolated. In addition, high sea levels meant that much of Europe was under water, forming an archipelago of small islands. At different times, these islands were either connected or separated, allowing their mammals to evolve in small populations and produce unique species at some times, and allowing intermingling at other times. The earliest and most primitive known artiodactyls are found around the world in the early Eocene. These animals, known as dichobunids, had very simple low-cusped teeth without the curved crests so typical of most artiodactyls. The best known of the dichobunids was first described in North America and named lJiacodexis (Fig. 2.5). It is often considered the ancestor of the artiodactyIs. Diacodexis was a tiny, rabbit-sized animal with very few specializations in its teeth to tell us that it was an artiodactyl. Unlike most later artiodactyls, it still had all five fingers, and four toes on the hind foot. It even retains the collarbone, which is lost in almost all ungulates (including more advanced artiodactyls). However, in the details of the skull, and especially in the ankle region, it was clearly already specialized. Diacodexis was very abundant in North America. Contrary to expectations, the skeleton of these animals does not have simple, primitive limb proportions. Instead, North American Diacodexis has relatively long, slender limbs, suitable for very fast running and even jumping; its proportions were very much like some of the tiny deer we will discuss in Chapter 4. This is also true of the dichobunid relatives of Diacodexis, such as Bunophorus, Antiacodon, and Pentacemylus. Although these long limbs seem specialized, they are actually scaled appropriately for such a small, lightweight deer-like mammal. As body size increased in their later descendants, such as pigs and hippos, the limbs became less adapted for running and leaping. In fact, not all Diacodexis were as delicate as the North American species. Specimens of Diacodexis from the early Eocene of Pakistan are not only smaller and more primitive than those from North America, but they also have shorter limbs with no obvious specializations for running or leaping. Thus, the shorter-limbed artiodactyls could be descended from Asian Diacodexis, rather than from the highly specialized species found in North America. This leads to the most puzzling question of all: where did the artiodactyls come from? When Diacodexis appears worldwide at the beginning of the Eocene it already has a fully developed artiodacty1 limb with the specialized ankle bones. In the past most paleontologists have looked at relatively well known and complete specimens from North

America in seeking the artiodacty1 ancestor. Almost all of them have derived artiodactyls from one of the groups of archaic ungulates found in North America in the late Paleocene, such as the arctocyonids or the hyopsodonts. Certainly, the teeth of some of these animals are very similar to those of Diacodexis. But, as Ken Rose has shown, the rest of the skeletons of these "candidates for ancestry" have their own specializations, and do not show much affinity with Diacodexis. In addition, Earl Manning has shown that the most primitive artiodactyls are even more primitive than most of the known arctocyonids or hyopsodonts, and must have branched off first before these other groups evolved. The discovery of the primitive Diacodexis from Pakistan suggests that our North American bias was a mistake. As we get better and better fossils from poorly explored places such as Asia and Africa, we are finding many specimens that shatter old notions of deriving everything from well-known North American fossils. Later in this book, we will discuss the new evidence that shows the elephants and the perissodactyls probably originated in the late Paleocene of Asia or Africa. The Pakistani Diacodexis suggests the same thing. Several scientists, including Malcolm McKenna, David Krause, and Mary Maas, have pointed out that India was an island continent at the beginnin~of the age of mammals. After breaking off from Africa in the late Cretaceous, it traveled northward through the Indian Ocean, lying just off the eastern coast of Africa (Fig. 2.6). These scientists have suggested that the ancestors of several groups of mammals, including artiodactyls (and possibly lemur-like primates and perissodactyIs) island-hopped from Africa to Madagascar to India during the late Cretaceous and early Paleocene. Then India moved further north, and through the rest of the Paleocene it was isolated from the world. In this isolation lab, ancestral populations could evolve into specialized groups such as artiodactyIs, perissodactyIs, and lemur-like primates without competing with animals found around the rest of the world in the Paleocene. Then, when India collided with Asia at the beginning of the Eocene, they hopped off their floating "Noah's ark" and spread around the world. For these scientists, this explains why Diacodexis, Hyracotherium and certain primates appeared suddenly at the beginning of the Eocene in Europe and North America with no obvious local ancestors in the late Paleocene. This idea certainly seems to fit the available facts, so far as they are known. Unfortunately, no Paleocene mammals have yet been found from the Indian subcontinent to test this hypothesis. The oldest mammals come from early Eocene beds in both India and Pakistan and they contain animals that are known worldwide (although some, such as Diacodexis, are the most primitive known). However, the evidence from the recently discovered relatives of elephants and perissodactyIs discussed later in this book clearly shows that most of the dominant groups of Iiving ungulates must have originated in this region of continents bordering the ancient Tethys seaway, including Africa, India, and southern Asia. We may never be able to pinpoint their exact time and place

CLOVEN HOOVES

25

for many years before its true scientific value was realized. Much of the phosphate in the Quercy mines was in the form of actual vertebrate bones, and some were remarkably well preserved. Each pocket of phosphate occurred in a cavern or fissure dissolved in the ancient limestones which formed the bedrock. However, these pockets and fissures began to fill with fossils in the Eocene and Oligocene, so they preserved ancient bones that had washed or fallen into them 40 million years ago. The quality of the fossils rivaled the great finds of Cope, Leidy, and Marsh in North America. In the introduction to his 1876 monograph on the Quercy mammals, the French paleontologist Henri Filhol enthused, "The localities of Quercy must be considered as having yielded the most interesting evidence hitherto discovered in Europe for the study of fossil mammals, and the animal forms which they reveal are no less valuable than those which have been brought to light in America in recent years."

Figure 2.6. Hypothesis of origin of artiodactyls, perissodactyls, and several other mammalian groups from isolation on the "Noah's ark" of the Indian microcontinent during the Cretaceous and Paleocene. When India collided with Asia in the early Eocene, its natives may have escaped, explaining their sudden appearance in Eocene rocks around the world. (From Krause and Maas 1990). of origin, but it was certainly not North America. The appearance of artiodactyls, perissodactyls, lemur-like primates, hyaena-like creodonts, and even rodents in Europe and North America during the Paleocene-Eocene transition was clearly due to immigration, not evolution from native animals. PHOSPHATE AND FOSSILS One of the most important chemicals used in fertilizers and gunpowder is phosphate. Mineral deposits of phosphate are quite rare in most regions of the world, so when an abundant source of phosphate is discovered, it is quickly exploited. Much of the world's phosphate comes from animal sources. Bird droppings and other fecal matter are rich in phosphate, and in some places the abundant droppings of fish-eating seabirds (known as guano) is so encrusted on sea cliffs and islands that it can be mined commercially. Bat guano at the bottoms of heavily used caves has also been mined. Vertebrate bone is made mostly of phosphate, so abundant sources of bone can serve as fertilizer. In areas with abundant fishing, ground-up fish meal is used. In other parts of the world phosphate occurs in pockets of ancient limestone. One such deposit is located in the Quercy region of south-central France. First discovered in 1865, it was mined

Unfortunately, fissures opened at different times, so they were all of different geologic ages. At first this jumble of fossils confused the scientists, who assumed that everything found in the Quercy pockets was the same age. After 1890 the commercial value of the French phosphate plummeted, since much cheaper phosphates (also a source of vertebrate bones) were found in North Africa. The phosphate mines were abandoned. In the 1960s scientists from the uni versities of Montpellier and Paris began to systematically reopen the old mines. Since nobody knew what pocket (and therefore what age) the fossils in the old collections had come from, it was necessary to re-excavate them and sort out their complex sequence of ages. Over the last few decades they have now worked out the sequence of more than 100 localities, and determined which level each fossil comes from. They have also found many more fossils (especially of small mammals) that were undiscovered, or neglected, by the nineteenth-century scientists. The Quercy deposits contain a staggering array of opossums, carnivores and hyaena-like creodonts, bats, rodents, lemur-like primates, and primitive hoofed mammals. Among the most common elements, however, were extremely primitive artiodactyls. Their feet had not yet lost the side toes, although they clearly were cloven hoofed. Some of the artiodactyls were more specialized, including European relatives of the camels, and others distantly related to the pig-hippo family. Most, however, were members of groups unique to Europe in the Eocene, and not found elsewhere. Except for paleontologists, few people have heard of choeropotamids, cebochoeres, mixtotheres, cainotheres, dacrytheres, haplobunodonts, xiphodonts, and amphimerycids. All of these evolved in isolation in Europe in the Eocene, and with few exceptions were only distantly related to artiodactyls of other continents. Since Europe was an archipelago in the Eocene, it had many unique endemic

26

HORNS, TUSKS, AND FLIPPERS

Figure 2.7. The big entelodont Archaeotherium, common in the upper Eocene-Oligocene beds of the Big Badlands of South Dakota. (Painting by R. B. Horsfall, from Scott 1913). mammals, including such bizarre perissodactyls as palaeotheres and lophiodonts. Like these other endemic forms, the majority of these unique artiodactyls became extinct in the late Eocene as the climate deteriorated. When the island isolation ended in the early Oligocene artiodactyls from the outside world replaced them. PSEUDOPIGS North America and Asia, which were not isolated, also had a great radiation of artiodactyIs in the middle and late Eocene. The descendants of the dichobunids began to specialize in a number of different ways. Some remained primitive forms with simple, low-crowned cusps on their teeth, and ShOlt limbs. One such group, the leptochoerids, survived in North America well into the Oligocene. Most developed longer limbs with reduced side toes, and eventually highercrowned teeth with sharp curved crests for eating tougher vegetation. These groups evolved into the oreodonts and camels, which dominated in North America, and the earliest relati ves of ruminants, which were found in both Asia and North America. We will discuss these animals in greater detail later. A third line of specialization is represented by the pigs and peccaries today (Fig. 2.2). These animals are mainly

omnivorous, eating a wide variety of foods, including fruits, roots and tubers, fungi, ferns, grasses, and even insects, earthworms, and occasional carrion and small vertebrates (such as frogs and mice, if they can catch them). This generalized, omnivorous diet means that their teeth cannot become too specialized for meat slicing or plant grinding. Instead, all of these animals have low, rounded cusps on their teeth, which are suitable for many purposes. This kind of tooth structure is known as bunodont, and it is also found in other omnivorous animals, including bears and most primates (even humans !). Because they eat just about anything they can find on the forest floor, omni vorous artiodactyIs do not need large home ranges to supply their food, which are inhabited by large herds of fast running ungulates. Instead, omnivores rely on concealment in the underbrush, and retain the primitive shorter limb proportions of a generalized walker. Of course, as artiodactyls, they still have cloven hooves and the specialized ankle joint. However, they usually retain four toes on both their front and hind feet, so that they can get good traction on marshy soil. This pig-like mode of life evolved several times in the artiodactyIs during the Eocene. In the European archipelago there were animals such as cebochoerids and choeropotamids which had bunodont teeth and four-toed feet, but

CLOVEN HOOVES were extinct side branches unrelated to pigs. In Asia similar animals known as helohyids, entelodonts, and anthracotheres performed this role. North America also had helohyids and a bizarre hippo-sized animal known as Achaenodon. Most of these groups did not survive into the Oligocene. However, the entelodonts and anthracotheres were very successful "pseudopigs" and "pseudohippos," dominating North America and Asia through much of the Oligocene and Miocene. The most spectacular of these groups was the entelodonts. They first appeared in the middle Eocene of China with an animal known as Eoentelodon. By the late Eocene, they had reached North America, represented by a peculiar animal known as Brachyhyops ("short pig face"). In the late Eocene and Oligocene deposits of the Big Badlands of South Dakota one of the most common large mammals is the ugly entelodont Archaeotherium (Fig. 2.7). This animal was the size of a large hog,. and very pig-like in most of its features. Undoubtedly, it also had a very pig-like diet, feeding on roots, fungi, carrion, and occasional meat. Its face was truly grotesque. The huge, heavy head had broad flaring cheekbones, and there were weird bony protuberances sticking out of the bottom of the jaw. Each male had a very impressive set of canines, which were probably not used so much for catching prey as for fighting and intimidating rivals and predators. Indeed, several specimens have been found which have deep "battle scars"-healed wounds in the bone around the eye that could only have been formed from the canines of a rival male. The "warts" on warthogs have a similar function-they pad the blows during head-tohead wrestling matches between adult males. Although entelodonts have bunodont teeth, they have a very bizarre pattern of wear. In many mammals it is typical for the grinding molars and premolars to be worn down from the top of their crowns. But the biting incisors ("eye teeth") and stabbing canines usually keep their sharp points. Entelodonts, however, have conical premolars much like their canines and incisors, and all of these teeth are worn flat on the tips. Apparently, they were using all their front teeth for crushing, rather than the usual stabbing and cutting. Matt Joeckel has studied the jaw mechanics of entelodonts, and concludes that they probably ate a great deal of bone and carrion, since this same wear pattern is seen in scavengers like bears and hyaenas. In addition, he found that they were capable of tremendous side-to-side movement of their lower jaw as they ground up the food with their simple bunodont teeth. Although this is also seen to some degree in pigs, no animal ever ate quite like an entelodont! Entelodonts migrated to Europe in the early Oligocene, replacing the cebochoerids and choeropotamids that had occupied the piglike ecological niche in the Eocene. They are also found in the youngest of the Quercy deposits, although they were never as important as they were in North America. By the late Oligocene and early Miocene, entelodonts reached the culmination of their evol ution. The last and most spectacular of these was Daeodon (formerly

27

known as Dinohyus) from the famous early Miocene locality at Agate Springs, Nebraska. (We will discuss this place further in Chapter 14). This animal was truly hippo-sized, reaching almost 8 feet (2.4 m) at the shoulder, and 11 feet (3.4 m) long, and with a skull over five feet (1.5 m) long! Its weight is estimated around 2000 pounds (900 kg), although it was not fat and short-limbed like a hippo. Instead, it has fairly long, robust limbs, and most of its weight was in the pig-like body and huge head. Daeodon was like Archaeotherium in having the broad, flaring cheekbones and bony protuberances on the base of the jaw, but they were even more extreme. The cheekbones of Daeodon even had a thick bony flange that stuck out from the side of the face like a set of wings. No one knows what all this bone was for. Some have suggested that it served as an attachment point for complicated jaw muscles. However, it is hard to imagine that their diet was so different from smaller pig-like forms that it required such unusual bony growths. Their presence around the eyes suggests another hypothesis-they were used for threat and display rituals~ Most artiodactyls today used their horns or antlers to signal their position in the herd, and threaten rivals with a display of their size. Since the piglike artiodactyIs never developed either horns or antlers, they must have used their huge canines and their weird bony cheekbones for the same purpose. Daeodon was the last of the entelodonts found anywhere in the world. Why the group died out is a mystery since no large pig-like form appeared in North America in the early Miocene to replace them. Indeed, the pig-like niche on this continent was not filled by anything that large until late in the Miocene, when peccaries reached the peak of their evolution. SUI GENERIS Everyone is familiar with the pig family, the Suidae, and many of the typical members, such as the domestic pig, the wild boar, and the warthog. Few people distinguish between the Old World Suidae, and their New World counterparts, the peccaries or Tayassuidae. Superficially, pigs and peccaries look very similar. Most people have trouble telling them apart, and they occupy virtually the same ecological niche. In evolutionary terms, however, they have been distinct since the late Eocene, over 35 million years ago. Pigs have longer skulls than peccaries, with wide flaring tusks, whereas peccaries have a relatively short head with downward-pointing tusks (Fig. 2.8). This is particularly apparent in a side view of the skull. In pigs, the jaw joint is high on the side of their head, rather than just above the plane of the teeth, as itis in peccaries and most other mammals. The rear of a pig's lower jaw has extended flanges in the back to support this high jaw joint and anchor the long jaw muscles. Pig molars often develop very wrinkled, complex surfaces, and pigs have diversified into many more ecological niches than have peccaries. Unlike peccaries, however, they have never become long-limbed, efficient runners.

28

HORNS, TUSKS, AND FLIPPERS

Figure 2.8. Comparison of the skulls of a living warthog (right) with a large extinct peccary Macrogenis (left). Although both have large flaring ridges below their eyes, the tusks of pigs flare outward, whereas the tusks of peccaries point straight up and down. (Photo courtesy C. Janis). Another difference is their biogeography. Although both groups apparently originated in Asia in the late Eocene and spread widely across Eurasia in the early Oligocene, wild pigs never left the Old World. Peccaries, on the other hand, were rare visitors to the Old World, but had no pig competition in the New World until Europeans brought domesticated pigs to this continent for the first time. The earliest known pig, Propalaeochoerus, is found in the early Oligocene of China. At about this time it immigrated to Europe after the late Eocene extinctions discussed in other chapters. Pigs are rare in the Oligocene of Eurasia compared to the competing anthracotheres. By the early Miocene, however, they began to flourish all over the Old World. Hyotherium, the typical early Miocene pig of Europe, also managed to hop across the narrowing Tethys seaway and invade the island continent of Africa. Another early Miocene pig from Africa, Xenochoerus, is part of a specialized side-branch, the sanitherines, leading to pigs like Sanitherium, Hyosus and Hippohyus, which flourished in Pakistan in the middle and late Miocene before becoming extinct. These pigs were among the first to adopt a grazing mode of life, with complexly folded enamel on their highcrowned teeth. Another extinct side branch are the tetraconodontine pigs. Early Miocene forms like Conohyus from Asia differ

very little from Hyotherium except that they have enlarged premolars. Their evolution culminated in the late Miocene of the Siwalik Hills of Pakistan with forms known as Tetraconodon and Sivachoerus. Tetraconodon had huge crushing premolars and gigantic tusks; its teeth converge on those of a hyaena, suggesting that it was a bone-crushing scavenger. During the Pliocene the tetraconodontine lineage underwent a great evolutionary radiation in Africa. Pigs such as Nyanzachoerus and Notochoerus developed wide flaring cheekbones similar to those we have already seen in entelodonts and peccaries. One peculiar tetraconodontine pig from the early-middle Miocene of North Africa was Kubanochoerus. This pig was truly bizarre in that the males had a small bony horn above the forehead (Fig. 2.9). Since horns are rare in other primitive artiodactyl families, and common in ruminants, this pig is a true exception to the rule. A third lineage of middle Miocene pigs did not go extinct, but is related to the living suines. Although many of these animals, such as Bunolistriodon, retained primitive pig features, there are specialized beasts such as Listriodon, from the middle-late Miocene of Pakistan. Its molars have transverse cross-crests which closely resemble those found in a tapir, or many mastodonts. This suggests that it was a specialized leaf-eater, abandoning the typical pig omnivorous habitat. The main line of pig evolution can be seen in

CLOVEN HOOVES

Figure 2.9. The Miocene horned pig Kubanochoe-rus. (From Agusti and Anton 2002).

forms like Propotamochoerus and Dicoryphochoerus of the middle-late Miocene of Pakistan. By the late Miocene, fossils that are put in the living pig genus Sus are known from Europe and Pakistan. Sus falconeri from the late Miocene of Pakistan has many features that place it near the living warthog, including a long snout and skull, with the eyes placed far back on the skull. In the Pliocene, several modern lineages of pigs replaced the tetraconodontines in Africa. The bush pigs (Potamochoerus) and forest hogs (Kolpochoerus, Hylochoerus) replaced Nyanza-

29

choerus, and the warthogs (Metridiochoerus, Phacochoerus) replaced Notochoerus. One warthog, Metridiochoerus compactus, from the Pleistocene of Tanzania was a true giant. It stood over a meter high at the shoulder, and had long curved upper and lower tusks, and a single elongate, high-crowned molar in each jaw that had complexly folded enamel. This condition parallels the pattern evol ved independently in the elephants. At the end of the Pleistocene, this variety of warthogs went extinct, leaving only the living warthog, Phacochoerus aethiopicus. The face of the warthog is so grotesque that its name has become synonymous with "ugly" in our language (Fig. 2.10). Its bony protuberances in front of the eye and along the upper jaw are coupled with huge, flaring canine tusks that are reminiscent of the extinct entelodonts. Warthog boars have more elaborate "warts," and their primary function is protection during head-to-head wrestling and butting with other males. Although their large upper tusks are more impressive, the smaller, sharper lower tusks are their primary weapons, not only against other males of their own species, but especially against predators. Even lions do not want to be slashed by their fearsome tusks. As I.-P. Hallet described it, "Every family of warthogs has its own aardvark hole where the wary pigs sleep, hide out, bear babies and raise them. Senge, as he is called in Swahili, is a good natured but rather timid fellow, much less apt to stand and fight than the Indian wild boar. When disturbed, whole families or solitary males literally hightail it to the burrow,

Figure 2.10. The warthog, Phacochoerus aethiopicus, wallowing in the mud. (Photo courtesy A. Walker).

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HORNS, TUSKS, AND FLIPPERS fleeing to safety with their tufted tails stiffly erect. They enter hindfirst so that they can use their huge tusks to stave off enemy pursuit, and leopards rarely push the issue: full-grown male warthogs may weigh as much as 200 pounds and the leopard prefers, as with all sizable prey, to attack them from the rear. Lions may claw at the burrows like a pack of excited dogs, trying to dig out the holed-up pigs. If they succeed they have a fine pork dinner, but the dinner fights back, often inflicting serious wounds before the lions seize and snap the neck. At waterholes the warthog also approaches hindfirst, kicking at the edge with his back feet before turning to drink. He is stamping some salty crust into his drinking water-he doesn't like to take his salt straight-but Azande tribesmen say, observing that strange little ritual, that Senge has another reason. According to their legend, the first-created walthog saw a savage-looking creature lurking in a pool of still water. Appalled, timid Senge ran away to hide in his burrow. But he never forgot, warning all of his descendants to stir the water well before they faced it (so that they wouldn't have to see their own reflections). Big-headed, broad-snouted, maned on the neck and back with bristling brownish hair, Senge has a pair of huge warty protuberances just below his eyes and another pair flanking his massive ivory tusks. Unlike those of true pigs, his tusks are upper canines, not lower ones; the paired warts protect his small, rather dim-sighted eyes as he plows up wild roots and tubers for a living" (Hallet, 1968: 251-252).

Although they are omnivores like other pigs, warthogs are the most specialized for grazing. They drop to their knees and pluck the tender growing tips of grasses with their lips, and grind them with their enlarged last molars. At the end of the rainy season, they take grass seeds, and during the dry season, they use the tough upper edge of their noses to scoop grass rhizomes out of the dry, sun-baked savanna soils. Contrary to popular accounts, they seldom use their tusks to dig up food. Warthogs are not strictly territorial, but divide the grasslands into home ranges that vary from 60 to 370 hectares. They share water holes and aardvark burrows when necessary, although their grazing areas may be marked with saliva and secretions from glands around the eyes. They can have a population density as great as ten individuals per square kilometer, although typically there are fewer than, two. The abundance of available aardvark burrows largely determines their population density. The population is divided into clans, each composed of several bands, or "sounders," plus associated loners. Most sounders contain 46 warthogs, although some are as large as 40. The sounders

consist mostly of females and their young, plus immature males that have not yet gone off on their own. Adult boars only join the sounders during mating, at which time they undergo a complex ritual of display and head wrestling for dominance. Once the dominant boar has been established, he sniffs the sow's urine to determine if she is in estrus. Then there is a long, drawn-out courtship ritual. A boar may squirt urine where the sow has urinated, and then pursue her, raising his mane, champing his jaws, and salivating as he mumbles deep in his throat. Eventually the sow gives up and the boar places his head across her back, and massages her rump. This induces her to stand still, and he mounts her for as long as ten minutes, jerking his head along with his thrusts. His spiral penis fits into her grooved cervix, and after copulation, a plug forms to prevent further mating. Mating occurs in May and June, and births in October and November, about 170-175 days later. Although the sow has only four teats, she may have as many as eight young, but one to three is more typical. The piglets hide in the grass-lined burrow for a long time, since they are especially sensitive to the temperature fluctuations outside. After about 50 days, they leave the burrow and accompany their mother, and they are weaned by 21 weeks. They start eating grass early, as well as their motheE's dung, so they can pick up her gut bacteria. The young are driven away when the sow is about to bear a new litter, although they may return later. After 15 months, the male young leave for good, but the females may stay indefinitely. They become sexually mature at 18 to 20 months, but males may not be strong enough to win sows until they are four years old. Young warthogs are extremely vulnerable to predation by lions, leopards, and cheetahs, and less than half Iive past the first year. Although they have lived as long as seventeen years in zoos, they seldom live that long in the wild, and their high reproductive rate must compensate for this. Besides the diversity of warthogs in the PlioPleistocene, there is a second major lineage of forest pigs in Africa. Kolpochoerus (formerly called Mesochoerus) was one of the most characteristic pigs of the cradle of humankind. In fact, Kolpochoerus figured prominently in the dating of early hominid fossils. Don Johanson, in his book Lucy, describes a controversy between Richard Leakey and other scientists regarding the dating of the oldest Homo habilis specimens from Lake Turkana. Leakey and his group insisted on a date of 2.9 million years, based on the controversial KBS Tuff. Mammalian paleontologists said that the pig and elephant fossils were comparable to those found in beds about 2 million years ago in the Omo Valley of Ethiopia and elsewhere in East Africa. The foremost pig expert, Basil Cooke, had found that Kolpochoerus limnetes was especially characteristic of the interval around 2 million years everywhere except East Turkana, where Leakey insisted that it was three million years old. At a 1975 conference in London the conflict c:ame to a head. One of Leakey's group came wearing a "pig-proof helmet." Cooke came wearing a tie embroidered with the initials "MCP," which

CLOVEN HOOVES

Figure 2.11. The bushpig, Potamochoerus porcus (Photo by D.R. Prothero). were widely available for "Male Chauvinist Pigs." When asked about the tie, Cooke said that the initials stood for "Mesochoerus Correlates Properly." Eventually, the problematic KBS Tuff date was redated and the results supported the pigs. From Kolpochoerus, two major lineages evolved. One became the giant forest hog, Hylochoerus meinertzhageni. The second is now represented by the bushpig or red river hog, Potamochoerus porcus (Fig. 2.11). Both pigs are found in dense forests, primarily in the Congo Basin and other parts of central and eastern Africa. Bushpigs are able to plow up soil and tum over heavy logs in search of a varied diet of roots, fruits, cultivated plants, fungi, beetle larvae, giant snails, small amphibians, reptiles, and mammals, as well as eggs and bird nestlings. They will also eat carrion when it is available. Forest hogs eat a diet of grasses and shrubs, and are particularly characteristic of the forest margin, where there is a mixed habitat of trees and grasslands. The bush pig is spectacularly marked. It has long russet-red hair with a white mane on the head and a crest along the back, white spectacles around the eyes, white ear tufts and white side whiskers. Ivan Sanderson vividly describes his encounter with them in Animal Treasure: "Abruptly I came upon them, a veritable herd of the weirdest animals I have ever seen. Rich orange in color, with monstrous heads, they formed a vivid contrast to the sombre greens of the water weeds. It seemed, in fact, as if they were more than half head, since their short legs were sunk deep in the morass that they were busily creating in the soft earth. On their heads they bore tall crests of spotless white which passed backward into a long white mane falling this way or that over their shoulders. Their ears were long and pointed, terminated by a long white plume, which they constantly flicked and

twitched as they ploughed up the ground in long, even furrows. All the while they grunted and grumbled contentedly. A herd of river hogs (Potamochoerus porcus) is an unusual sight. They seem as contented and lazy as ordinary farmyard pigs, yet their vivid coloration and grotesque form make one pause to consider whether one's sight is playing a trick. In the wilds they don't look like pigs at all. They are, in fact, unlike any other animal with their big heads, long tapering plumed ears, and tall narrow bodies ... They are indeed peculiar hunters. I had always supposed them to be herbivorous, yet I saw one large sow unearth a cluster of huge snails and set to work cracking the shells and munching up the juicy contents. In this she was assisted by three small hogs who tussled and bit each other in an effort to get at the morsels. The tactics consisted of flying tackles in which they threw their whole weight into their shoulders and banged their opponents, one of whom was sent sprawling into a muddy bog. The sight of a wild animal floundering on its back was really most remarkable and gave me the impression of watching a group of school children at play. One old hog who kept looking at me as if realizing that I might be potentially dangerous made a most comical misjudgment. He was rooting along the edge of the marsh, stopping now and then with his long snout several inches in the mud to crunch up some hidden root, when he inadvertently pushed under a particularly tough root extending from a large tree on the solid ground nearby. It appeared that he had small tusks (as I saw later) and these must have got locked under a root, for he suddenly set up the most terrific racket, dancing about with his back legs and giving little hops like a ballet dancer, heaving, pulling and squealing as if caught by the nose. At first I thought he was fighting something on the ground, since his nose was out of view behind a small plant, and I stupidly moved to see what it was all about. This worried the others, who began to move off hun~iedly, but I got a good view of the hog as he writhed in fury, tugging at the root. Then my attention was drawn to one of the loveliest sights I have ever seen. As the herd moved past me with increasing speed, out trotted some indi viduals I had not seen before. Among them was a swarm of tiny piglets, each immaculately striped with gold on its little, otherwise unmarked body. They trotted along in a line uttering high-pitched grunts and herded from behind by an agitated mother who kept prodding their delicate little

31

32

HORNS, TUSKS, AND FLIPPERS

Figure 2.12. A family group of giant forest hogs, Hylochoerus meinertzhageni. (Photo courtesy A. Walker). hind legs as if to say: 'Go on, hurry up, or the bogeyman will get you.' The whole scene was so perfect that I stood spellbound at the sight of it" (Sanderson, 1937: 75-78). Unlike the warthog, the upper tusks of female bushpigs point downward and wear against their lower tusks. The boar has walts in front of his eyes, which are usually covered by the long hair; these serve as protection during head wrestling with other boars. The white facial markings are particularly important in face-to-face displays, since they accentuate the facial expressions and ear position, and signal the intentions of rivals. Like the warthog, their sounders are composed mostly of sows and their offspring, with or without a dominant boar. Most sounders consist of only 4-6 pigs, but occasionally they form groups as large as 40. They mark their home ranges with secretions from glands found at the nape of the neck, the front comer of the eye, and the wart in front of the eye. Relatively little is known about their reproductive behavior since it is hard to follow them in the dense forests. The sow builds a nest in a deep thicket or hollow tree, lining it with reeds, grasses, and branches. She excavates the cen-

ter into a shallow dish, where she gives birth during midsummer to as many as ten piglets (although she has only six teats). The tiny piglets are marked with white or yellow spots on a black or brown background, which fade after six months. These markings conceal the young in the mottled forest light, and they freeze when they hear mother's alarm grunt and stay crouched until she returns. The young are vulnerable to many predators, including smaller cats and eagles, and the adults are also threatened by leopards and pythons. However, they are so aggressive that they have been seen to drive a leopard away from its kill and eat it themselves. Because of human hunting of leopards, the bushpig population of southern Africa has actually expanded, and they are now a serious threat to crops in many parts of the continent. They have been known to wipe out an entire peanut crop. Since they are so versatile, they have adapted to the loss of their forest habitat by raiding the spreading agricultural areas, making them very unpopular with the natives. The giant forest hog (Fig. 2.12) is the largest of all living wild pigs, reaching over a meter in height, two meters in length, and weighing up to 600 pounds (275 kg). After the discovery of the okapi in 1900 (see Chapter 4), it was

CLOVEN HOOVES thought that there were no more large mammals left undiscovered in the wild. Nevertheless, African tribes and early travelers (including Henry Morton Stanley) had long reported a "giant black hog" that had never been captured or described. Then in 1904 a Captain Meinertzhagen of the British East African Rifles in Kenya received the severely damaged skin of a large black pig from villagers near Mount Kenya. Later he received a huge skull and partial skin from near Lake Victoria. He sent these to the British Museum in London where the zoologist Oldfield Thomas recognized it as a new species and named it Hylochoerus meinertzhageni, or "Meinertzhagen's forest hog." Because of its size, the giant forest hog is not afraid to turn and fight off leopards or humans, and boars are known to charge without warning or provocation. With its huge head, broad flat bony ridges beneath the eyes, flaring tusks, and long coarse black hair, it can be a terrifying sight, and most natives fear it. Its forehead and snout form a broad, flat surface, which it uses in pushing contests with other boars. There is a concavity on the roof of the skull that can hold a cup of water. Like other wild pigs, the skull above the brain is protected by bony sinuses which act as a shock absorbers during impact (similar to that seen in the extinct brontotheres, who also may have head-wrestled). It is found in scattered local populations in tropical Africa, hiding wherever there is dense evergreen cover and fodder. It is known from subalpine areas and bamboo groves to lowland swamps, but prefers savanna-margin mosaics and wooded savannas. It frequently shares its habitat with Cape buffalo, rhinos, and others, helping to maintain the "buffalo glade" by their feeding. Like the warthog, it uses its lips to bite off grasses where they are dominant, but in other areas it eats herbaceous shrubs, lianas, bamboo, and some carrion; it rarely roots like bushpigs or other typical pigs. However, it does excavate soft earth to pick up salt and other minerals. Forest hog sounders may contain as many as 20 pigs, composed mostly of the mother and as many as three generations of her offspring, along with a dominant boar. These sounders may cover home ranges as large as 10 square kilometers. These social units are very loosely established, amalgamating and then breaking up into a new sounder. After a rough, noisy courtship, forest hogs breed nearly year round. Little is known about their reproductive biology, since they are so secreti vee Gestation is thought to be about 125 days, after which the sow bears 2-6 piglets in a protected dry spot under a fallen tree. They soon accompany their mother, and when they hear the sow's alarm grunt, they freeze flat against the ground. Nevertheless, they are apparently very vulnerable to predators. Population studies have shown that piglets have a high mortality rate, in spite of the fiercely protective adults. The biology of Asian wild pigs is less well studied than their African counterparts. Perhaps the most grotesque is the fabulous babirusa (Babyrousa babyrussa), found only on the Celebes and nearby islands in the Malay archipelago. It is one of the strangest beasts ever conceived (Fig. 2.13). Its

33

upper tusks actually pierce the roof of the snout and curl upward and backward, reaching lengths of seventeen inches. The lower tusks also protrude upward outside the mouth, giving it the weird combination of four upward and backward curling tusks in front of its eyes. Neither set of tusks occlude, so the uppers grow continuously and curl around until they eventually touch the roof of the snout again. The lowers must be sharpened against trees to keep them from becoming useless. Many explanations have been suggested for the function of these curled tusks. Native legends say that the babirusa hooks its head to a tree limb at night to rest. However, the extreme tusks occur only in boars, and are probably used mostly for sexual competition. The wear on them suggests that the boars spar and wrestle with them, with the upper tusks locking in the opponent's sharp lower tusks. In this sense they are very similar to deer antlers, whose primary function is display and combat between

Figure 2.13. The bizarre curve-tusked Asian pig known as the babirusa, Babyrousa babyrussa (Photo by D.R. Prothero).

34

HORNS, TUSKS, AND FLIPPERS

Figure 2.14. The bearded pig (Sus barbafus) , a unique wild pig found only in Malaysia and the Philippines (Photo by D.R. Prothero).

bucks. Indeed, "babirusa" means "pig deer" in the native tongue. The babirusa lives in moist forests, canebrakes, and the shores of ri vers and lakes. It is a swift runner, and a good swimmer, often swimming out to nearby islands to seek food. Its naked body is well suited for its swimming, wallowing habits. Its senses of hearing and smell are acute, and it is mainly nocturnal. Consequently, little is known about its biology. Babirusas travel in small sounders, making continuous low grunting moans as they move. They do not root with their snouts, but instead browse on leaves and fallen fruit. Offspring are borne in the early months of the year after a five-month gestation, and are not striped like other piglets. Only two piglets are born, both identical twins of the same sex. Their wild lifespan is unknown, although most captives live about 10 years, and the maximum in a zoo was 24 years. Native Malayans frequently capture young babirusas and tame them. They are also hunted regularly for food on Celebes. Because of this, and the destruction of their habitat on their only island home, they are now considered endangered in the wild. Recently, the New York Post reported that the babirusa is a "kosher pig," and could be bred to be eaten by Jews and Muslims. This is because babirusas are chiefly leaf eaters, and have a multi-chambered stomach like ruminants to aid in bacterial fermentation. However, they do not chew their cud like ruminants, so rabbinical authorities have rejected the notion of a "kosher pig." All remaining wild pigs are members of the genus Sus, which includes Sus serofa, the domesticated pig. Three rare species live in the Malay archipelago along with the babirusa. The most spectacular is the bearded pig, Sus barbatus (Fig. 2.14) found on the Malay Peninsula, Sumatra and Borneo. Its long white side whiskers flare out from the

cheeks, reminiscent of the red river hog. Bearded pigs live mainly in tropical rain forests and mangrove jungles, where they feed on a typical rooting pig diet of fruits, insect larvae, roots and shoots, and carrion. They especially favor the roots of cycads ("sago palms"), and occasionally raid cultivated yam and manioc fields. Bearded pigs often follow the sounds of monkeys or gibbons to collect the fruit that they drop. On Borneo they are noted for their long migrations; herds of hundreds of bearded pigs were easy prey for native hunters. These pigs permit the crowned wood partridge to pick worms right before their nose, and ticks from their skin. When the bird gives an alarm call, the pigs also flee. On Borneo they have no predators except the rare clouded leopard, and most of the Muslim population does not eat pork, so only the native tribes of the interior hunt them. Much less is known about the rare Javan warty pig, Sus verrueosus. Found only in Javan forests, it has three huge bony warts on the side of its head: one above and one below the eye, and a third on the far corner of the lower jaw, which may grow very large and look like a big, slack blister dangling from the jaw. Its biology, so far as it is known, is much like that of the wild boar. Even less common is the Celebes pig, Sus eelebensis, which is sometimes considered a subspecies of the Javan warty pig. Almost nothing is~known of its biology. The rarest of all wild pigs, however, is the pygmy hog, Sus salvanius. Found only in the Himalayan foothills, it is so small (less than 20 pounds, or 9 kg) that it looks like a toy pig. They live in small herds in dense brush, coming out mainly at night. It is now restricted to northwestern Assam, where only 100-150 individuals are thought to survive. Almost nothing is known of its biology, and very few sightings have been reported in recent years. Finally, the familiar domestic pig is a descendant of the wild boar, Sus serofa. Even before domestication and dispersal by humans, wild boars were long widespread in the Old World, occurring all over Europe, North Africa, and temperate and tropical Asia; they have been secondarily introduced to North and South America. Wild boars are extremely versatile in diet and habitat, as the large geographic range suggests. They are found in plains and mountains up to 13,000 feet (4000 m) in elevation, in swamps and dry steppes, and even close to civilization. They can live in cold regions with heavy snow cover, trekking single-file through their paths in the snow when it becomes too deep. In central Europe they eat not only grasses, but the full spectrum of pig foods found by rooting (such as fungi, roots, tubers, bulbs, nuts), as well as carrion, wounded animals, rodents and other small mammals, reptiles and amphibians, eggs and young ground-nesting birds, insects and their larvae (especially grasshoppers), crabs, clams, worms, and just about anything else they can catch or dig up. Wild boars have similar social habits to most of the other suids we have just discussed. Sounders consist of about 20 individuals, mostly sows and their offspring, with occasional dominant boars accompanying them, as well as

CLOVEN HOOVES peripheral bachelor herds of submature males. Their large home ranges (typically about 200 hectares) encompass a central den or sleeping area constructed of grass mats with a roof held up by grass, and several wallows. From these centers, they spend much of the evening foraging over a large area in search of anything edible. They mark their home ranges with cut marks from their canines on "marking trees," as well as scent from lip glands. Their eyesight is poor, since they live. in dense cover, and hunters have long known that hiding quietly in ambush is the best way to catch them. Their sense of smell, however, is acute, since they must find food underground; domestic pigs are used to hunt for truffles for this very reason. Their hearing is also excellent, and like domestic pigs, they are among the most intelligent of hoofed mammals. They quickly learn how to avoid danger and outwit hunters routinely. Males wage violent battles for estrus females, pushing and shoving shoulder to shoulder as they try to slash with their sharp tusks. During rutting season adult boars develop a thick, loose layer of connective tissue on their shoulders and on their face that helps protect them from bleeding to death of tusk wounds. By the end of mating season the older boars are covered with serious wounds and severely emaciated, losing up to 20% of their original weight. They then retreat to their solitary lives to recover their strength. In tropical climates mating occurs year round, but in more temperate regions the mating season is November to January. After a gestation of about 115-140 days, the piglets are born in late March and April in a quiet place with dense plant cover. They build large nests of branches, which protect the naked piglets from the cold. The sow has six pairs of mammae and the piglets squeal and push and shove to compete for a position at a teat. This "suckling order" often means that the smallest "runt" is starved to death, and piglets often injure each other with their emerging tusks. By two weeks they are rooting and eating solid food. Piglets are weaned after three or four months, but they do not become sexually mature until 12-18 months. Infant mortality is extremely high, and only one or two piglets make it to adulthood. Their lifespan in the wild is about fifteen years. Their major predator in most of Eurasia is the wolf. In other areas they may be hunted by lynx, leopards, or tigers. They were hunted by humans for a long time, and many ancient civilizations and Germanic tribes gloried in boar hunts. Because of their gregariousness and adaptability to any diet, pigs were remarkably easy to domesticate. The earliest certain record of domestic pigs is from 6500 B.C. in Mesopotamia, near the town of Jarmo, Iraq. Domestication is documented from China around 4900 B.C., and possibly as early as 10,000 B.C. in Thailand. They have apparently been domesticated in many different places over the centuries, although all domesticated pigs are descended from the Eurasian wild boar. Domestic pigs are found in cultures that are sedentary and usually agrarian, not in nomadic cultures. This is because pigs cannot be driven over long distances like cattle, sheep, or goats. On the other hand, they

35

are valuable to agricultural economies, since they are easily kept in a confined pigpen, mature sooner than other ungulates, have larger litters, and consume human refuse. In many cultures the pigs wander around the village, performing the task of garbage collector. Pigs are so versatile that a number of domestic stocks have been reintroduced to the wild, and become feral pigs. Many were released for sport hunting, or escaped from human settlements. Feral pigs are widespread from the Carolinas to California, on eight of the Hawaiian Islands, Puerto Rico and the Virgin Islands, and many other islands where Europeans have brought livestock. Under these conditions the domestic features tend to disappear after generations of wild breeding, and some begin to resemble the ancestral wild boars again. Feral pigs, along with goats, are the bane of the conservationist. Their rooting is far more destructive than the grazing of goats, and they easily destroy habitat for vulnerable native species that once lived in isolation. "NEBRASKA MAN" AND JAVELINAS Although we think of the "Roaring Twenties" as an age of bootleg liquor, flappers, and jazz, it was also an age of conservative backlash. After the stresses of the First World War, America yearned to return to "normalcy," as' Warren Harding promised when he was elected President. Businesses were allowed to make money without regulation, eventually leading to the stock market crash of 1929 and the Great Depression. The Ku Klux Klan returned to the South in force with lynchings and cross-burnings. During such conservative periods in American history it is common for religious conservatism to stage a comeback as well. Evangelists such as Billy Sunday were at the peak of their popularity. Tent revival meetings were so widespread that they became moneymakers for corrupt preachers so vividly described by Sinclair Lewis in Elmer Gantry. Amongst all this religious fervor, fundamentalist attacks on evolution returned. The battle between science and religion has a peculiar history in N011h America. In Europe, the religious objections to Darwin's book had virtually vanished by his death in 1882. Few educated people disputed the fact of evolution, although among scientists there was still disagreement as to whether Darwin's mechanism of natural selection was sufficient. In the United States, Cornell University President and historian Andrew Dickson White wrote A History of the Waifare of Science with Theology in Christendom in 1896 on the assumption that the war was over, and that religion had ceased interfering in scientific matters. Yet at the same time, religious conservatives who were upset at scholarly findings about the origin of the Bible founded the Fundamentalist movement in 1895 in Buffalo, New York. Their major tenet was the belief in the literal truth of the Bible. Long after the educated world had thought the issue settled, a handful of reactionaries tried to go back to the world before 1859.

HORNS, TUSKS, AND FLIPPERS

36

A

H_s,o.rt}~(-th.cu,s

~~t.~&""

:....r-·

.... .-,

1-· ....

('J~,.

On-t:.,.';'"

".",..

Lb~ (J

HtDnD

~4pi"'$

(N.a·,".~)

Figure 2.15. A. The teeth of "Nebraska man," which Osborn and many others mistakenly identified as a North American "anthropoid." They were eventually shown to be peccary teeth. (From Osborn, 1922). B. Reconstruction of "Nebraska man" (from the Illustrated London News, 1922). Fundamentalism virtually disappeared during the first two decades of the twentieth century, but its revival in the Twenties was paI1icularly strong. Many states in the "Bible Belt" passed laws prohibiting the teaching of evolution, which eventually led to the famous "Scopes Monkey Trial" of 1925. The famous populist orator (and three-time Democratic presidential candidate) William Jennings Bryan spent much of his time attacking evolution. This led Henry Fairfield Osborn, President of the American Museum of Natural History in New York, and one of the foremost paleontologists in the country, to answer Bryan's attacks. In a series of articles beginning in 1922, and culminating in the 1925 book, The Earth Speaks to Bryan, Osborn brought the strong case for evolution to the public eye. But his favorite piece ofevidence was a small, worn tooth that had been discovered by Harold Cook in Nebraska in 1917. The tooth appeared to be a tiny, square-shaped molar of an anthropoid ape or human (Fig. 2.15A). It was from a very old individual, so virtually all the crown surface had been

worn off, and furthermore it was very abraded before it was buried. Coming at a time when evolution was under attack and few fossil humans were known, Osborn was overjoyed. He received it in March, 1922, and a month later announced it to the world as Hesperopithecus haroldcooki, "Harold Cook's western ape." The scientific world was very skeptical. Not only was the specimen too poor to be sure it was an ape, but there was no evidence that apes had ever lived outside the Old World. This specimen, from the supposed Pliocene (now known to be late Miocene) Snake Creek beds just south of the famous Agate Springs Quarry in western Nebraska, would be the only primate in North America since their disappearance from this continent in the late Eocene. However, the specimen convinced the British anatomist Grafton Eliot Smith (one of the proponents of Piltdown Man, also recently discovered), who commissioned an overly imaginative "complete reconstruction" of the ancient ape (Fig. 2.15B). This illustration made the Illustrated London News, a classic example of the overzealousness of the scientists and the public to flesh out details about our ancestry. One of the strengths of science is that it is self-coITecting. Osborn's colleague, William King Gregory, was an expert on primate anatomy, and he had doubts about the specimen as well. While Bryan and Osborn were battling it out in print, more field work was being conducted in the Snake Creek beds. Additional specimens showed that among the Snake Creek fossils was an extinct peccary, Prosthennops crassigenus, which had remarkably humanlike teeth. By 1928 Gregory was convinced that the Hesperopithecus tooth was not anthropoid at all, but simply a very worn peccary tooth. His announcement was actually a relief for most scientists, who had doubts from the beginning, but it was seized upon with SCOIll by the fundamentalists and the newspaper editorials. How were Osborn and Smith so easily fooled? First of all, it was a very easy mistake to make. As we have already seen, both primate and pig teeth look very similar because they are square, bunodont teeth adapted for omnivorous diets. Most people would not be able to tell them apaI1. In addition, the specimen was highly worn and abraded, so any characteristics of peccaries had been lost. Even more misleading was the wear on the tooth. Apparently, it had rotated in its socket while the animal was alive, and had wear patterns that were more characteristic of primates than of peccaries. Osborn was also influenced by the fact that the Snake Creek beds contained immigrant Eurasian antelopes, so why not apes? He also saw many bone splinters which appeared to have been worked by humans. (We now know that they were fractured by an extinct family of bone-crushing dogs). Finally, there is the drive to discover our own ancestry. Osborn and Smith were not the first to misinterpret a fossil attempting to find a link to our past. As Piltdown and many other examples (detailed by Roger Lewin in his book Bones of Contention) have shown, there is tremendous pressure on paleoanthropologists to make the most of every find.

CLOVEN HOOVES

37

Figure 2.16. Restoration of the extinct long-nosed peccary, Mylohyus nasutus (right) and the flat-headed peccary, Platygonus compressus (left). (Drawn by C. L. Ripper, courtesy Carnegie Museum of Natural History). The demotion of Hesperopithecus from a primate to a peccary may have been a disappointment for some, but it actually highlights the fact that peccaries are an important part of North American mammal history. The oldest known peccary specimens occur in the late Eocene of China, and they quickly migrated around the world during the late Eocene. Among the best known of these early forms was Perchoerus, which occurs in the Big Badlands of South Dakota. It was about the size of a dog, with a relatively unspecialized skeleton. In these features, it resembles the first true pigs, which diverged from peccaries in the late Eocene. Peccaries specialized in a different direction from pigs, however. Unlike the long skulls of pigs, peccary skulls are usually shorter and deeper. Their long, slashing canines occlude only in the vertical plane, unlike the widely flaring canines of pigs. Peccary molars remain fairly simple, while those of pigs often develop very wrinkled, complex surfaces. The most significant difference is that peccaries develop significantly longer, more slender limbs with more reduced side toes than do pigs. Peccaries are much better at running from predators. From Perchoerus, several different groups of peccaries developed during the Miocene in North America. One group retained the typical short, deep skull, and was probably related to all the living species. Another group developed very long faces with broadly expanded cheek regions. In the late Miocene-Pleistocene, animals such as Prosthennops (the correct identification for the Hesperopithecus specimen), the flat-headed peccary Platygonus, and the longnosed peccary Mylohyus had wide flaring cheekbones that made their faces look very similar to the entelodonts (Fig. 2.16). Perhaps it also served to improve their threat displays and show dominance in the herd. Mylohyus was one of the most extreme of these animals, with a body almost the size of a deer, and long slender limbs suitable for running. Platygonus was the size of a very large hog, with a dis-

tinctive flat forehead. Unlike the solitary Mylohyus, Platygonus lived in large herds across the Great Plains. It was so well adapted for running on hard ground that it had lost its side toes, and was down to just two toes. Large numbers of these peccaries fell into sinkholes and collected in caves. Bat Cave in Pulaski County, Missouri, contains at least 96 individuals, and Zoo Cave in Taney County, Missouri, contains 81 (most of which are young individuals with baby teeth). Near Hickman, Kentucky, five individuals of Platygonus were found in a row, buried in a sand dune deposit, with their heads all oriented in the same direction and their backs turned toward the windstorm. One of the most famous finds was made in 1946. The owner of a brewery in St. Louis found some peculiar bones in his basement. They were sent to New York, where the famous paleontologist George Gaylord Simpson identified them as Platygonus. When he and George Whitaker went out there to investigate, they found that the "brewery" was a natural cave under an historic mansion; it had been used as a brewery in the nineteenth century because the cool cave provided an ideal place for storing kegs of lager. The cave had also served as an Ice Age trap, and had filled with clay that was studded with peccary bones "like raisins in a cake." Simpson and Whitaker camped out in the dilapidated mansion and began excavating the bones. They were perfectly preserved and easily dug out of the clay, but had to be immediately coated in preservative because they were drying out for the first time in 10,000 years. Simpson recounts a story of the time when the excavation was a big tourist attraction. While they were working, one of them let loose with an expletive, only to be reprimanded by a visiting clergyman, "Profanity will get you nowhere in this cave, young man." Despite their great success during the Ice Ages, Platygonus and Mylohyus went extinct at the end of the Ice Ages, probably due to a loss of habitat when the climate changed. Today only a remnant of the long, proud history of

38

HORNS, TUSKS, AND FLIPPERS

Figure 2.17. The collared peccary, Tayassu tajacu, has short bristly hair and a distinct collar of light fur around its neck. (Photo by D. R. Prothero).

Figure 2.18. The "extinct" Chacoan peccary, Catagonus wagneri, originally described from fossils and then discovered living in the Gran Chaco of Paraguay in 1972. (Photo by D.R. Prothero).

North American peccaries remains. The best known species are the collared peccary, Tayassu tajacu (also known as the javelina in Mexico) and the white-lipped peccary, Tayassu pecari. Both species are a little over a meter long and weigh about 70-90 pounds (30-40 kg) full grown (Fig. 2.17). They have gray-black to dark brown hair with long white bristles on the lips, chin, throat and rump; the collared peccary has a whitish band from the middle of the back to the chest that is responsible for its name. Both occupy a wide range of habitats, from dry chapparal to tropical forests. They range from Mexico to Argentina, although the collared peccary ranges as far north as Texas, New Mexico, and Arizona. As might be expected from their wide range of habitats, peccaries are omnivorous, although they prefer roots, seeds, and fruits, along with occasional insects or other invertebrates. Although they are not ruminants, they do have a three-chambered stomach with some microbial fermentation helping their digestion of cellulose. Their sharp tusks are palticular- . ly adept at digging out and cutting roots, which they love. They have strong jaw muscles, so they can crush tough seeds as well. Unlike pigs, which live in small sounders, collared peccaries live in herds of 14-50 individuals, and white-lipped peccary herds may include 100 animals. The herds are subdivided into family groups of females and their offspring, which are remarkably stable over the lives of the individuals. In the dry season, the herds tend to split up into subgroups and forage over a wide area, keeping in contact with a wide variety of barks, grunts, and nasal noises. The herd occupies a stable territory, which is defended from intruders' and marked by secretions from a scent gland in the rump. The core area of their territory is marked by dung piles. They also reinforce herd cohesion by standing side-to-side and rubbing each other's facial glands (located below the eye), which aids in scent recognition. There is also much

mutual grooming and scratching with snouts before they go off to feed in the morning. Adult males guard the periphery of the group: and battle with other males to defend the territory and prevent them from mating. Although the dominant male tries to prevent it, the females may mate with several different males. Because most males are excluded by the dominant male, there is typically a 3: 1 ratio of females to males in the herd. There is no courtship ritual, and copulation lasts only a few seconds. Gestation lasts 142 to 158 days, after which a single precocious young is born. It is weaned after 6-8 weeks, although it remains dependent upon its mother for 24 weeks. It is also protected by other family members, and if danger threatens, all will come to its defense, sheltering the young under their hind legs while they present a threat display. When threatened, they produce a remarkable rasping sound that is caused by the chattering of their teeth. Their natural predators are mountain lions or jaguars. Other than their sharp canines and speed, peccaries have few natural defenses. If the predator surprises the herd, they scatter while emitting alarm calls to confuse the big cat. If young are present and there is dense habitat to hide them, one peccary (usually a subadult) may stand up to the predator to allow the others to escape, at considerable risk to itself. This kind of fatal altruism is rare among mammals, and could only be evolutionarily successful in an animal with a highly developed herd structure and close familial bonds. When the Panamanian land bridge reconnected South America to the rest of the world about 3 million years ago, peccaries migrated southward. One of the first to do so was the flat-nosed peccary, Platygonus. In 1904 the great Argentinian paleontologist Florentino Ameghino described a fossil of one of its descendants as Catagonus. This animal was thought to have become extinct at the end of the last ice age. Since no more large mammals had been found any-

CLOVEN HOOVES where in the world after the discoveries of the okapi in 1901 and the giant forest hog in 1904, there was no reason to think that any more big unknown beasts had been missed by zoologists. When a group of zoologists, led by Ralph Wetzel, began to explore the Gran Chaco in 1972, they found a region full of a diversity of mammals that had never been studied. The Gran Chaco is a broad flat region about the size of California that covers 60% of Paraguay and parts of northern Argentina, yet only 5% of Paraguayans live there. It is covered with a thick thorny scrub with isolated islands of palms and grasses, with great extremes of both rainfall and temperature during the year. Imagine the shock and surprise of the zoological world when, in 1972, the supposedly extinct Catagonus wagneri was discovered alive and well and living in Paraguay (Fig. 2.18)! Although the local people knew it well and hunted it for its meat, they considered all peccaries to be alike. This animal was marked like the collared peccary, only it was much larger, weighing up to 95 pounds (43 kg). It had white jowls and a black stripe along the middle of its back, and more importantly, it had a long snout with eyes high in the back of its head like Platygonus. It was also a long-limbed runner like Platygonus, although it still had four toes on its front feet. Only limited zoological studies have been done on the Chacoan peccary to date, but in most features its biology is similar to the other two species. However, it has herds of only five individuals, and is known to be much more waterloving than the other two species which live with it. The Chacoan peccary is more of a browser and less omnivorous than other species, feeding mostly on legume seeds, roots, and cacti; it munches down the spiny pads without flinching! It has a more complicated system of nasal sinuses than other peccaries, giving it an advantage when breathing the dry, dusty air of the Gran Chaco. All of the evidence indicates that this species is a remnant of a much larger animal found widely over South America during the Ice Age. Its teeth are large for its body size, and they are crowded together, indicating that they have undergone some kind of postglacial dwarfing. The remaining populations in the Gran Chaco are probably a relict which survived in the thorny scrub, where it is difficult for jaguars or cougars to find them, and there are few people to hunt them. Zoologists confidently assert that most large mammals around the world have been found, and therefore no such things as unicorns could exist. As the Chacoan peccary shows, however, not everything has been discovered. THE "RIVER HORSE" When most people hear the word "hippopotamus," they think of a fat, jolly, droll, slow-moving, lazy, roly-poly beast that eats water plants. Hippos from the Nile were familiar to the Egyptians, and thus to the Greeks and especially Romans, who put them in the arena to fight to the death. In medieval legends, there were many myths about the strange beast the Romans called hippopotamus (from the Greek hip-

39

grazing in the savannas near their river homes. (From the IMSI Master Photo Collection) pos, "horse", and potamos, "river"). Hippos were frequently portrayed as biting other animals or humans in half, or breathing fire from their gaping mouths. In actuality, hippos are very different from the popular perception. Although they are indeed fat, they are well adapted to their aquatic lifestyle, and can swim very quickly and gracefully under water. Even on land, they can move remarkably well, and a charging hippo can outrun a human over short distances! More importantly, they rarely eat water plants. Instead, they sleep in the water during the day and come out at night to graze along the riverbank, sometimes wandering miles from their homes (Fig. 2.19). In his book Animal Kitabu, Jean-Pierre Hallet writes: "Hippopotamuses, or 'river horses' as the Greeks called them, love to horse around in rivers, lakes, shallow pools, and evil-smelling mudholesgrunting, rumbling, snorting, blowing, bellowing, and burping, or sleeping in the shallows with their heads pillowed on each other's backs. They can swim at more than ten knots per hour and stay beneath the surface for as long as five to ten minutes, but when darknrss falls, they· march inland to conduct the second and nocturnal phase of their amphibious operations. [At the] Jinja Golf Course in Uganda ... they trek from green to green during the night, happily mowing the grass while leaving sets of parallel tracks that look like ruts impressed by broad-tired cart wheels. Golfers raved and cursed until Jinja club officials made a new ground-rule: if your ball lands in a hippo's footprint, you may remove it and drop it on the adjacent turf without being penalized. At the Rwindi Camp in Congo's Albert National Park, the hippos sometimes used to come out on moonlit nights, walking a full mile from the Rwindi River, just to stand outside the restaurant and watch the tourists eating, drinking,

40

HORNS, TUSKS, AND FLIPPERS chattering, and playing cards. During the day, the tourists went to the river and watched the hippos. Zoo-going citizens of the Western world ... visit the hippo pool and peer at a vast shadowy form lurking on the bottom. After a few minutes, it surfaces. They catch a glimpse of turreted eyes and slit-like nostrils on a bulging snout. It submerges. Then they leave the hippo pool, convinced that the fat, stodgy-looking animal spends his entire lifetime in the water. At best, they feel, he may creep along the shore. The mere thought of hippos ambling through a golf course or a churchyard strikes them as a Disney-style cartoon or an LSD-inspired hallucination. Kiboko [Swahili for hippo] may be fat, but he is far from stodgy. Aside from his proficiency in water sports, he is surprisingly agile on land, where he roams from dusk to dawn and even ventures forth on cloudy days. On longer treks, when his skin begins to) grow too dry, subcutaneous glands secrete a sort of 'suntan lotion,' a reddish oily liquid that soothes and lubricates his skin, and has led men to believe ever since Biblical times that hippos 'sweat blood.' [Switching the tail back and forth to break up their dung] is the hippo's homely method of staking out territory; and he stakes it out so thoroughly, switching his tail like a frantic pendulum, that zoo hippo pools must be drained and refilled every day. Odder still, if one hippo dares to invade another's territory, the rivals stage a weird duel: they 'shoot' each other, not with guns but with bowels, whisking their tails to send the dung flying. The intruder then retreats, but for some obscure reason both parties feel that honor has been satisfied. If a younger bull is, however, bent on issuing a serious challenge to an older one's established territorial rights-especially in overcrowded areas-the two of them will really fight, booming and splashing half the night while they gash each other's hides with their tusks and sharp incisor teeth. It is an epic battle, for mature hippos may reach twelve or fourteen feet in length, measuring five feet tall at the shoulder and weighing over three tons. Some bulls may even exceed eight thousand pounds ... Kiboko looks like an up-ended barrel covered with slate-colored, nearly hairless skin. His girth is nearly equal to his length, so his pinkish belly barely clears the ground while he goes galumphing forward on his stubby little legs. Port and starboard sides move independently in a rather sprightly pacing gait, preceded by his huge boxshaped head and followed by his foolish eighteeninch tail. His rounded ears, placed at· the very summit of his head, are equally minute but never

stop twitching. His eyes, close beneath them, are set in periscopic turrets like the eyes of crocodiles or frogs, so that he can watch the passing scene while the rest of him is underneath the water. His squared off muzzle, two feet broad, is tipped with bristling hairs and crowned at its highest point by two slit-like nostrils; like his ears, they seal completely at will, enabling him to dive swim, walk, or even sleep beneath the surface. To submerge, he has two separate and distinctive styles: if he decides to dive while already in the water, he lets his rear end sink slowly while his front end follows after; but if startled while he is standing on a high bank, he launches himself headlong, landing among the fish with a gargantuan belly-whopping splash. When he surfaces he spouts a column of water, blowing air through his nostrils with a loud snorting noise ... When [his mouth] is opened to the widest, whether he is merely yawning or challenging an enemy in water or on land, his entire head appears to split apart. His gaping mouth, some three feet from jaw to jaw, looks like a huge red cavern edged with ivory '4 stalactites and stalagmites. He has fourteen pairs of molars and premolars, all of them grinding away daily at some two to four hundred pounds of grass and ground forage plus the few water plants he eats as tidbits, mostly lotuses and water lilies ... Tusks and incisors, all composed of fine-quality, extremely hard ivory, are not used in feeding. Hippos clip grass with their heavy lips, trimming it as closely as a flock of sheep. The front teeth are employed for fighting among themselves, since no animal predator will attack a full-grown hippo, not even twenty-foot Nile crocodiles who may weigh a ton." (Hallet, 1968: 132-138). By most animal standards, hippos have enormous appetites. A typical 5-6 hours of feeding each night will yield 80-100 pounds (35-45 kg) of short grasses. As much as this sounds, it is actually only about 1-1.5% of their body weight, compared to 2-3% for most hoofed mammals. Like peccaries, hippos have two extra compartments in their stomach, but it is not as efficient as a fully ruminating stomach. Instead, hippos get by on proportionately less food by conserving energy better. The short active feeding period is balanced by almost 18 hours of sleeping nearly motionless in warm, buoyant water. This minimizes the energy expended holding their bodies up, moving for protection or feeding, or keeping themselves warm. The drawback of this lifestyle is their dependence upon water. When there are severe African droughts, hippos often have to fight for the few remaining mud holes. Many die from heat prostration because they have few mechanisms to dump heat from their well insulated bodies other than immersion in water.

CLOVEN HOOVES

41

Figure 2.20. The pygmy hippopotamus, Choeropsis liberiensis. (Photo by D.R. Prothero). Mating season occurs at the peak of the dry season, when hippo populations are concentrated in the rivers and larger waterholes. As described above, bull hippos go through noisy, violent combat rituals to establish dominance in their pool (Fig. 2.1). Hippos mate in the water, with the female submerging for some length of time, lifting only her head to breathe. In dry years only 6% of females will be pregnant, but in wet years as many as 37% will be carrying calves. After about 240 days of gestation the cow leaves the group and seeks out a secluded pool where she gives birth underwater, or sometimes bears the calf on land. The calf knows how to swim as soon as it is born, since at birth it may have to paddle to the surface to breathe. After 10-14 days of seclusion, the mother returns to the main herd, and the calf frequently rides on her back with his head above water. Although the cow is fiercely protective, and can attack any predator (she can even kill a lion or bite a crocodile in half), calves are very vulnerable to lions, leopards, hyaenas and crocodiles. Only half survive the first year, 150/0 are lost in the second year, and 40/0 each year thereafter until they reach maturity at about 7-9 years of age. Although hippos have a high infant mortality rate, their populations are actually expanding. They are the only megaherbivores thriving in Africa at present, since they do not have the ivory or horn that leads to the poaching of elephants and rhinos. In some areas hippo densities have become so great that they are overgrazing their habitat. Culling has been allowed to reduce numbers, and the hunted animals are prized by the natives for their meat. In addition to the familiar species, Hippopotamus

amphibius, there is another, less familiar animal, the pygmy hippo, Choeropsis (sometimes called Hexaprotodon) liberiensis (Fig. 2.20). This beast is less than five feet (1.5 m) long, only about a meter at the shoulder, and weighs 400600 pounds (180-275 kg). It is found only in tropical west Africa, primarily in Liberia, the Ivory Coast, Sierra Leone, and Guinea. Unlike the larger hippo, the pygmy hippo is more adapted for browsing in the dense forest on leaves, shoots, and fallen fruit. Its head is much more streamlined, without the eyes and nostrils set high on the skull for seeing and breathing submerged. Its feet are less webbed, and the toes spread out more broadly for better traction on land. Pygmy hippos hide in forests and swamps, tunneling through the bushes in the dense jungles. They do take to water to hide, but spend most of their time on land. Their prolonged exposure to air means that they secrete more of the red exudate ("blood") to protect their skins, and they typically have a sleeker appearance. Since they are rarely seen, however, very little is known of their biology. Sadly, most of their forest habitat in western Africa has disappeared, and they are now very seriously endangered in the wild. Africans have also hunted them for meat, since they are considered as tasty as pigs. Indeed, it appears that pygmy hippos have always been rare. Rumors of a "large black pig" were common in the nineteenth century, but most of these referred to the giant forest hog. Zoologists did not see bones of the pygmy hippo until the 1840s, when it was formally described and given a name. Not until 1870 did a live specimen come into scientific hands, where it was kept in the Dublin Zoo. Subsequent

42

HORNS, TUSKS, AND FLIPPERS

Figure 2.21. The piglike artiodactyls known as anthracotheres were found in Eocene and Oligocene riverbed deposits all over the world. This restoration of Bothriodon from the Big Badlands of South Dakota is not nearly as hippo-like as later descendants. (Painting by R. B. Horsfall, from Scott 1913).

expeditions to Liberia allow the observation of this strange beast in its natural habitat. The living pygmy hippo is not the only example of dwarfing in this family. Indeed, hippo dwarfing has happened often in the geologic past. Most of these dwarfs have occurred on islands, where there are no large grassy savannas, so they must take up a forest-browsing, pig-like habit. During the Ice Ages there were different species of dwarfed hippos on Cyprus (Hippopotamus minor), Crete, Sicily and Malta (Hippopotamus pentlandi), and Madagascar (Hippopotamus lemerlei). The dwarf hippo from Cyprus was only the size of a small pig! This pattern of large grazer and small (or dwarf) browser is actually quite common in hoofed mammals. As we shall see in later chapters, the forest species of African buffalo and elephant are small versions of their plains counterparts. There were also dwarfed species of rhinos in the Miocene of Texas which were apparently more adapted to the coastal forests than their High Plains relatives. Where do hippos come from? They have an excellent fossil record in Africa over the last seven million years, and they were widespread over Europe during the Pleistocene interglacials. Indeed, hippo fossils have been found even in the London suburbs! Hippo fossils are known from the Pliocene of the Siwalik Hills in Pakistan, and even from Burma and Java, so they once spread across the Old World tropics. In East Africa their evolution can be traced from Olduvai Bed I (1.8 million years old) with relatively small, short-snouted forms to Olduvai Bed IV (300,000 years), where we encounter Hippopotamus gorgops. This beast had truly periscopic eyes elevated well above its head, so it could see when submerged even better than the living hippos.

Prior to seven million years, however, the hippo fossil record is very poor. Until recently, only a few scraps of teeth were known from lower Miocene beds that suggested an earlier history. The same ecological niche suitable for hippos was occupied by an ancient group of artiodacyls known as anthracotheres (Fig. 2.21). These beasts are known as early as the late Eocene in Burma, China, and North America, and were very successfully performing the role of aquatic grazerlbrowser all over the world during the Oligocene and Miocene. Indeed, their name means "coal beasts" because their fossils were first found in coal seams that were remnants of ancient swamps. In the Big Badlands of South Dakota, anthracotheres such as Heptacodon, Bothriodon, Elomeryx, Arretotherium, and Kukusepasatanka are rare, but typically found' in the river channel deposits. Anthracotheres were even more diverse in the Oligocene and Miocene of Eurasia. In the early Miocene Dera Bugti locality in Pakistan, for example, there are dozens of species and genera of anthracotheres, whereas there were only four species of pig and one of peccary, and only a few species of deer, antelope, horse, tapir, rhino, and mastodont. (This locality is also unusual in that the last survivors of the amynodont and indricotherine rhinocerotoids, discussed in Chapter 14, peristed here almost 10 million years after they had become extinct elsewhere in the world). Anthracotheres were also one of the first groups to successfully invade the island continent of Africa and compete with the native endemic species. The last of the anthracotheres, Merycopotamus, persisted until the middle Miocene in Africa, and the early Pleistocene in Asia (especially Pakistan and China). It was by far the most hippo-like of anthracotheres, with a broad flaring snout, prominent tusks, and a lower jaw whose shape

CLOVEN HOOVES is extremely hippo-like. Most paleontologists such as Edwin Colbert and Shirley Coryndon had used this similarity to suggest that hippos were descended from anthracotheres. In 1983 Martin Pickford described the oldest known hippo fossils from the middle Miocene, about 15 million years ago, in Kenya. Called Kenyapotamus, these fossils led Pickford to suggest that hippos were not related to anthracotheres, but to peccaries. Like peccaries, hippos have extra stomach compartments, distinctive features of the jaw, a buried groove in the palate, and vertically pointing canines which do not show sexual differences (unlike pigs). Since there were peccaries in many parts of the Old World before Kenyapotamus, there is no problem with their closer relationship to the typically New World peccaries than the typically Old World pigs and anthracotheres. According to Pickford, most of the features which are similar in Merycopotamus and hippos are due to evolutionary convergence. Anthracotheres disappeared from the aquatic grazer niche in Africa about 15 million years ago, but not until about 7 million years ago did hippos evolve to fill it again. A remarkable beast, the hippo. What better way to conclude our discussion than with a poem?

Much more an enormous pig than a sort of horse, Hippo lives, as a matter of course, Both in water-still or running, fresh or saltAnd on adjacent land, where its Gestalt Takes fifty poonds (dry weight) of grass per night. In human cropland, which it freely samples, Much of what it doesn't eat it tramples, And signs point to a final interspecies fight. The losing bull in an intraspecific bout Hides wounded skin and pride in water, where, With only eyes and nostrils out, He surveys the scene and takes the air. To save its skin from air as well as flood, Hippo "sweats" thick, oily "blood." (Burns, 1975)

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Figure 3.1. A guanaco male group at Torres del Paine National Park, Chile. (Photo courtesy W.R. Franklin.)

3. Tylopods

CAMELS WITHOUT HUMPS When we hear the word "camel," our minds make many associations: "ship of the desert," a brand of cigarettes we'd walk a mile for, an animal designed by a committee, a haughty foul-tempered scowling beast that spits on people. As children,· we heard the Rudyard Kipling "Just So Story" about how the camel got its hump from saying "harrumph" too often. From our earliest trips to the zoo, we learned to associate the word "camel" with humps and the Arabian desert. Contrary to expectations, most of these features are late developments in camel evolution; they are not typical of most of their 45 million year history. Camels evolved in North America in the middle Eocene, and remained restricted to this continent for about 40 million years. The latest research recognizes over 90 species and 35 genera in North America alone. They have a longer history on this continent than any other group except horses and rhinos, but they did not travel to other continents (as horses and rhinos did) during much of the Tertiary. For most of their history camels were not desert beasts with humps. On the contrary, camels had diverse ecologies, and acted as surrogates for African antelopes and giraffes in the North American savanna grasslands. Then, about 6 million years ago, they began to spread to other continents and establish the living species. Some went south along the new Panamanian land bridge and invaded South America about 3.5 million years ago, where they became the llama, alpaca, vicuna, and guanaco (Fig. 3.1). Others crossed the Bering land bridge and spread to Asia and Africa about 6 million years ago, eventually evolving into the dromedary and Bactrian camel. Finally, at the end of the last Ice Age, camels and llamas went extinct in their North American homeland. The earliest camels are represented by Poebrodon, which comes from the middle Eocene of Utah and California (Fig. 3.2). As we have seen, the middle Eocene was the time of greatest diversification of artiodactyls, but Poebrodon stands out. Many of the middle Eocene artiodactyls were changing their simple round-cusped cheek teeth (like those of pigs and peccaries) into specialized teeth with four high crescent-shaped crests (selenodont teeth) for shredding fibrous vegetation. But the rabbit-sized Poebrodon was the most selenodont animal of the time, with

the highest-crowned teeth by far, apparently adapted for the coarsest vegetation available. Since that time, camels have retained a stereotyped, high-crowned selenodont dentition, long before the rest of their skeleton evolved into its present form. Alongside the earliest camels in the middle and late Eocene was a group of close relatives, the oromerycids. For a long time, the oromerycids were mistakenly placed with the camels. The best known oromerycid, Proty[opus, is commonly portrayed in popular books as the ancestor of the camels. However, recent research has shown that oromerycids split off from camels early in the middle Eocene, and late in their history evolved high-crowned teeth like those of true camels. One of us (Prothero) described Montanaty[opus, the most camel-like of oromerycids, from the late Eocene of Montana. For 40 years after the specimens were discovered, they were misidentified as a camel. Oromerycids died out at the end of the Eocene, along with brontotheres and many other beasts we shall discuss later in this book. In addition to the diversification of camels and oromerycids during the middle Eocene in North America, there was a third group of strange-looking tylopods (camel relatives) on this continent. Known as the protoceratids (Fig. 3.3), they were long associated with the hypertragulids, one of the primitive hornless "deer" we will discuss later. However, recent research has shown that they are in fact the closest relatives of camels, and belong in the Tylopoda. The earliest protoceratids (from the middle and late Eocene) were hornless, but may have had a prehensile lip for browsing. The most distinctive feature of advanced protoceratids is the horn-like appendages on their heads. In the Oligocene deposits of the Big Badlands we find a striking animal known as Protoceras. Males (but not females) had a series of odd-looking short horns on their snout, over their eyes, and on top of their heads. The early Miocene Syndyoceras had a branched hom on its nose, and backwardpointing curved horns above its eyes. By the late Miocene its descendant, Synthetoceras, had a slingshot on its nose and the same curved horns above its eyes. Paratoceras, a middle Miocene beast from the Gulf Coast of Texas, had curved horns over its eyes, and a Y-shaped hom on the top of its head that vaguely resembles a propeller on a beanie.

HORNS, TUSKS, AND FLIPPERS

46

'lEIS.

OXydllCtylua

I Kyptoceras, the last of the family, was recently described from the late Miocene of Florida by Dave Webb. It had paired horns coming from its snout, and forward-pointing' horns arising from the top of the head. Although their horns seem grotesque, they are no weirder than the amazing suite of horns we will see in deer and antelopes. Dave Webb has argued that their horns were used for both combat between males, and for display to

Figure 3.2. Phylogeny of the tylopods, showing the major features of camel evolution. PLIO = Pliocene; PLEIS = Pleistocene (drawn by C. R. Prothero).

frighten rivals and attract females. This is the way that most horned ruminants use their horns, so it is reasonable to infer the same behavior for the horned tylopods. Kyptoceras, in particular, was well suited for display, and for neckwrestling and pushing, since the angle of attack of the horns would force males to interlock without seriously injuring their opponent. Protoceratids were always rare, and they probably lived

PLEIS

Synthetoceras

PLIO

W

Z

W

0

0-

~

W

Z

W

0

0
Syndyoceras

w

z

w

o

Protoceras

o

w

Figure 3.3. Phylogeny of the protoceratid tylopods. PLIO Prothero).

= Pliocene; PLEIS = Pleistocene

(drawn by C. R.

48

HORNS, TUSKS, AND FLIPPERS

in habitats that are not often fossilized. During the Miocene virtually all known protoceratids come from the swampy, forested Gulf Coast region. According to Christine Janis, their molars and broad, moose-like snout indicate a diet of swampy vegetation with little fibrous cellulose. They also have relatively short limbs, and do not fuse their toes up like camels or ruminants. This suggests that they were not open plains runners, but preferred more brushy or swampy terrain. The only protoceratid from the High Plains, Lambdoceras, has a narrower snout suitable for tree browsing. Like many other characteristic Miocene mammals in North America, protoceratids became extinct at the end of the Miocene. As we shall see for camels, horses, rhinos, and many other mammals, this was a time of climatic change, cooling and drying, with a destruction of much of the Miocene habitat-including, apparently, the swampy Gulf Coastal plain on which protoceratids depended. By the late Eocene and Oligocene true camels (Family Camelidae) had become well established in North America. Next to leptomerycids and oreodonts (discussed below), they are the most common artiodactyls in the deposits of the Big Badlands of South Dakota. They are most common in the more southern part of the continent (from Colorado and southern California to Texas), but rare in North Dakota or Canada, so they must have been sensitive to temperature. The typical Badlands camel, Poebrotherium, was the size of a goat, and built much like one. Unlike any other contemporary hoofed mammal, it had already evolved a relatively long slender neck and limbs. The central digits of its feet had already become elongated for running, and nearly fused together into a "cannon bone." A distinctive feature of camel cannon bones is that they fork at the far end, allowing the toe bones to splay out and giving camels their characteristic broad feet. The side toes were completely lost, so camels were the earliest two-toed artiodactyIs. The gap (or "diastema") between its nipping front teeth and the cheek

teeth was enlarging as the snout became longer, and the cheek teeth became even more specialized for grinding. Another characteristic camel feature is the spongy bone filling the chamber which surrounds the middle ear. All of these features were even further developed through the evolution of camels, but they were already well established in Poebrotherium of the late Eocene. In the late Oligocene and early Miocene, camels diversified in North America. Conservative, poebrothere-like camels such as Paratylopus lived alongside a more highcrowned group, the pseudolabines, including Pseudolabis and Miotylopus. The most specialized descendant of these pseudolabine camels were the stenomylines, whose long, narrow molar teeth were rooted deep in the jaw and skull (Fig. 3.4). Stenomylines were extremely graceful and gazelle-like in proportions, and have been found in large grazing herds much like gazelles. A third group was the bizarre floridatragulines, whose long snout is like that of a fish-eating crocodile! Found only in Texas and Florida, they probably lived in the subtropical forests of the Gulf Coast, but the purpose of their unusually long thin snout is unknown. There were also the long-necked, long-limbed oxydactylines, which eventually evolved into the g~raffe-like Aepycamelus (formerly Alticamelus). Oxydactylus may have been the ecological equivalent of the gerenuk antelope (Fig. 5.16B), which stands on its hind legs to reach bush tops and trees. Eventually aepycamelines became extremely longnecked and long-legged, with a neck capable of reaching leaves 18 feet (5.5 m) above the ground! These animals functioned as the ecological equivalent of the giraffe in North America, even though they are descended from camels (Fig. 3.5). By the middle Miocene there were at least 9 genera and 17 species of camel in North America, especially in the hilly country of Nevada, California, and New Mexico, and in the

A

B

Figure 3.4. A. Side view of the skull of the gazelle-camel Stenomylus. Some of the bone has been removed to show the extremely high-crowned, deep-rooted teeth adapted for eating grasses. (From Frick and Taylor 1968). B. Restoration of Stenomylus, showing its gazelle-like proportions. (Painting by R. B. Horsfall, from Scott 1913).

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Figure 3.5. The antelope-camel Oxydactylus and the giraffe-camel Aepycamelus, both common in the middle and late Miocene savannas of North America. Primitive gomphothere mastodonts and horses are shown in the ba~kground. (From a mural by R. Zallinger, courtesy Yale Peabody Museum). swampy Gulf Coast forests of Texas and Florida. They performed virtually all the roles that antelopes and giraffes do in the East African savanna today. Along with the gazellelike stenomylines and the giraffe-like aepycamelines, there were two other major groups. Both the miolabines (including Miolabis, Homocamelus, and Nothotylopus) and the protolabines (including Tanymykter, Protolabis, and Michenia) became more short-legged and stockier than their oxydactyline relatives. The teeth of miolabines eventually became relati vely low-crowned again, whereas protolabines are distinctive in having a long, narrow snout. Both groups have strong ecological similarities with a number of African antelopes which specialize in browsing certain low-level bushes and grasses. Fossil footprints show that camels had acquired their distinctive walk by the Miocene. When camels move, they pace, moving both legs on the same side of the body together. Most other hoofed mammals trot (the foreleg on one side moves at the same time as the diagonally opposite hind leg).

Pacing is particularly useful for long-legged animals, since legs on the same side of the body never end up hitting each other (as they can when trotting). The disadvantage of pacing is that they lift both feet on the same side, so they are less maneuverable and stable, and can fall over. (This is why camel riders sway so much and feel seasick riding the "ship of the desert"). Camels have compensated by developing widely splay-toed feet, strong ligaments supporting the feet, and placing their limbs near the midline of the body. Dave Webb has shown that the low forward placement of the head also helps to counterbalance the body sway during pacing. Pacing is very well suited for animals which run across open plains, and requires fewer steps and less energy than trotting to cover the same distance. This is one of the many tricks that gives camels an advantage over other hoofed mammals when crossing the desert. At the end of the Miocene the great camel radiation was decimated. Miolabines, protolabines, and aepycamelines all disappeared, along with many other mammals characteristic

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HORNS, TUSKS, AND FLIPPERS

of the North American Miocene savanna. Climates were again changing around the world. Many mammals which had been abundant in the middle and late Miocene savannahs of North America were severely reduced in numbers. Horses, which had been so diverse in the late Miocene, are represented by only a few genera. Oreodonts were extinct, as were several other types of artiodactyIs, such as the protoceratids. Rhinos (discussed in Chapter 14) also went extinct in North America. The great profusion of deer-like animals and pronghorns was diminished. Several genera of mastodonts also disappear. Small mammals show less of an effect, although several archaic rodent families (the mylagaulids, or "horned gophers" and the eomyids) die out, as do a number of other rodents, rabbits, shrews and moles. What caused these late Miocene changes in North American land mammals? The end of the Miocene experienced a worldwide climatic event whose effects can be seen in Europe and Asia, and especially in the microfossils of the deep sea. This event, known as the "Messinian crisis," has recently been explained. During the late Miocene the northward drift of Africa toward Europe had been steadily closing off the Mediterranean and raising the Alps. The Mediterranean was already closed off at its eastern end in the Middle East, and water flowed only through the western opening. About 5.5 million years ago a major expansion of the Antarctic glaciers caused a large drop in sea level. When this happened there was no further oceanic flow across the present-day Straits of Gibraltar. The Mediterranean, without its oceanic flow, became first a gigantic stagnant sea, like the Black Sea, and then an evaporating lake, like the Great Salt Lake. Finally it completely evaporated away, leaving a giant basin 10,000 feet deep covered with a mile-thick deposit of salt and gypsum. For thousands of years this basin remained cut off and empty, until sea level rose again as the ice caps melted. When the Gibraltar barrier was finally breached it formed a gigantic waterfall with a flow of 10,000 cubic miles of water per year. This is a thousand times the flow of Niagara Falls. The water rushed into this gigantic salty basin and filled it up again, producing the modern Mediterranean. Naturally such a dramatic event had worldwide consequences. All of the world's oceans are closely linked in a global system of circulation and chemical balances which are the main force controlling climate. When such a large body as the Mediterranean is first isolated and then catastrophically reunited with the world's oceans, it has major effects. Global oceanic circulation changed, and the withdrawal and sudden reintroduction of all that salt caused severe salinity imbalances. For this reason the terminal Miocene is often called the "Messinian salinity crisis." These oceanic changes, combined with the Antarctic glaciation, meant a drastic change in worldwide climate. Naturally, the vegetation on land responded to this climatic change. The land mammals were not far behind. This time, however, many did not adapt, but instead were driven to extinction. By the Pliocene the mammal fauna of North America has a very modern look, and many beasts of the Ice

Ages had already appeared. The habitat had changed from the savannas so typical of the Miocene to a steppe vegeta.. tion. Most of North America's native groups which had dominated so long, such as rhinos, oreodonts, protoceratids, camels, horses, and others, would never again be so abundant. The first three were gone from North America for good. Only the two modem groups of camels, the lamines (now represented by the llama and its relatives) and camelines (now represented by the Old World camels) survived. According to Jim Honey, lamines are derived from more primitive aepycamelines, but the camelines are related to Procamelus, a more advanced aepycameline characteristic of the late Miocene. Lamines are distinctive in having a larger, more domed skull than camelines, since they have larger brains, and in their distinctive "llama buttress," a pillar-like feature on their molars. The most successful and long-lived of the North American lamines was Hemiauchenia, which persisted for 11 million years from the middle Miocene until late in the Ice Ages. Long-limbed and fast running, it was found all over North America in the Pliocene and Pleistocene. In Florida it lived alongside its short-limbed relative, Palaeolama, whose stout legs suggest that it originated in the Andes and then migrated back, over the Panamanian land bridge to North America. The last and best known of the lamines was Camelops, found everywhere in western North America from Saskatchewan to Mexico (but not in the southeast, where other llamas dominated). Camelops was about 20% larger than the living dromedary, with a longer neck and legs, a long slender face and large, deeply split, mobile upper lips which were prehensile for grasping food. The high arch on its backbone suggests that it had a hump, unlike any other lamine. Camelops is known from many deposits characteristic of the end of the Ice Ages, such as the famous La Brea tar pits. Mummified remains of Camelops have been found in the arid Southwest, radiocarbon dated as young as 10,000 years ago, so it survived until the present interglacial. Although there are no clear kill sites, its extinction may have been caused by overhunting by humans, since it has been found in association with Clovis arrowheads. In the mid-Pliocene (about 3.5 million years ago) the Panamanian land bridge rose up and reconnected South to North America after tens of millions of years of isolation. In the early Pleistocene (about 1.5 million years ago), one of the northern invaders were lamines such as Hemiauchenia, which quickly became established all over South America. From these ancestors arose the modern species of South American lamines: the wild vicuna and guanaco, and their domestic derivatives, the llama and alpaca. The vicuna and guanaco are humpless camels that give us a glimpse of what prehistoric camels must have looked and behaved like (Fig. 3.6). The vicuna (Vicugna vicugna) live almost exclusively in the alpine puna grassland in the Andean foothills of Peru, Bolivia, Chile, and Argentina at elevations of 12,000-16,000 feet (3500-4900 m). It is the

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Figure 3.6. An adult territorial male vicuna in the Pampa Galeras National Vicuna Reserve in Peru. Note the large bib of white hair in the chest region of this Peruvian subspecies (not found in the Argentinian subspecies). (Photo courtesy W.R. Franklin.) smallest of the wild camels, weighing about 100 pounds (45 kg), and reaching three feet (1 m) at the shoulder. It is covered with long, soft cinnamon-colored fleece, with white undersides. The males may have a white bib. The vicuna is very graceful, and very adept at running over rocky terrain at high altitudes. It can run 30 mph (5 km/hour) at elevations of 15,000 feet (4500 m), which leaves most humans gasping for breath. Since it lives in open terrain, it has excellent vision for spotting predators at a distance, but does not need as good a sense of smell or hearing. It spends much of its time grazing low .perennial grasses of the Andean tundra. This harsh environment is characterized by extremes of heat, cold, wind, and aridity. A mild rainy growing season from December to April alternates with a cold, dry season from May to November when temperatures and wind chills are below freezing and little plant life can grow. William Franklin has shown that vicunas are one of the few ungulates to defend a year-round feeding territory and separate sleeping territory. A feeding territory of approximately 45-acres is connected to a 6-acre sleeping territory

51

by an undefended corridor. Territories are marked by numerous communal dung piles. Family groups consist of a dominant male, several females, and associated young-up to 5-10 individuals. The male warns the others of dangers with a loud alarm trill. He leads the group in its daily rounds, and defends it against other males. Lone males and bachelor herds of 15-25 individuals constantly provide challenges to the dominant male in each family group, resulting in occasional vicious· fights. Like other camels, vicunas have sharp canine teeth in males that can be used to slash a rival. The males typically fight by biting at the front legs and hind quarters or crossing their necks to force their rival to his knees. Like other camels, vicunas mate with the female lying down on her chest, and the male mounting her from behind. Copulation lasts 10-20 minutes, and is accompanied by many grunts and squeals. Mating occurs during the end of the rainy growing season in March and April, and births take place 11 months later at the middle of the next growing season. The single young vicuna can stand and walk 15 minutes after it is born. It runs and sleeps alongside its mother until about 10 months of age, when it is weaned. Young males and females are driven away by the dominant male before they reach one year old, when they join another group. Females mate at about 2 years of age, and can reproduce until 10-12 years of age. The maximum captive longevity is 24 years and 9 months. The Incas routinely rounded up wild vicunas and sheared them of their wool. The Andes may have supported as many as 1.5 million vicunas before the arrival of the Spaniards. The slaughter of the Incas also led to the slaughter 'of vicunas, mostly for their wool and meat. By the 1950s there were fewer than 400,000, and intensified hunting diminished that number to 10,000 by 1967. Since that time, they have been classified as an endangered species, and there are believed to be about 80,000 today. The guanaco (Lama guanicoe) is similar in many ways to the vicuna, but larger, weighing 220-265 pounds (100120 kg) and reaching 4 feet (1.2 m) at the shoulder (Fig. 3.1). It has a cinnamon brown color with white undersides, but it may also have blackish fleece on its face. The guanaco lives not only in barren grasslands, but also in lower-elevation pampas and desert scrubs of Peru, Chile, and especially Argentina. Since it lives in the dry pampas, it must be able to go a long time without drinking, unlike the vicuna, which must drink daily. It can run 35 mph (55 km/hour) across the plains, and swims well, too. Depending upon its habitat, it can be both a grazer and/or a browser, and populations are either migratory or sedentary. Family groups consist of 4-10 females and a single dominant male. Like vicunas, guanacos use communal dung piles of small, dry pellets, which reach 8 feet (2.4 m) in diameter and a foot (31 cm) in height. Females mate and give birth every other year after an II-month gestation. Unlike the vicuna, the guanaco mating season is in August and September, at the beginning of the pampean spring. The

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famous paleontologist George Gaylord Simpson, while collecting fossils in Patagonia, wrote a memorable description of guanaco behavior: "The favorite child of Patagonia is surely the guanaco. A guanaco looks like a small, humpless camel, which it is, and it also looks like a careless mixture of parts intended for other beasts and turned down as below standard, or like the result of a long period of miscegenation. It has a head something like that of a hornless deer, long ears like a mule, a neck that tries but fails to reach the giraffe standard, a scrawny, shapeless body, and gangling legs like those of a young colt. To top off the joke, it has a stubby little brush of a tail, only a few inches long, which it carries crooked, the base vertical and the tip curved back and down, so that it looks very much like the handle of a jug. Unlovely and miscellaneous as is his exterior, it is less erratic than a guanaco's mental processes. If actions are a fair guide, his mind is often vacant, sometimes hysterical, and always stupid. It would be charitable to suppose that some of the guanacos I have seen were insane, and that all suffered from a sort of animal arrested development of the intellect and emotions. Their psychology, if such apparently vague and disordered thoughts can be dignified by such a term, seems primarily to involve a lifelong conflict between curiosity and timidity. Among the first guanacos I saw, and the one that I came to know best of all, was a solitary animal that used to watch me work on the barranca south of Colhue-Huapf. Safely separated from me by an impassable gorge, he would appear every afternoon and curse at me for intruding in his realm, yammering by the hour. Imagine a tin horse that has been left out in the rain until thoroughly rusty, and then imagine that the tin horse has colic and is trying to whinny, and you will have a faint conception of a guanaco's yammer. The only other sound I heard them utter was an expression of fright and sounded like the first notes of a coloratura donkey, also rusty. Yammering expresses all at once, 'I see you, ' 'What the hell are you doing on my property?' 'Look out, boys, here's something queer!' and 'Oh, dear, oh, dear, oh, dear, what shall I do about this?' A full translation would aso have to include some obscenity, for there is something distinctly indecent about the noise as it issues from the beast's protrusile and derisive lips. Any unusual thing, such as a man, is sure to attract the attention of every guanaco in the vicinity, and a chorus of yammers results. A gua-

naco is an artist who simply must express himself. Not for him to take in a situation and then silently slip away. He must get close enough for a good look, and then must express his disgust with the whole arrangement in a full and decisive way. Here is the conflict in guanaco psychology again: when he is afraid of anything he proceeds to call attention to it himself. Often we should have been quite unaware that there were any guanacos around if they had not insisted upon telling us so. When we heard a yammer, we could be sure that the beast was in plain sight, perhaps half a mile away, but surely somewhere where he had a good, clear view of us. This is also demonstrated by the guanaco strategy of retreat. They never hide. When startled, their primary idea is always to keep their presumed enemy in sight. They make for the nearest good lookout point, and if they decide on flight, they run along ridges and in exposed places as much as possible. Perhaps this is not quite so dumb as most of their doings, since it might well be an ideal system against their primeval enemy, the puma, but it is worse than useless against their present archenemy, man. Still, they have only known man for a few generations and their learning ability is practically zero. What was good enough for their ancestors in the Pliocene Epoch is good enough for them. Climbing seems to have an irresistible fascination for them and they spend hours running up and down barrancas. There is no food for them there, or any other apparent legitimate business, and they seem to climb for fun and because they do not have anything better to do. All the cliffs are covered with their trails, often the most practicable routes for human climbers to follow, and they go almost anywhere that a man can and many places that he should not. Often we have cursed at them as we toiled slowly up an almost vertical trail behind a guanaco who went bounding lightly along, having the time of his life. One of the most curious and inexplicable of all the habits of these curious and inexplicable beasts is their way of depositing their dung in certain fixed places. The dung, which resembles that of a sheep but is larger, is always deposited on an old pile, and some of these piles still in use must be many years old. How they get started and whether the piles are individual, communal, or used by all comers we were unable to learn" (Simpson, 1934: 189-195). Although Simpson was a colorful writer, he was a poor observer. William Franklin and others have shown that guanacos are actually quite intelligent, adaptable and handsome

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Figure 3.7. A. The two-humped Bactrian camel of Asia. (From the IMSI Master Photo Collection). B. The onehumped dromedary camel of Africa. (Photo courtesy A. Walker). animals, expert at coping with the harsh conditions in Patagonia. Simpson may have insulted the guanaco for the sake of humor, but it is not a modem view of their intelligence or behavior. When settlers brought their sheep to Patagonia, the puma began to hunt the slower, stupider sheep in preference to its usual prey, the guanaco. This drove the humans to kill the pumas, which led to a population explosion in guanacos. Then people were angry that guanacos were eating all the grass for their sheep, and began a senseless slaughter of guanacos. Adult guanacos were hard to catch, but the gauchos had no trouble catching their young, the chulengos, with their bolas. Soft chulengo hide was worth several pesos, and nearly all the young guanacos were destroyed, resulting in a severe population crash when the adults began dying off without replacement. From an original population of millions, they were driven to near extinction, and are now endangered in Peru and Bolivia. However, the Argentinian government stepped in and declared them protected, so now there are about half a million in Patagonia. Llamas and alpacas are believed to be domesticated descendants of the guanaco, although some argue that they may be partly bred from vicunas, or descended from some other extinct lamine. Domesticated by pre-Incas, llamas and alpacas numbered in the tens of millions before the Spanish conquest. Like the Plains Indians with the bison, Incas made good use of their llamas: as a beast of burden, the meat used as food, the wool for clothing, the hide for sandals, the fat for candles, its hair· for rope, and its dried dung as fuel. Llamas were the prime source of wealth of the Incan civilization, carrying their loads, helping build their cities, packing out the ore in their gold and silver mines, and moving their armies. Incan royalty was always accompanied by a napa, a white llama dressed in a scarlet shirt, gold earrings, and a necklace of red shells. During religious ceremonies, thousands of llamas and alpacas were sacrified to the gods. The Incan civilization was essentially bounded by the range and ecological limits of the llama. Today, llamas are used primarily as pack animals, but their numbers are declining

because they are being replaced by trucks and trains. The Incas concentrated on breeding the alpaca for its long, fine wool. Today, alpacas are replacing llamas in terms of numbers and importance, since their wool is so valuable. Each alpaca produces 3-5 pounds (1.7-2.3 kg) of wool a year, so that Peru alone exports over 6 million pounds (3 million kg) of wool valued at about $24 million a year. SHIPS OF THE DESERT In contrast to the lamines, the camelines have had a slightly different history. After evolving from Procamelus in the late Miocene, most Pliocene camelines went in for huge size. As their names testify, they were giants: Megatylopus, Megacamelus, Titanotylopus, and Gigantocamelus are typical late Miocene and Pliocene camelines, and some reached 11 feet (3.4 m) at the shoulder. Their limbs were massive, and the skulls of some were almost 3 feet (1 m) in length! Apparently, most of them had humps, as do all living camelines. Like Camelops, the camelines were restricted to western North America, and were not found in the llama haven in Florida. However, camelines died out in North America at the end of the Pliocene, and only lamines persisted on this continent until the end of the Ice Ages. The earliest record of camels in the Old World is from the late Miocene (about 6-7 million years ago) of Venta del Moro, Spain. They are proof that North American camels had migrated across the Bering land bridge by this time, and immigration continued sporadically through the Pliocene. The genus Camelus quickly became established all over the Eurasian desert region. There are sparse fossils that indicate camels were in northern and eastern Africa in the Pliocene. By the Pleistocene, species of extinct camels resembling the two-humped Bactrian were known from southern Russia and Romania to India, and ancestors of the one-humped dromedary were known from the Middle East and North Africa (Fig. 3.7). Today, the Bactrian and dromedary maintain the same separation, with the long-haired, cold-adapted Bactrian found in the mountainous regions of central Asia, and the dromedary in the deserts of the Middle East and

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North Africa. The two species coexist in Turkey, Afghanistan, and Turkmenistan, where they may interbreed. They are not very different genetically, and as embryos, dromedaries have two humps that merge into one as they develop. Research indicates that the Bactrian was domesticated before 2500 B.C. in the plateaus of northern Iran and southwestern Turkmenistan. The origin of the domestic dromedary is more controversial; some say that it happened as early as 12,000 B.C. in southern Arabia, while others argue that there is no good evidence of domestic dromedaries before the 4th century B.C. Camels are legendary for their strength and endurance, especially in the harsh deserts and steppes of Africa and Asia. Caravans of dromedaries have crossed 375 miles (600 km) of the Sahara Desert in three weeks with little water and with scant feed. In winter, camels can graze for two months without water. In summer camels endure desert heat for eight days without water, and may lose up to 40% of their body weight. By contrast, a man is dehydrated when he loses only 5% of his water, delirious at 10% loss, and dead at 12%. A donkey can lose no more than 25% of its body weight before dropping dead. Camels have been clocked at 40 mph (65 kmlhour), and are good swimmers. Normally they walk about 20 miles (32 km) per day, carrying loads of 220 pounds apiece. Over a four-day period, camels have been known to carry 600 pounds (275 kg) at a rate of 30 miles (50 km) per day and 3 mph (5 km/hour). How do they manage these feats of endurance? Camels have a wide variety of physiological and anatomical features that are uniquely suited to harsh conditions. We have already seen how the pacing walk of camels is more efficient than the trot of most other herbivores. In addition, all camels have unique crescentic red blood cells. This enables the high-altitude South American camels to retain oxygen better. The red blood cells of Camelus hold onto water longer than any other mammal, and can reabsorb large amounts of water without exploding, as human red blood cells would after a long dry spell. Camel blood retains water in the bloodstream longer than other mammals, so when the camel is dehydrated, its blood doesn't become too thick (as human blood does). Camels also allow their urine to become very concentrated, so they do not need to excrete water as often. Many people think that camels store water in their humps, but this is not exactly true. The hump is made entirely of fatty tissue, which serves mostly as a food reserve. When the camel has gone a long time without food or water, its hump becomes flaccid, and its ribs show. Water is also stored in the rumen of their stomach. Once they have fed and watered, the hump fills up again, and they plump out. Camels are capable of prodigious drinking bouts after a long period without water. In hot weather, thirsty camels can guzzle down 35 gallons (132 liters) of water in about 6 minutes, and under extreme conditions, a really thirsty camel can drink 50 gallons (190 liters) in a day! When necessary, camels can drink brackish and even salty water. They eat virtually any vegetation found in their desert habitat, includ-

ing salty plants that are rejected by other mammals, and even flesh, fish, bones and skin in a pinch. Besides their blood, camels have many other anatomical specializations. Chief among these is their method of temperature regulation. Camels have very few sweat glands, so they cannot dump heat quickly as most mammals. Instead, camels do not try to regulate their body temperature as closely as we do. Their large body mass takes a long time to heat up or cool down, and they can allow their temperature to rise as much as 1OaF (6°C) without ill effects, retaining much of this body heat in the cold nights. (By contrast, humans only tolerate about 2°F, or 1°C, in temperature fluctuation before they have a fever or chills). Camels turn broadside to the sun when they are trying to warm up, and face their narrow profiles into the sun at midday when they want to minimize heat gain. The rest of their anatomy is ideally suited for desert conditions. They have a bony "visor" in the skull to shield the eyes, and long eyelashes to catch the sand. If these fail, they have a "third eyelid" which sweeps the sand from their eyes. In sandstorms, they can see through this "third eyelid" and continue walking with their eyes protected. Their nostrils are slit-like, so they can close them and keep out the sand as well. The groove in their cleft upper lip helps direct moisture from the nose into the mouth. Finally, their widesplayed toes give them broad feet like snowshoes, giving excellent traction and are less likely to sink into loose sand. Camels are indispensable to many nomadic cultures of the arid regions of Africa and Asia. The Bedouins of the Sahara use them not only for riding and carrying loads, but also to pull plows, provide milk, meat, wool for clothes and tents, and leather for water bags. They use dried camel dung as fuel, and the urine is used as an antiseptic, as a baby bath, a cure for acne, a mouthwash, and an aphrodisiac. Women use camel urine as a henna rinse for their hair, and men for reddening their beards. Camels are also the prime source of wealth and currency in much of the Sahara and Arabian peninsula. Naturally, the Bedouin consider them "the gift of Allah." However, to others they are very difficult, temperamental beasts. The camel has terribly bad breath, strays away unless watched constantly, and it is legendary for spitting on people. All camelids are capable of drawing foulsmelling gastric juices up the length of their throats and spitting them with great precision. When a camel is really angry at its master, it can bite with its sharp teeth. At these times, camel owners have learned to give the camel the coat off their back. The angry camel will bite it to shreds, but its anger will be displaced from its owner. Since camels now depend on humans for their water, a sudden rainstorm in the desert can cause a stampede of camels who don't need peopIe any more. A particularly vivid description of life with a camel was provided by Arthur Weigall: "All camels are discontented. They hate being camels, but they would hate being anything else,

TYLOPODS because in their opinion all other living creatures are beneath contempt, especially human beings. The expression upon their faces when they pass you on the road indicates that they regard you as a bad smell. They nurse a perpetual grievance against mankind and ruminate upon their wrongs until they groan aloud. When you go to them to find out what is. the matter they give you no hint of any specific trouble, but merely look at you with sad, reproachful eyes and groan more loudly. In certain cases when their sense of unbearable insult is overwhelming, they try rather halfheartedly to bite you. The fact that a camel has yellow teeth, a harelip, a hump, corns and halitosis places the poor creature beyond the range of ordinary sympathy. People never put their arms around camels or stroke or kiss them, and yet their sorrowful eyes, fringed with long, languishing lashes, are beautiful, and their whimpering is heartbreaking. But camels do not ask for love or pity. They make no response whatsoever to overtures of that sort. They have no hope, and they make no friends. When they are being ridden, they do not attempt to cooperate with their riders, and when they are being used as beasts of burden they try their best to make you feel like a cad ... Like all camels, Laura was extremely stupid. For instance, she could never be taught that she must remain crouched until her rider was in the saddle, and must not scramble to her feet just at the moment when he was mounting... Laura always watched me out of the comer of her eye until she caught me at a disadvantage. When I swore at her she only gazed at me sorrowfully and uttered her inconsolable grumbles. A camel, by the way, can do more than look at you out of the corner of an eye. It can turn its head completely round and stare at you full in the face with both eyes. I know of nothing more disconcerting ... It is not customary to allow a riding-camel to walk, because the motion is rolling and you lurch from side to side in a sickly manner which suggests a reason for calling the camel the "ship of the desert." A quick jog trot is the usual gait; you simply bump up and down in the saddle like a cavalry trooper, the bumps becoming bigger and better as the pace increases to a gallop. Laura used to add to the fun by occasionally jumping over low rocks, but she never fell. In fact, I have never heard of a camel falling. Laura became a mother when she was about ten. In the spring the male camels attract the attention of the females by making gurgling noises, like water running out of the bath, and inflating their tongues until they hang out of their mouths like

55

pink balloons. Laura could not resist the blandishments of a magnificently disdainful he-camel who hailed from down Suez way and was in the transport business. As she appeared to be all wrought up in her own melancholy fashion, we arranged a rendezvous. Although Laura was not a large animal as camels go, the resulting foal stood three feet high when it was a week old ... Laura's various expressions of loathing, together with endless groans and complaining, made you think she could not possibly be in good health. I used to watch her teaching her foal· to grumble. When she saw me coming she would start bleating and bubbling, putting her head close to her infant's as she did so, in order that the sounds might be imitated" (Weigall, 1933). The success of camels in Old World deserts eventually inspired people to bring them back to their original homeland in the New World, where Camelops had roamed just 10,000 years before. In 1836 a young Army major named George Crossman suggested that camels be used for western exploration, but .nothing came of it for 15 years until Crossman became deputy quartermaster general. His subordinate, Major Henry C. Wayne, investigated the idea and supported it enthusiastically, and eventually they prevailed on Secretary of War Jefferson Davis to get $30,000 from Congress to fund the project. In 1855 Wayne went to Syria, Egypt, and Tunisia on a camel-buying trip, eventually obtaining 20 dromedaries and 13 Bactrians. He also hired six Levantine Arabs and a Turk to accompany the animals back to the United States on the corvette ship U.S.S. Supply. Quartered in wooden stalls on the deck, all but one survi ved the three-month journey, and two more were born on the trip, in spite of the rough seas. The Turk, acting as veterinarian, had no medications, so when a camel became ill, he tickled its nose with a lizard's tail. The camels landed on May 14, 1856, near Galveston, Texas, but most of their Arab attendants deserted when they reached America. The two remaining Arabs had to instruct American cavalrymen on the feeding and watering of this strange animal that did not behave like a horse. Naturally, their instructions were hampered by the language barrier. In those days Army rations included a daily amount of beer, but the Arabs, as strict Muslims, could not drink theirs. Instead, they poured it into the camel's water, since they knew camels would drink anything, and water was scarce. The troopers assumed that beer was an essential part of camel's diet, and this practice continued until the commander halted the issue of beer when he saw drunken camels lurching around the compound. When the camels sobered up, they were tested, and the War Department report concluded that they could carry 1000-pound (450-kg) loads for 30-40 miles (50-65 km) a day, and would not require water for 6-10 days. This was the necessary impetus for further camel imports. In February 1857 the Army brought 44 more

56

HORNS, TUSKS, AND FLIPPERS

camels to Texas, and they soon became a familiar sight, plodding along between San Antonio and the Gulf Coast ports. Along with the second shipment was an Arab named Hadji Ali, who was known to Americans as "Hi Jolly." He soon became the primary defender of camels in America, helping the Army understand their psychology and trying to overcome the resistance of lifetime cavalrymen. The major problem was that the troopers had not been raised around camels as the Arabs had, and had little patience or understanding for their idiosyncrasies. Time and again, they got angry when camels wouldn't do things that horses do, and they never did learn to appreciate what camels were best at. The other problem was the strong scent of camels always frightened horses, and frequently caused a stampede. The city of Brownsville, Texas, even passed an ordinance banning camels from the city streets. Again, this was a problem of unfamiliarity, because Arab horses raised around camels are not bothered by their smell. In 1858 a British company landed two more cargoes of camels in Texas for the Watson Ranch near Houston. A San Francisco company brought in 20 Bactrians to haul s~lt over a 200-mile (320-km) trek in Nevada. These camels so frightened horses that Nevada passed a Camel Traffic Law in 1857, barring camels from public highways. The largest experiment used camels to haul supplies between Fort Tejon, just north of Los Angeles, and Fort Defiance, New Mexico. This was so successful that they had a camel corral in downtown Los Angeles, where the Los Angeles Times building now stands. By this point, camels were breeding successfully in their long-lost homeland, so that over 100 were found across the country. The Great Camel Experiment seemed destined to make camels a common feature of the western landscape, along with mustangs and longhorns. Our western movies might have shown Tom Mix or Roy Rogers on his faithful camel, Trigger. Unfortunately, the Civil War broke out, and the Army lost interest in the camels, or the West in general-it had more pressing matters to deal with in the East. Hi Jolly struggled to keep the camels ali ve during the 1860s after the Army abandoned them, but it was a futile effort. By the late 1860s he had to turn the rest of them loose to forage for themselves. Hi Jolly eventually died in Arizona, broken and disappointed; his grave is marked by a statue of a camel. Feral camels continued to wander around the American desert for the rest of the century, but they were hunted viciously by cattle ranchers who did not want them grazing on their lands. The last one supposedly died in 1900, although the Paiute Indians claim to have seen three wild camels in the Mojave Desert near Victorville, California, as late as 1928. Another historian insists that the last U.S. Cavalry camel died as late as the 1930s. The camel could have become well established in the land of its origin, but it never caught on due to intolerance, not to its own inability to adapt. Camels became very successful when introduced to the Great Australian Outback, and are still found there. Ironically, these camels were mostly derived from American zoo-bred stock!

Figure 3.8. Joseph Leidy, the founder of vertebrate paleontology in North America. This photo was taken in 1853, at the height of his career describing fossils. (Photo courtesy Academy of Natural Sciences, Philadelphia).

"MOUNTAIN TOOTH" After the expeditions of Lewis and Clark in 1803-1805 there were few scientific ventures into the Great West fo; over 40 years. Most of the exploration was carried out by fur traders and mountain men, who were interested primarily in beaver furs and routes through the mountain passes. In 1846 a fur trader brought a fossilized jawbone down to the Missouri River to St. Louis, and showed it to Dr. Hiram Prout. It had come from the forbidden region known to the French fur traders as the Mauvaises Terres, or "bad lands," because they were bad lands to travel across or find water in. As described in Chapter 12, Prout recognized it as the remains of a gigantic extinct beast he called Palaeotherium although today we call it a brontothere. ' News of this discovery prompted others to leave the Oregon Trail or the Missouri River route in search of more fossils. In 1849 David Dale Owen, U.S. Geologist, sent John Evans nOlth of the overland trail up the Platte Valley, and he managed to pacify the Sioux long enough to make a short visit to the "bad lands." Evans came back with many specimens of fossilized teeth and jaws. In 1850 the Smithsonian Institution sent Thaddeus Culbertson to the "bad lands," and

TYLOPODS he came back with an even larger collection. Almost all of these specimens ended up with Dr. Joseph Leidy of Philadelphia, one of the few men in the country who was interested in them (Fig. 3.8). Joseph Leidy was then a 25-year-old professor of anatomy at the University of Pennsylvania, and a gifted naturalist. Abandoning his medical practice, he concentrated on the many natural objects that excited his curiosity. It was an age when almost all scientists were true amateurs (since no one made their living from science), and few were specialists. A good natural historian had state-of-the-art expertise in virtually any animal or plant that came his· way, since very little was known about the great fauna and flora of America at the time. Leidy published short one-page papers in the Proceedings of the Philadelphia Academy of Natural Sciences almost weekly, describing the many interesting finds he had displayed at their meetings. His publications ranged over many subjects, from the wings of locusts, to the anatomy of the sloth, the red snow of the Arctic, and the parasites of fishes. Collectors were happy to send him their finds, because he always gave them credit (often naming a new animal after them), and published it promptly. When Joseph Leidy began to receive these fossils, he realized that they represented extinct animals never seen on this continent, or among any fossils previously described. In 1847 he described the first American camel, Poebrotherium, which we discussed earlier. In 1850 he described the first American rhinoceros (as we shall see in Chapter 14), and in 1853 he described a little deer-like beast he named Leptomeryx evansi (after the collector, John Evans); we shall discuss leptomerycids in the next chapter. By this time, he was specializing in fossil vertebrates from North America, and he became the father of vertebrate paleontology in this country. He published several large monographs on the fossils he had received, including two on the fossils of the "bad lands." He remained one of the few men studying vertebrate fossils in this country until he retired in 1870, tired of competition from Edward Drinker Cope and Othniel C. Marsh (see Chapter 1). Although he acquired and named the camel Poebrotherium first, the commonest animal in the collections was a strange beast with primitive pig-like limbs, but selenodont teeth like those of a ruminant (Fig. 3.9). In 1848 he described this animal and called it Merycoidodon culbertsonii from the Big Badlands. (Merycoidodon means "ruminant-like tooth," and the species name honors the collector, Thaddeus Culbertson) . Later, Leidy used the name "Oreodon," which means "mountain tooth," since it was based on teeth found in the Rocky Mountains. Since Leidy had first called it Merycoidodon, this is the proper name of the beast so common in the Badlands that hundreds of thousands of specimens are known. They occur in virtually every rock shop around the country, and if you collect fossils in the Badlands, the odds are very good that the first fossil you pick up will be an oreodont. But what is an oreodont? In most features, it is not too

57

Figure 3.9. The typical Badlands oreodont Merycoidodon culbertsoni, a sheep-sized beast that is the most common fossils in the Badlands. It was relatively primitive compared to later oreodonts. (Painting by R. B. Horsfall, from Scott 1913).

different from other primitive Eocene artiodactyls. It still has relatively short toes, with all five digits on the front foot, characters shared by all primitive hoofed mammals. Oreodonts never became long-limbed or specialized for running. Early oreodonts also had relatively unspecialized heads-no long snouts, or horns, or bizarre changes in their front teeth as we shall see so often in artiodactyIs. However, they are more advanced than pigs in that their grinding teeth have crescent-shaped crests, or selenodonty, as we saw in camels, and in all ruminants as well. Their selenodont teeth, however, rarely get as high-crowned for gritty grasses as in camels or ruminants. According to Jeremy Hooker, oreodonts have specializations that place them as distant relatives of the camel/oromerycid/protoceratid group, and so they are now classified as tylopods. Oreodonts, like most of the artiodactyls we have seen so far, originated in the middle Eocene in North America. But unlike the others, they became one of the most common mammals in this continent, and never migrated elsewhere. Protoreodon is the fossil most often found in the middle Eocene deposits of the Uinta Basin, and this abundance prevails throughout their history. Given that they were such an unspecialized herbivore, it is not clear why oreodonts were so abundant. Perhaps they weren't fussy, eating a wide mix of vegetation, which was important during the climatic and vegetational changes that marked the end of the Eocene jungles and the gradual change to open savannas by the middle Miocene. If oreodonts were like "ruminating swine," they could have lived in large numbers in a variety of habitats, which might be why we find so many of them in the floodplain deposits of the later Eocene and Oligocene. By the late Oligocene, however, more specialized oreodonts appeared on the scene (Fig. 3.10). One Oligocene lineage descended from the sheep-sized Merycoidodon was

HORNS, TUSKS, AND FLIPPERS

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TYLOPODS

59

Figure 3.11. The late Oligocene oreodont Leptauchenia, with its high-set eyes and deep jaws. In this reconstruction by Bruce Horsfall, it is shown as an aquatic beast, although most specimens apparently lived in desert habitats. (Painting by R. B. Horsfall, from Scott 1913).

the much larger Mesoreodon. A second group 'was the dwarfed oreodont, Miniochoerus, which shows progressive dwarfing during the climatic stresses at the EoceneOligocene boundary. One of the most common and characteristic beasts of the middle Oligocene is known as Leptauchenia. It was a small oreodont with high-crowned teeth, and eyes, ears, and nostrils on the top of its head (Fig. 3.11). Some have suggested that this is an aquatic adaptation, but this is difficult to reconcile with the fact that they are found in large numbers in the arid dunes of volcanic dust that dominated the High Plains in the late Oligocene. The high-crowned teeth suggest a much grittier, coarser diet, and there are living desert animals with high-placed nostrils and eyes, and openings on the snout like Leptauchenia for the filters which keep dust out of the lungs. In the early Miocene oreodonts had reached their peak in diversity. Although the leptachenids were gone, there were small, slender forms known as Merychyus which were the swiftest oreodonts ever. The most peculiar, however, were the amphibious oreodonts, such as Promerycochoerus, Merycochoerus, and Brachycrus. These animals were shortlimbed and heavy bodied, like pygmy hippos or pigs, with wide flaring cheekbones and broad snouts (Fig. 3.12). Through the early and middle Miocene, the skulls of Merycochoerus and Brachycrus show a progressively more retracted nasal opening. This suggests that they developed a short trunk or proboscis like a tapir. Clearly, these oreodonts were more specialized for living in rivers and marshy habitats, browsing on leaves which they pulled down with their proboscis. By the middle Miocene, however, oreodonts were on the decline. The last of their line, Ustatochoerus, was a pigsized beast which also had a tapir-like proboscis, although

Figure 3.12. A. The hippo-like or pig-like oreodont Promerycochoerus, from the early Miocene. B. The middle Miocene oreodont Brachycrus, which had a distinct tapir-like proboscis. (Paintings by R. B. Horsfall, from Scott 1913). not as large as that of Brachycrus. Oreodonts were extinct by the end of the middle Miocene (listed as Pliocene in older, outdated books). The cause of their extinction is unknown. It is interesting, though, that they were most prolific and di verse during the gradual transition from forests to grasslands from the middle Eocene to early Miocene. The last of the oreodonts were almost all amphibious beasts with a proboscis or prehensile lip, suggesting that they were specialized leaf-eating browsers who lived mostly in riverine forests. With the exception of Leptauchenia, few oreodonts even developed high-crowned teeth for grazing. When fullfledged open savanna grasslands (which favored fast runner grazers such as horses, camels and ruminants) finally developed and the forests retreated in the middle Miocene, the slow, primitive oreodonts disappeared.

Figure 4.1. The giraffe truly towers above the plains, and is able to see for miles. (Photo courtesy A. Walker).

4. Where the Deer and the Antelope Play

GRAVEYARD OF THE AMAZONS "It was a bright November morning. A tang of fall was in the air. The underbrush was aglow with the rosy-pink of cyclamen ... fields were gay with yellow whins, and heather was coming on the hills. There was no indication whatever of the great moment that was about to break-no trumpets blaring-no angels singing. Barnum [Brown] had gone to the quarry as usual, and I was giving Pups a bath, when I heard loud talking down the trail. Looking up, I saw Niko and Pan in feverish conversation. Then they both came running toward me, shouting in Greek. 'Calm down,' I pleaded. 'What gives? I can't understand a word you're saying.' Niko gulped for breath. 'Dr. Brown... ' he panted. 'Dr. Brown wants you at the quarry quick.' 'Barnum isn't hurt?' Niko laughed. 'Right now he's the happiest man in the world. He's ... ' 'I know! I know!' I shouted. 'He's found the Samotherium! ' I raced to the qualTY. A cloud of dust rose from one corner. It was coming from Barnum's pick. He was digging furiously, around him the crew. Pushing through, I knelt beside him and touched his arm. He was trembling. Before him, where the clay had been dug away, lay a small skull with sharp pointed horns. Twisting away from it into the bank was a long line of neck bones. It was some minutes before he spoke. When he did, his voice was shaking with excitement. 'This is it! This is what we've been waiting for, Pixie. I believe the entire beast is in here-a SAMOTHERIUM! Do you know what this means? The expedition's a success!' With a whack of the pick he cut still further into the bank, exposing another vertebra. 'I can see them back at the Museum when they get my wire,' he chortled. 'President Osborn will be shouting hallelujahs all over the place. And dear Charlie Lang ... he's so excitable anyway.' Barnum was laughing-a little hysterically, I

thought. It made me happy to see him this way. He had been hoping so long for this moment ... and now it was like a dam breaking. 'This will mean a lot to us, Pixie, when we get back to New York,' he was saying. 'It's a big thing to make a discovery like this. Look at those neck bones .. how solid and graceful, like an antelope's. And that skull-how finely formed the eye sockets! The teeth are perfectly preserved!' 'And that jaw!' he exclaimed. 'That jaw did plenty of chewing in its day. See how powerful the ascending ramus is? And to think this fellow has been lying here five or more million years-waiting for me. That's why I am a paleontologist, Pixiejust for moments like this." (Brown, 1951: 201203). So wrote Lilian Brown, the wife of Barnum Brown, one of the most celebrated fossil collectors of this century. These events took place in 1924, his last year of excavations on the Greek island of Samos, off the coast of Turkey. Samoshas proven to be a treasure trove of fossil bones-over 30,000 were collected there between 1850 and 1963. Even the Greeks had myths about Samos to explain all the bones found there. According to Aelianus, they were the bones of huge beasts, the Neades, which could fracture the earth with their voices and scare off travellers. Plutarch wrote that they were the bones of Amazons, killed by Dionysus, and the ground was so covered by their blood that it is now called Panhaema ("blood covered"). From these myths, the expatriate Englishman Charles Forsyth Major decided that there must be fossil bones on Samos, and he made large collections between 1885 and 1887. Between 1890 and 1920 Samos was collected by Germans. The last and biggest excavations were made by Barnum Brown for the American Museum of Natural History in New York between 1921 and 1924, removing some 56 crates of bones in 1924 alone. In recent years, the entire area has been recollected and sorted out by Nikos Solounias. It has proven to be one of the richest and most important late Miocene (around 8.5 to 9 million years old) localities in the world. Samos contains over 100 species at latest count, including bears, weasels, badgers, skunks, otters, hyaenas, cats,

HORNS, TUSKS, AND FLIPPERS

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Figure 4.2. Phylogeny of the tylopods and ruminants, showing the different types of cranial appendages in each group. (From Janis and Scott 1987). sabertooths,· aardvarks, three kinds of mastodonts, hyraxes, three-toed horses, clawed chalicotheres, and five species of rhinoceros. More than half of the mammals, however, are artiodactyls, and most of these are ruminants: muntjacs, deer, giraffes and sivatheres (Samotherium was a primitive giraffe, discussed further below), a huge variety of antelopes, including gazelles and many extinct forms, and extinct relatives of the musk ox and nyala, chamois and mountain goat. This diversity of a11iodactyls is repeated at localities such as Pikermi, near Athens, which was first discovered in 1838, and Maragheh in Iran, and the Siwalik Hills of Pakistan. These bonebeds show that most of Eurasia and Africa was a vast savanna grassland in the late Miocene, dominated by dozens of species of ruminants. If you take the diversity of antelopes, giraffes (Fig. 4.1), and cattle in the modern East African savanna and double it, you can get some sense of what immense numbers of game roamed all over Eurasia back then. Since they first arose in the Oligocene, the dominant group of large mammals throughout the Old World has been ruminants, just as hornless artiodactyls (especially camels and oreodonts) and horses dominated in North America. Along with the suines (pigs, peccaries, and hippos) and tylopods (camels, oromerycids, protoceratids, and oreodonts), the ruminants represent one of three great divisions of the living artiodactyls. Unlike the other two groups, however, ruminants far outnumber all other artiodactyIs: there

are over 164 species living today, compared to the six species of tylopod, and fourteen suines. In fact, ruminants outnumber all other living terrestrial hoofed mammals combined (since there are only 16 living species of non-hyracoid perissodactyls and two elephants, plus the 11 species of hyrax). As we saw in Chapter 2, this advantage is probably due to their specializations of digestion. Foregut-fermenting herbivores, such as the ruminants, have a great advantage in efficiency of digestion, and thus can specialize into many different feeding niches. Not all cud-chewing artiodactyls are classified as members of the Ruminantia, however. As we saw already, some pigs and hippos have a form of foregut fermentation, even though they do· not have a fully four-chambered stomach. Camel stomachs are three-chambered in that they do not separate the last two stomach chambers, the abomasum and the omasum. The Ruminantia are distinguished by having a fully four-chambered stomach, as well as specializations of the teeth and of the ankle joint. The first chamber, or rumen, is the big fermentation vat. After the fermented food is regurgitated and chewed in the mouth as cud, it bypasses the rumen and goes to the second chamber, the reticulum, for continued fermentation. The food then passes through two more stomach chambers, the abomasum and the omasum. In the latter chamber, it is treated with gastric juices before moving on to the small intestine and caecum for digestion.

WHERE THE DEER AND THE ANTELOPE PLAY HORNS AND ANTLERS The most striking features of ruminants are their cranial appendages, whether they are horns or antlers. In Africa, the horns are the easiest method to recognize antelopes, from the graceful curves of the sable antelope to the spirals of the eland to the straight shafts of the oryx. The broad horns of Cape buffalo and water buffalo are their most prominent and dangerous feature. Hunters try to shoot the deer with the most impressive racks. Both humans and the ruminants themsel ves use horns or antlers to recognize species, their age, size, sexual maturity, and their status in their herd. In addition, these appendages are essential in sparring with other males for dominance, and in defense against natural predators-even if they are a handicap when they attract human hunters. It is not surprising that such a useful feature has evolved several times in the ruminants (Fig. 4.2). Horns are formed from a solid bony core that is covered by a sheath of the protein keratin, the same protein found in your hair or fingernails. The bony part of the hom grows only once and is permanent; it is never shed like an antler. True horns of this type are found only in the cattle and antelopes and a number of their extinct relatives. Giraffes have short bony knobs (called "ossicones") capped with keratinous sheaths on their heads which have been called horns, but their structure is fundamentally different. In giraffe development, the bony core is preceded by cartilage, while the true horns of cattle and antelopes have no cartilage precursor, but arise directly from the skull and skin. Thus, giraffe ossicones are a distinct structure from true horns. Pronghorns (which are not closely related to true Old World antelopes) also have a bony core in their horns, but the keratinous sheath is shed each year. Thus, their "horns" are anatomically distinct from cattleantelope horns. Antlers are a completely different structure entirely. They form as direct outgrowths of the skull roof, growing very rapidly with a blood-filled layer of "velvet" covering them during growth. Antlers are pure bone, and never have a keratinous sheath, but shed their velvet when growth stops and the breeding male is ready to use them for combat and defense. Then, the antler is shed after the breeding season, only to grow back next year. True antlers are found only in the deer family, including the moose, elk and caribou. Hornlike appendages occur elsewhere in the hoofed mammals. Rhinos have a horn-like structure formed of cemented hair fibers, not bone. The extinct brontotheres had huge paired bony knobs on the tips of their noses. The extinct pig Kubanochoerus had a small median unicorn-like hom on its skull, and the leptauchenine oreodonts had tiny paired horns on their noses. The extinct protoceratids had a variety of curved and slingshot-like horns, which were apparently made of bone covered with skin. This was also true of a number of extinct deerlike forms we will review in this chapter, including the dromomerycids, the merycodonts, and the climacoceratids. Surprisingly, horns are not universal among hoofed mammals. Camels never developed

63

them, nor did most pigs, peccaries or entelodonts. No horse has ever had horns, despite the myths of unicorns. Even among the higher ruminants, a variety of small deer have large canine teeth instead of horns. The mystery of horns has been extensively studied by Peter Jarman. He has shown that hom types are correlated with ecology (Fig. 4.3). Tiny ruminants (Jarman's Category A), for example, live as solitary individuals or pairs in thick forests, browsing selectively on low-fiber shoots and berries. Since they have an efficient ruminating stomach, they cannot eat too much fibrous vegetation, and must restrict themselves to small amounts of more nutritous vegetation; this restricts their maximum size as well as their habitat. Consequently, they must forage far and wide for succulent vegetation, and cannot defend a· single territory. Tiny ruminants do not show much difference between the sexes in size, and consequently have no need for complex cranial appendages. In fact, such structures might hinder their movements in the thick brush. Instead, males of mouse deer, musk deer, water deer and muntjacs have long saberlike upper canine teeth, mostly for displaying and driving off other males. Above a body weight of 33 pounds (15 kg), ruminants have more choices in diet and habitat. Most of these animals live in moderately wooded habitats, eating leaves of all types. In more open country with less restricted diets, it is practical for a male to defend a territory of palatable bushes. These antelopes (Category B, such as the bushbuck and reedbuck) tend to have the greatest difference between sexes: larger males with spectacular horns and smaller females that are hornless. Some examples, such as the kudu, differ not only in size and horns, but even in coloration. Their dietary versatility also allows the females and young to forage together in small herds, and there is less direct competition for the food among individuals. Once ruminants reach an even larger size, their diets cannot be so selective. They must eat a larger percentage of less nutritious grasses in their diet, which requires a much larger foraging range. Male antelopes or deer can no longer maintain a boundary patrol of a small territory, but instead concentrate on defending a roaming herd of females. Category D includes large antelope such as wildebeest, which have males and females that are equal in size and have horns. These animals roam over the grassland, and males defend a small area of turf against other males only during the breeding season. In Category C (including the impala and gazelle), males hold territories for part of the year, but form mixed herds with females during the rest of the year. Males may be slightly larger than females, and have more elaborate horns. The largest horned ruminants, such as the buffalo (Category E), have no territories. In these animals, the male and females both have horns, but the males are much larger, and fight among each other to establish dominance in the herd. According to Christine Janis, this ecological segregation explains the development of horns in ungulates. At the

64

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Figure 4.3. Jarman's feeding categories of ungulates as modified by Christine Janis. The top fauna is the living East African savanna fauna; the middle one is from the early Miocene of North America; the bottom one is from the late Miocene of North America. Letters identify animals in each of Jarman's feeding categories. Numbers identifying each of the silhouetted animals are given by Janis (1981). (From Janis 1981). beginning of the Oligocene the continents of the Northern Hemisphere were covered by a subtropical woodland, inhabited by hornless artiodactyls. The subtropical woodland was gradually replaced by a grassland in Eurasia in the late early Miocene (about 18-20 million years ago), and large horned ruminants appear there for the first time. These animals must have developed a strongly territorial phase in their habitat, where horns became essential; sexual differences and large, single-male herds became the rule. And so we see that the history of the Old World is dominated by horned ruminants, with little competition from camels or horses. Why, then, didn't the New World ungulates also develop horns? As we have seen, one group (the protoceratids) did so, in the late Oligocene in North America. According to Janis, this was the time of the transition to more open, grassy habitats, but it was much more abrupt than in Eurasia. Consequently, the protoceratids became the equivalent of small antelopes (Category B), with sexual differences in horns and body size, and a diet of leaves. Camels, on the other hand, moved straight from the forest (Category A) to the open grassland (Category C or D), bypassing the need to develop a territorial strategy and the requirement for horns. According to Janis, horses bypassed the threshold for hom development for a different reason. Since they are hindgut

fermenters, they always need to forage wider and eat more low-quality vegetation than ruminants of comparable size. As horses got larger during the Oligocene and began to rely more on grasses, they were already ranging over much larger territories; they could not pass through the Category B stage of browsing on leaves, and defending small territories. The key concept is the idea of a threshold for size and diet; only lineages which gradually move from non-territorial forest browsers (Category A) into territorial mixed woodland browsers (Category B) before reaching large body size and grazing can develop horns. Janis' hypothesis fits most of the available evidence quite well, although it is difficult to find a critical test, since these events happened long ago and are no longer being repeated. Horns and antlers have long been used to unite the five living families of ruminants: the giraffids (Giraffidae), the Iiving cattle-buffalo-antelope-goat-sheep family (Bovidae), the musk deer (Moschidae), the American pronghorn (Antilocapridae), and the deer family (Cervidae). Together these five families compose the Pecora and are all closely related. The pecorans apparently originated during the Oligocene in the group of primitive Eurasian fossil ruminants known as the gelocids. However, the relationships of these five families to each other has long been controversial. Until recently, the prevailing idea was that giraffes, prong-

WHERE THE DEER AND THE ANTELOPE PLAY horns, and bovids (with their bony horns or ossicones) formed one group, and deer (with antlers) and musk-deer formed the other. However, W.R. Hamilton, and later Christine Janis and Kathleen Scott argued that the embryonic development and anatomical details of deer antlers, giraffe ossicones, and bovid and pronghorn horns are very different (Fig. 4.2). Giraffe ossicones are covered only by skin, whereas both bovids and pronghorns have bony horn cores covered by hard horny keratin sheaths-but pronghorns shed theirs and bovids don't. Janis and Scott argue that the four different kinds of cranial appendages evolved independently and cannot be used to group various pecorans. When other features of the anatomy are considered, Janis and Scott find that pronghorns, deer, and musk-deer form one group (the cervoids), bovids another, and that giraffes are more primitive than any of them. Although their ideas have not yet been accepted by all ruminant specialists, we find them convincing and adopt their classification here. In recent years, most of the new evidence from molecular similarities seem to support their hypotheses. However, even more recent molecular data dispute their conclusions. For the moment, we find the molecular arguments inconclusive. "MOUSE DEER" The earliest and most primitive ruminants are hornless rabbit-sized animals from the middle and late Eocene known as leptomerycids. Leptomeryx evansi, mentioned in the last chapter, is particularly characteristic of the Big Badlands; it "is the most common artiodactyl after oreodonts. Along with the very similar hypertragulids, leptomerycids are very closely related to a living fossil, the chevrotains, or "mouse deer" (Fig. 4.4). These tiny hornless "deer" are not actually deer at all, but relicts of the origin of ruminants over 40 million years ago, and give us a good idea of the transition between ruminants and more primitive artiodactyls. As might be expected from these primitive, transitional ruminants, they lack many of the specializations in the skeleton seen in all deer, pronghorns, giraffes, antelopes, sheep, and cattle. They still have all four front toes, which have not yet fused into a cannon bone, and they have tough skin on their rumps like pigs to protect against the canines of ri val males. Chevrotains, or the tragulids (Family Tragulidae), are ruminants in the sense that they have the four-chambered stomach, but the separation between the reticulum and the abomasum is so weakly developed that they have a functionally three-chambered stomach. In the past the tragulids have been considered to be either somewhat intermediate between pigs and camels, closely related to camels, intermediate between camels (Tylopoda) and the true Ruminantia, or essentially a type of primiti ve deer. Today the living tragulids are best regarded as true members of the Ruminantia, but also the most primitive living members of this group. In some respects they appear to be living fossils, closely resembling the ancestral forms that inhabit-

65

Figure 4.4. The lesser mouse deer, Tragulus javaniGUS, showing the distinctive backward-pointing tusks. (Photo courtesy C. Janis). ed the globe in Oligocene times and subsequently gave rise to the living higher ruminants. They have successfully persisted in their ancient tropical forest habitat, while most other ruminants evolved into other niches offered by the spread of grasses and other vegetation. Christine Janis suggests that this might explain why the Old World has always been the center of ruminant evolution, since there is a land connection between the tropical forest refuges and more temperate latitudes. In the Americas, by contrast, the isolation of the Amazonian tropics from North America prevented many archaic animals from surviving in this potential refuge. It is not surprising that fossil tragulids and tragulid-like animals, classified into various extinct families and genera (such as the Hypertragulidae and the Leptomerycidae), are known from the Oligocene through Pleistocene of Eurasia, Africa, and North America. These were all small, hornless, primitive ruminants that have persisted until the present in the form of the two survi ving genera of tragulids, the water chevrotains (Hyemoschus aquaticus) of tropical central and west Africa, and the three species of mouse deer (genus Tragulus) of India, Sri Lanka, and Southeast Asia. Living tragulids are diminutive creatures (hence the name "mouse deer") that range in head and body length from about 20-36 inches (0.5 to 1 m), have a shoulder height of about 8-14 inches (20-36 cm), and weigh from 5-11 pounds (2-5 kg) as adults; the males tend to be somewhat smaller than the females. They have small heads, pointed snouts, long, thin, delicate legs, and short tails. The coat is brown to red-brown and decorated with horizontal white stripes and spots, and the belly is lighter in color than the back and sides. Relatively little is known about the detailed behavior and biology of tragulids. They inhabit exclusively equatorial tropical forests, jungles, and mangrove thickets where they feed on fallen fruit, various aquatic plants, and some foliage. They are shy, primarily nocturnal, solitary animals

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that communicate among themselves via scents and vocalizations, including a shrill, birdlike call. Their nocturnal lifestyle is particularly evident in their huge, dark-adapted eyes, which give them a timid, vulnerable look. Chevrotains have home ranges that they mark with urine and feces containing secretions from anal glands. These territories are criss-crossed with tunnel-like trails through the vegetation. The African water chevrotain is a good swimmer, and when threatened it will dive into the water and hide under a floating log or mat of vegetation with just its nose out to breathe. The three Asian species of Tragulus prefer rocky habitats. Chevrotains have chin glands that in the males of some species produce secretions which are used to mark the back of a mate or an antagonist. The males have long dagger-like canine teeth, which seem incongruous on a fruit eater, until you realize they do not have horns or antlers for display and combat between males. Instead, the males duel with a short, sharp rush, each antagonist biting his opponent all over the body with stabbing canines. As we shall see, other tiny deerlike animals have sub~tituted long canines for horns or antlers. Various large snakes, eagles, crocodiles, cats, and other forest carnivores prey on tragulids, but their most immediate long-term threat is caused by humans. Along with small hornless antelopes, such as duikers, they were one of the main prey of the Mbuti pygmies of the Ituri Forest in the Congo Basin of the Congo (described in Colin Turnbull's famous study, Forest People). The pygmies, however, never overhunted these beasts, since they also prayed to them, and depended on the forest animals for their survival. The wholesale destruction of African and Asian rainforests will probably do more than anything to drive chevrotains to extinction. The African water chevrotain is already on the endangered species list; too little is known of the Asian mouse deer species to determine if they are endangered or not. THE "FOREST DONKEY" Despite the fact that it stands five to six feet (1.5 to 1.7 m) tall and can weigh as much as 550 pounds (250 kg), the elusive okapi (Fig. 4.5) was unknown to western science until it was "discovered" by the British explorer Sir Harry Johnston in 1900. Of course, the pygmies that lived in the forests of the Congo had known and hunted the okapi for centuries and the animal was also familiar to the Belgian officials of the area. Yet the okapi was unknown in professional zoological circles. Who would expect that an animal the size of a horse remained incognito at such a late date? Sir Harry Johnston thought this might be the case, however. Sir Henry Stanley, the newspaper reporter turned explorer who rescued the missionary and explorer David Li vingstone on Lake Tanganyika in 1871, had reported tales of an otherwise unknown beast in his book In Darkest Africa (1890). An informant of one of the pygmy tribes of the Congo region stated that in their forests lived a creature that greatly resembled an ass in appearance that they occasional-

ly trapped in pits (the meat being highly prized). Based on this report, Johnston thought that there might be an unknown horse or zebra in the forests, and resolved to search for it if he ever had the opportunity. In late 1899 Johnston found himself on official business in Uganda and in the process of liberating some captured pygmies chanced upon the opportunity to learn more about the beast that Stanley's informant had mentioned. Several years later Johnston recounted that "I came in contact with a large party of dwarfs [pygmies] who had been kidnapped by a too enterprising German impresario, who had decided to show them at the Paris Exhibition. As the Belgians objected to this procedure, I released the dwarfs from their kidnapper, and retained them with me for some months in Uganda, until I was able personally to escort them back to their homes in the Congo Forest. . . . As soon as I could make the dwarfs understand me by means of an interpreter, I questioned them regarding the existence of this horse-like creature in their forests. They at once understood what I meant; and pointing to a zebra-skin and a live mule, they informed me that the creature in question, which was called OKAPI, was like a mule with zebra stripes on it" (Johnston, 1909: 268). On reaching Fort Mbeni, Congo Free State, 10hnston questioned the Belgian officers concerning the okapi. They were familiar with the animal for the native soldiers were in the habit of hunting it and returning with the skins and flesh for use at the f011. In fact, the officers thought there was a fresh skin lying about the fort that Johnston could have. Upon finding the skin,· however, they discovered that most of it had already been thrown away-only a bit of the gaudier portions (with fancy zebra-like stripes) had been saved and already cut up into thin strips to be used as belts and bandoliers. These strips of hide were given to Johnston, and he forwarded them to the Zoological Society of London in August of 1900. On the basis of these sparse remains Dr. P. L. Sclater tentatively named a presumed new species of zebra after Johnston, Equus? johnstoni. Johnston was determined to obtain a complete okapi. He entered the Congo forest and remained there for some days searching for the beast, but to no avail. Thinking that he was looking for a zebra or horse, Johnston expected the okapi to have typical horse-like hooves. Therefore when the natives pointed out the tracks of a cloven-footed animal and claimed they were the tracks of the okapi, he did not believe them. Sickness and time constraints forced Johnston to give . up his search, but his Belgian officer hosts promised to work on obtaining an okapi skin for him. After Johnston returned to Uganda, an okapi skin and two skulls were forwarded to him. Upon inspecting these specimens he realized that the okapi was not a horse at all, but a very primitive relict of the ancestors of the giraffe family. Indeed, the okapi struck Johnston as being a "living fossil," very similar to both the ancient Samotherium from the Samos fauna and the ancient Helladotherium found in the Pikermi fauna of Greece. The skin and skulls were sent to

WHERE THE DEER AND THE ANTELOPE PLAY

Figure 4.5. The okapi, Okapia johnstoni, the only living relative of the giraffe. (Photo by D. R. Prothero). London, and arrived in June of 1901. After studying them Professor E. Ray Lankester declared that they represented a previously unknown genus of giraffid which he formally named Okapia, thus giving the okapi its full modem scientific name: Okapia johnstoni. The okapi remained a recluse to western scientists for many decades. It was not until the mid-1930s that an okapi was captured alive and kept for any substantial length of time in a zoological park (there were a few earlier captures of live okapis, but they all died within a short period of time). Indeed, the official seal of the International Society of Cryptozoology, an organization dedicated to finding beasts such as the Sasquatch, the Loch Ness monster, unicorns, and the Congo brontosaur, features the okapi. Even today little is known about the behavior of the okapi in the wild. Adult okapis do indeed resemble horses in a vague way. They have long heads and drawn-out muzzles, large dark eyes, relatively large ears and a long neck, long limbs, a long black tongue (so long that they can reach their eyes with their tongue), and the males have small giraffe-like skin-covered horns. Most distinctive is the okapi's markings. The body is covered with short, sleek hair that varies in overall appearance from deep reddish-brown to purplish to not quite black. The face is lighter in color with a dark muzzle. The haunches and upper portions of both the front and back limbs have zebra-like horizontal black and white stripes, and the shanks of the limbs are lighter colored and

67

unstriped. Okapis inhabit the dense equatorial rain forest of northern Congo, particularly the riverside woodlands of the area. They are apparently active at daytime, relatively solitary, and spend much of their time wandering around singly or occasionally in pairs or small family groups. They beat tracks through the forest to their favorite feeding areas, and have glands on their feet which they may use, along with urine marking, to stake out territories. In the forests the okapis feed on various leaves, fruits, and seeds. They are reportedly very timid, running at any sign of danger-their principal enemies are leopards, snakes, and man. Their hearing is very acute. The female okapi stays in heat for up to a month at a time, advertising her condition by urine marking and vocalizations. Courtship encounters between male and female are marked by female aggression and male dominance displays, including lip-curling, displaying of a white throat patch, head tossing, and leg kicking. In the presence of a female in heat, male to male encounters may involve ritualized neck fighting, butting, and charging. Calves are born during the period of maximum rainfall, from about August to October after a gestation period of approximately 430-460 days. Babies are born with a small head, short neck, and a conspicuous mane which is essentially lost in adults. It has been suggested that stripes on the legs and flanks of the adult okapi may be important for calf imprinting. Female okapis will defend their young by kicking potential predators. The longevity of okapis is unknown, but they are reported to have lived for over 15 years in captivity. The okapi keeps to fairly localized areas, and is reported to remain relatively common in some parts of the Congo. It has fallen under government protection since 1933, yet it is difficult to prevent poaching in dense and remote forests. Even though the okapi is not at present officially an endangered species, invariably increased human pressures could unfortunately always change this for the worse. THE CAMELOPARD Arab poets and prophets considered the giraffe the queen of beasts, with enchantingly long eyelashes, delicate features, and fragile form. The Koran referred to her as the serafe, roughly translated "the lovely one." Eastern sultans prized them as very special pets. Yet Westerners since the time of the ancient Greeks tended to view these beasts at best as strange marvels, but more often as peculiar monstrosities-hybrid forms that mixed the parts of known creatures and did not quite fit into God's natural order. Just imagine a beast with a long neck, long legs, and even a hump on its back like a camel, spotted like a leopard or panther, with a tail like a pard (as panthers and leopards were once known), and horny bumps on its head that resembled those of a stag after sheddings its antlers. The camelopard (as the giraffe was called) was an odd beast indeed, thought to be the product of miscegenation between a male camel and a female leopard. Even today the giraffe (scientifically

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known as Giraffa camelopardalis) is often referred to as "the animal built by a committee," presumably assembled from left-over parts of animals at the end of creation. Giraffes were known to the ancients of the Mediterranean region. Pompey, for instance, is said to have exhibited ten of them at his theatre in Rome. During the Middle Ages giraffes seem to have been nearly forgotten, except in legends and embellished tales from Arab travelers. When they were mentioned at all they might be confused with large, bizarre antelopes. In the mid-fifteenth century Europeans had the opportunity to see a giraffe in the flesh for the first time in many centuries when Cosimo de Medici acquired one for his zoological park in Florence. According to the story, Cosimo could not decide whether the camelopard was more of a camel or more of a pard. To help him make up his mind, when honored by a visit from Pope Pius II, he set up a little experiment for his and the Pope's amusement. Cosimo had the giraffe placed in an enclosure along with a few lions, some blood-hounds, and a few fighting bulls--then he aI1d the Pope eagerly awaited the outcome. Presumably if the giraffe was more of a leopard it should put up a good fight, but if it was more of a camel it would quickly succumb to the lions and dogs. Fortunately for the poor giraffe, the lions, blood-hounds, and bulls all ignored the giraffe and only gave the gentle vegetarian a good fright. For centuries after Cosimo's display and experiment the giraffe remained relatively unknown to Europeans. In the late sixteenth century one Melchior Lorch of Flensburg (northern Germany) considered a giraffe the greatest wonder he had seen during his travels to Constantinople and back. Likewise, France (and probably much of Europe) was suitably impressed when, in 1783 while on a trip to what is now South Africa, the adventurer Francois Levaillant became the first modern European to shoot a giraffe. The specimen was shipped to the Jardin du Roi (reorganized during the French Revolution as the Musee National d'Histoire Naturelle in 1793) and a couple of decades later was used by Jean Baptiste Lamarck as an example of his newly proposed evolutionary mechanism. Today, many associate the introduction of modem evolutionary theory with the name of Charles Darwin and his publication of On the Origin ofSpecies in 1859. But Darwin did not invent evolution; rather, he convinced the scientific community that evolution had occurred and proposed a mechanism of evolution, namely evolution by means of natural selection. Proposed simultaneously by Alfred Russel Wallace, it is also commonly known as "the survival of the fittest." Within each species or population, during each generation of organisms more offsping are born than mature and reproduce. Furthermore, not all offspring are identical; there is variation in every trait to a greater or lesser extent. The driving force of evolution, according to Darwin, is that certain individuals that by chance have certain variant traits may be more successful in surviving and reproducing than other members of their generation, and thus pass their use-

ful variant traits on to the next generation. By analogy to artificial selection, in which a breeder picks certain animals and plants with desirable traits and allows them to propagate, Darwin termed this weeding out and choosing of individuals during each generation "natural selection." According to Darwin, just as selective artificial breeding over the centuries could produce new varieties of plants and animals, so too natural selection working over millions and millions of years could produce whole new species and kinds of organisms. Darwin was not the first scientist to espouse evolution. Jean Baptiste Lamarck, the French soldier turned botanist turned zoologist, actively espoused a theory of evolution from the year 1800 until his death in 1829. Among his many ideas, Lamarck followed the widespread notion that evolution occurred due to the inheritance of acquired characteristics. By the "habit" or "striving" of organisms in a certain direction from generation to generation evolutionary changes might actually be effected. Under this idea, the strong muscles of the blacksmith would be passed on to his sons. Although only briefly mentioned in the large corpus of Lamarck's work, the notion that the giraffe acquired a long neck by continually stretching it to reach high leaves, generation after generation, soon became the classic textbook example of Lamarckian evolution (and remains so to this day). Lamarck's own ideas along these lines are as follows: "It is interesting to observe the result of the habit in the peculiar shape and size of the giraffe (Camelopardalis): this animal, the largest of the mammals, is known to live in the interior of Africa in places where the soil is nearly always arid and barren, so that it is obliged to browse on the leaves of trees and to make constant efforts to reach them. From this habit long maintained in all its race, it has resulted that the animal's fore-legs have become longer than its hind legs, and that its neck is lengthened to such a degree that the giraffe, without standing up on its hind legs, attains a height of six metres (nearly 20 feet)." (Lamarck, 1809: 122). Unfortunately for Lamarck, he found few supporters of his evolutionary theory during his lifetime, largely due to his battles with the politically more astute Baron Georges Cuvier. The puzzle of inheritance was such a problem for evolutionists that even Darwin continued to believe in the inheritance of acquired characters until the end of his life. A number of prominent scientists of the second half of the nineteenth century, including paleontologists such as Edward Drinker Cope, accepted the inheritance of acquired characters. By the turn of the century, however, the experiments of August Weissman demonstrated that features acquired during one's lifetime never made it into the next generation. In 1900, long after Darwin and Lamarck, modern genetics was born with the rediscovery of Mendel's

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20

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Figure 4.6. Phylogeny of the giraffes, modified from W. D. Hamilton (1973). (Drawn by C.R. Prothero). work. Weismann and the neo-Mendelian geneticists destroyed the credibility of acquired characters in evolution. To give this concept a label, they called this notion "Lamarckism." Thus, the wide-ranging work of one of the eighteenth century's greatest naturalists was reduced to a single idea. Ironically, acquired inheritance was a notion that all Lamarck's contemporaries believed in, and was peripheral to most of his main ideas. Nevertheless, we still refer to any idea about inheritance of acquired characters as "Lamarckism." Today, we believe that the great neck of the giraffe can be explained much more cogently as the result of Darwinian natural selection. Short-necked giraffe ancestors evolved into present-day long-necked giraffes because over a number of generations offspring that developed (by a combination of inheriting genes for long necks from long-necked parents and random favorable variation) slightly longer necks would be at a competitive advantage. On average, they would out-reproduce their shorter-necked contemporaries. In each generation, the longer-necked giraffes would pass on their genes for long necks in disproportionate numbers and cause the giraffe population to evolve toward having long necks.

But what of these evolutionary scenarios? Whether you believed Darwin or Lamarck, the presupposition was that modern giraffes had evolved from short-necked ancestors. Was this really the case? The answer was forthcoming from the rocks. UntiI the. very end of the nineteenth century only the single species of giraffe was known among living animals. No other living animals appeared to be closely related to giraffes, and zoologists argued whether giraffes were closely related to deer, pronghorns, bovids, or perhaps to none of these artiodactyls. Beginning in the 1830s, however, close relatives of giraffes were found-but from Miocene, Pliocene, and Pleistocene rocks. In such late Miocene deposits as those at Samos and Pikermi in Greece, from the Siwalik Hills of Pakistan, and from numerous other Miocene to Pleistocene deposits of eastern Europe, Africa, and Asia, numerous giraffe-relatives were discovered (Fig. 4.6). According to Janis and Scott, the most primitive giraffoid is Propalaeoryx from the early Miocene of Africa. By the middle Miocene, there were several giraffe lineages coexisting in Africa. Climacoceras, for instance, has long, thin, branched, antler-like ossicones. Canthumeryx (also called Zarafa) had two long pointed ossicones directed side-

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Figure 4.7. The moose-like giraffid Sivatherium, with its palmate horns, was common in the PlioPleistocene of Asia and Africa, and may be represented in cave paintings. (Neg. no. 327253, courtesy Department of Library Services, American Museum of Natural History). ways away from the top of its eyes. The okapi is a living relict of these middle Miocene giraffoids, even though its fossils are known only from the Pleistocene. According to W.R. Hamilton, the next more advanced group· of giraffids are the sivatheres, which roamed Africa and Asia from the early Miocene until the end of the Pleistocene, and may even have co-existed with man but a mere handful of millennia ago. Giraffokeryx, from the middle Miocene of India, had two sets of V-shaped ossicones over its eyes and its ears. Brahmatherium (including Helladotherium) , a late Miocene sivathere from Eurasia, had thick conical ossicones on its head. Sivatherium (from the Plio-Pleistocene of Asia and Africa), was a huge, burly, short-necked giraffid that had gigantic palmate and branching ossicones resembling the horns of a moose (Fig. 4.7). There are petroglyphs, perhaps dating to 8000 years ago, of possible moose-like sivatheres known from a rock shelter in the central Sahara. An ancient Sumerian bronze figurine, possibly representing a sivathere, has also been reported. Following the sivatheres was another sidebranch, the samotheres. Derived from "Palaeotragus" eminens of the middle Miocene, Samotherium was widespread over Africa and Europe in the late Miocene and Pliocene. As the anecdote at the beginning of this chapter describes, little was known of it until Barnum Brown found a nearly complete skeleton on the Greek island of Samos, from which it took its name. Samotherium had two long, curved ossicones on its head that looked like a pair of bananas pointed upward and outward. These animals were distinctly members of the giraffe family, yet they had short necks and in other features were very different from the known living giraffes. The speculations of the early evolutionists were in principle correctthe modern long-necked giraffes had short-necked fore-

bears. But the fossil record did not answer the question of how the giraffes evolved their long necks, either by Lamarckian "stretching" or by Darwinian natural selection. The lineage leading to modern giraffes began with "Palaeotragus" tungurensis from the middle Miocene of Mongolia, Hunanotherium from the late Miocene of China, and Bohlinia from the middle Miocene of Greece. None of the extinct genera have the long neck or legs, although most are known only from teeth and skulls. The earliest known species of Giraffa, G. jumae, from the late Miocene of eastern and southern Africa, apparently already had long legs, and presumably also a long neck. For decades, zoologists pointed to the giraffe neck as an example of the flexibility of the mammalian body plan. Like almost all other mammals, giraffes appeared to have only seven vertebrae in their neck, despite the fact that it is much , longer. Instead of adding additional short vertebrae as it lengthened, they lengthened each vertebra itself, making them long and spindly. However, Nikos Solounias has shown that this is not true. Giraffes have actually added an additional vertebra between the second and sixth vertebrae of the neck. But the last neck vertebra (the seventh cervical in anatomical terms) has been shifted to the thoracic region, where it supports a rib like the rest of the thoracic 'Vertebrae. Consequently, the giraffe's neck begins slightly behind its forelimbs, and this gives the giraffe its unusual appearance of a neck located further back on the torso and the forelimbs protruding. Solounias interprets this unusual addition as a functional shift in vertebrae to balance the long neck on such a slender body-if the neck were hinged too far forward on the body, it would be unbalanced and prone to topple forward. Living giraffes inhabit much of the open woodland and wooded grassland of Africa south of the Sahara desert. They all belong to a single species (Giraffa camelopardalis), but within this species there is much variability and some nine different subspecies are generally recognized: West African giraffes, Kordofan giraffes, Nubian giraffes, Reticulated giraffes, Rothschild giraffes, Masai giraffes, Thornicroft giraffes, Angolan giraffes, and South African giraffes. Giraffes are large mammals. The head and body length of an adult male can range from 12-15 feet (3.8-4.7 m), the shoulder height can be 8-12 feet (2.5-3.7 m), and the height to the horn tips can be 15-17 feet (4.705.3 m). Females tend to be somewhat smaller, the height to the horn tips for females generally ranging from 13-15 feet (3.9-4.5 m). Giraffes have tails that range in length from about 31-39 inches (80-100 cm), not including the terminal tuft or tassel of black hairs that may be up to a meter in length. Adult giraffes can weigh from 1200 to over 4200 pounds (5501900 kg), the lighter weights being among females. Of course, giraffes are known for their extremely elongated necks, but their odd appearance is further accentuated by the fact that their bodies are relatively foreshortened from front to back, and the fore-legs are slightly longer than the hind-legs. The giraffe's skin is very thick and tough-it

WHERE THE DEER AND THE ANTELOPE PLAY is reported to be up to an inch thick in some old males. It is so tough that it is commonly used for sandals in Africa. The coat pattern is extremely variable in different populations of giraffes, giving rise to the number of subspecies that have been named. All giraffes are covered by dark, more or less polygonal patches separated by a network of lighter (creamy, yellowish-white, or white) lines, but the network of lighter lines may be more or less thick and is better defined in some varieties than others. The dark patches can vary from pale orange through a number of shades of brown and red-chestnut to almost black. Apparently specific variants on patterns of coat markings are unique to individuals, and such patterns remain constant from birth to death (although the color of the patches and network may change during the life of the individual, growing darker with age). On this basis individual giraffes may be able to recognize each other. The basic giraffe skull has two short horns, called ossicones, on top of the head. These are formed of bone and covered with skin and terminal tufts of black hair (which may be lost, especially in males). In males the ossicones tend to be thicker, heavier, and may fuse together at the base. At birth the ossicones are present as flat-lying cartilaginous cores that during the first week after birth take an upright position and subsequently ossify and fuse with the skull. Giraffe skulls are also characterized by their increase in bone deposition throughout life, especially in males. Bony lumps and concretions are often deposited on the skull, especially on the back of the nasal bones and also above each eye socket, and sometimes at the back of the skull. Due to these bony growths giraffes are seen with from three to five "horns." The eyes are large, dark brown, and protected by long lashes. The lower canine teeth are splayed out, lobed, and used to "comb" leaves off tender shoots. Giraffes also have long black tongues that are useful in gathering food into the mouth, and tough, hairy, prehensile lips. Giraffes have extremely acute sight, probably the best sight of any large mammal, and this combined with their high heads allows them to survey the area for many miles. They also have well-developed senses of hearing and smell. It is a common misconception that giraffes are completely mute; although they seldom vocalize, they can produce various moans, grunts, snorts, and bleats. Confined to open woodlands and wooded grasslands of sub-Saharan Africa, giraffe populations are most often associated with acacia plants upon which they frequently feed. In the wild giraffes are highly selective browsers, feeding on leaves, shoots, fruits, and seeds. Giraffes may be able to go for weeks or months without water, but they do make regular visits to water supplies when such are available. When watching giraffes feed from a distance, one can distinguish males from females; adult males typically fully stretch the neck and head vertically so as to feed on high vegetation, whereas females tend to feed with the neck curled down thus reaching vegetation which is at body or even knee

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height. Giraffes spend about half of each twenty-four hour day feeding (a bit more for females, and a bit less time for males). Feeding occurs primarily in the mornings and evenings, and during bright, moonlit nights. During the heat of midday giraffes rest and chew their cud. In order to drink or reach food on the ground, giraffes can spread their forelegs widely to the sides and slightly in front of them, and bend their knees. Giraffes band together in loose herds (whose composition changes daily), ranging in size from less than a dozen individuals up to 70, presumably simply because they are social animals and also for protection from predators such as lions, man, and to a lesser degree leopards. Because of their excellent eyesight, giraffe herds may be able to communicate visually over many miles. Giraffes have large home ranges (on the order of 120 square km), but they are not territorial. Instead, there is a distinct dominance hierarchy among adults where their ranges overlap, especially among the bulls. Young males in particular undergo ritualized fighting in order to determine and secure their position in the hierarchy. They typically intertwine their necks ("necking") and push from one side to another. Occasionally heavy blows will be exchanged using the sides of the bony head and horns. Dominant bulls spend much of their time searching for females in heat with which to mate. On sighting and joining a herd of giraffes (usually composed of cows, calves, young males, and perhaps an older male leader), a dominant bull will sample each female's urine using the flehmen, or lip-curl, response to determine if she is in heat. The bull lays his head on the flanks of the cow and while she urinates collects the urine in his mouth. He then curls his lips and spits out the urine in a thin stream; this probably forces molecules of scent to Jacobson's organ (located above the palate) and in this manner the male can determine the female's condition. If a cow is in heat a dominant bull will displace any subordinate bull that may be with the herd and consort and copulate with the cow, only to leave later and search for more cows in heat. Giraffes can breed year round. The gestation period is approximately 450 days, and the young stand 5.5-6.5 feet (1.7-2 m) tall shortly after birth. Cows give birth standing up, so the newborn drops several feet to the ground. A newborn giraffe will often join a group of calves when only one or two weeks old. The female giraffes are reported to be excellent mothers, and will defend their offspring from lions, leopards, hyenas, African wild dogs, and other predators by kicking with their feet; a single well-placed blow can kill a lion. Normally only a single calf is born at a time, and the mortality rate is approximately 50% in the first six months. Giraffes reach maturity at five to eight years, and have a usual life span in the wild of 15 to 25 years (in captivity one giraffe lived to be 28 years old). Other than intraspecific dominance rituals and fights, giraffes are naturally quiet, shy, and inoffensive animals. When around man, however, they will quickly get used to his presence. Giraffes have an interesting and unusual form of loco-

HORNS, TUSKS, AND FLIPPERS

Figure 4.8. Giraffes must spread their forelegs to drink. This posture also diminishes the dangers of the sudden changes in blood pressure to their head. (Photo courtesy A. Walker). motion. At slower speeds they pace, or raise and swing the two legs on one side of the body at almost the same time. When galloping, however, the two hind legs are brought forward almost simultaneously and land outside of the front legs, which are then moved forward. Giraffes rest or sleep standing up or lying down with their legs folded beneath them. The head may be rested on the rump, the neck forming an arch, for very short periods (on the order of five minutes at a time) of sleep. Otherwise the neck remains vertical, with the eyes only half-closed and the ears alert. The fact that their heads are about ten feet (3 meters) higher than their hearts creates unusual physiological problems. Not surprisingly, they have a huge heart about 2 feet (60 cm) long, weighing about 25 pounds (11 kg), with muscular walls up to three inches (7.5 cm) thick. Their hearts must pump about twice as hard as a human's for blood to reach their heads and permeate their brains. Such high blood pressure would probably rupture the blood vessels of any other animal, but giraffes have unusually toughwalled blood vessels, and they maintain fluid pressure within the tissues of their body with their tightly stretched thick skin, which functions like an anti-gravity suit. The tight skin also prevents the blood from pooling down in the legs. When you stand up too quickly after lying down, you feel faint because blood pressure to your brain drops suddenly. Giraffes have the same problem, only more extreme. When they get up, they must do so slowly and in stages to allow their blood pressure to stabilize gradually, or they will pass out. When a giraffe is drinking, its head is lower than the heart, which creates too much blood pressure (Fig. 4.8). Giraffes have a series of one-way valves in their jugular vein that prevents the venous blood headed back to the body from flowing back to the brain when the head is down. For the arterial blood to the head, giraffes have a rete mirabile, or "wonderful net," sponge-like network of vessels in the

arteries leading into the brain, which buffers the pressure before it causes brain capillaries to burst. By spreading its front legs to drink, the giraffe not only brings the head down, but also lowers the heart, so the gradient isn't as steep and the pressure difference is less. Another problem with having a long neck is the enormous volume of dead air in the windpipe. As the giraffe breathes, it must expel all 5 pints of dead air in its neck with each breath, and then inhale enough air to refill its lungs and its windpipe. Since this reduces the total air flow, the giraffe has to breathe much faster-20 breaths per minute, compared to 12 for us and 10 for an elephant-to get enough oxygen into its blood supply. Yet breathing faster is more difficult, since it requires moving all that dead air up and down a long pipe. It is not surprising that they move much slower, run more efficiently, and cannot run with much endurance. Giraffes and humans have had a long relationship. North African Stone Age men produced rock drawings of modem giraffes. Certain tribes of the Sudan, Chad, and Ethiopia have traditionally hunted giraffe on horseback, eating the meat with reverence. The thick hides of giraffes have been used to make shields, whips, and other objects. Although giraffes have been reported to reach speeds upwards of 30 mph (50 km per hour), David Livingston stated that at times a rider on a good horse could chase a giraffe only a few hundred yards before it might drop dead from exhaustion. Writing in the early twentieth century the hunter H. A. Bryden stated that to chase a troop of giraffes on horseback and place a bullet through the root of the tail from behind (which would then penetrate the length of the body and surely kill the exhausted giraffe) "is one of the most thrilling and exciting of all human experiences." One hopes that tastes in recreation have changed over the years. To Bryden's credit, however, he did advise that for the sake of the giraffes, the "humane hunter" not partake of this pleasure more than a few times. At present giraffes are still relatively common in East and South Africa, although they are always subject to the threat of poaching. Giraffe-hair bracelets, made from the tail tufts, are particularly popular with tourists and have encouraged some poachers to slaughter animals, removing only the tails, and leaving the carcasses. Giraffe meat has been eaten for centuries and is said to have a good flavor (like gamey veal), and the roasted marrow of the long bones is considered by some to be a delicacy. It has been suggested that giraffes, properly managed and cropped, could become an important source of animal protein for human consumption in parts of Africa, especially since they feed on vegetation that is unused by domesticated animals and therefore would not compete with other livestock. DEER PERFUME The deer superfamily, the Cervoidea, forms another large group of artiodactyls. Among living ungulates, the cervoids include the musk deer, the American pronghorn "ante-

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Figure 4.10. Extinct relatives of the musk deer, the blastomerycids, were common in the early and middle Miocene in North America. (Painting by R. B. Horsfall, from Scott 1913).

Figure 4.9. The living musk deer, Moschus, has long protruding canines instead of antlers. (From Whitehead, 1972). lope," and approximately three dozen species of true deer (family Cervidae). Of these three living groups of cervoids, the musk deer (Fig. 4.9) are generally considered the most primitive (perhaps reminiscent of the ancestors of the true deer) and are placed in their own family, the Moschidae. Musk deer are comparatively small, deer-like animals with an adult head and body length of about a meter, and a weight of about 15-38 pounds (7-17 kg). They lack horns or antlers, but the male musk deer have long upper canines that project down from the lips as long tusks similar to the familiar canines of an extinct saber-tooth cat. Musk deer inhabit the high, mountainous forests of Asia, especially China, Manchuria, Korea, Siberia, Mongolia, Tibet, Kashmir, and Nepal. To this day relatively little is known about their biology and habits. Not long ago it was the opinion of most mammalogists that all musk deer belonged to a single species, known as Moschus moschiferus, which was divided into a number of subspecies. It is now believed that there are at least three, and maybe four, distinct species of musk deer. Musk deer tend to be solitary (except during the rutting season) and extremely territorial; the males mark their turf by rubbing scent glands against stones, trees, and other vegetation. In the presence of man they are shy and timid, quickly fleeing if disturbed. Moschids feed on a variety of plant matter, including young shoots, leaves, flowers, grasses, twigs, buds, and mosses and lichens. Moschids are the source of natural musk, an ingredient

that has been used in perfumes and expensive soaps for centuries, and in the Far East is also traditionally used for all sorts of medicinal purposes, such as a treatment for fevers, sore throats, and rheumatism. The highly prized musk is carried only by males; at sexual maturity a musk sac develops in front of the genital area, and glands within the sac secrete the brownish, wax-like musk. No one is exactly sure why the males produce musk, but most likely it is used for signalling and attracting females, or repelling other males. When filled, the musk sac may contain about an ounce of musk. Because of the high human demand for musk, resulting in very high prices for the substance, musk deer are probably slaughtered by the hundreds of thousands annually. Many of the musk deer are captured by traps that do not discriminate between musk-bearing males, and the worthless females and young; as a result these animals are becoming increasingly rare and endangered. However, there is actually no need to kill musk deer in order to obtain musk, as was demonstrated by an experimental program in Sichuan, China. Musk deer can be caught alive and bred in huge, enclosed parks. Periodically the adult males can be captured by hand and while they are restrained the musk can be spooned out of the musk sac (which contains a natural opening), then the musk deer can be released and will secrete more musk. Still, the raising of musk deer and the extracting of the musk is a time-consuming and laborious process. Furthermore, the musk deer have not proven to breed well, or live a long time, in captivity. The earliest known moschid is Dremotherium, from the late Oligocene of Europe. By the early Miocene, fossil moschids were spread all over the Northern Hemisphere. Early Miocene deposits in Nebraska produce the first American moschid, Blastomeryx (Fig. 4.10), as well as the earliest pronghorn and the earliest dromomerycid (an extinct family related to true deer, which we discuss below). Blastomerycid musk deer persisted until the late Miocene in North America, but they were never particularly numerous.

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Figure 4.11. Male prongbucks have an impressive set of horns, which are shed annually. (Photo courtesy B. O'Gara.) ALL-AMERICAN-BUT NOT AN ANTELOPE "Hurra for the prairies and the swift antelope," wrote the pioneering naturalist John James Audubon on an expedition up the Missouri River in 1843, "they fleet by the hunter like flashes or meteors . . . they pass along, up or down hills, or along the level plain with the same apparent ease, while so rapidly do their legs perform their graceful movements ... that like the spokes of a fast-turning wheel we can hardly see them, but instead, observe a gauzy or film-like appearance..." (Audubon, 1851). Prior to the middle of the nineteenth century the pronghorn (Antilocapra americana) and the American bison were the dominant ungulates of the western plains, roaming the grasslands and deserts from northern Mexico, through the western United States, and into southwestern Canada. It has been estimated that some forty to fifty million pronghorns roamed the land before 1850, but just as the bison was brought close to extermination, so too the pronghorn population was decimated by man. The pronghorn did not come as near to total extinction as did the bison, however. An estimated 13,000 remained in 1920, and today there are perhaps half a million pronghorns. Pronghorns are unique among the living ungulates. On their heads they bear horns composed of a solid and perma-

nent bony core (as in giraffes, cattle, and antelopes) covered with a sheath of fused hairs (keratin) that is shed yearly (Fig. 4.11). In contrast, the keratin covering the horns of cattle and true antelopes is never shed during the lifetime of the individual. True deer (discussed below) have antlers that are composed of bone and shed annually as are the hom sheaths of the pronghorns. But deer cranial appendages are very different in structure from those of pronghorns. In deer, the mature antler is not covered with any type of sheath, but is composed of solid deciduous bone that is completely shed each winter and subsequently regrown in its entirety. Although everyone calls them "antelopes," it is clear that they are not related to the true antelopes of Africa, which are bovids. Taking the horns and other characteristics into account, the pronghorn does not neatly fit into either the Bovidae or the deer family (Cervidae). In the past they were placed with the bovids, or simply given the distinct family Antilocapridae without specifying whether they are more closely related to cattle or deer. Recent work on the phylogenetic relationships of the ruminants, notably by J.J.M. Leinders, Christine Janis and Kathleen Scott, suggests that the pronghorns are most closely related to the true deer, and belong in the Cervoidea along with moschids and true deer. The pronghorns are true native Americans. They are the sole living survivors of the family Antilocapridae, an American group of cervoids that was once much more diverse than it is currently-just one or two million years ago there were over a dozen species of antilocaprids roaming the plains of North America (Fig. 4.12). In recognition of this true American origin, the American Society of Mammalogists uses the pronghorn as its official symbol on their journals and emblems. Originating from some late Oligocene Eurasian cervoid, pronghorns reached North America in the earliest Miocene and became established as the antelope surrogate for this continent. Like African antelopes, they diversified into a tremendous variety characterized by different horn shapes. The earliest form, Paracosoryx, had long straight horns with forked tips. Other members of this group, the merycodonts, had long gazellelike horns, deer-like horns with multiple tines, or flat bladed horns with comb-like edges. Merycodonts had very highcrowned cheek teeth, and were small gazelle-sized creatures. According to Christine Janis, they lived in more open grasslands, and may have competed with and displaced the stenomyline camels mentioned in Chapter 3. From the merycodonts evolved the more advanced antilocaprids of the later Miocene and Plio-Pleistocene. Some, such as Hexameryx and Hexobelomeryx, had six horns. llingoceros had long straight horns twisted into a spiral. Stockoceros was a third larger than the living pronghorn, and had four horns arranged in simple V-shaped prongs. Hayoceros had four horns arranged with a typical short pronghorn in front, and a long straight horn in back. In merycodonts, only the males had horns, but all more advanced antilocaprids (including the living species) have horns in females as well.

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Tht prt'prun,i!horn, P/ioctros

Ramoenes, from New MIX;C()

ParfUOSflryX.

ftom N,brtUU

Figure 4.12. The variety of horns in the extinct pronghorns of North America was truly impressive. (From Scheele, 1955). Except for the Ii ving species, all pronghorns went extinct at the end of the last Ice Age, along with many other large mammals discussed elsewhere. Several have been found in association with kill sites, so there is a good chance that they were overhunted by the first humans on this continent. Pronghorns are well known for their speed. They are the fastest mammal in the Americas, capable of reaching speeds of 55 miles per hour (86 kmlh) in short bursts. They can maintain a speed of 45 miles per hour (70 km/h) for approximately four miles (6.4 km), outrunning horses and most vehicles in rough terrain. They have enormous windpipes for efficient breathing, and a heart twice the size of a sheep's (which has a similar body size). They are extremely agile, and can make horizontal leaps over 20 feet (6 m). However, they do not like to jump vertically. They have a habit of leaping between the wires of a barbed wire fence, rather than over it, as deer will. One of us (Prothero) witnessed a pronghorn that jumped between the wires and then became snagged. It tore itself free before anyone could approach. Adult pronghorns stand about just over one meter at the shoulder, typically have a head and body length of 3-5 feet (1-1.5 m), and weigh about 80-130 pounds (36-60 kg). The

horns have tips that point backwards and a short prong midway up the horn that points forward. Although found in both sexes, the horns are considerably larger in the males. The coat is reddish brown to tan, with a white belly, rump, neck, and head markings. A short black mane runs down the back of the neck, and males have black patches on their faces. Pronghorns have excellent eyesight (useful on the open plains) and are naturally inquisitive and curious. Their curiosity will even induce them to approach unknown objects, sometimes to their detriment. It is reported that early settlers would attract the otherwise fleetfooted pronghorns within shooting distance by waving flags and handkerchiefs tied to poles, thus sparking the pronghorns' interest and attracting them closer to humans. Their eyes are large and set on the extreme sides of the skull, which allows a nearly 360 0 field of view. Their eyesight is so acute that one old hunter commented, "What a live antelope don't see between dawn and dark isn't visible from his standpoint; and while you're a gawkin' at him thro' that 'ere glass to make out whether he's a rock or a goat, he's a countin' your cartridges and fixin's, and makin' up his mind which way he'll scoot when you disappear in the draw to sneak on 'im-and don't you ferget it."

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Figure 4.13. A small herd of pronghorns does and fawns feeding in Wyoming. Their white rump patches produce a "signal flash" when they start to run. (Photo courtesy B. O'Gara.) Highly territorial, dominant prongbucks defend their territories and the forage they contain. Pronghorns also congregate in bands, or small herds (containing up to about a hundred individuals), especially during the winter (Fig. 4.13). After a summer of feeding, the prongbucks become restless, jumping sideways from a standing position and fighting among themselves. They gather harems of as many as fifteen does during the rut, marking their territories with their many scent glands. After mating, up to four fertilized eggs implant, and several embryos grow in the compartmentalized womb. After eight months of gestation, twin fawns are born in late May and June. They lie quietly where they are dropped for two or three days, with their lack of scent and mottled brown color concealing them from coyotes. The mother moves cautiously between the two hidden fawns to nurse them one at a time. She will distract predators away from her hidden fawns, or attack wolves and coyotes with her horns and sharp front hooves if necessary. After two days, the fawn can run faster than a horse for short distances, but stays hidden for almost a month since it lacks the stamina to outrun a predator over distance. The naturalist George Bird Grinnell witnessed several occasions where the doe led her fawns into a cactus patch, knowing that the coyotes could not walk there without getting their feet full of thorns. The coyotes tried rushing at the fawns to get them to panic and run out the other side, but the predators would not enter the cactus. At three weeks the fawn begins eating green vegetation, and by three months it acquires its adult coat coloration. The fawns are weaned by 4-5 months, and are sexually mature by 16 months. Pronghorns signal each other with the white hairs on their rump, which flash in the sunlight when they take off. This alerts the rest of their herd much quicker than sound,

and can be seen from two miles away. At the same time, the rump flash also releases a musk from their rump gland which further alerts any pronghorns downwind. Their main enemies are now humans and their sheep, who destroy their range. Coyotes and wolves cannot outrun pronghorns, but a pack may cooperate to ambush them and run one in circles until it tires. Fawns are also very vulnerable to coyotes and eagles. Most pronghorn deaths, however, occur during the winter months, when snow covers their forage and decreases their advantage in speed. Their worst problem is deep snow drifts, where they can become trapped, and crusty snow, which their sharp hooves break through (but a wolf's pads don't). During the winter, pronghorns seek shelter in the forested hills or deep ravines, and move away from the blizzards in the unprotected plains. Their hollow hair shafts give them excellent insulation, trapping air like a down jacket. However, in severe storms their fur becomes wet, and many pronghorns freeze to death. DEER TO US ALL From the prehistoric cave paintings that Cro-Magnon men used to help their hunting, to Santa's reindeer, Bambi, and Bullwinkle the Moose, deer have long been a part of human culture. Cave paintings from ten to twenty thousand years ago clearly depict various species of deer. Red deer remains have been found on more than 95% of all European Paleolithic and Mesolithic archeological sites. Deer were so important in the Middle Ages that Norman kings planted special forests in southern England as their exclusive game reserves. Besides hunting deer for meat, hides, sinew, and bone, Pleistocene and early Holocene humans also apparently gathered the shed deer antlers in large quantities. Antlers could be carved into a variety of tools, such as picks

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Figure 4.14. A. Each year, cervids must grow a new set of antlers from scratch. By late summer, this elk's antlers are nearly complete, but covered with their coating of "velvet" under which the rapid bone growth occurs. (Photo courtesy B. O'Gara.) B. In the fall, the bucks shed their "velvet" in long strips as they begin to battle for breeding rights. (Photo by D. R. Prothero). and other digging implements, needles and fishhooks, atlatls (spear throwers), and spear straighteners. The strong but resilient nature of antlers made them ideal for use as handles for stone knives and axes. Deer are still the most popular large game animal in many parts of North America and Europe. The annual fall deer hunt is still an important ritual for many American males, as depicted in the Oscar-winning Vietnam War film "The Deer Hunter." Other wild hoofed mammals, such as pronghorns and bison, have been displaced by domestic cattle and sheep. But deer still thrive, because they browse mostly in forested habitat, and do not compete with domestic grazers for open grasslands. The true deer, family Cervidae, are unique among ungulates in bearing antlers. These are structures growing from the head of the animals, somewhat analogous to horns. But unlike horns, which consist of permanent bone covered with a sheath of keratin or skin and remain on the animal for life, antlers consist of deciduous bone (Fig. 4.14). The outer layer is composed of compact bone surrounding a spongy core. Once fully grown and in place, antlers lack a covering sheath of any kind, and they are lost (leaving only a short protuberance, known as the pedicel, at the base) and regrown each year. Antlers are found only in males, except

in the case of reindeer, where both sexes have antlers. Antler is said to be one of the fastest-growing animal tissues known. In the common European red deer (Cervus elaphus) the antlers are cast or shed in the late winter or early spring and new antlers begin to grow. As they are growing the antlers are covered with velvet (fur-covered skin) and the growing bone is well-supplied with blood vessels. By around August the antlers are fully grown and the velvet dries up and begins to peel off in long strips of dead skin; the animal may rub its antlers against trees and other vegetation in order to wear off and remove the velvet (Fig. 4.14). The male deer (stags) are now ready for the rut (mating season), prepared to use their new antlers as weapons to fight with each other for the possession of females. Antler growth appears to be controlled by growth and sexual hormones, and as the male deer matures every year he will typically grow larger sets of antlers with more bifurcations and projecting points. Why are antlers lost and regrown each year, rather than being permanent appendages as are typical horns of other ungulates? Perhaps it is to give all males (especially older males) another chance if their antlers are damaged during the rut in any particular year. In the red deer, for instance, it is known that rutting success is reduced for the season if the individual's antlers are dam-

78

HORNS, TUSKS, AND FLIPPERS

Figure 4.15. The "Irish elk," Megaloceros, was neither an elk nor strictly Irish. It was a huge Ice Age deer with moose-like palmate antlers that were gigantic, but proportional to its huge size. (Photo from Millais, 1897). aged. This reduced success would be permanent (because the damage to the antlers would be permanent) if the antlers were not lost and regrown each year. The Ii ving red deer, the moose, and the reindeer can produce huge antlers year in and year out, but antlers of some extinct deer were phenomenal. Perhaps the most famous example is that of the extinct giant deer, Megaloceros giganteus, from the Pleistocene of Great Britain and continental Europe (Fig. 4.15). Often misnamed the "Irish Elk," it was neither an elk, nor exclusively Irish. (It was probably related to the fallow deer). The mature males of the giant deer commonly bore antlers that exceeded 11 feet (3.5 m) across, and weighed 100 pounds (45 kg)! As in other species of deer, these antlers were lost and completely regrown annually. Scientists have long thought that this beast was an example of evolution run amok-its antlers seemed too large to have any function. Stephen Jay Gould has shown that its antlers were scaled appropriately to its huge size, and were valuable for impressive displays for females and competing bucks. There is no reason to think that they were "maladaptive" or caused extinction. At certain times of the year, it seems that the ground should literally be covered with shed antlers where deer are abundant. However, once a deer loses its antlers, it will typically gnaw at them, and consume most or all of the antlers (if left alone and not disturbed). Presumably this is done in order to retrieve the mineral content of the old antlers which

can then be put to use in growing new antlers. Rodents are also responsible for gnawing at antlers and recycling them. It has been suggested that in prehistoric times (such as during the late Pleistocene), perhaps this eating of the antlers was unnecessary if the soil and vegetation at that time contained a higher mineral content than do many of the relatively depleted soils of today. Among modem deer, the antlers will be stunted or dwarfed if the animal's diet is inadequate or lacking in the necessary vitamins and minerals. The earliest deer share a common ancestor with other cervoids (moschids, pronghorns) in the late Oligocene of Eurasia. Although the late Oligocene Mongolian antlerless ruminant Eumeryx is often called the first deer, it is actually the oldest known cervoid. The oldest cervid relative, Amphitragulus, is known from the late Oligocene of Europe. By the early Miocene there were deer such as Palaeomeryx in Asia, Dicroceros in Europe, and the bizarre Prolibytherium in North Africa. Prolibytherium had two long parallel front-to-back-pointing horns over its head that looked a bit like a TV antenna. Long considered a primitive giraffe by most scientists, Janis and Scott have suggested that it is a cervoid related to Palaeomeryx and the North American dromomerycids, or "pseudo-deer." By the middle Miocene deer were flourishing all over Eurasia with over a dozen different genera. Most of these primitive deer had tusks like the antlerless Ii ving Chinese water deer, Hydropotes. If they had any, their simple antlers had only one fork, and were usually borne at the end of a long bony pedicel, like the living barking deer, or muntjacs (genus Muntiacus). Muntjac-like deer, like the extinct form Euprox, were common in the late Miocene of Eurasia. From one of these forms evolved a more modern deer, with no tusks and larger antlers anchored to a short pedicel. The most spectacular of these Plio-Pleistocene Eurasian deer were the "Irish elk" mentioned above, and Eucladoceros, which had as many as twelve tines on each antler! Close

Figure 4.16. Hoplitomeryx was a truly bizarre deer, with five horns and long curved canines. (From Leinders 1984).

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WHERE THE DEER AND THE ANTELOPE PLAY

.

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Figure 4.17. The deer-like dromomerycids of the Miocene of North America sported an amazing variety of cranial appendages. (From Scheele, 1955). relati ves of the true deer were the bizalTe five-horned Hoplitomerycidae, from the late Miocene of Italy (Fig. 4.16). Hoplitomeryx had long curved canines, a backwardcurved horn over its eyes, and two sets of horns over its ears: the inner set curved backward, and the outer set curved forward. This animal takes the prize for one of the weirdest horn combinations ever seen. Deer relatives migrated to the New World on two occa-

sions. The first was during the earliest Miocene, about 22 million years ago, when the earliest pronghorns and moschids also arrived. The immigrants Barbouromeryx, Aletomeryx and Sinclairomeryx established a new sidebranch of native North American "pseudo-deer," known as the dromomerycids (Fig. 4.17). Like American pronghorns, the dromomerycids evolved an amazing variety of horn types, since they had no competition from Eurasian cervids

HORNS, TUSKS, AND FLIPPERS

80

Figure 4.18. Collection).

Muntjac~

(From the IM31 Master Photo

in the Miocene savannas and forests of North America. According to Janis and Scott, they occupied the browsing woodland habitat along with the protoceratids (discussed in Chapter 3). However, unlike other cervoids, the males did not have antlers, but permanent bony horns. Some dromomerycids, such as Aletomeryx, occur in huge numbers in a single early Miocene quarry in western Nebraska. Aletomeryx had short multi-tined horns on long bases, and apparently lived in large, mixed-sex herds in open habitat, rather than defending territory. Others had inwardly curved horns, like Dromomeryx or Rakomeryx, or broadly palmate incurved horns, like Drepanomeryx. Matthomeryx had gazelle-like horns, and Sinclairomeryx had forward-curved horns. The most spectacular of the dromomerycids were the cranioceratines. In addition to a long horn over each eye tipped with a forked tine, they had a long curved horn originating from the back of the head! Dromomerycids reached their peak of diversity during the middle Miocene, then declined and went extinct during the terminal Miocene event that wiped out so many other native North American groups we discuss in this book: rhinos, most camels and horses, protoceratids, most pronghorns, and many others. In the early Pliocene, a second wave of immigration of deer from Eurasia took place. This established the modern deer of North America, the odocoilines, along with another extinct deer, Bretzia. In fact, the genus Odocoileus (including the living white deer and mule deer) dates back to the beginning of the Pliocene on this continent. When the Panama land bridge reconnected, deer continued their invasion and soon spread all over South America as well. Today, native wild deer are common on every continent except sub-Saharan Africa, Australia, and Antarctica. The last two have long been isolated from the Eurasian homeland, but the exclusion of deer from sub-

Figure 4.19. Fallow deer (From Whitehead 1972). Saharan Africa is probably due to the competition with true " antelope, which dominate the forest browsing niche. Among the approximately three dozen species of living deer (usually classified in about sixteen different genera) there is considerable diversity in size and external morphology. They range in height and weight from 15 inches (38 cm) at the shoulder and a weight of 17-18 pounds (about 8 kg) in the case of the southern pudu (Pudu pudu), to 9 feet (about 2.6 meters) and some 1,750 pounds (800 kg) in the case of the moose (Alces alces). Deer are best known for their antlers, but in some deer (such as the pudu), the antlers are nothing more than simple spikes and Chinese water deer (Hydropotes inermis) lack antlers altogether. Four subfamilies of deer are recognized. The most primitive are the Chinese water deer (Hydropotinae) and the muntjacs (Muntiacinae). As mentioned above, they are both relicts of the Miocene deer radiation in Eurasia. Males in both subfamilies have long canines, like tragulids and moschids. Chinese water deer weigh less than 30 pounds (13 kg), and live in swamps and reedbeds in China and Korea. They escape by humping their backs and leaping like rabbits. In addition to the long canines, muntjacs (Fig. 4.18) also have long antler pedicels, with a short branched antler at the tip. Weighing about 20-40 pounds (9-18 kg), the seven species of muntjacs live mostly in dense jungles of southeast Asia, browsing on leafy vegetation and tender shoots. Their habitat is similar to that of the tragulids of the jungles of Africa and Asia. Muntjacs are also known as "barking deer," because bucks emit a deep barking sound during breeding season or when they are alarmed. They will bark for over an hour if they sense a predator, such as a tiger, in the area. Most Old World deer are members of the subfamily Cervinae. The most familiar include the typically European fallow deer (Dama dama) and red deer (Cervus elaphus),

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81

Figure 4.20. Mule deer (From the IMSI Master Photo Collection).

Figure 4.21. The pudu deer, showing its tiny antlers. (Photo by D.R. Prothero).

which are mixed grazers/browsers living in dense forests, and open woodlands and grasslands (Fig. 4.19). With their distinctive spots and antlers flattened into a "hand" with "fingers," fallow deer are easy to recognize. There are a number of rarer species of the genus Cervus in southeast Asia, including the Japanese sika deer (Cervus nippon), the endangered marsh-dwelling Eld's deer (Cervus eldi), the Indian sambar (Cervus unicolor) and the little-known Indonesian rusa deer (Cervus timorensis), the endangered barasingha, or swamp deer (Cervus duvauceli) of India and Nepal, and the "humped" Thorold's deer (Cervus albirostris) of Tibet. The most familiar member of the genus Cervus, however, is the American elk (Fig. 4.14) or wapiti (Cervus canadensis). Although it is found in China and Mongolia, it crossed the Bering land bridge (along with mammoth, bison, and others) late in the Ice Age and established itself as the only New World cervine. During the summer, wapiti roam the mountain pastures of the Rockies, and in the winter, they shelter in the valleys. Their distinctive thick antlers, heavy build, shaggy neck, and famous bugling during mating season have long given wapiti a place in Western lore. The common deer in India is the axis deer, or chital (Axis axis), a mixed. feeder which is easily recognizable by the distinctive white spots in the adults. Closely related is the hog deer (Axis porcinus), so-called because it is heavily built with a short face and legs, and has a pig-like habit of charging head down through the brush, rather than leaping like a typical deer; it is characteristic of the rice paddies and grasslands of southeast Asia. Except for the wapiti, New World deer are members of the subfamily Odocoilinae. The most familiar of these is the genus Odocoileus, which includes the white-tailed deer (Odocoileus virginianus), denizen of the eastern deciduous forests, and the big-eared mule deer (Odocoileus hemionus), found all over the montane western states (Fig. 4.20). South America is home to a number of distinct types of deer, including the rare marsh deer (Blastocerus dichotomous) of

the floodplains of Brazil and northern Argentina, the endangered Pampas deer (Ozotoceros bezoarticus), which grazes in the pampas of Argentina and Paraguay, the two species of high-altitude Andean huemul (Hippocamelus) , the three species of brocket deer (Mazama), and the two species of tiny pudu (Pudu) (Fig. 4.21). Both brockets and pudu have simple unbranched spikes for antlers, and are typical forest dwellers. The most unusual of all deer is the moose (Alces alces), with its huge set of palmate antlers (Fig. 4.22). Its characteristic broad snout is suited for eating water vegetation, willows and poplar branches and bark, in the lakes and marshes it calls home. A male moose can also be recognized by the hump on its shoulder, and the thick flap of skin beneath its throat, known as a "bell" or dewlap. Found all over the northern hemisphere, moose are particularly common in the dense northern forests of Canada and Siberia. Originally, the Europeans called them "elk," and the wapiti was mistaken for a moose when explorers first came to NOlth America. As a result, the word "elk" means moose in Europe, and wapiti in North America. (This is also why the giant deer was called an "Irish elk," because its palmate antlers looked more like those of a moose.) Deer have marked differences between sexes, since bucks are usually larger than does and only they bear antlers (except in reindeer). While some deer are primarily solitary (such as the moose), many species form small groups (perhaps composed of a stag and his harem) or even small herds. Deer which live on patchy food supplies, such as moose, pudu, brockets, and white-tailed deer, live singly or in small groups. Those which live in more open habitats and depend heavily on grazing (such as wapiti and Sika deer) live in large herds. Wapiti are the most polygamous of all, with a single bull defending sixty or more cows. Although there is tremendous variability in the social and reproducti ve behavior of the 36 different species of deer, there are also some patterns that are typical. Bucks and does have a very different yearly cycle. Males of temperate species are seasonal

82

HORNS, TUSKS, AND FLIPPERS

4.22. The moose is a deer with thick, palmate antlers; it is adapted to browsing tender vegetation in northern swamps and bogs. (Photo courtesy B. O'Gara).

breeders, spending most of their spring and summer feeding alone, building up strength and waiting for their antlers to grow. In the fall, as their testosterone levels increase, they scrape the velvet off their antlers, and become aggressive. They then fight pitched battles with other males, sparring with their antlers locked, and sometimes dueling to the death. Stags eat little during the rut, so by the end they are gaunt and worn out. Some deer, such as red deer, defend harems against other bucks; muntjacs defend a fixed territory within overlapping female ranges; white-tailed deer stags defend an individual female. Once mating is completed, most bucks have little or no further parental investment in their offspring. Their antlers are shed, and they devote their solitary existence to surviving the winter and preparing for the next rut. They do not even recognize their own offspring, and behave with hostility toward them. Tropical deer do not have a fixed breeding season, so they invest even less energy in their young. By contrast, the doe spends nearly her entire year in some aspect of reproduction. After copulation in the fall, the female struggles to survive through the winter while she is pregnant. Gestation in most deer is 210-240 days, so that she gives birth in the spring. She then must leave her normal range and remain solitary for weeks while she protects her fawn. The fawn lies motionless for the first few weeks, concealed by its lack of scent and its white spots, which blend in with the dappled light on the forest floor. The doe returns to suckle it until it is able to keep up with her. Lactation lasts about 7 months, so the fawn is not weaned until the doe

comes into heat for the next mating season. Because body size is critical to mating success in males, they either have a more rapid growth rate or a longer growth period than do females. Their gestation period is also longer, and there is good evidence that the does devote more attention to their male offspring. Most young male deer must survive several years in bachelor herds before they are large enough to challenge and displace a stag with his harem. They usually do not succeed until they reach full adult size at about the fifth or sixth years. Since harems are typical of many species, most males do not mate in a given year, and many will never successfully overthrow a dominant buck and acquire does of their own. Deer use their senses of smell, hearing, and (to a lesser extent) sight to detect predators or other danger. In communicating and signaling to members of their own species, smell may be especially important. Most deer have facial glands, located in front of the eyes, and various glands on the feet and legs. These produce odoriferous secretions that are used to leave scent trails and mark territories. Many deer, such as the white-tailed and mule deer, flash their white rump patches when they run, signaling danger to their herd. Despite humanity's close association with deer for tens of thousands of years, these animals (with the exception of the reindeer, discussed below) were never domesticated. Why? As Juliet Clutton-Brock has pointed out, deer tend to be territorial and are not predisposed to being herded and led by a single leader (unlike goats and sheep). Ultimately,

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Figure 4.23. The reindeer is the only cervid in which both males and females have antlers, presumably because they use the long palmate front tines for scraping away snow to find food. (Photo courtesy B. O'Gara.)

because of their innate social disposition and their unpredictable behavior in captivity, it is virtually impossible to convince typical adult deer that they are to form a pal1 of a larger, human-oriented society. Fully domesticated animals (dogs or horses, for instance) come to accept their role within human society. As noted above, antlers are found only in males with the exception of reindeer (Fig. 4.23), Rangifer tarandus (commonly called the caribou in NOl1h America). Why should this be? Yet even in the reindeer, the antlers of mature males are typically larger than those of mature females. To survive in the harsh environment they inhabit, reindeer differ from the remaining deer in other important ways also. Unlike other cervids, reindeer are highly gregarious (travelling in large herds) and non-territorial. They spend most of their time browsing on the short grasses and herbs of the northern tundra. It has been suggested that for reindeer the antlers serve a different purpose than that for most deer-to gather food. In the winter reindeer congregate in large, mixed-sex herds and males and females alike use their antlers to dig under the snow and reach the sparse vegetation below. The reindeer are also the exception among the deer

family when it comes to domestication. Unlike most deer, reindeer travel in large herds that are easily directed by humans, are nonterritorial, and are relatively tolerant of human intruders entering their herds. In Lapland and pal1s of Russia, reindeer are used in the same manner that cattle (and horses to a lesser extent) are used in warmer climates. They can be milked and the meat eaten; they serve as pack and draft animals; they can be ridden; and their hides, bones, and hooves are used as raw materials. The domestication of reindeer may have occurred relati vely recently, however. This is suggested by the fact that the bones of domesticated reindeer are virtually identical to those of wild reindeer. The domesticated reindeer have not been bred over a long enough period to accumulate significant anatomical changes. The various uses for reindeer parallel those of domesticated cattle and horses, which is what would be expected if the latter were domesticated earlier. Indeed, some researchers suggest that the "domestication" of the reindeer is little beyond the stage of simply taming wild animals. For millennia bands of human hunters may have migrated with reindeer herds, taking individuals as necessary, and also helping to provide the herds with food (perhaps by scraping snow from vegetation during the winter).

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Figure 4.24. The endangered Pere David's deer, showing the peculiar?multipronged antlers and long tail. (From Whitehead, 1972). Eventually, rather than simply following the herds, humans may have begun to direct and control the movements of the herds, even driving them into corrals at times. From this stage of contact between humans and reindeer further taming and eventual domestication could easily develop. ABBE DAVID AND HIS DEER Perhaps one of the most elusive members of the deer family, Pere David's deer (Elaphurus davidianus) has never been known in the wild, but it has never been domesticated either (Fig. 4.24). For centuries the only living members of this strange deer lived in the huge Imperial Hunting Park, known as the Nan-Hai-Tze, south of Peking (modern Beijing), China. Until the end of the nineteenth century this park was surrounded by walls forty-five miles (72 km) long, guarded by Tartar soldiers-nobody, either Chinese or foreign, was allowed into the park, or even to look over the wall. This was the exclusive domain of the Imperial household. A French Catholic missionary priest and naturalist, Abbe Armand David, is credited with being the first Westerner to set eyes on what was within the park. It is said that while travelling in China in 1865, Abbe David bribed the guards of Nan-Hai-Tze and thus was allowed to scale the wall and have a look over the side. Presumably just at the moment that Abbe David looked over the wall, a herd of strange deer passed by within the enclosure. These deer were nothing like any that Abbe David was familiar with, and he was familiar with all of the types of deer then known from China. They were heavily built deer with long tails, broad hooves, big ears, and what seemed like antlers that were put on backwards. At first Abbe David thought that they might be a new species of reindeer. When he asked the

guards about it, he was told that the animal was called the sse-pu-hsiang which translated as "not a deer, not an ox, not a goat, and not a donkey" in reference to the animal's bizarre appearance. Abbe David was also told that the punishment for killing one of these remarkable animals was death. Abbe David was intrigued by this new animal, and made it known that he would like to obtain an example of the species. He persuaded the French embassy to officially ask the Chinese emperor and government for a specimen of the sse-pu-hsiang. In 1866 a couple of skins and three live specimens (which subsequently died on the way to France) were obtained by Abbe David and the French embassy, and were shipped back to Paris to be studied by the great zoologist Henri Milne-Edwards, who named the new species after Abbe David (Elaphurus davidianus). However, in his article Milne-Edwards incorrectly stated that the Chinese called this deer mi-lou (milu), a name actually used by the Chinese for the much better known sika deer (Cervus nippon) of China, Korea, Japan, Vietnam, Manchuria, and adjacent areas. Yet once the name mi-lou was applied to Pere David's deer in the western literature, it stuck. Once Pere David's deer was known to western science, many European diplomats requested live deer for their zoos. By the middle 1890s there were perhaps a dozen individuals of the species in various zoos in France, Germany, and Great Britain; in addition the Duke of Bedford was able to obtain specimens which he raised on his private estate at Woburn Abbey in Bedfordshire, England. At Woburn Abbey, the Duke revelled in his private collection of exotic animals. The specimens reached Europe just in the nick of time. In 1894-1895 disaster struck the deer population in China. The Hun-Ho River flooded and destroyed part of the wall that surrounded the Nan-Hai-Tze park, and a majority of the herd escaped. As the deer left the park, most were killed by hungry Chinese peasants. It is estimated that only some twenty to thirty Pere David's deer remained alive by the time order was restored. In 1900 the deer were again threatened. The Boxer Rebellion erupted in China, and an international coalition of European troops were sent to Peking to help control the situation. What exactly happened at Nan-Hai-Tze park is unclear-Chinese soldiers, Boxer rebels, Tartar guards, and the European troops have all been blamed for the tragedybut by the end of the conflict all that remained of the Pere David's deer herd was a sole female. She reportedly died of old age in 1920. Unfortunately, the specimens of Pere David's deer scattered throughout various European zoos did not do well, and slowly their numbers decreased. They did not breed adequately because individuals were dispersed among many different zoos, and no one zoo had an actual breeding herd-a necessity for properly producing healthy offspring. In fact the only place where an actively breeding population of Pere David's deer existed was on the private estates at Woburn Abbey. At the beginning of World War I almost

WHERE THE DEER AND THE ANTELOPE PLAY ninety deer lived at Woburn Abbey, while they were virtually extinct everywhere else. Even the Woburn herd almost perished. During World War I the Duke of Bedford could not obtain adequate food for his deer, and to make matters worse the British government used the estate's pastures to feed cattle. As a result many of Pere David's deer starved to death, and in 1920 the Woburn herd numbered only about fifty individuals. In the

85

last seventy years Pere David's deer have readily multiplied, increasing their numbers by at least an order of magnitude. From Woburn Abbey, living deer were sent to various zoological parks around the world, and in 1960 Pere David's deer from Woburn Abbey were reintroduced to China. If it had not been for Abbe David, and a private collector of exotic animals, the sse-pu-hsiang would be extinct.

Figure 5.1. The bison has long been a symbol of wildlife on the American plains. (Photo courtesy B. O'Gara.)

5. Hollow Horns

A WORLD OF BOVIDS "Perched on the lofty rim of Tanzania's Ngorongoro Crater to watch the ant-like movements of untold thousands of wildebeest milling about on the distant crater floor, is to me one of the unforgettable experiences of Africa. Here, captured in this vast amphitheatre like some gigantic fishbowl, one can see at a glance the character of wild Africa, with its antelopes-antelopes in countless numbers. Antelopes which once roamed all over this vast continent; through its woodlands, its plains, and even its deserts; in an exuberance of forms that have been with us for over fifteen million years. God may have had an inordinate fondness for beetles, as J.B.S. Haldane, one of England's great biologists once remarked, but luckily for us, when it came to Africa He was equally fond of antelopes. At least 74 species greet the eye, ranging in size from the 4 kg pygmy antelope to the giant eland weighing almost a tonne; and with some species reaching concentrations which make those of the American bison look impoverished by comparison. Who could fail to be captivated by this vast assemblage; their colours, their graceful forms and soft brown eyes, and above all, their striking horns, twisting and curling in a baroque extravaganza of shapes?" (Spinage, 1986: 1). The Bovidae are the most diverse and species-rich family of ungulates. Since most of our domestic animals (cattle, goats, sheep, yaks, and water buffalo) are bovids, they are also the most important mammals for human society (Fig. 5.1). There are approximately four dozen genera of living bovids, consisting of well over a hundred species: domesticated and wild cattle such as buffalo and bison, various forms of gazelles, antelopes, duikers, goats, and sheep. The Bovidae are primarily an Old World family found all over eastern Europe, Africa, and Asia, although they also occur naturally in North America (mountain goats, bighorn sheep, and bison). Because of man's influence, domestic bovids (especially cattle, sheep, and goats) roam every continent except Antarctica. Most living bovids are adapted to deserts, grasslands, and scrublands, although some inhabit such

diverse habitats as swamps, forests, and the arctic tundra. Despite their diversity, all bovids share a few features in common. Bovids are true ruminants with four-chambered stomachs, and most are grazers or browsers. Most living bovids have two horns (except the four-horned Tetracerus of India) composed of bony cores encased in hollow sheaths of horny material, keratin. The detailed internal structure of the horns distinguishes bovids from other types of ungulates. Among the bovids, however, there is considerable variation in the sizes and shapes of the horns. Like most ruminants, bovids have no upper front teeth (canines or incisors) on their skulls. Instead, they have a tough, horny pad against which their lower incisors bite. They use their rough tongues to pull grass and leaves into the mouth, and the lower incisors to shear it off at the base. Many bovids have highcrowned cheek teeth, typical of animals that live on gritty vegetation, especially grasses. Bovids have elongated limbs with the main foot bones fused into a single "cannon bone" and the lateral toes either reduced or absent. Some bovids can run very quickly, while others are very agile climbers and leapers. Most bovids tend to be gregarious, social animals that live in herds. Many have scent glands on their hooves that release chemical substances to the ground that other members of the same species can smell. An individual separated from its herd may find its way back to its compatriots by scent. A few bovids are either primarily solitary or Iive in small groups. In the early Miocene in Eurasia bovids began diversifying from cervoids and giraffoids. A number of poorly known early Miocene fossil teeth and jaws have been identified as bovids, but without the bony horn core, they could just as easily be cervoids or other types of primitive ruminants. By the late early Miocene, about 20 million years ago, there were undoubted primitive bovids in Africa and Eurasia. The best known of these was Eotragus, a small bovid about the size of a Thompson's gazelle (40 pounds, or 18 kg) with simple, straight horn cores about 3 inches (8 cm) long. Horns were found only in males; females were hornless. Eotragus was common during the middle Miocene in Europe, and it has also been reported from Africa. By 16 million years ago bovids are known from the Siwalik Hills of Pakistan, and they appear somewhat later in the middle Miocene in China. Living in woodland savannas, these early

HORNS, TUSKS, AND FLIPPERS

88

Antilopini Reduncini

Aepycerotini

Cephalophini Neotragini

Tragelaphini

Hippotragini

Figure 5.2. Relationships of the bovids (based on Vrba and Schaller, 2000). Note the differences between this classification and the others discussed in the text.

bovids were moderately diverse, with perhaps 15 different genera, mostly found in Asia and Africa. Among these middle Miocene genera was Gazella, the genus of the living gazelles. By the late Miocene, about 10 million years ago, bovids began an explosive evolutionary radiation, with over 70 new genera. This great diversification is clearly a response to the late Miocene climatic drying and expansion of grasslands and savannas, which led to a much greater diversity of habitats. As we have seen, the North American savanna saw a similar late Miocene diversification, except that there were no native bovids. Horses, camels, dromomerycids, and pronghorns acted in their stead. Bovids remained a tropical/subtropical group in Eurasia through most of the Miocene and Pliocene, just as cervids have dominated the temperate latitudes. When the ice sheets advanced during the Plio-Pleistocene a number of different kinds of bovids became adapted for cold climates as well. Today, yak, muskox, and many types of sheep and goats are tolerant of cold mountain peaks and tundra. Increased tolerance of cold climate also allowed bovids to cross the Bering land bridge during the Pleistocene and invade the New

World for the first time. Although only a few types of bovids reached this continent, they were very successful. Muskoxen dominated the Arctic tundra (along with caribou), and bison were the dominant ungulate on the Great Plains. Bighorn sheep and mountain goats are practically the only hoofed mammals that thrive in steep mountainous habitats. Bovids never reached South America before Europeans introduced domestic cattle and sheep, but bison did reach as far south as EI Salvador. With so many different species of bovids, we obviously cannot describe them in the same detail as the ungulates in the rest of this book. Instead, we will discuss the major groups of bovids in general terms, and concentrate on some of the better-known species. Currently, there are six major subfamilies (indicated by the -inae suffix, or "-ine" informally, and shown in bold face below) and 14 tribes (indicated by the -ini suffix, or "-in" informally, and shown in italics below) of the family Bovidae recognized by most specialists: 1. The Bovinae, which include the primitive Boselaphini (the four-horned antelope, and the nilgai, relicts

HOLLOW HORNS of the Miocene); the Tragelaphini, or Strepsicerotini, the spiral-homed antelopes (bongo, eland, kudu, nyala, sitatunga, bushbucks); and the familiar Bovini, the cattle, bison, and buffalo. 2. The Cephalophinae, or duikers, small, short-homed forms which live in dense jungles in tropical Africa. 3. The Hippotraginae, or grazing antelopes, including the aquatic Reduncini (reedbuck and waterbuck), and the horse-like antelope, or Hippotragini (oryx, addax, sable and roan antelopes). 4. The Alcelaphinae, including the gigantic herds of Alcephalini (wildebeest and hartebeest), and the leaping Aepycerotini (impalas). 5. The Antilopinae, or true antelopes, including the Antilopini (gazelles, blackbuck, springbok, gerenuk) and the Neotragini or dwarf antelopes (dik dik, klipspringer, Royal antelope, steenbok). 6. The Caprinae, or goat-like forms, including the Saigini, with their inflated nostrils; the mountain-dwelling Rupricaprini (chamois, mountain goat, serow, goral); the Ovibovini, or muskoxen and takins; and the Caprini, or true goat tribe (sheep, goats, and the ibex). Although the fossil record is excellent for most of these groups, there is no consensus as to how they are interrelated. Wildebeest and impalas are usually placed together, but most specialists are noncommittal about a family tree which ties all six subfamilies together. This seems surprising, since most of these groups can be traced back to the late Miocene. However, the fossils of these animals consist mostly of teeth, horn cores, or isolated limb elements, and these features tend to be highly stereotyped into characteristic subfamilies and tribes early in their history. Jonathan Kingdon published his version of bovid phylogeny in his multi-volumed East African Mammals. He sees a major division between the Bovinae and the rest of the family early in the Miocene, with the major bovine radiation in Eurasia, and the rest concentrated initially in Africa. According to Kingdon, the Eurasian bovines were suited to cooler, moister habitats characteristic of temperate regions, whereas Africa was colonized by small antelopes, which were physiologically superior in the drier African habitats. Bovines, for example, appear to sweat to cool their bodies by evaporation, while the others do it by panting. Kingdon places the cephalophines, neotragins, and reduncins in one group descended from a dwarf antelope ancestor, and the antilopins, alcelaphines, hippotragins, and caprines in another group descended from an antilopin ancestor, with both groups splitting off during the middle Miocene. In 2000, Elisabeth Vrba and George Schaller published another phylogeny of the ruminants, based largely on behavioral characteristics (Fig. 5.2). Sable antelopes and wildebeests were grouped together in a larger group that included the caprines, while the impalas and antilopins were grouped with the reduncines. The cephalophines form yet a third group, and the bovines form the other major group of ruminants. In addition to the formal zoological classification of

89 bovids, there is also an ecological classification based on their choice of habitat and mating strategy. This system was first introduced by Peter Jarman in 1974 and discussed in the previous chapter. It is very useful in noticing the similarities between unrelated ruminants. As extended by Christine Janis in 1982, the categories are as follows: Category A: tiny ruminants that live singly or in pairs in the deep forest; they selectively forage non-fibrous leaves and fruits over a wide area, so they do not defend a restricted territory; there is little difference between sexes, so they either have simple cranial appendages, or large canines instead. These include tragulids, musk deer, water deer, muntjacs, certain cervids such as the pudu, huemal, and brocket deer discussed in the previous chapters, and a variety of bovids, including all the duikers and dwarf antelopes. The extinct gelocids, leptomerycids and hypertragulids were probably also Category A, as were the early Eocene ancestors of almost all perissodactyls and artiodactyls, including the dichobunid "bunny deer," and the earliest horses and tapirs. Category B: slightly larger (above 33-44 pounds, or 15-20 kg body weight) closed-canopy woodland browsers; males patrol a small territory of choice bushes, so they may have spectacular horns; females are hornless; small polygamous herds are guarded by a single dominant male. These include some tragelaphins (lesser kudu, bushbuck, sitatunga), some antelopins (gerenuk), most reduncins (reedbuck, reebok, waterbuck), and most cervids. According to Janis, the extinct dromomerycid "pseudo-deer" of North America were probably also in this category, as were the extinct protoceratids with their bizarre slingshot horns, the tiny twohomed rhinoceros Menoceras, the oreodonts, and the browsing three-toed horses. Category C: medium-sized to larger (average about 190 pounds, or 85 kg) open-canopy woodland browsers and grazers, in which males hold territories part of the year, but form mixed herds the rest of the year. Males are slightly larger than females, with more elaborate horns. These include impalas and most antilopins (gazelles, springbok), some tragelaphins (greater kudu, nyala), and some reduncins (some waterbuck, puku, lechwe). Besides bovids, this category may include pronghorns, guanacos and vicunas, most extinct giraffes and camels, and most rhinos and tapirs. Category D: larger grazing antelopes (average about 330 pounds, or 150 kg) which roam over open grasslands; males defend a small territory only during the breeding season, and there is no difference in males or females in either size or horns. Among bovids, most alcelaphins (wildebeest and hartebeest) fall in this category. According to Janis, grazing forms among the horses (including zebras and most equines), deer (caribou and reindeer), rhinos, and camels also fall in this category. Category E: the largest homed ruminants (average about 880 pounds, or 400 kg) which have no territories, but feed over open grasslands; the males are much larger in size than females, with larger horns, and fight among themselves

HORNS, TUSKS, AND FLIPPERS 90 for dominance of the herd. These include the grazing bovins about 1-1.5 inches (2.5-4 cm) tall, and rear pair that may be (Cape buffalo, bison, eland) and some hippotragins (oryx, 3-4 inches (8-10 cm) long. Four-horned antelopes tend to be relatively solitary creatures (thought to be an evolutionarily gemsbok). Notice that these categories are purely ecological, rather primitive feature) whereas among the larger nilgai (head and than taxonomic. Category A, for example, includes families body length on the order of 2 meters), the females and their from all over the Ruminantia: Tragulidae, Moschidae, four calves often congregate in herds. In the wild bovins (members of the Bovini) occur in groups of cervids, and two tribes of bovids. Clearly, a given niche can be occupied by animals of different descent when North America and Mexico, Africa, Europe, Asia, and the the opportunity presents itself. In addition, Jarman's classi- islands of the Philippines and Indonesia. (Domesticated fication was originally worked out mostly for savanna and forms have been introduced to South America, Australia, woodland habitats. Obviously, it is less relevant to other and New Zealand as well). The typical bovin is a relatively large, stout beast bearing horns on its skull (although hornhabitats, such as mountain peaks or swamps. less breeds of cattle have been developed). Some bovins, such as the bison, can reach shoulder heights of 6 feet (2 m) BOVINES The quintessential bovids are the domestic and wild cat- or more, and a number of bovins can reach maximum tle and their close relatives, classified as the subfamily weights in excess of 2200 pounds (1,000 kg). The bovins Bovinae. Since we depend on their beef, milk, manure, and probably originated as warm temperate creatures of the leather, bovines are the most familar ungulate for most of us. Eurasian plains. While most cattle, wild or domestic, are At present there are well over a billion, and perhaps closer fairly tolerant of cold weather, a few forms (such as the yak to 1.5 billion, domestic head of cattle on Earth (as compared and bison) have become adapted to harshly cold climates. In to the 2001 human population of approximately 6.2 billion). the tropics most bovins di vide their time between eating and The living members of this subfamily are conventionally attempting to stay cool-for instance by wallowing in mud grouped into three tribes: the primitive Boselaphini, the spi- or water, and concentrating much of their activity at night. Bovins tend to congregate in herds centered,on females ral-horned Tragelaphini (or Strepsicerotini), and the Bovini. The Bovini include the various forms of wild and domesti- and their young. Depending on the species, such herds may cated cattle proper (the "true cattle") of the genus Bos, the number from less than a dozen individuals to hundreds of water buffaloes of the genus Bubalus, the African buffalo of animals or even more (such as the enormous bison herds that the genus Syncerus, and the European wisent and American once roamed the plains of North America). Such herding behavior serves, at least in pat1, as a defense against predabison (sometimes called "buffaloes") of the genus Bison. The Boselaphini currently consists of only two species, tors. The genus Bos includes not only the domestic cattle the four-horned antelope (Tetraceras quadricorfJis, also known as the chousinghas or the guntada), and the nilgai (Bos taurus) and their ancestor, the aurochs (Bos primige(Boselaphus tragocamelus). Both from India, they are living nius), but also the shaggy Himalayan yak (Bos grunniens) relicts of the animals which evolved into the true cattle and three rare species of cattle in southeast Asia. The Indian (Bovini). The four-horned antelope is a moderate-sized ani- gaur (Bos gaurus), resembling a large black bull, is the mal (with a head and body length of about a meter) distin- largest of bovids, weighing over a ton (900 kg) and reaching guished by two pairs of short, conical horns on the skulls of six feet (2 m) at the shoulder. It once frequented the upland adult males-a pair of horns in the front that are usually bamboo forests and glades of India, Burma, and southeast

Figure 5.3. The water buffalo, Bubalus bubalis , the main beast of burden in Southeast Asia. (Photo by D.R. Prothero).

Figure 5.4. The Cape buffalo, Syncerus caffer, has a distinctive "helmet" of horn over its forehead. (Photo courtesy A. Walker).

91 HOLLOW HORNS Although the deadliness of Cape buffalo has certainly been exaggerated, they are still the major source of death among humans, surpassing even the lion. However, in the protection of game reserves, Cape buffalo spend their daylight hours grazing the savanna and blissfully wallowing in water holes. Even when their excellent senses pick up humans, they ignore them. Only after repeated persecution by hunters do they become wary and aggressive, fighting for their lives. Most of the time, however, they hide from humans, and if the hunter misses, they usually retreat. A close relative of the Cape buffalo is the extinct giant ox, Pelorovis, which flourished in East Africa during the Ice Ages. This immense beast had horn cores which curved forward in front of the head in a great arc, and spanned 13 feet (4 m); with the keratin sheaths, its horns may have spanned 17 feet (5 m)! Peloravis has been found in Olduvai Gorge, where some of the earliest human remains are also found, and Louis Leakey even discovered shattered Peloravis leg bones among the stone tools in Olduvai Bed II. Presumably our ancestors butchered the beast and took the leg bones home to get at the marrow. Figure 5.5. The eland, Taurotragus derbianus, is the The final subgroup of living bovines are the spirallargest of all antelopes, weighing as much as a ton; it horned antelopes, Tribe Tragelaphini (or Strepsicerotini). is more closely related to cattle than it is to other Just as the relatively primitive Boselaphini are believed to antelopes. (Photo by D. R. Prothero). be representative of the ancestral stock of the true cattle, so too they are believed to be representative of the ancestral stock of the African Tragelaphini. Thus these three groups, Asia. The banteng (Bos javanicus) looks more like a lightcolored Jersey cow, and is endangered in the jungles of the true cattle, the four-horned antelope and nilgai, and the Indonesia and Malaysia. The kouprey (Bos sauveli) hid in nine species of spiral-horned antelopes are united in the sinthe deep forests of Cambodia and Laos until 1937 when a gle subfamily Bovinae. The spiral-horned antelopes include the elands (genus specimen was sent to a zoo in Paris. It looks like a large brown ox with a long tail, and the horns of the bulls burst Taurotragus) and the bongo, bushbuck, kudu, nyala, and open at the tips, exposing the black core. Fewer than 200 of sitatunga (genus Tragelaphus), among other species. These animals tend to be more slender and graceful than the true these endangered cattle survive in the wild. cattle, with long faces and beautiful spiraled, often More typical of Asia are the true buffalo, genus Bubalus. The water buffalo, Bubalus bubalis, with its huge corkscrew-shaped horns. In social organization they tend to arc of horns, is the most familiar form because of its domesbe nonterritorial (unlike the Boselaphini) and generally gretication (Fig. 5.3). There are also two endangered species of garious, but tend to congregate in somewhat smaller groups than do the true cattle. Spiral-horn antelope species have anoas, or dwarf water buffaloes. The lowland anoa (Bubalus become adapted to all of the major habitats found in Africa depressicornis) lives in the coastal swamps of northern Celebes in Indonesia. The mountain anoa (Bubalus quarsouth of the Sahara Desert. lesi) is restricted to the mountain slopes of Celebes. The The largest of all the antelopes is the eland (Fig. 5.5), which reaches 6 feet (2 m) at the shoulder and may weigh a tamarau, or Philippine pygmy buffalo (Bubalus mindorensis), is a small but aggressi ve nocturnal ox found only in the ton (990 kg). Although it has straight horns with a tightly bamboo forests and marshes on the Philippine island of spiraled surface, its heavy, bull-like neck and ox-like size Mindoro. Little is known of its biology and it is extremely remind one more of cattle. Yet it has the speed, grace, and agility typical of antelopes, not cows. Their light tan coat is endangered. crossed by vertical white stripes. Elands are remarkably Wild African cattle are represented by the Cape buffadocile, and yet have never been domesticated, despite the lo, Syncerus caffer (Fig. 5.4). It is distinguished by the fact that they provide excellent milk and meat and are much broad horns which form a boss over the head, and may span over three feet. This beast is infamous among hunters for hardier in the harsh African savanna climate than domestic fighting back more fiercely than any other wild animal of cattle. Kudus are slightly smaller, with horns that make a Africa, including lions and leopards. Legends and stories recount the anger of the wounded Cape buffalo goring and broad corkscrew spiral reaching 60 inches (150 cm) in length, and a long fringe of fur at the throat (Fig. 5.6A). trampling hunters, sneaking up on them for revenge, or even Bushbucks and nyalas are solitary animals which live in attacking unprovoked.

HORNS, TUSKS, AND FLIPPERS

B

Figure 5.6. A. A male greater kudu, Tragelaphus strepsiceros, shown atop a mound guarding its territory. (Photo courtesy C. Janis). 8. The beautifully striped bongo. (Photo by D.R. Prothero).

deep forest. They are about 3 feet (1 m) at the shoulder, with dark brown fur covered with white stripes and spots. Their horns are only about 18 inches (45 cm) in length, and go through a single spiral. Sitatungas are very similar, except that they are beautifully adapted for living in marshy habitats. They have banana-shaped hooves over 7 inches (18 cm) long which prevent them from sinking into the mud, but make them awkward runners. One of the most beautiful of the tragelaphins is the bongo (Fig. 5.6B). Despite the fact that it is over 4 feet (1.2 m) at the shoulder, with a rich chestnut coat broken by white stripes, this animal is so elusive that it is rarely seen by humans in the wild. AUROCHS AND WISENT Before recorded history there lived in Europe, north of the Alps, two ferocious animals commonly known as the aurochs (plural, aurochsen) or urus (Bos primigenius, the ancestor of common domestic cattle), and the wisent, wysent, or European bison (Bison bonasus). Both of these species survived into historical times, but the former is now extinct and the latter has only just been saved from extermination by the intervention of concerned zoologists. Across the Atlantic in North America an estimated 40 to 60 million head of the mighty American bison (commonly called the "American buffalo," but technically Bison bison) once roamed the continent. In the nineteenth century these beasts were destroyed almost to the last individual. Again, we are indebted to the extraordinary efforts of a few concerned individuals for the preservation of this species in recent times. Julius Caesar wrote in his Commentaries on his wars in Gaul (mid first century B.C.) that the aurochs resembled a

bull, but was nearly as big as an elephant, extremely strong and swift (Fig. 5.7). These animals were said to be hunted by the natives via the use of pits in which they could be trapped and then slain. While the slain animals were eaten, and the thick hides used for various purposes such as the covering of shields, the horns in particular were highly valued. Caesar reported that hollow' aurochs horns were edged with silver along their bases and used as drinking vessels at feasts. During the late Pleistocene and into the early Holocene the aurochs was in fact a very common species throughout the Old World Northern Hemisphere. The wild aurochsen tended to look very similar to modern domesticated common cattle-their descendants-but were larger (males reached six and a half feet, or 2 m, at the shoulder), and were presumably fierce, temperamental beasts. The coats were often black or brownish red, with a lighter line down the back, and sometimes a large saddle of lighter hair on their back. Aurochsen were hunted during the Stone Age and right up into historical times. As human populations increased, and "civilization" spread, the size of aurochsen populations steadily decreased and became more and more restricted in range. During the Middle Ages the aurochsen were being rapidly driven to extinction, especially by the destruction of the dense forests in which they had taken refuge. Their populations were progressively restricted. In sixth century France they were already extremely rare, and by the fourteenth and fifteenth centuries they were confined to a few protected forests in Central Europe. Successive monarchs (such as the princes of Masovia in Poland) prohibited the general hunting of aurochsen; that privilege would be reserved for royalty.

93 By the sixteenth century living aurochsen were restricted to the forest of Jaktorovka in Masovia, near Warsaw, Poland. There they Ii ved in a protected reservation, provided with hay in the winter by the local villagers. Royal officers took periodic censuses of the aurochsen, and these numbers record the sad decline and eventual extinction of this magnificent species in grim detail. In 1557 there were approximately fifty aurochsen, in 1562 the number had declined to thirty-eight, and by 1599 there were only two dozen aurochsen known to be alive, despite the numerous decrees issued in an attempt to save the species. Two years later, in 1601, a plague killed twenty of the aurochsen, so that only four remained (three bulls and one cow). In 1630 the officer in charge of the preserve could find no living aurochsen, and he was told that the last individual (a female) had died three years earlier. Thus the year 1627 marks the extinction of the aurochsen. Even before the aurochs was actually extinct, it had become a beast of legend and a source of confusion. This was in large part because another large wild bovin, the wisent or European bison, also inhabited Europe. From early times some travellers, writers, and reporters confused the two types of beasts. In 1837 the Polish paleontologist Georg Gottlieb Pusch even tried to prove that the aurochsen, or the urus, had never existed. The core of his proof was that the Polish name for the aurochs, tur, and the Polish word for the wisent, zubr, were etymologically derived from the same source-thus there was only one animal (the European wisent) which had engendered legends of the mythical aurochsen. It is clear now, however, that the aurochs and the wisent were two distinct animals. The European wisent is a shaggy-furred relative of the American bison or "buffalo." The two types of beasts not only look remarkably similar, but in fact are very closely related. Indeed, the wisent and American buffalo will readily interbreed producing fully fertile offspring, and for this reason some zoologists consider them to be simply different subspecies of a single species. In fact, many of the species, and even genera, of Bovini are very closely related and can interbreed to a greater or lesser extent. In some cases hybrids can be produced between parents of different species, but these hybrid offspring may be sterile. Just as the European and American bisons can interbreed fully, so can common European domestic cattle, Bos taurus, and Indian humped cattle or zebu, Bos indicus, and some zoologists accordingly classify these two species as one. The American buffalo has been crossed with domestic cattle, producing the so-called "catalo." Like the aurochs, the wisent was once abundant in the forests of Europe. Caesar also wrote of the wisent in his Commentaries. From physical appearance the wisent seemed more wild and ferocious than the aurochs, though in fact the opposite was true. After all, the aurochs looked like an overgrown domestic cow while the wisent was nothing like any beast seen before. During the height of the Roman empire wisent and aurochs bulls were brought to Italy for

Figure 5.lA. Reconstruction of the extinct European aurochs, or urus, as drawn by Hamilton Smith. (Neg. no. 316032, courtesy Department of Library Services, American Museum of Natural History). B. The wisent (Photo by D.R. Prothero). use in gladiatorial combats. As civilization advanced and forest area diminished, wild wisents were confined to ever more restricted areas. In the seventeenth century they were still fairly numerous, but by the next century they were greatly reduced in numbers. The last pockets of wild wisents were in Prussia, Hungary, along the Polish-Russian border (in the forest of Bialowiecza, or Byelovyeh), and in the Caucasus. By 1755 wisents were extinct in Prussia, and by 1800 there were no more left in Hungary. In the early nineteenth century the Bialowiecza Forest was under Russian control, protected from tree felling and hunting by anyone other than the czars themselves and their privileged family and friends. In 1830 there were close to 800 wisents in the forest, and by mid-century about 1500, but by the beginning of World War I the number had dropped again to approximately 750. The primary reason for the decline in the wisent population, despite its protected status, was that other game animals were introduced into the forest and competed with the wisents. An overabundance of red deer, which the czar and his associates hunted, was apparently destroying the forest vegetation upon which the wisents fed. With the outbreak of World War I in August of 1914, the wisents of Bialowiecza were immediately put in danger. The next year the battlefront moved through the forest, and

94

HORNS, TUSKS, AND FLIPPERS

in September of 1915 it was captured by the Germans after heavy fighting and severe losses on both sides. Of the 770 wisents that are recorded in the park on the eve of the battle, 650 were killed. German zoologists were as concerned about protecting the wisents as had been the Russian czar, and they immediately pressured the German High Command to take actions to protect the wisents. The population of wisents increased during the next few years under German protection, until they numbered 185 when the Germans withdrew in November 1918. Unprotected, the wisents were killed by peasants and soldiers, both for their hides and their meat. The new Polish government issued orders protecting the wisents, but still they continued to be poached until the last survivor was shot by a former Russian forester, one Bartmoleus Szpakowicz, on 19 February 1921. The other herd of wild wisents that survi ved into the twentieth century was located in the Caucasus Mountains. This herd was virtually unknown to western scientists before the middle of the nineteenth century, although in fact it had first been discovered during a scientific expedition to the Caucasus during 176~ to 1773. The story goes that after one of the many Polish insurrections of the middle 1800s against their Russian overlords, a Caucasian lieutenant fighting alongside the Russian soldiers visited the museum in Lublin (Poland) and saw a specimen of a wisent from the forest of Bialowiecza. He mentioned to museum officials that he was familar with similar beasts from his native land, and the reports from the previous century were confirmed. A herd of perhaps a thousand wisents lived in the Caucasus region. Unfortunately the Caucasian herd fared no better than the Polish herd. Most of the beasts were wiped out by military machine-gun hunts during the period 1918-1919, and the last known wild Caucasian wisent was reported to have been killed in 1926. By the 1920s all known wild wisents had been exterminated. But were all wisents exterminated? There were a few small captive herds at the beginning of the century, notably at Tachina (Tashina) Park near St. Petersburg, at Minsk, and a small herd on the Crimea. But all of these Russian animals were killed during the Russian Civil War, most either by Cossacks or the Red Army. At Mezerzitz, on prope11ies split between Poland and Germany, the Prince of Pless had a herd of some fifty-five or fifty-six wisents that had originated from four animals donated by Czar Alexander II in 1869. But this herd too largely succumbed to the political turmoil of the times. When it was all over, only three animals survived, all with machine gun bullets in their bodies. Fortunately a few dozen wisents still survived in capti vity in various zoological parks and preserves, such as England, in the Budapest zoo and forest park, and in Swedish preserves. Planned breeding was can ied out, and by 1939 there were about ninety-four purebreed European wisents (along with some animals that had mixed wisentAmerican bison blood). Then World War II broke out and their numbers again suffered. In the next couple of decades, however, the breeding programs rapidly progressed and the 4

wisent numbers multiplied. Herds have now been reintroduced into the Bialowiecza Forest, the Caucasus, and other parts of the former U.S.S.R. After a very close call, it seems that we can optimistically say that the European wisent has been saved from extinction. WHERE THE BUFFALO ROAM The story of the decline and subsequent resurrection of the North American bison, the American "buffalo," is perhaps even more dramatic than that of the European wisent. It has been estimated that only a few centuries ago some 40 to 60 million bison (Bison bison) roamed through North America. Two subspecies inhabited the continent. The more numerous plains bison lived mainly east of the Sierra Nevadas and inhabited most of what is now the United States, except for the Great Lakes area, New England, and parts of the southern East Coast (Figs. 5.1, 5.8A, B). The plains bison extended north into Manitoba, Saskatchewan, and eastern Alberta (Canada). The woodland, wood, or mountain bison (of the same species, but generally considered a distinct subspecies from the plains bison) inhabited the Rocky Mountain region in Alberta and even further north. Bison first crossed the Bering land bridge to\America in the middle Pleistocene, about 500,000 years ago. Here they radiated into a number of different forms, adapted for the full spectrum of climates in North America. Perhaps the most spectacular was the giant bison, Bison latifrons, found from Mexico and Florida to Alberta during the last interglacial. Its huge horns spanned over almost 7 feet (200 cm wide), compared to 2 feet (65 cm) for modem bison (Fig. 5.8C)! The giant bison became extinct at the end of the last Ice Age, but the ancestral Bison priscus probably evolved into modern Bison bison before the beginning of the Holocene, about 10,000 years ago. For thousands of years these animals flourished, but due to American efficiency in their slaughter, they were all but extinct by the end of the nineteenth century (Fig. 5.9). Europeans and European descendants were not the only people to hunt the bison en masse. Bison were probably hunted from the arrival of the first humans on the American continent. Certain Native-American (Amerindian) tribes survived almost exclusively by hunting the bison, often utilizing the entire carcass of the animal for everything from food to fuel to shelter to tools. Indeed, in the midst of continuing hostilities with the indigenous cultures, the principal motive for the white man's destruction of the bison herds during the nineteenth century was to starve the Indians into submission. In 1869 General Phil Sheridan declared that, "Every buffalo dead is an Indian gone." In 1875 he said, "Those buffalo hunters have done more in a few months to bring about peace with the Indians than the whole Army could do in thirty years!" At any rate, buffalo hunting was certainly not confined to those of European extraction. There is a site in southeastern Colorado, dating from about 6500 B.C., where Paleo-

HOLLOW HORNS

95

Figure 5.8. A. A herd of American bison (Bison bison); note the distinctive shaggy hump and beard in the adults, and numerous calves. B. Two bison bulls battling for supremacy over the herd. (Both photos courtesy B. O'Gara.) C. A paleontologist measures the hornspan of the giant Ice Age species Bison latifrons. The total span would be even larger if the length of the horn sheaths is added to the bony horn cores. (Courtesy University of Nebraska State Museum).

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HORNS, TUSKS, AND FLIPPERS

A

B

Figure 5.9. A. Native American warriors hunting bison with their traditional bow-and-arrow methods, as recorded by George Catlin in the 1830s. B. When the railroads came, shooting stampeding bison from the train became a popular "sport" which decimated the herds in just a few years. (Both images courtesy Library of Congress). Indians drove a herd of close to two hundred bison to their death over the edge of a gorge. Unlike proper, ecologicallyminded "noble" savages, these Paleo-Indians removed only a portion of the meat from the animals they killed, and left the rest to rot. In historical times the North American Indians were known to hunt down bison in huge numbers. After the Spaniards introduced horses to the continent in the sixteenth century, the Plains Indians took up hunting bison with bow and arrow from horseback. Subsequently, the Indians adopted firearms which increased the kill. As late as the autumn of 1883, when the bison was virtually extinct, Sitting Bull and his comrades took about two months to decimate a herd of about ten thousand in North Dakota. Despite these abuses by the aboriginal peoples of the continent, the major blame for the near extinction of the North American bison must lie on the heads of the white men. The first European sighting of an American bison was, of all places, in a private zoo in Mexico. In 1521, upon reaching the Aztec capital, Hernando Cortez found a "rare Mexican bull" in King Montezuma's personal menagerie. It was almost another decade before a European laid eyes on a wild American bison. As the continent was settled, the bison quickly declined. The first major impact was along the east coast, so that by about 1800 the bison was extinct east of the Mississippi River. Elsewhere in North America, as late as the 1860s, bison were extremely abundant. On the plains dense herds of bison were described as being on the order of twenty-five miles (40 km) in breadth and some fifty miles (80 km) long, and the animals were so closely spaced that "the whole country was covered with what appeared to be a monstrous moving brown blanket" (letter from Col. C. Goodnight to Martin S. Garretson describing a herd in the early 1860s). In 1871 Col. R.I. Dodge watched a herd pass through the valley of the Arkansas River. It took several days to pass, and may have included four million animals.

Yet in less than 20 years-from 1865 to 1884-over sixty million bison were wiped out. The introduction of the railroad to the West provided an easy means of transportation for professional hunters to reach the herds, and a method to ship bison products back East. In the late 1860s the first transcontinental railway divided the Plains bison into two major "herds": a southern herd and a northern herd. It is reported that in 1871 five thousand professional buffalo hunters left from Kansas City to begin the slaughter of the bison in earnest. The professional hunters were joined by perhaps an equal number of amateur hunters. Hundreds of thousands, then millions of bison fell to the hunters. Carcasses were left to rot on the plains. Settlers complained of the stench. By 1875 only a few percent of the original bison population in the southern herd were left, and both Kansas and Colorado passed laws attempting to protect the bison. Still, a hundred thousand more bison, almost all that remained of the southern herd, were killed during the winter of 1877-1878, and at most a few hundred animals remained. These few surviving animals made their way to Texas, but by 1889 they too had been shot-and so ended the southern herd. Between 1881 and 1883 there was a massive attack on the less numerous northern herd. While white man and Indian fought each other, both waged war on the bison. Many bison were slaughtered in the area of Yellowstone National Park, and as mentioned above, Sitting Bull and his people did their part to reduce the bison population. By 1884 the northern herd that had inhabited United States territory was virtually wiped out. Conditions were no better in Canada. By 1885 the wood or forest bison of Canada was almost extinct in the wild. Why were the bison hunted so heavily? Although in many cases most of the bison carCass was wasted, virtually all of the animal could be put to a useful purpose, as the American Indian knew. Some hunters went after the meat in

HOLLOW HORNS 97 particular, for which there was a considerable market. A Roosevelt) quickly acted to increase bison population nummeat hunter often took only the tongue and the choice cuts bers. Reservations were established for the bison, and they of the hindquarters and the hump ribs-the rest was left to were provided with shelter and fodder. Results were rot. Others went after the hides which could be shipped back achieved quickly, since under favorable natural conditions and made into good leather that might go into numerous the typical bison cow will bear a new calf each year. In 1910 products, from machinery belts to shoes, saddles, or hol- there were over 2,100 bison in North America, and by the sters. There were fur traders that sought "buffalo robes" to 1930s there were over 20,000. Today ranchers keep herds be used as overcoats and wraps. Buffalo fat could be used in throughout the continental United States, from Florida to the manufacture of soap and candles, and buffalo horns were New York, to Texas, Wyoming, and California, and there are used in hat racks. sizable herds in government reservations such as Many bison were killed for pure sport which, it was Yellowstone Park and the Wood Buffalo Park in Alberta, claimed, could become highly addictive. Chasing and shoot- Canada. Buffalo meat is actually quite popular in some parts ing bison from horseback was considered great fun by some of the west, and bison are much easier to ranch, since they persons. Plinking expeditions were arranged where interest- are hardier than domestic cattle. ed parties could test their shooting skill, and have a bit of A sad footnote to the otherwise· happy story is the fact adventure, by slaughtering wild bison from a railway car. that the wood or forest bison no longer exists as a distinct Besides, it was thought to be in the best interests of the subspecies. The last remaining herd of pure forest bison United States to destroy bison and devastate the Native inhabited the Wood Buffalo Park, but unfortunately in the American populations. They depended on the bison for their 1920s plains bison were introduced to the same park. livelihood but were the enemy at that time. Naturally the two subspecies mixed and hybridized, so the Even after the bison were gone, these beasts still made rarer forest bison ceased to exist as a purebred form. a direct impact on the homesteaders of the prairies. In many areas the grounds were literally covered with scattered bison CATTLE CALL bones. The bones were collected and burnt as fuel, and they The modem domestic cattle are among the most versawere also shipped back East by the train load. These bones tile animals used by humans, and consequently they have could be ground up and used as fertilizers; they were used in been important to many societies for thousands of years. sugar refining (to neutralize acids produced during the refin- Modern Europeans and Americans tend to consider domesing process); the hoofs and horns were used in the manufac- tic cattle primarily as providers of various food stuffsture of glue. Well into the twentieth century bison bones milk, cream, and their derivatives such as butter and cheese, were being shipped to the East for commercial use. and meat-and to a lesser extent providers of leather. In According to one estimate more than 175 million bison large areas of central Africa and in eastern and southeastern skeletons may have been commercially processed-several Asia, however, there is no tradition of milking cows and times the estimated number that ever roamed the continent ingesting dairy products, and it is common for people to sufat anyone time. How could this be possible? The dry air of fer from lactose intolerance. Rather, in much of the world the plains could preserve bison skeletons for decades, so it cattle are viewed primarily as draft animals. Cows and oxen is feasible that this many skeletons accumulated before the (usually the castrated males) pull plows, turn threshing bone hunters came in earnest. mills, draw carts, and perform other heavy labor. The The demise of the North American bison occurred in a manure is used on the farm to replenish the soil, or it may be flash, and only after the fact did the Canadian and United burned as a fuel, or even used as a building material. Old and States governments intercede to try to halt the destruction. feeble animals are killed for their meat and the raw materiCanada passed legislation to protect the bison in 1885, while als they provide: horns, bones, and hide can be used to manthe United States did not move to protect the bison until as ufacture various goods; hooves are traditionally used for the late as 1899. By the 1890s there were only two groups of manufacture of gelatin and glue; and the fat may be used to bison remaining in North America: a mixed lot of plains and produce tallow that can be used in lighting devices, as a forest and wood bison in Canada, ,and a small herd of plains lubricant, or to make soap. bison in Yellowstone Park. At the close of the nineteenth The earliest unequivocal evidence of the domestication century William T. Hornaday, director of the New York of the aurochs-which would eventually lead to all of the Zoological Park, made a census of all known living North various European breeds of cattle, and possibly the Indian American bison. He found that there were just under 1,100 humped cattle or zebu-comes from 7000 B.C. in archeobison alive scattered among the "wild" herds in Canada and logical sites in Turkey. The other domesticated cattle of Yellowstone, those kept in zoos, and a few maintained on Asia-the yak, the water buffalo, the mithan, and Bali catprivate ranches. In 1905 Hornaday founded the American tle-arose from wild progenitors other than the aurochsen. Bison Society, the primary goal of which was to save the From Paleolithic rock paintings found in Europe, we American bison from extinction. know that our Pleistocene forebears hunted the wild The American Bison Society, with the support of some aurochsen. But as Juliet Clutton-Brock has pointed out, it is people in high places (such as President Theodore really very difficult to imagine how or why early humans

HORNS, TUSKS, AND FLIPPERS 98 switched from hunting these beasts to eventually domesti- to note that at present humped cattle are becoming increascating them. After all, the wild aurochs was a large, fierce ingly popular with certain groups of American farmers. beast that would be difficult to capture alive and also diffi- Driving through the Carolinas, for instance, one may cult to constrain once captured. Even if young calves were observe both European and Indian cattle, along with hybrid captured, tamed, and raised by humans they would probably forms, grazing in the fields. Theoretically if European domestic cattle, Bas taurus, mature to fierce adults. Early domesticated cattle could also prove something of a nuisance for early farmers. Cattle are the direct descendants of the aurochs, Bas primigenius, would tend to destroy crops if not properly fenced and then a common genetic heritage is shared between the two secured, and penned groups, perhaps composed of a large forms. For this reason, some scientists do not recognize the proportion of calves, might attract large and troublesome extinct aurochs as a separate species from European domespredators (such as big cats and wolves) to early human habi- tic cattle. Perhaps all the genes, that in the right combination tations. Cattle would also have to be kept away from human made an aurochs, are still carried within living domestic cattle-but simply diffused throughout the different breeds. water supplies which they might otherwise foul. Clutton-Brock also questions what captive aurochsen Looking at modern breeds of cattle, some have large horns would be used for. Even if a cow were tamed, she suggests shaped like those of aurochsen. Some have the size and genthat it would be very unlikely that one could milk it. Even eral build of aurochsen. Some have the coloration patterns of today it takes considerable effort to milk a "primitive" breed aurochsen, and so on. The reason aurochsen per se are conof domesticated cow that has not been explicitly bred for sidered "extinct" is because there is no longer a single breed milk production-the cow must be extremely relaxed, the of cattle that carries the full combination of aurochsen charpotential milker must be familiar to the cow, her calf must acteristics. But if we could select out the aurochsen characoften be present, and 'it may be necessary to stimulate her teristics from various domestic breeds and combine these genital area in order to induce the secretion of milk. characteristics into a single breed, then effectively the At the ancient site of Catal Hliylik, in present-day aurochs would be resurrected-or at least so the Heck brothTurkey, there is a famous shrine composed of Bas primige- ers reasoned. nius horn cores dating to approximately 6000 B.C. Perhaps The zoologists Lutz and Heinz Hecht, of the Berlin and the earliest semi-domesticated cattle were kept primarily for Munich Zoos respectively, had the idea of reconstituting ritualistic purposes, being sacrificed as needed. Subse- aurochsen in the 1920s, and each tested the idea starting quently they may have been used as a ready source of fresh from different breeds of domestic cattle. Amazingly, by meat "on the hoof' as well as for other materials, as men- crossing different breeds with supposed aurochsen traits, tioned above. Over the generations, increasingly tame ani- and artificially selecting the offspring for further breeding, mals could be harnessed and put to work. As aurochsen were both brothers (independently of each other) were able to penned and bred in captivity, it may have been found that the produce a strain of cattle that bred true and looked remarksmaller animals were easier to handle and thus selected by ably like the extinct aurochsen. Before their final extinction humans for further breeding. This is confirmed by the fact true aurochsen had been observed and described several that there was a dramatic decrease in the size of cattle as times, and a remarkable oil painting of an aurochs, apparthey became domesticated during Neolithic times. By the ently done from life by an anonymous Polish artist of the fourth and third millennia B.C. fully domesticated and dis- late sixteenth or early seventeenth century, was discovered tinct breeds of cattle had been developed in Egypt and by the English zoologist Hamilton Smith in a used bookstore Mesopotamia. These civilizations milked their cows, mark- while visiting Germany in 1827. So zoologists have a pretty ing the earliest evidence for the consistent use of dairy prod- good idea of what a living aurochs should look like, and the ucts. Heck brothers' creations certainly did look like aurochsen. The domestic humped or Indian zebu cattle (variously Furthermore, it is reported that these newly bred aurochsen referred to as Bas indicus or Bas taurus indicus) are gener- not only resembled the extinct forms in external appearance, ally thought to have been domesticated separately from but they also took on the personality attributed to the ancient European cattle. They may have originated either in India or aurochsen. They were fierce, shy of humans, and somewhat in southwestern Asia, and their ancestor is thought to have temperamental. Some of these beasts were even allowed to been the Indian aurochs (variously referred to as Bas primi- run wild in the Bialowiecza Forest, just as the true aurochsen genius namadicus or simply Bas namadicus). Zebu cattle once had. appear as early as 3000 B.C. on cylinder seals of ancient While not everyone even agrees that the effort expendIndus Valley civilizations such as Mohenjo-Daro and ed on attempting to "reconstitute" the aurochsen was worthHarappa, although their origin may be older still. Within the while, and virtually no one would claim that true aurochsen general category of "zebu cattle" there are a number of have been "brought back to life," ce11ainly the Heck brothbreeds found throughout the world today. In ancient times ers performed a fascinating experiment. Perhaps their work zebu cattle were introduced to Africa from India or the foreshadows the proposed (but still in the very early stages Middle East, and they were particularly popular in Egypt of development) reconstitution of extinct species by bioduring New Kingdom times (ca. 1500 B.C.). It is interesting medical cloning of preserved tissue fragments (such as those

HOLLOW HORNS

Figure 5.10. A blue duiker (Cephalophus monticolaJ, showing the typical coloration and short horns. (Photo by D. R. Prothero). of woolly mammoths and woolly rhinos recovered from the far North), or (perhaps even farther in the future) by biochemical engineering involving the manipulation of "ancient" or "ancestral" genes still found in the DNA of living organisms. DIVING BUCKS In Afrikaans they are called duikers (pronounced "dikers") which translates to "divers" or "diving bucks." These generally small, shy, agile antelopes are named after their habit of darting or diving quickly into dense vegetation if disturbed. Duikers have relatively short fore-legs, an arched back, longer hind-legs, a large brain-size to body-size ratio relati ve to other antelopes, and a short pair of unbranched spike horns that project backwards from the skull (Fig. 5.10). They are typical Category A ruminants not only in lacking large horns, but in their ecology as well. Distinct from all other bovids, duikers have been relegated to their own subfamily, the Cephalophinae. Within the family seventeen species are recognized, the sixteen species of the forest duikers (genus Cephalophus) and the common, bush, or savanna duiker (Sylvicapra grimmia). Duikers are found throughout Africa south of the Sahara. While there are no genuinely large duikers, among the species of duikers there is a considerable range in body size. The shoulder height of adults can range from about 14-25 inches (35-67 cm), the length of the head and body ranges from slightly over half a meter to almost a meter and a half, the tail length is in the range of 2.8-7 inches (7-18 cm), and the adult weights of various species can be anywhere from 9-175 pounds (4-80 kg). There is also considerable variation in the pelage. Some duikers are light buff or tan (almost white), while others range through various shades of yellow, orange, brown and reddish brown to almost black. Many

99 species have a stripe down the middle of the back, and the zebra duiker has dark ve11ical zebra-like stripes along its back against an orange coat. Duikers also vary in the habitats they prefer, some Ii ving in the dense forests (species of Cephalophus) while others live among the scattered trees and brush or on the open savanna (primarily Sylvicapra). At least some species of duiker are apparently primarily nocturnal. Their diets are quite varied. Like other Category A ruminants, they browse on high-quality foods such as leaves, shoots, fruits, buds, seeds, and bark, but unlike most ungulates they will also occasionally eat insects and carrion, and are even reported to kill and eat birds and rodents. Relatively little is known about the social habits and general natural history of duikers in the wild. They are usually observed alone or in pairs, and some species may be monogamous and mate for life. They appear to hold and defend small (on the order of 2 to 4 hectares), stable territories, and will show marked aggression toward other members of their species. Duikers have scent glands under their eyes, the secretions from which they apparently use to mark their territories; some species will even press the glands against other individuals so as to mark each other. Such mutual marking may occur between mates, or between male rivals before active fighting breaks out. F.W. Fitzsimons describes Cape duikers as: "solitary by habit, but a pair may be seen now and then together. I have on many occasions surprised several browsing in company in the forest glades during the early evening. Occasionally these duikers venture forth and nibble the young crops in cultivated fields in close proximity to their brushy homes. They do not venture abroad by day except just after sunrise and before sunset. During rainy weather, or when the sky is very overcast, they sometimes are seen on the move. Their food consists of tender shoots, leaves, wild berries, and fruit. This duiker is never found in dry districts where there is no permanent supply of water. It rests during the day in a cosy lair in the midst of a mass of dense, tangled, or creeper-covered scrub, and when startled, makes rapid rushes through the bush, meanwhile emitting a peculiar sniffling sound. Its cry, which is not often uttered, is a sharp whistle, but when caught by dogs or wounded and overtaken, its cry of terror is deep and rough, quite unlike the shrill, terrified scream of the Cape duiker. The chief enemy of the duiker is the python snake, which levies a heavy toll upon it. The python lies in ambush for it along a branch overhanging one of its beaten tracks through the forest, or hidden in the scrub on the ground. This crafty snake often submerges itself in the water at one of

HORNS, TUSKS, AND FLIPPERS mon is neck fighting (as we have seen in camelids), where they use their necks to pin down their opponent's head, and try to throw him off balance. Sometimes, they also try to bite their opponents, especially in the front legs. According to Valerius Geist, these are the primitive fighting positions for bovids, and when they began to develop longer, sharper horns, these strategies became too dangerous. Consequently, most horned antelopes fight head-to-head, so that their weapons are not directed at the vulnerable flanks, but at their foe's strongest point. There are three variations on this headto-head style of contest. The most common is a pushing or Whereas duikers are not generally sought by "sports- wrestling match, where the opponents try to capture their men," since they do not possess the large horns that are rival's head between their horns, and they lock together in a often prized in head trophies, they are taken by native sub- test of strength. This is seen in many kinds of antelopes, sistence hunters. They are said to be relatively easy to catch from elands to gazelles. The second variation is ramming, at night using bright lights that blind or dazzle them, or by where the opponents run together and clash at the base of driving them into nets, and their meat is popular among the their horns (which are enlarged and thickened to take the indigenous peoples. The rarest species of duiker, Jentink's blows). This is particularly common among sheep and goats. duiker (Cephalophus jentinki) of Liberia and the West Ivory Ibexes, on the other hand, rise up on their hind legs for fightCoast lowlands, is considered officially endangered, where- ing. The third kind of fighting is fencing, where the horns as the zebra duiker (Cephalophus zebra) is considered vul- meet in the center of the shaft, and the antelopes use their nerable in the wild. As of 1986 only nine and twelve, respec- horns like dueling sabers to deliver and ward off blows. tively, of these animals were reported alive in zoos (World Fencers tend to have long, spear-like horns, often bent backResources 1990-91), but there have been successful captive ward like a saber. Sable antelopes kneel down on, their front legs and fence in a stooped position. births of both species. Antelopes try to avoid inflicting wounds with their sharp horns, and have many other ritualized behaviors that "BRIGHT EYES" The Greeks first referred to a semi-mythical creature establish rank without dangerous conflict. Most antelopes that lived along the banks of the Euphrates as antholops, or show a "submissive" posture, with the head down, when "bright eyes." Sometimes combined with the legendary uni- they wish to avoid conflict, or raise their head and horns to corn, this myth probably had its origin in the Arabian oryx, maximum height when they challenge. In the greater kudu, which looked one-horned in profile. So struck were the the males use ritualized "neck-fighting" to push down the Greeks and Romans by· their large eyes that they referred to head of the female as a prelude to courtship. Several the gazelles as dorcas, from the Greek for "I see clearly." antelopes "kick" with their foreleg, often in an exaggerated The word "gazelle" itself comes from the Arabic ghazal, slow-motion manner, against the female's hind legs. This is which also means "bright eyed." Indeed, the large eyes pro- used as a ritualized courtship gesture, but it evolved from a trude from the skull, and give the animal an almost complete fighting method. In many courtship rituals, the males then view of its surroundings without moving its head. For most "hide" their horns by raising their noses high, presumably to antelopes, which live in open terrain and must see danger "assure" the females that they will not use their horns to coming, such large eyes are essential. harm them. Although antelopes must have horns for defense and Bullfighters take advantage of these instinctive rituals fighting rivals, their great variety of shapes are not con- to kill the bull when it is vulnerable. When the bullfighter strained by these basic functions. In fact, studies have shown steps aside, he refuses to take part in the head-to-head conthat most antelopes do not even use their horns against pred- test, and thus violates the bull's "fighting ethic." When he ators; most flee and rarely turn at bay. As we have seen in kneels down in front of the bull, the audience mistakenly deer, the details of the shape-whether spiraled, or S- applauds his courage. In fact, this kneeling is a submissive shaped, or hooked, or branched, as well as all the ornamen- posture which reduces the bull's aggression, and when he tal rings, bulges and ridges-are primarily for species recog- jumps up and stabs the bull, he has an unfair advantage. nition, and for advertising the age and status of an individ- Although bullfighting has long been deplored as a sadistic ual (especially dominant males). Yet even here, battles spectacle, it is even more abominable because the bullfightbetween rival males do not involve active stabbing with the er unfairly exploits the bull's instincts for a "fair fight." True antelopes (not including pronghorns) are comhorns, but ritualized fighting. The simplest of these behaviors is pushing body-to- monly classified in one of three subfamilies: the Antilobody, seen in hornless females, as well as the hornless bose- pinae, or gazelles and dwarf antelopes; the Hippotraginae, or laphines. Rivals stand parallel to each other, head-to-rump, grazing antelopes; and the Alcelaphinae, or wildebeest and and push and shove until the rival is off balance. Also com- impalas. These three groups make up a major radiation of 100

the favorite drinking places of this handsome little antelope, its nostrils alone being above water. When the unsuspecting buck is drinking, the snake seizes its nose or one of its forelegs with its jaws, which are armed with sharp recurved teeth, and with lightning rapidity its coils are around its victim. The leopard, serval, and ratel also prey upon this antelope. Eagles occasionally succeed in pouncing upon them in the early mornings (Fitzsimons, 1920: 35-36)."

101

Figure 5.11. The waterbuck (Kobus ellipsiprymnus), a typical water-loving reduncin. (Photo courtesy C. Janis). bovids that presently covers Africa and extends into Arabia and Sinai (in the form of the Arabian oryx, Oryx leucoryx). These groups trace their origins back at least six million years ago, to the late Miocene. Today there are 16 species of hippotragines, 10 species of alcelaphines, and over 30 species of antilopines, and dozens of recognized subspecies and varieties of each. The hippotragines are divided into two tribes: the Reduncini (reedbucks, waterbucks, and related species), and the Hippotragini (the horse-like antelopes, which include the oryxes and addax). The Reduncini consists primarily of the reedbucks (genus Redunca) and the waterbuck, kob, and lechwe (genus Kobus). In the reduncins only the males have horns, and the animals tend to inhabit the wetlands, tall grassland, woods, and savannas near lakes and rivers. The various reedbucks tend to be relatively small and graceful animals, often with a shoulder height somewhat under a meter and weighing around 110 pounds (50 kg). Waterbucks (Fig. 5.11), kobs, and lechwes tend to be larger; they may have a shoulder height of up to 4.3 feet (1.3 m), and may weigh up to 550 pounds (250 kg). The horns are considerably longer in Kobus, but in both genera they are heavy and ridged. Reduncins are territorial, with the dominant males holding and defending the same piece of property for several years. They will sometimes congregate into small herds of females and young, or bachelor males that lack territory. Sometimes included as a member of the Reduncini is the vaal (or gray) rhebok. The name rhebok (also spelled Reebok, source of the name for the athletic shoes) comes from the Afrikaans for the European roe-buck, or roe-deer. However, this species is markedly different from all other antelopes and is perhaps best classified as the sole species of a distinct, unnamed tribe. The vaal rhebok (Pelea capreolus) is a small antelope (shoulder height about 28 inches, or 70 em, weight about 46 pounds, or 21 kg) that inhabits rocky

Figure 5.12. A. The sable antelope. (From the IM31 Master Photo Collection). B. Like many hippotragins, the Arabian oryx (Oryx leucoryx), showing the typical horse-like body and long straight horns which in this side view could have led to the unicorn myth. (Photo by D. R. Prothero). areas, mountainsides, and high plateaus in South Africa. The males have short (8-10 inches, or 20-25 em long), vertical horns-the females are hornless-which they use very aggressively. During the rutting season male vaal rheboks may fight to the death, and it is reported that sometimes they will attack and kill goats and sheep. Outside of the rutting season the rheboks form small groups, usually of related animals, or small herds of a few dozen individuals. The Hippotragini are the horse-like antelopes that inhabit the open grasslands, savannas, and relatively dry countryside of Africa and Arabia. These are the roan (horse) and sable antelopes (genus Hippotragus) (Figs. 5.2, 5.12A), the oryxes (Fig. 5.12B) and gemsbok (genus Oryx), and the addax (Addax nasomaculatus). As their common name implies, members of this tribe somewhat resemble horses

102

HORNS, TUSKS, AND FLIPPERS

B

Figure 5.13. Typical examples of the Alcelaphini. A. A female topi (Oamaliscus lunatus) guarding her young calf. B. A herd of wildebeest, or gnu (Connochaetes gnou), the most abundant antelope of the African savanna. (Both photos by D. R. Prothero). (they even bear manes), but from the skulls of both males and females grow long, ridged horns that are either straight or scimitar-shaped (Oryx), curved dramatically backwards (Hippotragus), or spirally twisted (Addax). Shoulder height of hippotragins ranges from about 3-7 feet (1-2.2 m), and adult males of some species can weigh up to 620 pounds (280 kg). In coloration, members of the tribe can range from white with a "wig" of chestnut hair in the addax, through colorations of gray, black, and white, through reddish browns and jet blacks covering almost the entire upper body (with the underbody and belly typically being white or at least lighter in color). Although both males and females have horns, the males are larger in body size. Male sable antelopes are deep black, but the female is brown with a black mane; both have white faces. Hippotragins have tight, hierarchically dominated social structures and typically form herds of no more than a couple of dozen individuals led by a dominant male. Oryxes, addaxes and gemsboks, in particular, are adapted to the very dry, desert conditions of the Sahara or the Kalahari. Here temperatures reach 118-122°F (48-50°C) in the daytime and freezing at night, the wind and dust blow constantly, and rain may not fall for years. They feed on whatever vegetation they can find, and it is said that they can go for much of their lives without drinking water (they derive all their moisture requirements from the food they eat). The desert hippotragins have white coats for camouflage, and to reflect the sunlight, and broad hooves to avoid sinking into the sand. They can walk for hours on end to find food, covering 20 miles (32 km) in one night. Most of their daylight hours are spent sleeping or chewing their cud. They are small enough that they can creep into the shade of acacia bushes, excavating a scraped area to put their bodies against the cool sand underneath. This also reduces their surface area exposed to the hot dry winds. They "fine-tune" their heat regulation by timing their movements to take

advantage of breezes, and seeking shade earlier on hot days. Their barren environment means that their herds are small (10-20 individuals or less), and must spread out over a wide area to get adequate fodder. To minimize conflicts,'they have a strict hierarchy of dominance from the alpha male on down, so they spend much less energy defending turf or their herd. Like many large African mammals, the hippotragins have been seriously threatened by humans. Most of the Ii ving populations are at critically low levels. The scimitarhorned oryx is extinct north of the Sahara, and along with the addax, it is in danger of total extinction. Oryx horns were once particularly prized because of their legendary status as "unicorn" horns (even though oryxes are artiodactyIs, not horses, and have two horns, not one in the middle of their forehead). Most of these antelopes were only hunted by nomads on camels seeking trophies, so they thrived until the advent of motorized hunting and automatic weapons in 1945. The last wild Arabian oryxes were lost in 1972, although luckily this species has survived from captive animals which have since been culti vated into herds. Operation Oryx managed to build the captive populations up to the point that they were reintroduced to Oman in 1982. Unfortunately such actions did not save the bluebuck of the Cape Province (Hippotragus leucophaeus), known from historical accounts and mounted specimens. By the end of the eighteenth century, the bluebuck was exterminated due to the pressure of expanding human populations. The Alcelaphinae includes the various types of hartebeest (genus Alcelaphus), the hirola (Beatragus hunteri, sometimes called a Hunter's hartebeest), the wildebeest or gnu (genus Connochaetes), and the topi and bontebok (genus Damaliscus) (Fig. 5.13). Typically the size of medium or large reduncins, alcelaphins differ from members of the former tribe in that both males and females bear horns, the shoulders tend to be a bit higher than the hindquarters,

HOLLOW HORNS the face is slightly elongated, and the females are typically slightly smaller than the males of the same species. Alcelaphins are typically grazers and inhabit primarily open woodland and adjacent moist grasslands. Males are seasonally territorial, although this trait is expressed to different degrees depending on the species. Male topis may hold a territory, apparently continuously, for several years whereas some gnus may hold small, temporary territories during the rutting season only-and then these territories may. be held for only a matter of hours. Wildebeest are legendary for forming herds of hundreds to thousands across the grasslands. In the Serengeti, these herds move in response to rains and the grasses they bring. From January to May, the wildebeest are out on the open plains, mixed with herds of plains zebras, topi, Cape buffalo, and Thomson's gazelles. Buffalo and zebra consume the tough tops and stems of grasses, clearing these away so that wildebeest and topi can eat the tender leaves nearer the ground. Thomson's gazelles then eat the broadleaved herbs and forbs that are revealed by the other grazers. By the end of May, the short grasses and waterholes have dried up, and almost a million animals move about 150 miles (240 km) to the northwest to seek permanent water in the river beds of the Serengeti. These migrations once staggered hunters like Theodore Roosevelt, who enthused that he had seen "a Pleistocene day." During this migration they may cross swollen rivers, and many are drowned by the panic of stampeding animals trying to cross. After mon~hs of enduring the biting flies of the wooded areas near the flvers, the wildebeest become restless again. The second rainy season occurs in November, triggering a migration back to the short-grass plains. Here the females drop their calves, who must be able to stand up and run within seven minutes after birth. Their migrations do not always cycle this precisely, especially if the rains are not on schedule. However, they are almost continuously on the move, and seem to travel well over 1000 miles (1600 km) in a typical year. When they stop to feed, males hold territories of about 130 square yards. In the center of his territory, the male reigns in his bare patch known as a "stamping ground," where he rolls in the dust and marks his turf with urine, feces, and scent from his preorbital and hoof glands. When other males get too near, the territory-holder and intruder go through a long display ritual, challenging each other, urinating and sniffing the scent with their upper lips rais~d. in Flehmen, and standing side-to-side with their heads snIffIng the opponent's rump and marking him with their facial scent glands. They also drop to their front knees and face each other. These rituals allow the males to determine the opponent's hormonal levels, sexual status, and maturity without fighting. Wildebeest males may even displace aggression to the ground, but they seldom fight for any extended length ~f time. Although wildebeest seldom fight each other, they wIll charge at predators-but they usually stop short, since they are fundamentally timid. More often, they flee the lions, hunting dogs, and hyaenas which depend upon them for

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Figure 5.14. Only male impalas (Aepyceros melampus) have horns. Impalas are found in thick brush, which they leap with ease. (Photo courtesy A. Walker). their primary sustenance. However, wildebeest are so numerous that they continue to thrive in spite of predation; in fact, the predators cull the weak and aged from the herd, as well as hold down population growth by picking off the young. Because of their similar diets, the alcelaphins are seen as competitors for the same foods and resources as domestic cattle. Accordingly, they are hated by cattle ranchers. As the domestic cattle populations have burgeoned the antelope populations have contracted. A number of subspecies of antelopes belonging to the Alcelaphini have become rare and endangered, and at least one subspecies (the bubal or Northern hartebeest) is already extinct. Sometimes included within the Alcelaphini, but now more commonly relegated to its own closely-related tribe (the Aepycerotini) is the impala (Aepyceros melampus) of central and southern Africa (Fig. 5.14). Impalas stand one meter at the shoulder, and weigh in the range of 143-165 pounds (65-75 kg). Prominent horns are borne by the males only, and are shaped like a long, graceful lyre. In color the upper part of the body is fawn or reddish, the legs, thighs, and underbelly are whitish, and there are distinctive black vertical stripes on the sides of the thighs (seen from behind) and the tails. Impalas, similar to alcelaphins, inhabit open woodlands and savannas, grazing and browsing on grass and leaves of various bushes and shrubs. Especially during the dry season, impalas associate in large herds of a hundred or so individuals, mostly females and their young. These herds subsequently split into smaller groups of one or two dozen animals led by a dominant male. Impalas are known for the huge jumps that they can make; it is reported that they can take leaps nine meters (30 feet) in length, and they routinely jump over one another. Fitzsimons reports three successive bounds of 26, 16, and 28 feet, for a total of 70 feet (8, 5, and 8.5 m for a total of 21.5 m); in another case, an impala cleared an 8-foot (2.4 -

HORNS, TUSKS, AND FLIPPERS

B

Figure 5.15. The dwarf antelopes, or neotragins, include: A. Tiny Kirk's dik-dik (Madoqua kirki) defecating to mark a territorial boundary; B. The steenbuck (Raphicerus campestris) lowering its head in threat gesture; C. The klipspringer (Oreotragus oreotragus) lives among the rocks in its habitat. (Photos A and B courtesy C. Janis; photo C by D.R. Prothero.)

a

m) fence, and then jumped on the roof of a shed 9 feet (2.7 m) high. Given a clean run, impalas will clear a 12-foot fence easily. Impalas are also known for their speed. When they run, the black-and-white-striped rump and tail, and the black spots on the hind heels flash, alerting the rest of their herd, and allowing them to follow each other more easily. Elisabeth Vrba has used the evolution of alcelaphins and impalas to demonstrate some interesting evolutionary principles. Alcelaphins are quite diverse, with at least 32 different species in the last five million years. They show a wide variety of hom shapes, from simple spikes to backward curves, to the broad upcurved horns typical of wildebeest and the backward-curved S-shapes of hartebeest. By contrast, impalas have only one lineage (sometimes split into three species) for the same five million years, all with the same gently S-shaped horns. Vrba points out that alcelaphins are specialized grazers, whereas impalas are generalists, feeding on a variety of vegetation in the transition zone between grasslands and woodlands. During the

last five million years, Africa has seen tremendous vegetational changes in response to climatic changes associated with the Ice Ages. Not surprisingly, specialists such as the alcelaphins are vulnerable to extinction when their narrow niches disappear, but generalists such as the impala can always find something suitable to eat, no matter how climate changes. The contrasts between the patterns of evolution in alcelaphins and impalas furnishes a good example of how two closely related groups of animals respond differently to the same evolutionary stresses. Because of their ecological narrowness, alcelaphins respond by forming new species, or by going extinct. Evolutionary trends are accomplished by a succession of rapidly evol ved new species occupying changing niches. Impalas, on the other hand, have such a broad niche that stabilizing selection prevails, and they change very little. Either way, there is no predetermined "direction" built into evolution. Instead, long-term trends in specialization are simply an "effect" of evolution of new species in response to environmental change, or by "species selection" among the many competing species, weeding out those which are less adapted to unanticipated environmental stresses. The dwarf antelopes (Tribe Neotragini) and gazelles (Tribe Antilopini) together compose the subfamily of bovids known as the Antilopinae. Dwarf antelopes inhabit a variety of environments on the African continent, from the open grassy plains through the dense forests to rocky and moun-

HOLLOW HORNS tainous areas. There are about a dozen living species of dwarf antelopes, classified into six genera. Better known forms include the various dik-diks (genus Madoqua) (Fig. 5.15A). The name dik-dik is an onomatopoeic version of the call these animals make when startled and in flight. There are also the Royal and pygmy antelopes, and suni (genus Neotragus), the klipspringer (Oreotragus oreotragus), the steenbuck (Fig. 5.15B) and grysbucks (genus Raphicerus), and the oribi (Ourebia ourebia). As their common name implies, all dwarf antelopes tend to be small. Like the duikers and many other tiny forest ruminants we have seen, most neotragins are classic Category A ungulates. The smallest of the dwarf antelopes (indeed, the smallest of all living homed ungulates) is the poorly known Royal antelope (Neotragus pygmaeus) of western Africa (Sierra Leone, Liberia, the Ivory Coast, and Ghana). The Royal antelope stands only 10-12 inches (25 30 cm) tall at the shoulder, and weighs just 3-7 pounds (1.53 kg). Its diminutive pair of straight horns are only a couple of centimeters tall. The largest member of the tribe is the oribi of eastern southern Africa, which has a head and body length of about 3-4.6 feet (1-1.4 m), may stand 20-28 inches (50-70 cm) at the shoulder, and can weigh from 31-46 pounds (14 - 21 kg). Dwarf antelopes are unusual in that the females are often somewhat larger than the males (the reverse being the case in most ungulates). This is probably the case because the living dwarf antelopes are descendants of larger species (among which presumably the males and females were either subequal in size, or the males somewhat larger). As dwarf antelope species got smaller, perhaps in response to the decreasing extent of the African forest cover (which is their primary habitat) over the last ten to twelve million years, there has been a lower limit on how small females can be and still easily handle the strains of bearing young. Also in many species of neotragins the males bond for life with one or a few females, and therefore they are not subject to intrasexual selection for large size as are male ungulates that routinely fight with each other over the control of females. Because of their generally small size (which means that food passes relatively quickly through the gut, and in addition smaller mammals are characterized by higher metabolic rates), dwarf antelopes tend to feed on a diet that is of high quality and low in fiber, such as fruit, buds, young leaves, and tender new grass. Only the oribi, the largest of the dwarf antelopes, can afford to graze. In order to feed from the scattered patches of high quality food, the typical dwarf antelope comes to know its local habitat very well. Furthermore, it excludes potential competitors by defending its resources, so dwarf antelopes are territorial. Dwarf antelopes are well endowed with scent glands that they use to mark their territories. Of particular importance are the preorbital glands Gust in front of the eyes), the secretions of which are rubbed onto stems and branches, as well as on females by males, to mark a particular dwarf antelope's property. Glands on the hooves mark the ground

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along major dwarf antelope paths. Dwarf antelopes also deposit their feces and urine at particular spots, probably helping to further mark their territories and send a message to potential intruders. One of the most amazing dwarf antelopes is the klipspringer (Fig. 5.15C), whose name means "rock jumper" in Afrikaans. These tiny antelopes live exclusively on rocky outcrops, except when drought dries up their small drinking pools and forces them to migrate. Their peculiar habit of rock jumping is described by F.W. Fitzsimons in The Natural History of South Africa: "When surprised at the foot of their rocky fastnesses they, with elevated head, bound off with the most astonishing daring and agility, leaping like animated rubber balls from boulder to boulder, and from one pinnacle of rock to another. Poising with all four hoofs on a point of rock an inch to two square, this wonderful little animal launches itself into space to a similar point of rock. Balancing for an instant on a projection of rock on the very edge of a vast crevass, the nimble little creature bounds off from ledge to ledge and.point to point in a manner impossible to describe. That an animal with hard cloven hoofs is able to traverse these precipitous hills, abounding in chasms into which the slightest slip of foot would launch them, is almost beyond belief. In agility and surefootedness amongst the rocky fastnesses which are their home, they equal the famous chamois of Switzerland. The hoofs of the klipspringer are nearly rectangular in shape, with a narrow sole, and are on a line with the legs, making them excellently adapted for balancing the body on points of rock. Klipspringers, during the heat of the day, seek the shade afforded by rock crevices, or the cool shade of some deep cavern, or the bush which invariably grows at the foot of their rocky, elevated homes. When disturbed in these situations, they instantly spring off and away up the hillside. Their strength, vitality and energy is astonishing, for, without any apparent effort, a klipspringer will bound up the face of a hill covered with smooth, slippery rocks, and so steep that no animal other than a baboon could possibly find a foothold. The latter animal has hands and feet specially adapted for gripping the smallest projection of rock, but the klipspringer has no such aids, which makes its performance amongst the crags and crevasses so marvellous" (Fitzsimons, 1920: 46-48). Some dwarf antelopes have elongated snouts, most pronounced in certain species of dik-diks where an actual small tapir-like proboscis is developed. The large snouts may be simultaneously an adaptation for cooling, or for increased

HORNS, TUSKS, AND FLIPPERS

Figure 5.16. The gazelles, or antilopins, include: A. Thomson's gazelle (Gazella thomsoni), the commonest small gazelle of the African savanna; B. the gerenuk (Litocranius walleri), shown in its characteristic pose stretching for high vegetation. (Photos courtesy A. Walker).

sensitivity of smell, or for selectively feeding on only certain parts of plants. The gazelles (Tribe Antilopini) range throughout Africa and into the Arabian peninsula, Palestine, the Middle East, and through the Indian subcontinent into Tibet, China, Mongolia, and Inner Mongolia (Fig. 5.16). There are about 18 species, including such forms as the various species of gazelles proper of Africa and the Middle East (genus Gazella), the gerenuk (Litocranius walleri), the dibatag

(Ammodorcas clarkei), the springbok (Antidorcas marsupiaUs), the Tibetan, Mongolian, and Przewalski's (Chinese) gazelles (of the genus Procapra), and the Indian blackbuck (Antilope cervicapra). Gazelles tend to have slender bodies, long \lecks, and long legs, and unlike their fellow dwarf antelopes, the males are on average larger than the females. The horns are often S-shaped and ringed, and (again in contrast to the dwarf antelopes) in most species females as well as males bear horns, although the horns are shorter and thinner in females. Various species of gazelles range in shoulder height from about half a meter to just over one meter, and they can range in weight from about 66 pounds (30 kg) to over 180 pounds (80 kg). With the exception of the Indian blackbuck (which is black with a white belly and highlights), gazelles are shades of brown with lighter underparts, and some species have a prominent horizontal stripe or band of a darker color on each side (for example, in the springbuck). Gazelles have white rump fur with black tips on the tails, and sometimes other dark spots. Gazelles are also characterized by the gait they adopt when alarmed-they bounce on straight, stiffkneed limbs, landing on all four feet simultaneously. This is known as pronking or stotting, and it is thought to possibly serve several functions: it may give the animal a better view of potential danger, since it raises the animal relatively high in the air; it apparently communicates concern or alarm to other gazelles; and it may even intimidate or confuse a potential predator. Gazelles tend to feed on a mixture of vegetational types, browsing on virtually anything that is green. Certain species of gazelles, such as Thomson's gazelle (Gazella thomsoni) are primarily grazers, feeding almost exclusively on grasses. Other species take in mostly young shoots and leaves (Fig. 5.16A). The most unusual of the gazelles is the gerenuk (Fig. 5.16B), which browses on the tops of bushes using its long slender neck, and by rearing up on its hind legs. As we mentioned in the previous chapter, this kind of

HOLLOW HORNS

Figure 5.17. Springboks (Antidorcas marsupia/is) showing their characteristic "pranking" gait. (After Millais, 1895). feeding behavior may have also occurred in certain extinct camels and giraffoids. Dominant males are territorial, particularly during the breeding season. Similar to dwarf antelope behavior, gazelles mark their territories with gland secretions (they too bear preorbital glands) and piles of dung and urine. Territorial males will joust and fight over females and resources, placing their heads near the ground, interlocking horns, and twisting and pushing one another. Nonbreeding males (bachelors) that lack territories will associate together in groups, as will groups of females and their young offspring. Outside of the breeding season gazelles may associate in mixed sex and age groups. Pronking is peculiar to the springbok, which gets its name from this odd behavior (Fig. 5.17). When springbok pronk, they raise a crest of white fur along their spines, flashing white to inform the herd of danger. Then, as they race away, the crest folds down and disappears underneath black hairs. This maneuver is so characteristic of them that young springbok practice it in play when they are only a few days old. At one time springbok were phenomenally abundant in southern Africa, and held great migrations that outnumbered even the Serengeti herds. Four great springbok treks occurred in the Karoo District of the Cape Province between 1887 and 1896, and as described by T.B. Davie, they were literally overwhelming. "When the trek was in full move nothing but springbok were to be seen for miles upon miles at a stretch. The whole country seemed to move, not in any hurry or rush, as is generally associated in people's minds with a springbok, but a steady plodding walk march, just like locusts; no other animal or insect life can afford so apt an illustration. The writer has seen them in one continuous stream, on the road and on both sides of the road, to the skyline, from the town

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ofPrieska to Draghoender, a distance of 47 miles, plodding on, just moving aside far enough to avoid the wheels of the cart. On this occasion, the owners of the farm Witvlei were all sitting in a ring round the top of the well, which at that time was uncovered, the father, son and son-in-law armed with rifles, firing a shot now and then, and the women folk with sticks and stones trying to keep the 'boks' away. This was the family's only water supply left, as the 'boks'had already filled up the dam, thousands being trampled to death in the mud as they pressed on over one another to get to the water. At last the 'boks' beat the farmers, and got to the well and in a few minutes it was full of dead and dying 'boks.' However, the trek passed before evening with the exception of a few stragglers and the Witvlei people soon had their well cleaned out and rendered serviceable. In the course of a few days the trek seemed to melt away. They disappear, nobody knows where they have gone to" (Cronwright-Schreiner, 1925). The cause of these great springbok treks is unknown, and their herds are now too small to ever do it again. Perhaps they occurred when unusually wet years in South Africa led to a population explosion, and when dry times returned, the springboks were forced to migrate and seek new grasses. During their peak, the migrations covered about 100 miles (160 km) a day, a moving avalanche that carried along cattle, sheep, lions and even people until they were exhausted and trampled to death. Some treks moved westward right into the sea like lemmings. On one occasion along the Namaqualand coast near the mouth of the Orange River, millions of springbok drowned and their bodies formed a wall that extended 30 miles (48 km) down the coast! Unfortunately, human activity continues to reduce gazelle populations in the wild such that currently several species are considered to be endangered. Outright hunting, increasing cultivation of land which destroys the natural habitat, limited access to fresh water, and competition with domestic bovids (such as cattle and especially sheep and goats) all threaten the wild gazelles. MOUNTAIN MONARCHS The final subfamily of bovids is the Caprinae, which includes the goats, sheep, musk ox, and many other goatlike animals. Most caprines are adapted for living in mountains and steep terrain, and are rather stocky in build, with thick fur coats. They all have thick, curved horns that are suitable for ramming and wrestling. Some, like the ibex, have long arcuate horns, and others, like the bighorn sheep, have spectacular spiral "ram's horns." Although caprines are known from the middle Miocene of Africa, they flourished primarily in the mountainous regions of Eurasia. Tossunoria, from the middle Miocene of China, shows fea-

108

HORNS, TUSKS, AND FLIPPERS

Figure 5.18. Saiga antelope (Saiga tatarica) , with its characteristic bulbous nose. (Photo by D. R. Prothero). tures that are primitive for all caprines, including the short, slightly recurved horns. Their greatest success has been during the last 2 million;years of the Ice Ages, when glaciers and cold climates favored the cold-adapted caprines. From a primitive goat-like animal, they radiated into a variety of body forms and habitats all over Eurasia. Caprines are proverbial for being able not only to exist, but flourish, in the harshest of conditions. Most remained denizens of cold mountains, but some (such as the muskox) became adapted for the cold, flat tundra; others became adapted for desert mountains. In addition, they spread to North America, where we now have bighorn sheep, mountain goats, and the muskox. Twenty-six species in four tribes of Caprines are generally recognized. They include the Saigini, or big-nosed saiga "antelope;" the Rupicaprini, or chamois and mountain goat; the Ovibovini, or musk ox and takin; and the true goats and sheep, or Caprini. The tribe Saigini, sometimes classified with the Antilopinae (gazelles and dwarf antelopes), is typically associated with the Caprinae. Saigini include the chiru, or Tibetan antelope (Pantholops hodgsoni) and the saiga (Saiga tatarica). Chirus inhabit the Tibetan high plateau, and somewhat resemble a moderately large gazelle (they stand about 31 inches, or 80 cm at the shoulder and weigh 90-110 pounds, or 40-50 kg). They are perhaps most notable for the long (20-28 inches, or 50-70 cm), slender, almost straight vertical black horns carried by the males. At a distance, when viewed from the side, the two horns may appear as one and thus it has been suggested that the chirus was the original inspiration for the story of the unicorn. The saiga is presently found in Sinkiang (China), southwestern Mongolia, Kazakhstan, and in the northern Caucasus (Fig. 5.18). Formerly its range was reported to extend west into Poland. Saigas are famous for their huge, inflated nose that forms a proboscis in which the nostril openings point toward the ground. It has been suggested that the proboscis serves the purpose of warming and moistening air as it is inhaled, and saigas also have a very well-developed sense of smell. Comparable to the chirus in size, saigas

Figure 9. A. The Asian serow. (Photo by Prothero). B. The North American mountain goat (Oreamnos americanus) is found in the highest peaks and cliffsides. (From the IMSI Master Photo Collection) . grow heavy, light-colored buff coats, and they are fast runners-reportedly capable of reaching speeds of 37 mph (60 km per hour). The horns, found only in males, are 8-10 inches (20-25 cm) long, pale amber in color, and sometimes translucent. For centuries saiga horns have been used by Chinese pharmacies in much the same way as rhino horns and "dragon's teeth," so saiga have been over-hunted in the past. The horns were thought to act as an aphrodisiac among other uses. In the early nineteenth century hundreds of thousands of saiga horns were used in China each year. From prehistoric times nomadic tribes of the Russian steppe have hunted the saiga for its meat and hides. Since about 1920, however, they have been protected in the former Soviet Union and are reportedly the most abundant wild ungulate in that country. While unrestricted general hunting of the saiga is not allowed, they are selectively culled and thousands of tons of saiga meat is taken each year for human food. The members of the tribe Rupicaprini are generally considered the most primitive of extant caprines, and include the Asian serows (genus Capricornis) (Fig. 5.19A),

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HOLLOW HORNS

Figure 5.20. The bizarre dwarfed goat Myotragus balaericus, which lived on the Balaeric Islands near Spain in the Pleistocene. It has unusually stunted limbs, and a peculiar face. (From Bate 1909). the goral of the Indian subcontinent to Siberia (Nemorhaedus goral), the chamois that ranges through southern and central Europe (Rupieapra rupieapra), and the American mountain goat (Oreamnos amerieanus) (Fig. 5.l9B). In size rupicaprins range from the goral with a shoulder height of 24-28 inches (60-70 cm) and a weight of 50-70 pounds (22-32 kg) to the American mountain goat which can stand 4 feet (1.2 m) at the shoulder and weigh 165-310 pounds (75-140 kg). In rupicaprins there is little distinction between the sexes in size or appearance. Both sexes have horns, for instance, which tend to be short and curve slightly backwards. Rupicaprins often live on steep slopes, seek out shrub or tree cover, and browse on whatever plant resources are available-from grasses to shrubs and trees, sedges, lichens, and so on. Mountain goats will seek shelter in caves if the weather is bad. Rupicaprins are often referred to as "resource defenders." They live in and defend with their short but strong and sharp horns small areas that contain productive food supplies. In some cases they may be extremely aggressive, fending otf not only potential competitors of their own species, but also even large carnivorous predators. The mountain goat has been known to fight off a large grizzly bear, and in at least a few instances, kill it with multiple punctures to the heart from its sharp horns. All rupicaprins have an amazing ability to climb in terrifyingly steep terrain. Owen Wister, author of The Virginian, wrote of the mountain goat: "They chose places to lie down where falling off was the easiest thing you could do...The individual tracks we have passed always choose the inclined plane where they have a choice between that and the level ... If they play games together, it is probably to push each other over a precipice, and the goat that takes the longest to walk up again loses the game." The great naturalist Ernest Thompson Seton wrote, "If, on some lowering morning when clouds and flying scud are drifting low over Manhattan, one could look from the Times Building, out

and up to those higher peaks, the Equitable, the Metropolitan, and the Woolworth [this was before the Empire State Building was built], and see white creatures-goats, incredible goats-crawling along the cornices, pulling themselves up the turrets, or calmly chewing their cud as they lay looking down from the weather vanes, we should have much the same sensation as in watching the bearded mountaineer in his cloud-hung, perpendicular home." Mountain goats travel in small family bands, moving slowly and carefully as they pick their footholds. At treacherous crossings, they string out single-file, with the old billy goat leading, and the kids in the middle. Their hooves are very narrow for excellent traction in tight spaces, and they have suction-cups in their concave toes that improve traction. When their trail. ends in an abrupt drop, they can rear up and wheel around, or climb to a higher level. Because of their abilities to climb, mountain goats have few predators. Until the development of the long rifle, humans could not hunt them easily. Most hunters ignore them, because their meat is gamy tasting, and their horns are not spectacular trophies. Only the mountain lion or lynx attempt to scale their rocky habitat, and eagles will sometimes snag an unprotected kid. When mountain goats descend to valleys to find mineral licks, then they face bears, wol ves and coyotes. Their greatest natural enemies, however, are avalanches and landslides, which are hard to avoid in their craggy habitat. The strangest of the extinct rupicaprins was the cave goat, Myotragus balaerieus (Fig. 5.20). Found only in Ice Age deposits in caves in the Balaeric islands of Mallorca and Menorca, this beast is one of the strangest examples of what animals can evolve on islands. The cave goat only reached 50 cm at the shoulder, so it was probably a dwarfed descendant of one of the mainland rupicaprins, such as the chamois. Its legs are so short and stumpy that they resemble the bizan e Ancon, or otter sheep, which have been bred until their legs are too short to jump fences. In the otter sheep, this kind of aberrant limb development is called achondroplasia, and is caused by a single recessive· gene. For this reason, the shortened limbs of the cave goat have also been attributed to achondroplasia, probably associated with their dwarfing. Curiously, this same shortening of toe bones occurs in the cave bear and cave hyaena. The most bizarre feature of Myotragus, however, is its lower front teeth, or middle incisors, which have grown into huge chisel-like teeth similar to those found in rodents. The second pair of incisors were so small that they were mere vestiges. No one knows what they gnawed with these chisels, but there have been suggestions that they lived on lichens and mosses on rocks, or on the barks of bushes and trees. Whatever they ate, their food was highly abrasive, since their extremely high-crowned molars are highly worn. The musk ox group (Tribe Ovibovini) consists of but two living species: the takin (Budoreas taxieolor) of western China, Bhutan, and Burma, and the musk ox (Ovibos mosehatus) currently found in the tundra of northern 4

110

HORNS, TUSKS, AND FLIPPERS

Figure 5.21. The ovibovins include: A. the takin (Budoreas taxie%r) , found in the high alpine bamboo forests of the Himalayas. (Photo by D. R. Prothero); B. The musk-ox (Ovibos mosehatus) , forming their characteristic defensive circle to protect their calves. (From the IMSI Master Photo Collection).

Canada and Greenland. Fossil ovibovines include the bizarre Tsaidamotherium from the late Miocene of Mongolia, a beast which had strange horn asymmetry: the right horn was a large, blunt conical feature in the center of its head, and the left horn was a tiny vestigial point slightly to the front of it. During the Pleistocene, the musk ox or a closely related species was found throughout Eurasia (e.g., France, Germany, England, Siberia) and North America. As their name implies, these animals, especially the musk oxen, exhibit characteristics that make them look physically more like cattle than goats or antelopes. They are both large, heavy-set animals. Takins (Fig. 5.21A) have a shoulder height of up to a meter and can weigh up to 600 pounds (275 kg), whereas musk oxen can reach a shoulder height of 5 feet (1.5 m) and weigh over 880 pounds (400 kg). In both species the males and females are similar in appearance, but the adult females are typically smaller than the adult males (females may be only 60% of the comparable male weight). The takin lives in dense thickets and bamboo forests at the upper limit of tree growth (about 7800-14,000 feet, or 2,400 to 4,250 meters in elevation). They have thick, shag-

gy fur that can range in color from yellowish white to a very dark brown. An oily, strongly smelling substance is secreted over the entire body. They have massive, thick horns that sweep outward, backward, and upward. Takins will gather in large herds above the tree line during the summer months, but in the winter tend to live in smaller groups in valleys at lower elevations. Musk oxen (Fig. 5.21B) bear very thick, highly protective coats that are composed of two parts. The dark brown outer guard hairs are coarse and long (almost dragging on the ground-single strands may be two feet long); this outer coat protects against rain and snow and covers the inner hairs. The inner coat is a very dense mat of soft, fine, light brown hairs that keeps cold and moisture from reaching the animals' bodies. The legs of musk oxen bear a lighter fur than the rest of the body, and generally only the feet and lower legs are seen from under the long shaggy coat. The neck and tail are short, the face large, and there is a hump over the shoulders. Their horns meet in the middle of the head and then curve down each side of the head before flaring out at a level below the eyes, so a musk ox appears to be

HOLLOW HORNS

111

B

Figure 5.22. A. The ibex (Capra ibex) , characteristic of the high Alps (Photo by D. R. Prothero). B. The markhor sheep, with its twisted horns. (From the IMSI Master Photo Collection).

wearing a helmet. Musk oxen are gregarious, and they may gather into herds of up to a hundred or more. If a herd is attacked or disturbed by wolves or bears, the musk oxen will form a defensive circle, with horns pointed outward, sheltering the young inside. If a herd is approached too closely by the curious human observer, the males may threaten to attack. As one of us (Schoch) has found by experience on Ellesmere Island in the Canadian Arctic, having an angry musk ox coming at you can be a bit frightening! However, if captured and raised as young, musk oxen are actually fairly docile and easy to tame. Experimental breeding farms have raised musk oxen in Alaska, Quebec, Norway, and Siberia. It is possible that someday a strain of these animals may become fully domesticated. The main incentive to tame and raise musk oxen is for their undercoat which is a very fine wool ideally suited for certain garments. This undercoat is naturally shed in the spring and can be easily gathered from the animals at that time, without killing them or even shearing them. The Caprini (Fig. 5.22) include most domesticated and wild goat species (genus Capra), the domesticated and wild sheep species (genus Ovis), the tahrs of the Himalayas, India, and the Oman district of Arabia (genus Hemitragus), the Barbary sheep or aoudad of northern Africa (Ammotragus lervia), and the blue sheep or bharal of the mountains of Asia from the Himalayas to Mongolia (Pseudovis nayaur). Unlike the rupicaprins, the caprins (true goats and sheep) are not resource defenders, but have moved generally into more open landscapes and have taken up grazing on relatively productive grasslands. Caprins form

loose, cooperative herds that serve as protection from predators. There are also major distinctions between the males and females as far as weight, general external appearance, and horn development. The caprins typically are characterized by hierarchical social systems. In shoulder height caprins typically range from about 2-4 feet (0.6-1.2 m), and in weight they can range between 55 and 400 pounds (25 kg180 kg). The true goats (genus Capra) include the ibex (Capra ibex), various other species of wild goats (including the markhor, and the East and West Caucasian turs), and the common domesticated goat. In the natural state, Capra is a widespread genus, extending from Spain through central Europe, the MeditelTanean region, the Middle East, northern Africa, and into India, Siberia, and Mongolia. Of course, domesticated goats are now the scourge of every continent and island where humans have brought them, eating everything in sight, destroying the habitat and all the native animals in the process. A favorite of crossword-puzzle aficionados, the ibex (Fig. 5.22A) is the most spectacular goat, with a long beard, and enormous horns that curve up and backward like a scimitar. Living mostly in the Himalayan foothills, ibexes fear only wild dogs and snow leopards. Ibexes were once found in the Alps as well, but have now been hunted out of Europe, except for a small protected population on the Italian side of Monte Rosa. Another unusual goat is the markhor, Capra falconeri (Fig. 5.22B). Also found in the Himalayan foothills, it prefers the cover near the treeline rather than the open cliffs

112

HORNS, TUSKS, AND FLIPPERS

Figure 5.23. The American bighorn sheep (Ovis canadensis), found throughout the Rocky Mountains. Here, a ram lifts its lip in the Flehmen gesture to detect whether this ewe is in estrus. (Photo courtesy B. O'Gara.) and slopes. Largest of the wild goats, it may stand 40 inches (100 cm) high and weigh more than 200 pounds (90 kg). The markhor has long been a hunter's favorite, both for its bushy beard and throat hair, and its spectacular spirally twisted horns. The tahr (Hemitragus jemlaicus), on the other hand, is beardless, and has simple short horns. Although it is difficult to hunt in the steep Himalayas, its bones are prized in India for treating rheumatism. True sheep (genus Ovis) include such wild forms as the Middle Eastern and Asian urial, argalis, mouflon, and snow sheep, the North American bighorn sheep, as well as the common domesticated sheep. The details of sheep (and goat for that matter) taxonomy are very complicated and controversial. There are many different species, subspecies and races of both sheep and goats recognized by various authorities; not all sheep even have the same number of chromosomes. In the wild, sheep species are found predominantly in the Middle East, Asia, and the northern and western portions of North America. Sheep have been introduced to Europe by humans on at least several different occasions since their domestication, and domesticated sheep are now found wherever humans can raise them. Of the wild sheep, the most familiar are the bighorn sheep (Ovis canadensis) of North America (Fig. 5.23). They are famous among hunters for the spectacular ram's horns

on the males, which are used in mating fights. During the rutting season in December, the younger males begin to challenge the old rams with females. The challenger butts the old ram in the side, and they face off. Eyes flaring, they back off to about 40 feet (12 m) apart, then charge each other at 20 mph (32 km/hour). At the moment of impact, they rear up and then drop on all fours. The crash can be heard for miles, echoing off the cliffs. Dazed, they stand side-to-side and eye each other, then back off for another charge. Chips and splinters fly from their horns, and blood oozes from ears and noses; they reel drunkenly. The battle may rage over an hour, until one male has had enough. Falling to his knees, he is driven down by a pile-driving blow from the victor. Sometimes the vanquished is killed by these combats, but most live to see another day (if not to breed again). By January the mating season is over, and the rams return to bachelor herds. Two lambs are born to each female in Mayor June. Minutes after birth, the mother licks the lamb from head to toe, a ritual called "owning the lamb." Not only does this get rid of amniotic tissues, and fluff-dry its fur, but it also gives the lamb its mother's scent, and prevents blowflies from laying eggs on it. Before the day is out, the lambs are running with their mothers. They form small flocks during the summer, led by one of the grandmother ewes, who keeps constant watch over her charges.

HOLLOW HORNS Bighorn sheep are even better climbers than mountain goats. They bound over their rocky homeland, equipped with elastic pads on their feet which absorb the shock of their bouncing gait and provide traction on hard, rough, or slippery surfaces. Bighorns can skip up narrow canyon walls, ricocheting to the top, and never come close to falling. They balance on tiny footholds, and leap chasms over 15 feet (4.6 m) wide. John Muir describes a flock of bighorns plunging off a ISO-foot (46-m) cliff, "descending in perfect order ... controlling the velocity of their half-falling, halfleaping movements by striking at short intervals, and holding back with their cushioned, rubber feet upon small ledges and roughened inclines until near the bottom, when they 'sailed off' into the free air and alighted on their feet, but with their bodies so nearly in a vertical position that they appeared to be diving." Occasionally a ram is killed in one of these amazing plunges, but barring an accident, they have few threats on their lives; their only predators are wolves or bears. Before telescopic sights and high-powered rifles, most mountain sheep lived long, untroubled lives on the sunlit mountain tops, reaching their prime at 10-12 years, and living to 20 years in some cases. Bighorns spend most of their time migrating with the seasonal vegetation. Winter is spent down in the shelter of the timber and lower valleys, and summer up in the grassy meadows above the timber line. All of this migration, however, takes place within a well-marked home range, since territory is one of the prerogatives that rams must guard in order to keep their harems. Goats, as compared to sheep, tend to be better suited to cliffs and more rugged terrain; sheep prefer more open and rolling country. Whereas female sheep and goats often appear to be very similar, male goats tend to have chin beards and long, backward-arching horns; in comparison, male sheep lack chin beards and have massive, curled horns. Male goats also tend to exude a strong odor (sometimes enhanced by the male spraying himself with urine). Along with horses and cattle, sheep and goats are among the most familiar ungulates-primarily because the domesticated species of these bovids have been closely associated with humans for some 10,000 years. The common domestic goat, Capra hircus, and the common domestic sheep, Ovis aries (there are innumerable varieties and breeds of both species) are extremely closely related. As was discussed above, both are classified as members of the tribe Caprini, subfamily Caprinae, family Bovidae. And both domesticated goats and sheep appear to have been derived from wild forms that inhabit the mountains of western Asia, namely the Bezoar goat (Capra aegagrus) and the Asiatic mouflon (Ovis orientalis) respectively. Unlike most ungulates, wild goats and sheep have a social system and behavioral repertoire that is ideally suited to potential domestication. They are accustomed to a single dominant leader (young wild animals that are tamed and

113 reared by hand will "imprint" on a human as their leader). Eurasian sheep have a natural submissive posture (which aids in taming and domestication) and they are gregarious but nonterritorial. This last point is extremely important because in territorial species (such as most species of antelopes, gazelles, and deer), even if otherwise gregarious and social, the males in particular will defend a set territory-and this makes these animals particularly unruly and difficult to manage in captivity. In contrast, goats and sheep have home ranges within which they wander in search of food, but they do not defend territories. Likewise, human pastoralists and hunter-gatherers may have home ranges, but not defended ten~itories. Simply by living in the same area sheep, goats, and humans may have grown used to each other, leading the way for domestication. Domestic sheep are particularly useful to humans as meat and also for their wool. Wild progenitors of the domestic wool-bearing sheep have a stiff, bristly, long outer coat of hair (known as kemps) that covers the fleece-the woolly undercoat. Primitively the fleece is shed in the form of dense mats each year, and early humans found that it could be spun into thread or made into felt. Certain domestic forms have been bred such that they lack the kemps and the fleece grows continuously, and is not shed naturally; humans cut it as need be. Wild goats have many features like wild sheep that make them especially amenable to domestication. Goats are adapted to living in harsh mountainous areas, browsing on brush and scrub. Goats are well known for being extremely hardy-they seem to eat virtually anything, and they can survive a wide range of temperatures. Goats can provide humans with everything from meat and milk to hides and bone for clothing and tools, to manure. Furthermore, goats and sheep will naturally complement each other under domesticated conditions. While the flock of sheep concentrates on grass, the goats will browse on the brush. It is little wonder that goats and sheep seem to have been domesticated at about the same time, perhaps around 8000 B.C. at the beginning of the Neolithic. Because of their tendency to eat virtually anything in sight, it has been suggested that goats may have helped early farmers clearland. On the negative side, browsing domesticated goats have been seen as a major contributing factor in the expansion of desert areas in North Africa and the Middle East. Since the late Miocene the globe has become a world of bovids. There are more species of bovids than any other family of mammals, and given their large size, versatile ecology, and geographic spread, they are now the most important large herbivorous mammals in just about every part of the globe. Since domesticated cattle, goats, and sheep are now replacing almost all wild hoofed mammals (whether bovid or not) wherever humans settle, it is fair to say that this planet will continue to be a world of bovids-even if humans don't outlast them.

Figure 6.1. The Eocene archaeocete whale Basilosaurus. Although it was fully aquatic, it still had tiny vestigial hind limbs, and a mesonychid skull. (Painting by Z. Burian).

6. A Whale's Tale

"As on land there are some orders of animals that seem formed to command the rest, with greater powers and more various instincts, so in the ocean there are fishes which seem formed upon a nobler plan than others, and that, to their fishy form, join the appetites and the conformation of quadrupeds. These are all of the cetaceous kind; and so much raised above their fellows of the deep, in their appetites and instincts, that almost all our modem naturalists have fairly excluded them from the finny tribes, and will have them called, not fishes, but, great beasts of the ocean. With them it would be as improper to say men go to Greenland fishing for whale, as it would be to say that a sportsman goes to Blackwall a fowling for mackarel. But it is not only upon land that man has exerted his power of destroying the larger tribes of animated nature, he has extended his efforts even into the midst of the ocean, and has cut off numbers of those enormous animals that had perhaps existed for ages. We now no longer hear of whales two hundred, and two hundred and fifty feet long, which we are certain were often seen about two centuries ago. They have all been destroyed by the skill of mankind, and the species is now dwindled into a race of diminutive animals, from thirty to about eighty feet long" (Goldsmith, 1825). DR. KOCH'S "SEA SERPENT" In 1845 the talk of Philadelphia was the skeleton of a gigantic beast that the showman "Dr." Albert Koch called Hydrarchus, the great "sea serpent." It stretched 114 feet (35 m) through three rooms, and at the front were great flippers and a gaping maw. The masses flocked to see the marvel, and most thought it proved that sea serpents still roamed the oceans. However, Koch had bought the bones from local farmers who had excavated them from Eocene beds in Alabama. He was no~natomist, but he was definitely a good promoter. By cobbling together the bones of several skeletons he could make the animal look much longer and more serpentine. [He had previously done the same with several

mastodont skeletons, making a giant composite he called the "Great Missourium." We will discuss this animal further in Chapter 8]. Koch brought one of his great "sea serpents" to Europe, where he presented it to King Frederick William IV of Prussia in 1847 as the "behemoth of the Bible." The King was so impressed that he gave Koch an annual pension of one thousand imperial talers. Most people thought the King was getting a bit senile, and this reinforced their opinion. The scientists protested that the specimen was a fraud, but the King did not back down. Koch kept moving from Dresden to Breslau to Prague to Vienna, because scientists in Berlin and London were denouncing him for this forgery, as well for his "Great Missourium" fraud. In each city, an indignant Gideon Mantell (discoverer of the first dinosaur) warned them about the damnable swindler. When Koch brought the wonder to New York, the anatomist Jeffrey Wyman demonstrated in a learned article that it was not a reptile, nor was it from a single individual. When Koch visited Philadelphia the specimen inspired Edward Drinker Cope, then all of six years old, to study fossils. But Mantell's and Wyman's letters had ruined Koch's welcome in the East, so he began touring with the "sea serpent" in rural backwaters, where people were more easily fooled. Finally, he sold the monster to the Wood Museum in Chicago, where it was dismantled. Eventually the specimen was destroyed in the Great Chicago Fire of 1871, triggered by Mrs. O'Leary's cow. Others who had found similar bones before Koch had mistaken them for reptiles too. They were first described in 1834 by Richard Harlan, who named them Basilosaurus, or "emperor lizard." But when the great British anatomist Richard Owen saw the bones in 1839 he realized at once that they were not reptilian. He pointed out that they were the remains of an extinct Eocene whale, which he called Zeuglodon. Unfortunately, the name Basilosaurus is the proper one, since it was used first, even if it is inappropriate to call a whale a reptile. [The reverse is also true. A giant sauropod dinosaur from England was named Cetiosaurus, or "whale lizard," since it was discovered before dinosaurs were understood. Only whales were thought to get that large!]. Today, all of these Eocene whales are called "archaeocetes," or "ancient whales."

HORNS, TUSKS, AND FLIPPERS

116

65 .

60

55

50

45

40

3S

30 million years 'ago

._--------Paleocene

I

I

Eocene

Oligocene

Mesonychlds

Pakicetus

~~~ Ambulocetus Dalanistes

Rodhocetus Ta kracetus

Gaviocetus

~~ Figure 6.2. Family tree of the early cetaceans, showing the remarkable transition between terrestrial mesonychids and advanced whales. (From Zimmer, 1998).

4-2on

:~

Mystlcetes

Although these animals are unmistakably whales, they are very different from Ii ving whales or dolphins (Fig. 6.1). Most Eocene whales did have a streamlined body, with flippers modified from front feet and tiny hind legs, and a fluke on the tail. But their relatively small skulls are still very unspecialized, with nostril still on the tip of the snout rather than having a blowhole on top of their head, nor were their ears specialized for echo sounding. Even more striking are their teeth, which are shaped like triangular blades with

notched edges. Some people have looked at these teeth and speculated that they were used for filtering krill, as the teeth of the seal Lobodon are used. However, a study of the jaw structure by Ken Carpenter showed that fish were a much more likely diet, and that the similarity to krill-filtering teeth is purely superficial. Contrary to "Dr." Koch, large basilosaurine archaeocete whales are now reconstructed at about 80 feet (24 m) long, and weighing about 12,000 pounds (5400 kg), still

A WHALE'S TALE remarkably large. Another group of archaeocetes, the dorudontines, were much smaller-about the size and shape (and probably habits) of a killer whale. Archaeocetes probably had a discrete neck, unlike modern whales, and nasal openings part way back from the tip of the snout. They probably had a humped back or a small dorsal fin, although the fin has no skeletal support to be fossilized. Reconstructing the tail is difficult, but most scientists today believe it had a large horizontal fluke .like that of living whales. Their front flipper structure is more flat-tipped than any living whale. As we shall see below, some had vestigial hind limbs protruding from their bodies. Archaeocete whales are known from Eocene beds all over the world: Great Britain, Germany, North Africa, the United States, New Zealand, Antarctica, and India. They were clearly very successful, and occupied virtually the entire world ocean during the Eocene. However, when they appear in the fossil record they are already very aquatic, with a streamlined body, paddles for front feet and a tail fluke for swimming. How does one get from land-dwelling animals to a whale? And more importantly, why do we say that whales are hoofed mammals? WALKING WHALES? One key to this question lies in the teeth. This kind of teeth is characteristic of an archaic ungulate group, the mesonychids. If you compare the skulls and teeth of some mesonychids with those of primitive whales, they are similar in almost every critical detail. Yet the rest of the mesonychid body is not yet aquatic; instead, they looked very much like large wolves or bears in their body shape. Some were the largest carnivorous land mammals of the Eocene, and must have been the ecological equivalent of bears or hyaenas. Somewhere between the mesonychids and the first aquatic whales, there must have been animals which made the transition to aquatic life. Although this seems far-fetched at first, there are actually modern analogues for the process. A coastal fish-eating scavenger could become more and more aquatic as it wades out to catch live, rather than dead fish. The brown hyaena, which does this along the South African shoreline, is even called the "strand wolf." As this

117

lineage became more aquatic, the feet would become better adapted for swimming (as has happened with the webbed feet in many mammals), and ultimately became flippers (as happened independently in seals and walruses, which are related to bears). The hind limbs are not visible on the body of living whales, but they are still there. Buried deep in their streamlined torso are the remnants of their hip bones and thigh bones. These vestigial bones would not be there if whales were not descended from a four-legged ancestor. Vivid confirmation of this idea has been discovered in recent years (Fig. 6.2). In 1983 Philip Gingerich, Donald Russell, and their colleagues discovered a transitional animal, Pakicetus, from the early Eocene of Pakistan. Although it had an archaeocete braincase, it still had very primitive ears that were incapable of echolocation. In addition, its teeth were intermediate between those of mesonychids and more advanced archaeocetes. Finally, it occurs in river sediments bordering on shallow seaways. Gingerich and his colleagues reconstructed this animal as partly aquatic and partly terrestrial, although none of the skeleton is known. In 1990 new specimens of the archaic whale Basilosaurus from the Eocene deposits of northern Egypt answered more questions about the skeleton. They were more complete than previous specimens, and showed that Basilosaurus had functional hind limbs complete with toes. However, the limbs were so tiny they could not have supported the animal's weight on land. The discoverers suggest that the limbs might have been used to help the male hold the female during mating, as many aquatic organisms do. Eventually, whales lost these limbs completely, and only their vestiges remain within their bodies. In 1994, a specimen of an another Eocene whale, Rodhocetus, was found in Pakistan. It was much more like a modem dolphin, yet it also had the tiny vestigial hindlimbs like Basilosaurus. Since then, several more transitional whales, such as Takracetus and Gaviocetus, have been found, which also retain vestigial hind limbs. The most important breakthrough (Fig. 6.3) was the discovery of a classic "missing link" in Pakistan in 1994. Known as Ambulocetus natans ("walking swimming whale"), it was about the size of a large sea lion, with functioning flippers on both its forefeet and huge hindfeet-

Figure 6.3. A. Skeleton of Ambulocetus natans, the walking whale. (Photo courtesy J.G.M. Thewissen). B. Restoration of Ambulocetus. (From Zimmer, 1998).

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HORNS, TUSKS, AND FLIPPERS

Figure 6.4. The bear-sized carnivorous ungulate Mesonyx, typical of the group from which whales arose. (Painting by Charles R. Knight; Neg. no. 35777, courtesy Department of Library Services, American Museum of Natural History). although it still had tiny hooves on its hindfeet. In addition to this ungulate hallmark, it still had the primitive skull and teeth of the mesonychids, with relatively few whale-like specializations. Based on its highly flexible vertebrae, Hans Thewissen has suggested that Ambulocetus swam with an up-and-down flexure of its body, similar to the swimming motion of an otter, rather than paddling with its feet like a penguin or seal, or wriggling side-to-side like a fish. This would have been a good precursor for the up-and-down motion of the whale's tail when it propels modem whales through the water. A few years after this discovery, another whale known as Dalanistes was found. Like Ambulocetus, it still had full functional front and hind limbs with webbed feet and a long tail. But it was much more whale-like, with a much longer snout that foreshadowed the long snout of archaeocetes. If this still seems far-fetched, there is now good molecular evidence that whales are ungulates. Whenever molecules are compared, whales are always more similar to artiodactyIs than they are to any other living group of mammals. Some molecular biologists have argued that whales are artiodactyIs, since they tend to cluster with pigs and hippos on molecular family trees. Then just before this book went to press, two groups of researchers found skeletons of the

primitive whale Pakicetus and the protocetids. Both animals have the distinctive "double-pulley" astragalus found elsewhere only in artiodactyls. According to Thewissen and others (2001), this suggests that mesonychids are the primitive relatives of both whales and artiodactyls. In addition, whales and mesonychids have numerous features in the skeleton which show they are ungulates more specialized than hyopsodonts or periptychids. These include the loss of the collarbone, a specialized shoulder blade and upper arm bone, and many unique features of the holes in the base of the skull and the arteries that pass through them. Indeed, some mesonychids had claws which were so blunt and broad that they might be called hooves. Mesonychids are unusual among ungulates in that they were probably scavengers or carnivores. Whales, too, live on fish, squid or other invertebrates, but are never plant eaters. ANDREWS' GIANT "BEAR" Roy Chapman Andrews was a dashing explorer who made a reputation traveling "to the ends of the earth." Many consider him to be the model for the archeologist Indiana Jones, played by Harrison Ford in the movies. Andrews visited nearly every remote corner of the earth, braving bandits and horrendous weather. His most famous travels were to

A WHALE'S TALE

119

Figure 6.5. Skull of the giant late Eocene Mongolian mesonychid Andrewsarchus compared with a modern Kodiak bear, the largest living carnivore. (From Fenton and Fenton 1987).

the Gobi Desert of Inner Mongolia, where he led several expeditions for the American Museum of Natural History in New York from 1922 to 1928. These expeditions were the marvel of their time, traveling in early Dodge cars and bringing most of their supplies on the backs of camels. Although they originally set out to find the earliest remains of humans in Asia, they found much greater scientific treasure: spectacular dinosaurs and fossil mammals, including the first known dinosaur nests full of eggs. Andrews' main account of these expeditions, The New Conquest of Central Asia, is full of hair-raising accounts of their exploits, and tales of great discoveries. Typical of these tales was his account of the discoveries at Irdin Manha in 1923: "The day after our arrival at Irdin Manha, we experienced one of the worst windstorms that I have ever seen in Mongolia. At two 0' clock in the afternoon a full gale was raging, and every hour the wind increased. I went out at four 0' clock to find [Walter] Granger, but I could hardly stand against the blasts of sand and gravel which mutilated my hands and feet until they bled. The basin below us was "smoking" as if from a prairie fire; the yellow blanket rolled and swayed, now and then parting for a moment to show a bit of vegetation on the floor, only to have the vista closed as a fresh wave of sediment swirled across to the escarpment's rim. In the tents we were almost buried in the sand; beds, clothes, tables and chairs were thickly covered with a yellow layer. The windstorm gave us an excellent demonstration of the methods by which the depression had been made. Great clouds of sand whirled and eddied over the edge of the escarpment; thus was accumulated sediment carried out. The geologists believe it possible that a river started the excavation, but the enclosed basin must have been scoured out by the wind. Although small stream courses, dry most of the year, led from the sur-

rounding bluffs toward the salt marsh at Iren Dabasu and a certain amount of sediment must be transported by them into the basin, yet the depression does not fill. Only the wind could remove it, as we saw it doing in those gales, which continued for three weeks with only momentary lulls. It was impossible to work except at intervals, and then under the most trying circumstances... Although the beds are richly fossiliferous in certain places, the remains are usually fragmentary. A few limb bones were found intact, but no associated skeletons. Teeth, pieces of jaw and ends of limb bones were the most usual material, although some fine skulls, nearly complete, were discovered. Remains of lophiodonts [discussed in Chapter 13] were extraordinarily abundant, and it was possible to collect a handful of teeth in an hour, at almost any part of the exposure near camp. The entire absence of horses was a surprising feature of this and other early Tertiary faunas of Mongolia... [One] afternoon, we discovered the superb skull of a gigantic beast, which I believed to be a carnivore. The next day Granger dashed our hopes by pronouncing it to be that of a pig, Entelodon [discussed in Chapter 2], which, because of its omnivorous habits, resembled a flesh-eater. However, Morris made a drawing of the skull in situ; this was forwarded to Doctor Matthew at the American Museum. When we returned from Mongolia, a letter was awaiting us, stating that my original supposition was correct, and that the specimen represented one of the primitive creodonts of the family Mesonychidae. Later it was named Andrewsarchus mongoliensis by Professor Osborn, who says that, 'This is the largest terrestrial carnivore which has thus far been discovered in any part of the world. The cranium far surpasses in size that of the Alaskan brown bear, the largest living land carnivore, which when full-

120

HORNS, TUSKS, AND FLIPPERS

grown, weighs 1500 pounds; in length and breadth of skull, Andrewsarchus mongoliensis is double the Alaskan brown bear and treble the American wolf' (Andrews, 1932: 195-196). So Andrews described the discovery of the last and largest of the mesonychids. It is known only from a single skull from the late Eocene of Mongolia. However, what a beast it must have been! The skull is almost three feet long and two feet wide, more than twice the size of the largest bear known (Figs. 6.4, 6.5). Since the skull is wolflike or bearlike, the animal is· often reconstructed as if it were a gigantic bear. If its skeleton were bearlike, it probably would have been twelve feet (3.7 m) long and more than six feet (1.8 m) high at the shoulder! It is unfortunate that no skeleton is known from this animal. Its skull is so whale-like in many features besides its immense size (which is similar to the size of early whales) that one wonders whether its skeleton might have been more adapted for aquatic life. The only evidence against an aquatic lifestyle is the fact that Andrewsarchus is known from terrestrial river sediments. Perhaps it lived in rivers and estuaries, scavenging both land and aquatic animals, as well as turtles and fish. THE PEDIGREE OF LEVIATHAN "When I stand among these mighty Leviathan skeletons, skulls, tusks, jaws, ribs, and vertebrae, all characterized by partial resemblances to the existing breeds of sea-monsters; but at the same time bearing on the other hand similar affinities to the annihilated ante-chronical Leviathans, their incalculable seniors; I am, by a flood, borne back to that wondrous period, ere time itself can be said to have begun; for time began with man. Here Saturn's grey chaos rolls over me, and I obtain dim, shuddering glimpses into those Polar eternities; when wedged bastions of ice pressed hard upon what are now the Tropics; and in all the 25,000 miles of this world's circumference, not an inhabitable hand's breadth of land was visible. Then the whole world was the whale's; and, king of creation, he left his wake along the present lines of the Andes and the Himmalehs. Who can show a pedigree like Leviathan? Ahab's harpoon had shed older blood than the Pharaoh's. Methuselah seems a schoolboy. I look round to shake hands with Shem. I am horror-struck at this antemosaic, unsourced existence of the unspeakable terrors of the whale, which, having been before all time, must need exist after human ages are over" (Mel ville, 1851: 380). Archaeocetes dominated the world ocean throughout the Eocene, from about 54 to 34 million years ago. In the Oligocene, however, they began to decline, and few specimens are known. The last archaeocete, Kekenodon, is known

from the late Oligocene of Oregon, about 25 million years ago, so they straggled on for some time. By this point, however, they were being replaced by a great radiation of modern whales, the mysticetes (baleen whales) and odontocetes (toothed whales). For a long time, there was no fossil evidence about the origin of these two groups, and there was even controversy as to whether they even had a common ancestor. Most scientists today agree that mysticetes and odontocetes are closely related, and descended from archaeocetes, but until recently the fossil record of this transition was remarkably poor. However, the last few years have produced primitive odontocetes in Oligocene deposits of Europe, Russia, California and Oregon, Canada, Japan, Australia and New Zealand (Fig. 6.6). Discoveries by Ewan Fordyce in New Zealand have shown that primitive members of both groups were particularly abundant in the Southern Hemisphere. This makes sense. The beginnings of modem oceanic circulation occurred in the early Oligocene when Antarctica began to separate from Australia and South America. During the Eocene these three continents were joined, and waters from the tropical Atlantic and Pacific mixed with south polar waters and kept the climate warm. During the early Oligocene, however, Australia pulled away and 'Permitted deep water to circulate around Antarctica. As Jim Kennett has shown, this triggered massive changes in oceanic circulation and global climate. The cold polar waters got trapped in a Circum-Antarctic current, circling around Antarctica and trapping cold water (as it does even today), rather than exchanging with the equatorial waters (as it did in the Eocene). Eventually, this led to refrigeration of the South Pole, the first glaciers and ice sheets, and the development of cold bottom waters which sank beneath the surface waters and traveled north. This oceanographic change had a profound effect on world climate, causing a cooling and vegetational change that led to the extinction of many of the animals discussed in this book. However, it had a favorable effect on the whales. The development of the Circum-Antarctic Current and cold bottom waters released an enormous flow of nutrients once trapped on the deep ocean bottom. This upwelling of water and nutrients was the necessary trigger for a huge bloom in oceanic productivity. Tiny microorganisms living in the ocean utilize these scarce nutrients to make their shells, and soon every cubic meter of water was filled with millions of submicroscopic animals and plants. This process is still operating today. The Antarctic is one of the world's richest and most productive regions, even if it appears to be one of the most bleak and inhospitable. The south polar waters are full of plankton, which suppo11s a population of millions of crustaceans and fish. These in turn support much larger predators, including larger fish, penguins, seals, and finally whales. Fordyce suggests that the bloom of oceanic productivity in the early Oligocene created a new source of food for an aquatic organism that could feed on abundant plankton.

121

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Some mysticete whales, with their filter-feeding devices, have taken up the challenge directly. However, the most primitive mysticetes, and the toothed whales have responded to the challenge indirectly by feeding on fish and squid that feed on plankton.

LIFE OF A LEVIATHAN "There Leviathan, Hugest of living creatures, in the deep Strech'd like a promontory sleeps or swims And seems a moving land; and at his gills Draws in, and at his breath spouts out a sea." Milton (1667)

The living members of the order Cetacea (whales, dolphins, and porpoises) are wholly aquatic mammals. None of the approximately eighty species (equally competent authorities disagree on exactly how many living species there are) of living cetaceans can survive outside of water for any extended length of time. The order consists primarily of marine mammals, but a few members live in freshwater rivers. The animals of this order range widely in size, from small porpoises that are only 5 feet (1.5 m) long and weigh about 50 kg to the blue whale which, at a maximum of about 100 feet (30 m) in length and a weight of over 125 tons, or 110,000 kg (and perhaps up to 165 tons, or 150,000 kg), is the largest living animal on Earth, and larger than the largest dinosaurs.

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Figure 6.7. Diagram of the evolution of the skull bones in whales, from the mesonychid Sinopa to the archaeocete Basilosaurus to the Oligocene-Miocene squalodont whales to the bottle-nosed dolphin (Tursiops.) Note how the bones of the nose and face (na = nasals, pmx = premaxillary, mx = maxillary) have been pushed back over the top of the skull as the nostrils moved back to form a blowhole. (Modified from Gregory 1951). The living cetaceans compose two suborders: the Odontoceti or "toothed whales," comprising the majority of species in the order including white whales, sperm whales, beaked whales, porpoises, dolphins, and river dolphins; and the Mysticeti or "moustached [i.e., baleen, or so-called whalebone] whales," including the gray whale, the rorquals (such as the blue whale and the humpback whale), and the right whales. On an informal basis, whales, dolphins, and porpoises are sometimes divided into three groups on the basis of their sizes. The "great whales" are cetaceans that as adults are usually greater than 30 feet (9 m) long. This includes all of the baleen whales and the sperm whale (the largest toothed whale, of Moby-Dick fame). The next group is the smaller whales, which generally range from about 13-30 feet (4-9 m) in length, such as the killer whales, beluga, pilot whales, beaked whales, and

the narwhal. Some of these smaller whales, including the killer whale and pilot whale, are actually related to dolphins and not "true whales," and thus are not necessarily considered "whales" by all experts. The third group, the dolphins and porpoises, range in length from about 5-13 feet (1.5-4 m). In common parlance the terms dolphin and porpoise are used interchangeably, but in fact porpoises (family Phocoenidae) are usually smaller than most dolphins, generally have a blunt snout (as compared to the beak of dolphins), and have spade-shaped teeth whereas dolphins have cone-shaped teeth. In general, all small nonphocoenid odontocetes are called dolphins. Of all of the living orders of mammals, the Cetacea are the most in need of study. The ecologies, habitats, behaviors, and social organizations of many cetaceans are either poorly known or totally unknown. In fact some living species are still known only on the basis of one skull or a few skeletons washed up on beaches. There is even the distinct possibility that there are unknown species of cetaceans still swimming the oceans. Periodically there are credible reports by competent observers of living cetaceans swimming close to the surface that do not match the description of any known species of cetacean, and a new species, Mesoplodon peruvianus, was described in 1991. Whales, dolphins, and porpoises are well-adapted to their water environment. Their bodies are fish-like in shape (converging with the genuine fish and the extinct reptilian ichthyosaurs), and there are no body projections other than the front flippers (which evolved from the conventional forelimbs of terrestrial mammals), the horizontal caudal flukes of the tail (in fishes the tail fins are generally vertical), and a dorsal fin on many species. The external ears have been reduced to small holes filled with tissue, and such features as nipples and sexual organs are pulled into slits in the body. There are no external traces of hindlimbs in modern cetaceans, although the remains of the pelvic girdle (and in some species the thighs also) remain internally and serve as muscle attachments for the reproductive organs. Body temperature in cetaceans is regulated in large part by the blubber. This is a fibrous layer of fats and oils that lies just beneath the skin. Blubber provides good insulation when diving in cold waters, and it may also serve to further smooth and streamline the body of the animal. The cetacean skin surface is smooth, and may be capable of muscular shape change that helps dissipate eddies around the body as they begin to form. Cetaceans swim with the flukes of their tails, which are moved up and down to generate forward thrust. Large and powerful muscles connect the flukes to the latter half of the body, and most cetaceans are capable of swimming fairly quickly-so quickly that they can breach free from the water and jump through the air. The pectoral fins or flippers are used to steer and balance the animal. Even though they continue to breathe air like terrestri-

A WHALE'S TALE al mammals, cetaceans have evolved the ability to stay submerged for long periods of time. Dolphins, porpoises, and smaller whales typically can remain under water for ten or 15 minutes at a time and can dive to depths of over 1000 feet (300 meters). Sperm whales; the cetaceans that can dive longest and deepest, may remain submerged for an hour and a half and can reach depths of well over 6600 feet (2,000 meters). Most cetaceans breathe from a blowhole or blowholes at the top of their heads approximately above the eyes; in the sperm whale (Physeter macrocephalus) and pygmy sperm whales (Kogia) the single asymmetrically placed blowhole is at the front end of the snout, and baleen whales have a doubled blowhole. The blowhole is simply the nostrils that have migrated from the tip of the snout (as in all mammals primitively) to the top of the head. In very small whale embryos (on the order of5 mm long) the nasal opening is still located at the end of the snout, but quite early in development (by the time the embryo reaches a length of approximately one inch, or 2.5 cm) the nasal opening shifts to the position found in adult whales. As a result of this backward movement of the nasal opening, the bones of the cetacean skull have been telescoped or compressed toward the rear, while the front bones of the mouth and jaw·have been greatly stretched forward (Fig. 6.7). In order to exhale and inhale, the cetacean needs only to break the water surface with the back of its head. Spent air is rapidly forced from the lungs through the blowhole, often resulting in a characteristic "spout." Many species can be recognized by the shape of their spout. The visible spout (which can reach 16-20 feet, or 5-6 m in the air in the case of large whales) is formed by the condensation of water vapor as it leaves the lungs and hits the air; whales do not actually blow liquid out of their lungs, as is sometimes commonly thought, but the spout may contain some mucus and foam. Once the spent air is ejected from the lungs, fresh air can be inhaled equally rapidly. Apparently cetaceans utilize the oxygen in the air more efficiently than do terrestrial mammals, and when diving a whale does not hold air in its lungs. Oxygen is combined with the large amounts of hemoglobin and myoglobin found in the blood and muscles respectively, and before diving the actual gases in the air are expelled from the lungs. The expulsion of gases from the lungs protects cetaceans from developing "the bends," the painful phenomenon of nitrogen dissolved in the blood forming bubbles as a diver returns to the surface without enough time to decompress. Just before diving, the blowhole is tightly closed off by the relaxation of muscular valves; to breathe, a whale must open its blowhole-closing muscles. During a dive the heart rate of the animal slows appreciably, and blood is directed primarily to the brain. Myoglobin in the muscles supplies them with oxygen, and once this oxygen is used up the muscles derive further energy through anaerobic metabolism. Cetaceans are more tolerant of both high levels of lactic acid (a by-product of anaerobic metabo-

123

lism) and carbon dioxide than are most mammals. In fact, whales lack the breathing reflex that is triggered in most mammals by high levels of carbon dioxide. During a long dive a whale may accumulate a considerable oxygen debt which it must balance once it surfaces again. Cetaceans give birth in the water, but since they are air breathers the baby must be quickly helped to the surface so that it can take its first breath. Mature females may assist an expectant mother during her delivery. Newborns are usually relatively large, being from one-fourth to one-third the length of the mother, and they grow very quickly. In order to feed the newborn, at first the mother floats on her side so that the infant can nurse while breathing. Later the young will feed underwater. Babies do not suckle in the true sense of the word; rather, milk collects in reservoirs around the mammary glands, and once the youngster attaches to a teat the mother can inject the milk down its throat by contracting certain body muscles. Depending on the type of cetacean, the young may nurse for six months to two years, and females may breed from everyone to five years. Some types of cetaceans appear to be monogamous, at least during the reproductive period, while others (for instance, the sperm whale) are definitely polygamous. There can be seasonal reproductive periods, or the animals may be reproductively active year round. Cetaceans generally have delayed maturation rates, not reaching sexual maturity until four to possibly over twenty years in some of the large toothed whales. It is not really known what the life expectancy of individuals of various species of cetaceans is, but certainly for most forms it would seem to be at least a decade, and perhaps many decades for the larger whales. Long-term studies have demonstrated that sperm whales, for instance, can live for over thirty years. Some think that the smaller cetaceans tend to have life spans of about 14 to 50 years, whereas the larger species (such as the large baleen whales, and sperm whales) may live for 50 to 100 years. In most cetaceans, the senses of hearing and sight are very important. Toothed whales have apparently lost the sense of smell, while baleen whales have lost the sense of taste. In some river dolphins the sense of vision has also been all but lost. They can only distinguish dark from bright, or night from day. This is probably an evolutionary adaptation to the muddy waters they inhabit. In the case of the Ganges dolphin (Platanista gangetica) the eyes do not even have lenses. In other types of dolphins and in porpoises the eyes are said to be fairly good, but in the larger whales the laterally placed eyes do not have overlapping fields of view. For this reason,. these animals lack stereoscopic vision and suffer from blind spots in their field of view. The sense of touch is poorly developed in most cetaceans, except around the face and especially about the mouth and lips in dolphins. Most cetaceans display various combinations of black, white, gray, and bluish-gray; the Atlantic white-sided dolphin (Lagenorhynchus acutus) has a yellow stripe on the

HORNS, TUSKS, AND FLIPPERS

124

blowhole

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melon focused calls

returning echoes Figure 6.8. Dolphins have a specialized system in their heads of sending and receiving their sonar. The '''melon,'' a structure of fatty tissue in their foreheads apparently amplifies and focuses the sound waves. The returning echoes are then picked up by special oil-filled sinuses in the lower jaw and transmitted to the inner ear. The inner ear is surrounded by a capsule of spongy bone that prevents extraneous noises from interfering with the signal. (From Matthews 1978). posterior portion of each side. Most whales tend to be darker above and lighter below, although there are exceptions. For instance, the beluga (Delphinapterus leucas)· is all white; the bowhead (Balaena mysticetus) is black with a white patch on the front of the lower jaw. A pattern of darker upper portions and a lighter belly tends to act as camouflage. Viewed from above the dark back blends with the depths while viewed from below, if the animal is near the surface, the lighter belly portion blends with the light from the sky above. To compensate for their general lack of other senses, odontocetes have developed sophisticated forms of echolocation. Though virtually blind, certain river dolphins can easily detect objects only a few millimeters in diameter using their echolocation. Sound travels much fa11her, faster, and more clearly under water than through the air. Like echolocating bats, odontocetes send out sound waves, using the throat or larynx (they have no vocal cords), nasal passages, and a series of air sacs near the blowhole. These sound waves bounce off of objects and send "echoes" back to the animal which can thus "picture" the objects. In echolocating, it is thought that cetaceans' sounds are emitted essentially through the melon in the forehead and returning sound waves may be channelled back through the lower jaw and on to the inner ear (Fig. 6.8). Cetaceans also use a variety of sounds in social communication. We have all heard of the "songs" of humpback whales, which are possibly a part of courting behavior. In many species of cetaceans there appear to be songs that are unique to ce11ain individuals. Various types of whales and dolphins can recognize the sounds of other cetacean species. Some of the low-frequency sounds, used especial-

ly by the larger whales, will travel great distances through the oceans, especially if the sounds propagate along deep ocean channels. Whales may communicate with each other over hundreds or even thousands of kilometers. Many cetaceans are social animals that Ii ve in groups and interact with each other on a regular basis. They have a large behavioral repertoire, engaging in cooperative behavior, play, sexual courtship behaviors, and parental care of young. Some cetaceans, especially the larger whales, also engage in annual migrations of considerable length. For example, the North Pacific gray whale feeds during the summer in the Bering Sea and Arctic Ocean, but migrates thousands of kilometers to the coast of Mexico where young are born during the winter. "SO LONG, AND THANKS FOR ALL THE FISH" "We must strip ourselves of our preconceptions about the relative place of Homo sapiens in the scheme of nature. We cannot continue to insist that man is at the top of the evolutionary scale and that no further evolution is possible. It is probable that their intelligence is comparable to ours, though in a strange fashion" (J. C. Lilly, 1975: 3). In the fourth book of Douglas Adams' trilogy, The Hitchhiker's Guide to the Galaxy, the dolphins suddenly and mysteriously vanish from earth. Seeking the answer to this mystery, the main characters end up at the house of a man known as "Wonko the Sane." He possesses a bowl with a message "So long, and thanks for all the fish" that magically appeared etched into its surface. The bowl was a farewell gift from the dolphins, whom Wonko had studied and whose language he had tried to learn. With their parting message, Wonko realized that dolphins are actually alien beings, smarter than humans, and capable of communicating with us if they wanted to-and that they were leaving the Earth before it was destroyed. Science fiction books and TV shows like "Flipper" have changed our images of whales and dolphins. No longer "dumb fish," many consider them as intelligent as humans. In science fiction, they are sometimes more intelligent. The dolphins in Adams' novel are actually aliens who were just visiting this planet. When they sense its imminent destruction, they leave with the cryptic message of the book's title. The intelligence of cetaceans is a controversial issue. It is true that these animals engage in complex behaviors and most have large brains with a relatively expanded neocortex (the portion of the brain to which creative and reasoning functions are attributed). The absolute sizes of the brains of some whales are also amazingly large. Probably the largest is that of the sperm whale, although this is by no means the largest whale. However, it is reported that the density of neurons in cetaceans is not particularly high. One can use various physical measures to attempt to quantify just how "smart" cetaceans are. One common measure,

A WHALE'S TALE known as the encephalization quotient (EQ) is essentially the ratio of the organism's brain volume to its body surface area. The EQ of most mammals is well under 2.0; in humans the EQ averages about 7.4. Chimpanzees, known as relatively "intelligent" non-human primates, have an EQ of about 2.5, whereas cetacean EQs range from about 1.5 in river dolphins to 5.6 in the bottle-nose dolphin. Does this mean that the bottle-nose dolphin has an intelligence intermediate between that of a chimpanzee and a human? Not necessarily. Certainly, whales do many startling and seemingly inexplicable things, so we tend to anthromorphize them as "intelligent beasts." Since ancient times, mariners have been amazed at the sociability of dolphins, and there are many stories of dolphins rescuing drowning people at sea. This is probably related to the strong social bonds within a pod of whales, and the fact that they will cluster around an injured or weakened relative and attempt to hold it up and sustain it. Their social cooperation is particularly strong when it comes to feeding or defense. Cetaceans often cooperate like cowboys on a roundup, surrounding and scaring schools of fish into tight clusters so they can feed easily. They are also capable of extending this social cooperation to include humans. Ancient authors, such as Pliny and appian, report dolphins helping humans with their fishing. In. modern times, there are documented cases of dolphins responding to a slap on the water or a tap on the canoe as a cue to herd fish where humans could catch them. This is not strictly altruistic, since the dolphin catches fish more easily as well. Of course, these behaviors can also be explained as learning based on payoff. Like many other animals that must interact with humans, dolphins and orcas (killer whales) have become famous for their ability to perform on cue. They are particularly creative when it comes to playing games with their human companions, and some credit them with creativity when dolphins invent un-whale-like stunts completely on their own. Another aspect that endears them to us is their strong social bonding. When they cannot bond with each other, they bond readily with humans. Trainers in marine parks have exploited this, so that the climax of the act is leaping killer whales that launch humans into the air on the tips of their noses. In recent years, their social flexibility has led to phenomena such as dolphin parks, where people swim with dolphins and pet them. In the wild, the learning ability of cetaceans comes into focus when they are feeding, or defending themselves against predators. In the days of open-boat whaling, sperm whales frequently moved upwind and out of reach of sailpowered whaling boats. Orcas have been shown to learn quickly how to distinguish between very similar types of boats, only one type of which was dangerous to them. John C. Lilly reports the story of a dying orca who was apparently able to communicate exactly how to recognize the cannon on a particular boat so that the rest of his pod would

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not get too near. Dolphins that have been exposed to certain types of nets quickly learn how to avoid them. Even what is meant by intelligence is subject to endless debate. The relatively large brains of certain cetaceans, such as the bottle-nose dolphin and other odontocetes in particular, are a result of their active predatory life and complex social arrangements that have evolutionarily emphasized advanced cognitive skills. As the cetologist Peter G. H. Evans has pointed out, it is not easy (and perhaps simply inappropriate) to attempt to compare cetacean intelligence to human intelligence. For tens of millions of years the cetacean line and human line have followed very different evolutionary paths-in many respects diametrically opposite paths. Humans and cetaceans live in very different environments, the terrestrial versus fully aquatic. We rely primarily on different senses, sight versus sound (as used in echolocation in many cetaceans). Homo sapiens is still a fairly generalized mammal in many respects (for instance, four limbs with full sets of digits), with a few peculiar modifications such as the bipedal gait that has freed the hands, led to the opposable thumb, and resulted in the development of tools. Cetaceans, in contrast, are among the most specialized of all mammals. Anatomically and physiologically they are extremely well adapted to live in the aquatic medium. They have very little in the 'way of appendages; the cetaceans have nothing equivalent to the human hand, for instance. But then we have nothing equivalent to their flukes. Perhaps rather than trying to decide whether cetaceans are as smart (or even smarter) than humans, we should simply acknowledge that both humans and cetaceans are both extremely derived, large-brained mammalian species adapted to very different niches and life styles. The most controversial aspect of cetacean intelligence is communication. Cetaceans clearly can communicate with each other via their high-frequency vocal repertoire, but can we understand them, or even better, communicate with them? If we could communicate with them, would we be able to understand their way of thinking? The pioneer in this field was John C. Lilly, who shocked the world in the 1960s with his discoveries of dolphin behavior and communication. He was one of the first to show how easily they can imitate human speech with their amazing vocal powers, although this is no more true speech than the chatter of a parrot. In fact, cetaceans are extremely good mimics, imitating sounds or gestures on just a single exposure. In the wild, they will often play "follow the leader," with each dolphin imitating the motion of the leader, like a dance contest. In some oceanaria, dolphins have been seen mimicking the behavior of seals, or other whales, or the airbubble sounds of divers. In one case, a dolphin watching a di ver scrape algae off the portholes picked up the scraper and did it himself. Although communication with other species is certainly a worthwhile goal, many scientists have criticized Lilly and his followers for clouding their science with

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wishful thinking. As Loren Eiseley points out in his essay, "The Long Loneliness," there is a strong urge for humans to break our isolation on this planet by communicating with another species, or with intelligent life on another planet. Lilly wanted to be Dr. Doolittle and talk with the animals. "Our major goal is breaking the interspecies communication barrier so we can mutually exchange information. Until we live with dolphins and they with us, the dolphin mind remains opaque to us, and the human mind remains dryly out of reach of dolphin teaching. . . Sometimes I feel that if man could become more involved in some problems of an alien species, he may become less involved with his own egocentric pursuits and deadly competition within his species, and become somehow a better being" (Lilly, 1975: 200,207-208). After experiments with teaching dolphins human speech began to fizzle out, research began to focus on the whales' own communication. Powerful computers have been dedicated to analyzing cetacean sounds, but the success in decoding has been limited. Synthesizers have been used to imitate dolphin sounds and attempt to communicate, but the results have been inconclusive. Other experiments have tried to detect if dolphins communicate on their own terms. In one experiment, dolphins in the same tank isolated by a screen appeared to communicate messages about food. When a light flashed in one tank, the first dolphin made a series of low clicks, indicating that the other dolphin could now get food from a feeder in his tank. After further testing, however, it appeared that the "communicating" dolphin was making the noise in response to the light alone, even when the other dolphin was absent. The "receiving" dolphin had learned by trial and error that that particular sound meant food. The most successful experiments have trained dolphins to respond to a repertoire of hand gestures or acoustic signals. Dolphins have been able to communicate a few things, such as whether or not a given object was present in their tank. In a few studies, dolphins have comprehended sentences of up to five "words," taking into account the semantics and syntax of the message. These are clearly the basic aspects of any language, and are comparable to the studies that have been done on apes. However, these simple messages about physical objects and attributes are a long way from any kind of communication as profound as language in the human sense. The real issue is whether dolphins and humans can expand their communication beyond simple and stereotyped vocalizations that are part of the dolphins' natural environment, and communicate on a level that approaches true thought. Critics of the idea of "a mind in the waters" point out that cetaceans sometimes exhibit very strange, seemingly inexplicable behaviors. The well-publicized examples of whales which had to be helped out of the Arctic pack ice, or Humphrey the Humpback, who had to be coaxed out of the Sacramento River delta, give whales a bad reputation for intelligence. Among the most puzzling of such behav-

Figure 6.9. Sperm whales stranded on a beach (From Martin, 1990) iors is the predisposition of certain species to beach themselves in mass live strandings that can result in the death of dozens, or in a few cases hundreds, of individuals of a species at a time. Such strandings have been recorded even for the larger whales, and have been recorded for hundreds of years. In 1970, 59 sperm whales were stranded off the coast of New Zealand, and another 72 were stranded off the same coast four years later. In 1979, 56 dead sperm whales were found on the beach on the Gulf Coast of Baja California, and in the same year 41 sperm whales became beached on the coast near Florence, Oregon (Fig. 6.9). Although these examples of strandings just cited are of the sperm whale, many odontocetes have been involved in mass strandings. In pilot whales (Globicephala) and the false killer whale (Pseudorca crassidens) strandings seem to be particularly common. In the 1980s there were a spate of pilot whale strandings in the United Kingdom. When historical records are analyzed, it turns out that only about twenty species of cetaceans are regularly or occasionally involved in such events. No baleen whales are recorded as having been part of a live mass stranding. Participants in these strandings are primarily deep water, oceanic odontocetes (such as the sperm and pilot whales, rarely various beaked whales [usually single strandings], and some oceanic dolphins) that typically live in tight social groups. Why do cetaceans strand en masse? This question has yet to be satisfactorily answered, and indeed there may be no simple answer-the reason may differ from one instance to another. In some cases seemingly healthy animals have become stranded, and concerned humans have forced the animals into deeper waters, but the beasts simply returned to the beach and became stranded once more. This has led some to believe that the animals might even be "suicidal," although such a suggestion is possibly little more than anthropomorphic conjecture. Other common explanations for mass strandings include: the concept of mass parasitic infections that attack the inner ears of the cetaceans, resulting in confusion and

A WHALE'S TALE beaching; very gently sloping beaches that do not allow efficient reflection of sound waves and therefore cannot be navigated by the echolocation of the cetaceans; bad weather conditions; predator attacks that drive the cetaceans to the land; confusing underwater sounds ("noise pollution," perhaps produced by humans, such as ships or explosions, or by natural phenomena such as earthquakes) that interfere with echolocation; or even the hypothesis that the animals are attempting to follow an ancient migration route that is now blocked by dry land. None of these explanations is particularly compelling. It seems unlikely that parasites would affect, simultaneously, a whole herd of animals. The cetacean sonar appears to be sophisticated enough to deal with gently sloping beaches. Mass live strandings appear to occur independently of weather conditions. There are no known predators that could drive sperm whales, for instance, to the shore. Human-induced oceanic noise pollution is a relatively recent phenomenon, yet cetaceans have been stranding for thousands of years. The concept that whales are following ancient, genetically ingrained migrational routes, now blocked by land, is simply untestable. One cogent suggestion is that individual cetaceans may instinctively come to shore and beach when sick or injured and are unable to keep themselves afloat near the surface. After all, cetaceans must breathe air or else they will drown. Given the social nature of the species that typically strand together in large numbers, perhaps the majority are simply following one or a few sick leaders. One recent theory that may account for many mass Ii ve strandings is that the cetaceans in question are having navigational problems. Maybe the animals navigate via Earth's magnetic field. Indeed, minuscule crystals of magnetite have been found in the brains of some cetacean species. In many cases such strandings occur where natural magnetic lines of equal force intersect perpendicularly with the coastline. Apparently the whales may be following the magnetic contours, even if they run into the land. As primarily deep-ocean species are involved in mass strandings, these animals could efficiently navigate using Earth's magnetic field in their natural realm far from the coast-but when they do run ashore using their navigational system they may have no good back-up system and become flustered and flounder. Whatever the cause of Iive mass strandings, one must keep them in perspective. Very few cetaceans are involved in mass strandings. Even if a couple of thousand cetaceans, spread among a dozen different species, are involved in these phenomena each year, under natural conditions this would not have any significant effects on the well-being of the species. MOBY DICK, FLIPPER, AND THEIR KIN The vast majority of whales (about 66 of the 76 living species, according to one count) are toothed whales, or odontocetes, and most of these are the smaller dolphins and porpoises. The teeth of odontocetes are highly modified

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compared to the primitive mammalian type. Within a single animal the teeth all look basically alike, being essentially conical pegs in sockets. There is no differentiation into molars, canines, and so on. The number of teeth varies greatly in different odontocetes, from 50 to over 60 on each side of each jaw (giving a total of over 240 teeth in the mouths of some individuals) in the South American La Plata river dolphin (Pontoporia blainvillei), to only one or two pairs of functional teeth (some individuals have additional small, non-functional teeth) in several species of beaked whales (Family Ziphiidae), and generally only one peculiarly developed spiral tusk (regarded as unicorn horns in medieval times) in the narwhal (Monodon monoceros). The teeth of odontocetes are not used for chewing or cutting, but simply for catching and grasping prey. Most toothed whales feed on fish and squid, and they swallow their catch whole. Some researchers have even suggested that the bright white teeth of the sperm whale serve primarily as a lure to attract the squid upon which it feeds. In contrast to most odontocetes, the orca or killer whale (Orcinus orca, actually a type of dolphin) will use its sharp teeth to bite and tear chunks of meat as it preys on seals, young walruses, sea otters, birds, large fish, and other cetaceans. In the majority of the toothed whales the jaws form an extended beak-like snout, and the forehead forms a rounded curve or "melon." Unlike all other mammals, including the baleen whales, odontocetes have only a single nasal opening. The nasal passages either join before coming to the surface in the single blowhole, or one nasal passage is suppressed and the other nasal passage is the only tube used for breathing. These modifications of the nasal passages have resulted in species with skulls that are not laterally symmetrical, and the blowhole may not even occur on the midline of the animal. In some classifications, there are ten living families of odontocetes, each of which merits at least a brief description. They include four families of river dolphins (Platanistidae, Iniidae, Pontoporiidae, Lipotidae); the Phocoenidae, or true porpoises; the Ziphiidae, or beaked whales; the Delphinidae, or typical dolphins, killer whale, and related forms; the Monodontidae, consisting of the narwhal and beluga; the Physeteridae, or sperm whale; and the Kogiidae, including the pygmy sperm whale, and dwarf sperm whale. Of the five living species of river dolphins (Fig. 6.10), four are freshwater dolphins (the Ganges dolphin of India, Nepal, and Bangladesh, Platanista gangetica; the Indus dolphin of the Indus Ri ver,Pakistan, Platanista minor; the baiji of the Yangtze River in China, Lipotes vexillifer; and the Amazon dolphin of the Amazon River system in South America, Inia geoffrensis) and one saltwater species (the La Plata dolphin, Pontoporia blainvillei, inhabiting a portion of the southeastern coast of South America). All five species are relatively primitive, small-brained, solitary forms (they lack the developed social behavior that is

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B

Figure 6.10. A. The Ganges river dolphin, Platanista gangetica. B. The Yangtze River dolphin, or baiji, Lipotes vexillifer. (Photos courtesy National Marine Mammal Laboratory, NOAA). exhibited in most cetaceans). Except for Pontoporia, they have poor degenerate eyesight, but well-developed echolocating abilities. The dorsal fins are poorly-developed; the beaks are long, narrow, and bear numerous small teeth (100 to over 200); and the flippers of some of these species are relatively primitive in that the digits are still vaguely visible through the skin. Unfortunately little is known about the behavior and ecology of river dolphins. They appear to reach sexual maturity more quickly than most cetaceans, probably at only two or three years of age. They feed primarily on fishes and shrimps; the La Plata dolphin also takes in significant quantities of squid and octopus. While all five species may ultimately be threatened, the Indus and baiji dolphins are in particular danger because of the construction of dams along the rivers they inhabit. At present there are probably significantly fewer than 1000 Indus dolphins still alive. The most endangered cetacean of all, however, is the Chinese river dolphin, Lipotes vexillifer, known as the baiji to the Chinese. Native to the Yangtze River, only a few hundred are left, and their populations are seriously threatened. The Chinese are now desperately trying to save it, focusing the same cultural attention and pride on the baiji that they do on their endangered pandas. Douglas Adams captures the essence of the problem in his book Last Chance to See: "Traveling in China, I began to find that it was the sounds I was hearing that confused and disoriented me most. It occurred to me, as we tried to find a table in one of the more muffled corners of the bar, that the dolphins we had come to look for must be suffering from the same kind of problem. Their senses must be completely overwhelmed and confused. To begin with, the baiji dolphin is half-blind. The reason for this is that there is nothing to see in the Yangtze. The water is so muddy now that visi-

bility is not much more than a few centimeters, and as a result the baiji's eyes have atrophied through disuse. As a consequence, the baiji had to use a different sense to find its way around. It relies on sound. It has incredibly acute hearing, and "sees" by echolocation, emitting sequences of tiny clicks and listening to the echoes. It also communicates with other baijis by making whistling noises. Since man invented the engine, the baiji's river world must have become a complete nightmare. China has a pretty poor road system, so the Yangtze is the country's main highway. It's crammed with boats all the time, and always has been-but they used to be sailing boats. Now the river is constantly churned up by the engines of rusty old tramp steamers, container ships, giant ferries, passenger liners, and barges. The dolphins are continually being hit by boats or mangled in the propellers or tangled in fishermen's nets. A dolphin's echolocation is usually good enough for it to find a small ring on the sea bed, so things must be pretty serious if it can't tell that it's about to be brained by a boat. Then, of course, there's all the sewage, the chemical and industrial waste and artificial fertilizer that's being washed into the Yangtze, poisoning the water and poisoning the fish. 'So,' I said, 'what do you do if you are either half-blind, or half-deaf, living in a discotheque with a stroboscopic light show, where the sewers are overflowing, the ceiling and the fans keep crashing on your head, and the food is bad?' 'I think I'd complain to the management.' 'They can't.' 'No. They have to wait for the management to notice'" (Adams, 1990: 152-155). The true porpoises (Fig. 6.11), or harbor porpoises, are a family (Phocoenidae) of six relatively shallow-water

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Figure 6.11. Dall's porpoise, Phocoenoides dalli. (Photo courtesy National Marine Mammal Laboratory, NOAA) coastal species that includes the common harbor porpoise, Burmeister's porpoise, the Gulf of California porpoise, the spectacled porpoise, Dall's porpoise (all of the genus Phocoena), and the finless porpoise (Neophocoena phocoenoides). Porpoises are small, usually about five to six feet (1.5-1.8 m) in length, and (except for the finless porpoise) have small fins on the back. Porpoises have blunt snouts, lacking the typical dolphin beak. Their teeth, numbering between about 60 and 120 per individual, are spadeshaped. The basic social unit of porpoises seems to be about 2 to 4 individuals. They are not as solitary as typical river dolphins, but they are much less gregarious than many cetaceans. Their diet consists primarily of various species of fishes, squid, and crustaceans. Various species of porpoises reach sexual maturity at between about 4 and 7 years, and they may Ii ve for 12 to over 20 years. Porpoises are found spottily throughout temperate and tropical waters, and into subarctic and subantarctic waters. Unfortunately, not much is known about porpoises in the wild. As with many cetaceans, the continued encroachment of humans threatens these species. The beaked whales, Family Ziphiidae, comprise a large cluster of species (about eighteen known species arranged in five genera) that are also among the most poorly known whales. Beaked whales are moderate-sized whales (ranging in length from about 13-43 feet, or 4-13 m, and weighing from about one to ten tons) that inhabit the open waters beyond the continental shelves of all of the world's oceans. Because of their moderate size, small family groups, and open ocean habitats, the beaked whales have never been a prime target of whalers (except for Baird's beaked whale, Berardius bairdii, found in the northern Pacific). For much the same reasons, they have not received much scientific study. Several known living species of beaked whales have apparently never been observed by humans alive-these species are known only from a few skeletons and carcasses that have washed up on

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various shores. Not all beaked whales are so poorly known, however. Probably the best known species of the family are the northern bottlenose whale and the southern bottlenose whale (Hyperoodon ampullatus and Hyperoodon planifrons, respectively). During the late nineteenth and early twentieth centuries, whalers hunted the northern bottlenose. Beaked whales are generally considered to be relatively primitive among living whales. The elongated upper and lower jaws form the "beak" (as in various dolphins) which gives rise to both the common name and the scientific name for the family, Ziphiidae (from the Greek xiphos, or sword). Most of the beaked whales have a reduced number of teeth, with only one or two pairs in the lower jaws-these teeth may protrude prominently from the mouth when the jaws are· closed. In many species the teeth of the females, although present, never erupt above the gums. It is probable that the teeth are used in some sort of aggressive social behaviors between males of the same species. Old males of many species bear scars on their backs that appear to have been produced by members of their own species. In obtaining and eating their diets of squid and deep-sea fishes, the teeth probably serve no function. The northern bottlenose whale, one of the best known ziphiids, occurs throughout the northern Atlantic. It is known to migrate seasonally, and travels in small herds of two to perhaps twenty individuals. Larger herds may be dominated by a mature male. The detailed ecology and behavior of the more obscure beaked whales is unknown. The family Delphinidae, true dolphins and their relatives, are by far the most diverse family within the order Cetacea, containing close to three dozen species classified into about seventeen different genera (Fig. 6.12). Here are included such well-known animals as the common dolphin (Delphinus delphis) , the bottle-nose dolphin (Tursiops truncatus), the killer whale (Orcinus orca), the false killer whale (Pseudorca crassidens), the long-finned pilot whale (Globicephala melaena), the short-finned pilot whale (Globicephala macrorhynchus), and the melon-headed whale (Peponocephala electra). Delphinids are small to medium-sized cetaceans (lengths and weights ranging from just over a meter and about 88 pounds, or 40 kg, to about 23 feet, or 7 meters and 9920 pounds, or 4,500 kg.). Many delphinids have well-developed beaks, but in some species (for example, the killer whale and melon-headed whale) this is lacking. Likewise, many delphinids have a well-developed, often backwards-curving dorsal fin. The mouth usually contains about one hundred sharply pointed teeth, and there is a distinct forehead melon used in echolocation. Delphinids present the greatest range of body pattern schemes seen in any cetacean family, although the colors are almost exclusively blacks, whites, and grays, with a few species bearing yellow patches. Delphinids are distributed throughout the world's oceans, and appear to inhabit a variety of small-cetacean

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B

Figure 6.12. Typical delphinids. A. Pacific white-sided dolphin, Lagenorhynchus obliquidens. (Photo courtesy National Marine Mammal Laboratory, NOAA). B. Orca, or killer whale, Orcinus orca. (Photo by D.R. Prothero.) C. Male bottle-nosed dolphin, Tursiops truncatus, engaged in erotic play with a cable in his tank. (From Matthews, 1978). D. The pilot whale, Globicephala melaena. (Photo by D.R. Prothero).

niches. Most of the species with well-developed, pointed snouts or beaks are fish eaters. Those with blunter snouts and reduced dentitions seem to feed more often on squids. Killer whales, which hunt in packs, feed not only on fishes, squids, and other invertebrates, but also on birds and marine mammals (including other cetacean species). The delphinids are relatively advanced cetaceans, with well-developed and complex social structures, and a correspondingly highly-developed intelligence. They tend to be highly gregarious, forming family groups of less than half a dozen in some shallow-water nearshore species to groups of well over a thousand individuals in deeper-water, pelagic species. Large groups are usually associated with longdistance movements and migrations. They cooperate in

hunting, herding, and shoaling prey species. In some species of dolphins, up to 2,000 individuals may congregate together at a single feeding area. Individuals of vari0us species seem to have home ranges of from less than 100 square kilometers to over 1,500 square kilometers. Delphinids seem to be sexually active all year long, although sexual activity may peak during certain months. Gestation periods range from about ten to sixteen months, babies may nurse for over a year, and depending on the species sexual maturity is reached between five years and sixteen years. For many humans, various common species of dolphins and the killer whale are the cetaceans they know best. They are easily maintained in captivity, their natural intelligence allows them to be trained to perform a variety of tricks, and they thus become the stars of various oceanarium shows. In the process of commercial tuna fishing,

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Figure 6.13. A. The beluga whale, Delphinapterus leuca. (Photo by D.R. Prothero). B. An early representation of the narwhal, Monodon monoceros ( from Wendt 1959).

many wild dolphins have been destroyed, and this has also caught the attention and sympathies of the public. There is little evidence that any of the delphinids are in any imminent danger of extinction, but one should never underestimate the destructive powers of humans. The Family Monodontidae consists only of two species: the beluga (Delphinapterus leucas) and the narwhal (Monodon monoceros) (Fig. 6.13). The family is now restricted to the north temperate and circumpolar regions of North America (including the coasts of Greenland) and Siberia. Overall both species are similar in body size and shape; they range in length from 10-15 feet, or 3 to 5 meters (not counting the tusk of the narwhal), weigh from about 1100-3500 pounds (500-1600 kg), and lack a dorsal fin. Superficially the two species are easily distinguished. The beluga is all white and, unlike most cetaceans, the beluga has a distinct and flexible neck that allows it to turn its head from side to side. The mouth of the beluga contains about three dozen peg-like teeth, and using its facial muscles the beluga can make a range of almost human-like facial expressions. The upper portion of the narwhal is pigmented with a splotchy, mottled set of darkish gray-green patches; there is a white belly underneath. Narwhals have only two nonfunctional teeth in the upper jaw. In most males only the left tooth develops to form the long, spiral tusk (sometimes referred to as a "horn") that is the most distincti ve aspect of narwhals. In a very few males, twin tusks are formed, and some females may grow one or a pair of short tusks. In the typical male, however, a single tusk grows to an enormous length-it can be up to ten feet (3 m) long. The narwhal tusk, growing from the left side, is slightly off-center and often points somewhat downward. No one really knows the function of the narwhal tusk. Certainly it is not used in spearing fish or breaking ice, as has sometimes been suggested. Most likely the tusk is used in social displays and combat between males. There is some evidence that they

may joust with their tusks and inflict mild injuries upon one another. For hundreds of years, the narwhal tusk has been valued as the "unicorn's horn" in medieval Europe (see Chapter 15). Both belugas and narwhals are social animals, often congregating in herds and interacting with members of their species. The beluga is known to be very vocal. These vocalizations, along with its facial expressions, are probably used in social communication. Many of the beluga vocalizations can even be heard from above the ocean's surface: thus, long ago the beluga was nicknamed the "sea canary" by sailors. Narwhals and belugas feed on a wide variety of organisms, including various fishes, cephalopods, crustaceans, and in the case of the beluga various bottom-dwelling worms and mollusks. Some researchers consider the Irrawaddy dolphin, orcaella brevirostris, commonly classified as a delphinid, to be a third species of monodontid. Irrawaddy dolphins occur in the coastal waters and mouths of large rivers off southeast Asia, northern Australia, and Papua New Guinea. The quintessential whale in the eyes of many people is the mighty sperm whale, Physeter macrocephalus, only member of its family, Physeteridae (Fig. 6.9). The sperm whale was the great white whale in Herman Melville's novel, Moby-Dick. This was the preferred species of whale hunted by the New England whalers of the late eighteenth and early nineteenth centuries. They are found in tropical and temperate waters worldwide, and male sperm whales range up into the polar regions, both north and south. The sperm whale is the largest of the odontocetes, and the most distinctive. They are sexually dimorphic, with the males reaching maximum sizes nearly twice that of females; males are reported to have ranged up to 66 feet (20 m) in length with weights of 66 tons (60,000 kg) or more. Such maximum sizes are somewhat problematic. Over two centuries of hunting has concentrated on the largest whales and thus drastically reduced the overall average and maxi-

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HORNS, TUSKS, AND FLIPPERS Left nasal passage Righ"t nasal passage Blowhole

I

Figure 6.14. The head of the sperm whale contains the spermaceti organ, which is filled with a waxy substance whose purpose is controversial. Some scientists argue that it is like the "melon" of dolphins for focusing sound wav~s; others argue that by changing its temperature with water through its nasal passages, the whale can change its buoyancy. Only the left nasal passage connects with its single blowhole, which is on the tip of its nose and produces a forward-directed spout. (From Matthews 1978).

mum sizes known. The sperm whale is a heavy, robust whale with propOltionally small flippers, no real dorsal fin (rather just a small dorsal ridge), and a distinctive, large head that is square in profile due to the enlarged nose (Fig. 6.14). Unlike most whales, the blowhole is located at the tip of the snout and when the sperm whale spouts it does so at a distinctive 45 degree angle. The spermaceti organ, from which the valuable sperm oil is derived, is located in the head/snout region of the whale. The exact function of the spermaceti organ is unknown, but it is thought that it may have a function in echolocation. The lower jaw is relatively thin and rodlike, compared to the size of the massive head. Functional teeth, up to 10 inches (25 cm) in length and numbering up to 20 or 25 on each side, are normally found only in the lower jaw. The upper jaw may contain a few smaller, non-functional teeth. As was mentioned earlier, the function of the teeth in the sperm whale is unclear-they may simply be a lure to attract prey such as squid. In some cases sperm whales with broken or otherwise damaged lower jaws seem to survive with no major difficulties. Sperm whales apparently depend much more heavily on echolocation and their ability to taste various chemicals in the water than on sight. The eyes of sperm whales are relatively small and fixed in their sockets. In diving they enter water that is totally dark. Totally blind sperm whales can survive with no problems. Typically sperm whales are

overall black or a shade of dark gray with white markings on the lower jaw and portions of the ventral surface. Occasionally white sperm whales are sighted. Melville's fictional white bull sperm whale, Moby Dick, was probably patterned partly on a real white sperm whale named Mocha Dick that attacked whaleboats in the Pacific during the early nineteenth century. Sperm whales are deep water whales that are known for their diving ability. It is well established that both male and female sperm whales dive to depths of 3300 feet (1000 m). Large males may dive to depths of over 9800 feet (3000 m), and stay underwater for an hour and a half, or possibly longer. Sperm whales feed on all manner of organisms, including many bottom dwelling organisms, but they concentrate primarily on giant squids that they swallow whole. It is not uncommon to find round scars produced by the suckers of giant squids on the heads of sperm whales, and giant squids found in the stomachs of captured sperm whales have been reported to be over 40 feet (12 m) long and have weighed up to 440 pounds (200 kg). Sperm whales are social, gregarious animals that join into groups (also known as pods) made up of a dozen or more individuals. If a sperm whale is sick or, injured, members of its group may gather around it and try to help or comfort it. They also undertake periodic migrations from tropical to temperate (and in the case of adult males, polar) waters during the spring and summer. When migrating they may travel in pods of hundreds. Sperm whales are slow to mature. Females reach sexual maturity at about seven to twelve years, but it is thought that males do not reach sexual maturity until 18 or 19 years old; males may not be socially mature until they reach their middle or late twenties. No one knows how long sperm whales can live, but it is probably at least 50 to 70 years. There has been a long history of humans hunting the sperm whale, and this has certainly depleted their numbers compared to their original stock. However, now that they are effectively protected it is thought that they are making a comeback. At this point there does not seem to be a danger that they will go extinct. Closely related to the sperm whale are the two species of the family Kogiidae, the pygmy sperm whale (Kogia breviceps) and dwarf sperm whale (Kogia simus). They superficially resemble their bigger relative, but they have proportionally smaller heads, bigger flippers, and small dorsal fins on their backs. In length they range from about 6.5-11 feet (2-3.5 m), and their maximum weights are probably only about 1100 pounds (500 kg). In general the pygmy and dwarf sperm whales seem to inhabit primarily warm waters at low latitudes, feeding on various fishes, cephalopods, and crustaceans. They are surprisingly convergent in the body form with sharks, even to the extent of having a pigmented "gill slit" along the side. Since Kogia has few predators, it does not seem to be protective camoflage, but no better explanation has been proposed.

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Figure 6.15. The famous explorer Roy Chapman Andrews (over 6 feet in height) standing next to the skeleton of a right whale. The skull and jaws of baleen whales are simply large toothless arches of bone to support their enormous mouth cavity and its filter of baleen hanging from the upper jaw. The plates of baleen in the mouth are smooth on the outside, but on the inside they are fringed to form a filtering device. (Courtesy American Museum of Natural History). FILTER-FEEDING MONSTERS Baleen whales were derived from toothed ancestors, since vestigial tooth buds are present in embryonic forms, and the earliest fossil mysticetes still had well developed teeth. They are characterized by hanging baleen plates that are used to strain small organisms out of the water. The name of this group of whales, the Mysticeti, is derived from the Greek word mystax (meaning "moustache" and referring to the baleen plates) and the Greek ketos ("whale"). The baleen consists of a keratinous outgrowth of the palate which hangs from the upper jaw in a series of plates, usually between 150 to 400 plates on each side of the mouth (Fig. 6.15). The baleen plates overlap one another slightly, and their outer edges (as seen when viewing the whale from the side with its mouth partially open) are smooth and somewhat resemble vertically set clapboards or the slats of a venetian blind. The inner edges of the baleen plates consist of frayed and intertwined coarse and stiff thread-like structures that serve as the sieve, filter, or strain to capture zooplankton. The plates can be up to ten feet (3 m) long in the bowhead whale (Balaena mysticetus). Melville gives a vivid tour of the mouth of a right whale: "Over this lip, as over a slippery threshold, we now slide into the mouth. Upon my word were I at Mackinaw, I should take this to be the inside of an Indian wigwam. Good Lord! Is this the road that Jonah went? The room is about twelve feet high, and runs to a pretty sharp angle, as if there were a regular ridge-pole there; while these

ribbed, arched, hairy sides, present us with those wondrous, half-vertical, scimitar-shaped slats of whalebone, say three hundred on a side, which depending from the upper part of the head or crown bone, form those Venetian blinds which have elsewhere been cursorily mentioned. The edges of these bones are fringed with hairy fibres, through which the right whale strains the water, and in whose intricacies he retains the small fish, when open-mouthed he goes through the seas of brit in feeding time. In the central blinds of bone, as they stand in their natural order, there are certain curious marks, curves, hollows, and ridges, whereby some whalemen calculate the creature's age, as the age of an oak by its circular rings. Though the certainty of this criterion is far from demonstrable, yet it has the savor of analogical probability. At any rate, if we yield to it, we must grant a far greater age to the right whale that at first glance will seem reasonable. In old times, there seem to have prevailed the most curious fancies concerning these blinds. One voyager in Purchas calls them the wondrous 'whiskers' inside the whale's mouth; another, 'hogs' bristles;' a third old gentleman in Hackluyt uses the following elegant language: 'There are about two hundred and fifty fins growing on each side of his upper chop, which arch over his tongue on each side of his mouth.' As everyone knows, these same 'hogs' bristles,' 'fins,' 'whiskers,' 'blinds,' or whatever you

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Figure 6.16. A-B. Photos of a right whale, showing the tongue and baleen in place. Detail of baleen in upper right. (Photo courtesy National Marine Mammal Laboratory, NOAA). C. Mechanism of water intake (top) and expulsion through the filters with the tongue (bottom). (From Martin, 1990).

please, furnish to the ladies their busks and other stiffening contrivances. But in this particular, the demand has long been on the decline. It was in Queen Anne's time that the bone was in its glory, the farthingale being then all the fashion. And as those ancient dames moved about gaily, though in the jaws of a whale, as you may say; even so, in a shower, with the like thoughtlessness, do we nowadays fly under the same jaws for protection; the umbrella being a tent spread over the same bone" (Melville, 1851: 282-283). The baleen whales vary widely in length and weight, from the pygmy right whale (Caperea marginata) which

can be just 16-20 feet (5- 6 m) long and weigh a mere 2,700-3,200 kg (3-3.5 tons) to the blue whale (Balaenoptera musculus) which may attain a length of over 100 feet (30 m) and a weight of over 135,000 kg (150 tons). Arguably the blue whale is not only the largest mammal, but the largest (by weight) animal that has ever inhabited Earth, surpassing even the largest dinosaurs for this title. Despite its huge size, the blue whale is an extremely swift and powerful swimmer. Able to reach speeds of over thirty mph (48 km/hour), the blue whale is the fastest large whale, exceeded only by dolphins in speed. There are four families of baleen whales, each of which exhibits a slightly different feeding method. Among the members of the Family Balaenidae (including the bow-

A WHALE'S TALE head whale [Balaena mysticetus], the right whale [Balaena glacialis]), and the Family Neobalaenidae (the pygmy right whale [Caperea marginata]) the strategy is to simply swim slowly through the water with the mouth open and the baleen extended (it folds into the mouth when the jaws are closed). As the whale passes through the water, the baleen sieves small animals from the medium, which the whale then swallows (Fig. 6.16). In these animals, the head and baleen can account. for up to one-third of the total body length. Due to their feeding strategy and lack of streamlining, they tend to be slow swimmers. Their slow swimming gave right whales their common name-they were the correct, or "right," whale for earlier whalers to capture using sailing ships, long boats, and hand-thrown harpoons. The rorquals, or Family Balaenopteridae, include such species as the blue whale, fin whale, sei whale, minke whale, and Bryde's whale (all species of the genus Balaenoptera) , and the humpback whale (Megaptera novaeangliae). Sometimes the common term rorqual is used only to refer to the whales of the genus Balaenoptera. Balaenopterids have more streamlined bodies and are much faster swimmers than the bowhead and right whales. They also feed in a different manner, essentially by engulfing large quantities of water that bears food items (such as crustaceans and other invertebrates, or schools of small fishes like herrings, sardines, or anchovies) and then forcing it back out again through the sieve formed by the baleen. The baleen, of course, traps the organisms which are subsequently swallowed by the whale. To assist in this mode of feeding, rorquals have a large, expanded cavity that is formed in the throat and has the capacity to hold an immense volume of water. Some researchers believe that the blue whale can engulf six times its body volume in water. This cavity appears on the outside of the whale as a series of pleated folds that run along the underside of the animal from the snout to just short of the navel. The common name "rorqual" is derived from the Norwegian phrase ror hval, or "furrow whale," referring to the throat pleats. It is reported that some rorquals herd their prey together in order to concentrate it before feeding. Humpback whales will concentrate small fish or zooplankton by encircling the prey with a .stream of bubbles from below. Humpback and Minke whales also may scare and concentrate schools of prey fishes by encircling them quickly and then breaching the surface of the water. Fin whales (second in size to blue whales) are conspicuously asymmetrical in their coloration; the lower jaw is consistently black on its left side and white on its right side. The fin whale is the only known mammal that has such a consistent and obvious asymmetry in its pigmentation. Fin whales may circle a small school of fish clockwise, using the white patch to startle them into a tight cluster. Others suggest that the fin whale does just the opposite-it circles a school of fish counterclockwise, showing the dark patch, which helps to camouflage the whale against a dark background. Certain observational studies of

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fin whales have suggested that the animals show no preference as to the direction they take in encircling their prey, so the fin whale's peculiar markings are still a mystery. Gray whales (Eschrichtius robustus, sole living species of the Family Eschrichtidae) feed primarily on marine invertebrates that live on the ocean floor or a few inches into the sediments. In feeding, a gray whale swims on its right side across the ocean bottom, plowing its head through the sediment, and sucks in the mud, gravel, and any organisms it contains. The whale then surfaces and strains the sediment through its baleen and extracts any organisms, which it subsequently swallows. Feeding in this way, the gray whales leave shallow trenches along the bottom of the ocean floor. Possibly this disturbance by the gray whale may increase local ocean floor productivity. Gray whales may also feed on fishes swimming close to the surface of the water by rushing through the school with open mouth, gulping as many as possible. If the whale rushes the school of fish from below, it may breach the surface. SAVE THE WHALES! For thousands of years humans have been fascinated and inspired by whales, dolphins, and porpoises. Rock carvings of whales dating back to over 4,000 years ago have been found in Norway. The native Alaskans were using whale products as early as 1500 B.C. At these early dates whales were not actively hunted, but merely scavenged when found stranded in shallow water or on a beach. The early Greek cultures of the late second millennium B.C. incorporated dolphins and whales into their legends and art, a reverence for these animals that continued into classic Hellenic, Hellenistic, and Roman times. The Judaic tradition included the cetaceans: the Old Testament of the Bible records that Jonah was swallowed by a great whale. Late twentieth-century humans continue to be fascinated by the dolphins, whales, and porpoises. We marvel at their size and grace, and relative obscurity. We take special day-long cruises, "whale watches," to observe large whales in the wild. However, the largest animal, the blue whale, has been observed first-hand by very few people. We are drawn by their intelligence, often manifested to the public in the form of circus-like antics performed by trained dolphins, porpoises, or killer whales as part of large aquarium and oceanarium shows. We attempt to train some of the smaller cetaceans to act as underwater "dogs," to be companions and perform tasks for us. Some have trained cetaceans for military use. "Flipper," a . TV series that starred a dolphin (sort of a cetacean equivalent of "Lassie"), was popular with the American public for several seasons. We boycott canned tuna if the methods that are used to catch the fish also happen to hurt. or kill innocent dolphins. Yet over the centuries, and culminating in the last two to three hundred years, the primary relationship between humans and whales has been that of hunter and prey.

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Figure 6.17. Nineteenth-century lithograph of a sperm whale hunt. (Courtesy Library of Congress). Whales have provided meat for human consumption, or for use as pet food. The bones and baleen have been used to produce many artifacts. In the eighteenth and nineteenth centuries, corset stays, umbrella ribs, skirt hoops, whips, and other items were commonly made from whale bone. Ambergris, a waxy substance found in the stomachs or intestines of some sperm whales, was highly valued and utilized in the production of fine perfumes. Historically, the most important whale products were the oils that they produced. These oils were used for heating, illumination, cooking, lubrication, and other purposes. Spermaceti oil, derived from the spermaceti organ of the head (or more correctly, nose) of the sperm whale, was used to make smokeless candles. Other whale oils were used in the manufacture of soaps and margarine. The earliest well-documented incidents of whale hunting date back to the Scandinavians of the ninth century A.D. By the eleventh and twelfth centuries the Basques were hunting whales in the Bay of Biscay, and by the sixteenth century Basque whaling ships were traveling as far north and west as the coast of Greenland in pursuit of their prey. The earliest whale hunting may have been from shore, perhaps attacking stranded (but still live) animals. From such activities men quickly graduated to hunting whales in small open boats with hand-thrown harpoons,

and finally pursuing whales with sailing ships which carried small, oar-propelled open whaling boats that were let down when a whale was sighted. Not only early Europeans, but also Orientals developed whaling. For at least the last 400 years, the Japanese have also been actively involved in whale hunting, using the whale primarily as a source of meat. Just after World War II and into the 1960s, whales have sometimes reportedly supplied up to a quarter of the meat consumed in Japan in any given year. Some whale meat continues to be eaten in Japan. The first whales to be actively hunted were the right whales and bowhead whales. These are both slow-moving whales, so they were actively pursued with early ships, boats, and hand-thrown harpoons. A further advantage was that because of their thick layer of blubber, the carcasses of these whales would float after dying. By the early seventeenth century the British and Dutch had taken up whaling, and they sent ships into the Arctic to pursue the large populations of animals that inhabited that region. Later in the same century right whales and humpback whales were pursued as they migrated along the eastern coast of North America. From the seventeenth century on, European and American whaling activities accelerated their pace. In the late eighteenth and early nineteenth cen-

A WHALE'S TALE

Figure 6.18. An example of scrimshaw. (Photo by R.M. Schoch). turies whaling was a big business. It constituted a major industry in New England, supporting such ports as Nantucket, New Bedford, Sag Harbor, and Mystic. It led to the development of a quintessentially American folk artscrimshaw, or carving on whale teeth (Fig. 6.18). It inspired folklore and tales of adventure, including the book that many claim is the greatest American novel: MobyDick or, The Whale by Herman Melville (first published in 1851). At first most whaling was conducted in the North Atlantic and Arctic waters, but in the eighteenth century European and American whaling ships began to move into the southern Atlantic, then around Cape Hom into the Pacific and around the Cape of Good Hope in South Africa into the Indian Ocean (Fig. 6.17). Soon they were plying all the world's oceans on long voyages of several years' duration. This may have been necessary, as overhunting

137

appears to have caused the decline of North Atlantic whaling by the end of the eighteenth century, and the decline of North Pacific whaling throughout the nineteenth century. Indeed, the North Atlantic populations of the gray whale were wiped out by whalers early on. As vessels and technology improved, and once abundant species became rarer, the whalers began to pursue deeper-water species, such as the valuable sperm whale. American sperm whaling reached its height in the early nineteenth century, but declined rapidly after 1850. The decline of the American sperm whale industry has been attributed to numerous factors, such as a decline in the sperm whale population, the increasing emphasis on pursuing bowhead whales in the western Arctic and northern Pacific Oceans, the coming of the California gold rush that lured sailors away from the ships, the increasing expense of outfitting ever longer voyages, the continued growth of the cotton industry, and the 1859 discovery of petroleum in Pennsylvania (which could replace sperm whale oil for many purposes). A definitive explanation for the sudden demise of American sperm whaling may never be possible. During the latter half of the nineteenth century there was a sudden resurgence in global whaling activity. Svend Foyn, a Norwegian, invented the first practical harpoon gun with a head that exploded once it penetrated the whale's body. The harpoon gun, combined with newly developed steam-powered ships (faster and more dependable than the old sailing ships and oar-powered open whaling boats), allowed whalers to efficiently hunt the swift rorquals for the first time. In the first decade of the twentieth century the Antarctic feeding grounds of the rorquals were discovered, and the history of twentieth century whaling has been primarily one of carnage inflicted on this group of whales. This carnage was further expanded by the development of modem factory ships that began operating in the Antarctic waters in the middle 1920s. Perhaps the peak catch of whales was during the 19301931 season, when nearly 40,000 rorquals were captured in the Antarctic waters. This may not have been the record for the number of whales taken during a season, but it may have set a record in terms of whale biomass harvested. Of these 40,000 whales, over 29,000 were huge blue whales (some individuals were recorded as being over 89 feet, or 27 meters long) and over 10,000 were fin whales (with individuals up to 72 feet, or 22 meters in length). Less than two hundred were the smaller sei whales (reaching maximum lengths of only about 50 feet, or 15 meters). Between 1930 and 1980, the general trend was for whalers to concentrate on the largest whales first. Once that population was exploited to the point where not enough whales were left, they would move on to the next largest species. In this manner the natural populations of the blue, fin, sei and other whales were quickly reduced from sizes that were minimally 50 to 70 thousand individuals per species (and maybe as many as 400,000 per species) to perhaps only a

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few thousand individuals in the case of the blue whale, pygmy blue whale, humpback, and right whales. In contrast, the relatively small minke whale (seldom over 26 feet, or 8 meters in length) has flourished, despite harvesting, as their competitors for krill and other resources-the larger rorquals-were drastically decreased in numbers. Early in the history of whaling the field was dominated by the Norwegians and the British, and secondarily by the Dutch and Americans. Since World War II, however, the whaling industry has been led by the Japanese and the Soviet Union. During the last few decades these have been the most active whaling nations, although the United States, Canada, Iceland, South Korea, South Africa, and other nations have also continued to hunt whales. The International Whaling Commission, established in 1946 to promote whaling, has historically been relatively ineffective in regulating whaling activities. Since 1972, under the aegis of the United States Marine Mammal Act, the importing of marine mammals or their products into the United States has been generally prohibited. Also in 1972 the United Nations Conference on the Human Environment advocated a ten year moratorium on all whaling, but this was not supported by the International Whaling Commission. Finally, in 1982 the International Whaling Commission issued a moratorium on commercial whaling which was to take effect beginning with the 1985-1986 Antarctic whaling season. However, both the Japanese and Soviets objected to this moratorium, and have continued to hunt minke whales to a very limited extent since 1986. Since 1986 such countries as Iceland, South Korea, and Japan have caught whales ostensibly for scientific purposes, but once the "scientific analyses" of the whales are completed the carcasses are often sold to be eaten. Most recently Japan has requested permission to catch approximately 3,000 minke whales, but the International Whaling Commission has denied the request. Today aboriginal subsistence whale hunting utilizing traditional methods, such as practiced by the Eskimos, Inuits, and peoples of the Faeroe, Shetland, and Orkney Islands, apparently continues. Even though the active large-scale commercial hunting of cetaceans has subsided, they continue to be endangered by human activities. In many instances, cetaceans and humans prey on the same species, or humans undermine the food pyramid by preying on a species which are the prey of the target species of the cetaceans. For example, . there is a real concern that the increasing human take of Antarctic krill, upon which large whales, seals, birds, and many other types of wildlife depend (either directly or indirectly), will have a devastating effect on the natural populations of these animals. In some cases the cetaceans and humans are directly fighting for the same prey items, and there are many documented instances of fishermen having slaughtered whales and dolphins simply to keep them from taking or otherwise interfering with the fish that the fishermen want. In the late 1970s Japanese fishermen of Iki

Island mistakenly believed that cetaceans were driving away the yellowfish upon which the Japanese depended. Accordingly, they set about slaughtering the whales and dolphins. Later, after thousands of cetaceans died, it was demonstrated that the cetaceans were not even responsible for the decline in yellowfish-rather it was due to human overexploitation. Cetaceans also suffer even when humans are hunting species that are not the prey of cetaceans. Whales are known to have become entrapped in ocean-floor cables. Huge, curtain-like hanging nets placed in the world's oceans invariably catch more than just the target prey. Known as drift nets, these monofilament curtains of death formed great submerged walls as long as 30 miles (50 km) between boats. Whales, dolphins, and porpoises often become entrapped in such nets and drown or suffocate. On November 26, 1991, Japan finally announced that they would begin phasing out drift nets by December 31, 1992. With over 600 boats, they had the largest drift net fleet in the Pacific. Taiwan, the second largest user, also agreed to phase out drift nets by July, 1992. Now only South Korea remains as the primary user of these indiscriminate killers.. South Korea is still resisting, since their fishing boats are older and harder to convert to other uses. Japanese fishermen are very angry, since they have no chance without drift nets. The drift nets are so effective that they were seriously depleting world fish populations, along with killing many dolphins. Because of overfishing, no other method is now effective in catching the estimated 169,000 tons of squid per year. Each Japanese consumes an average 80 pounds (36 kg) of squid each year, so the demand is great. Environmentalists worry that drift net fishermen will simply fly flags of whatever nation does not recognize the ban, and try to satisfy the demand (and keep their livelihoods) anyway. Perhaps more disturbing was a method of tuna fishing developed by the U.S. tuna fleet that included the deliberate entrapment and slaughtering of dolphins. For reasons that are not really understood, schools of yellowfin tuna often swim underneath schools of dolphins (the dolphins and tuna may feed on the same small fish, and tuna and dolphins may scare prey fish toward each other). Fishermen took advantage of this fact by locating schools of dolphins on the surface and then encircling the dolphin school with bag-like purse seine nets. The nets were then drawn in by winch and captured both dolphins and the tuna that swam below the surface. Sometimes attempts were made to release the dolphins alive, but invariably most were injured or killed. In other instances the dolphins were simply slaughtered and dumped. In the United States it took nearly 30 years for these methods of tuna fishing to receive much negative publicity, and many individuals boycotted commercial tuna. As a result, the larger companies now claim that they take more care not to deliberately harm cetaceans while fishing, although many doubt it. Fishing is not the only threat to natural cetacean pop-

A WHALE'S TALE ulations. Perhaps even more pernicious and long-term are the effects of environmental degradation and pollution. Even in the major oceans of the world levels of harmful pollutants are increasing. Cetaceans, organisms that are relati vely high on the food chain, tend to concentrate pollutants (such as heavy metals, pesticides, polychlorinated biphenyIs [PCBs] and so on) in their tissues. Another potential hazard to cetaceans is the dumping of oil (whether accidentally or purposefully) and oil products into the oceans. Unfortunately little is actually known about any detrimental effects that these pollutants may be having on cetacean populations. Although the future looks grim for whales, there are signs of hope thanks to the various fishing bans and elimination of drift nets. Public opinion against the slaughter of our intelligent aquatic brethren has increased in many countries, even in Japan and the Russia. Whales have ruled the world's oceans for over fifty million years, and it would be a great shame if an interloping, landlubber primate wiped out these great beasts for non-essential meat and oils. In 1851, Herman Melville had no doubts that these primordial Leviathans would survive the last-minute arrivals, humans:

"But still another inquiry remains; one often agitated by the more recondite Nantucketers. Whether owing to the almost omniscient look-outs at the mast-heads of the whale-ships, now penetrating even through Behring's straits, and into the remotest secret drawers and lockers of the world; and the thousand harpoons and lances darted along all continental coasts; the moot point is, whether Leviathan can long endure so wide a chase, and so remorseless a havoc; whether he must not at last be exterminated from the waters, and the last whale, like the last man, smoke his last pipe, and then himself evaporate in the final puff... Wherefore, for all these things, we account the whale immortal in his species, however perishable in his. indi viduality. He swam the seas before the continents broke the water; he once swam over the site of the Tuileries, and Windsor Castle, and the Kremlin. In Noah's flood he despised Noah's ark; and if ever the world is to be again flooded, like the Netherlands, to kill off its rats, then the eternal whale will still survive, and rearing upon the topmost crest of the equatorial flood, spout his frothed defiance to the skies" (Melville, 1851: 382-385).

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Figure 7.1. One of the strangest beasts of the Fayum was Arsinoitherium, a rhino-sized creature with huge paired horns on its nose. Once placed by itself in its own order of mammals, the "Embrithopoda," Arsinoitherium is now thought to be closely related to proboscideans. (Painting by Z. Burian).

7. Out of Africa

Ex Africa semper aliquid novi. (Out of Africa there is always something new). Pliny the Elder, Natural History, VIII, 17 THE TETHYTHERES The doctors were insistent. Charles Andrews' illness was getting worse in the cold, wet British winters. He wanted to stay and work in his office at the British Museum of Natural History in London, but the labs were particularly damp and uncomfortable. The doctors demanded that he spend his winters in some warmer, drier climate, or his health would fail completely. Many of his friends went to the Mediten~anean during the winter, or booked a long passage to one of the British colonies in the tropics, such as India. Andrews decided he would go to Egypt and collect some of the mammals living there for the Museum. After all, Egypt was a British crown colony, so he could be sure of safety and the support of local authorities. So, in April, 1901, Andrews sailed to Alexandria. When he arrived, he found plenty of mammals to trap or shoot for the collections. But something else caught his attention. Just a few years before, the British geologist H.J.L. Beadnell had been mapping the rocks at a barren, rocky area called the Fayum Depression, in the Sahara Desert 70 miles southwest of Cairo (Fig. 7.2). In the process, he had come across abundant mammal bones, lying there on the desert floor, exposed by the howling winds. In just three weeks, Beadnell and Andrews made major collections of extinct mammals, finding many large skulls, vertebrae, ribs, and teeth, as well· as abundant petrified wood. As Andrews collected, it became apparent that most of the fossils he found were unlike anything ever seen before. There were strange beasts with paired horns on their noses (Fig. 7.1), archaic whales, archaic mastodonts, and many other extinct forms that had no living descendants. Even more surprising was the lack of animals typical of Eurasia: no carnivores, no rhinos or horses, almost no rodents, and few of the artiodactyIs that were so abundant everywhere else. It was like stepping into a lost world. It is not surprising that these Fayum mammals were so novel. Indeed, there were almost no fossil mammals known from anywhere in Africa until the German Nile explorer, Georg Schweinfurth, found the fossils of a primitive whale

in the Fayum in 1879. Africa was truly a "dark continent" back then, and explorers were roaming the continent, describing new animals and peoples, or trying to discover the source of the Nile. The fossils from the Fayum were the first window to the ancient history of the "dark continent." As Beadnell and Andrews went back each winter, they enlarged their collections and opened this window still wider. By the time they finished in 1904, there were crates containing tons of fossil bones jamming the basement of the British Museum and the Egyptian Museum, waiting to be studied. Andrews had gone to Egypt for a rest, and came back with so much new material that his life's work was completely changed. Today he is best known for his descriptions of the bizarre beasts found on his Egyptian "vacation." The bizarreness of the Fayum mammals, and the scarcity of mammals typical of Eurasia, clearly showed one thing. Africa must have been an island continent, isolated at times from the Northern Hemisphere and its mammals during the Paleocene, Eocene, and Oligocene. Some of the mammals of Africa evolved in isolation there, never leaving Africa, until they went extinct. Others had evolved in Africa, but later escaped to Eurasia. In the case of mastodonts, they did this by the Miocene and spread around the world. Still others, the hyraxes (discussed later in this chapter), had diversified greatly from a single common ancestor and developed ecological equivalents of pigs, hippos, cattle, antelopes, and horses. These animals filled the ecological niches of more familiar Eurasian ungulates, yet they evolved these shapes independently. Clearly, without the Eurasian mammals, there were unoccupied niches for pig-like or hippo-like forms to fill, no matter what their ancestry. The Fayum area, and many other localities in Egypt, were collected by a variety of other scientists in the next few decades. The German paleontologists Ernst Stromer von Reichenbach and Richard Markgraf collected there just before the First World War, and found the Fayum's most famous denizens: the first anthropoid primates, ancestors of monkeys, apes and humans. In the 1960's, several expeditions from the Yale Peabody Museum renewed collecting in the Fayum, primarily because of the interest in our primate ancestors. Yet the bulk of the material from the Fayum is of large mammals from these archaic African groups. These include the most primiti ve proboscideans (elephants,

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Figure 7.2. A. The Fayum badlands are barren and heavily wind eroded. B. In many places, the wind exposes skeletons of late Eocene mammals, such as this archaeocete whale. (Photos courtesy D. T. Rasmussen.) mastodonts, and their relatives), the aquatic sirenians (represented today by manatees and dugongs, or sea cows), the bizarre twin-horned Ar,sinoitherium, as well as a variety of hyraxes and archaic whales. Since many of these animals first appear in Africa, it seems likely that they originated and diversified on that continent during its period of isolation. Although this idea was suggested by a number of scientists, including de Blainville in 1816 and Andrews in 1906, it was formalized by Malcolm McKenna of the American Museum of Natural History in New York. In a famous and controversial paper in 1975, he reclassified the entire Mammalia by using only shared specializations to define groups. One of the new groups he called the "Tethytheria," after the ancient Tethys seaway that used to run along the Mediterranean and southern Asia before Africa and India collided with Eurasia. The Tethytheria included the proboscideans, the sirenians, and the extinct desmostylians (discussed below), all of which seem to originate in areas bordering the ancient Tethys seaway, such as the Fayum. Although he did not give specific anatomical evidence in 1975 for uniting these animals in a new group, the wisdom of his idea soon became apparent. As scientists looked at the shared specializations of elephants and sea cows, it was more and more obvious that these orders were closest relatives among the mammals. One of the most enigmatic of the Fayum animals was the bizarre beast known as Arsinoitherium. Beadnell named it after Queen Arsinoe, wife of King Ptolemy II Philadelphus of Egypt (309-246 B.C.), who had a palace near the Fayum. Arsinoitherium was as big as a large rhino or elephant, but its skeleton was completely unlike any mammal known. Its most striking feature was the giant pair of yard-long horns on its nose (Fig. 7.1). These horns arise from the skull roof and are fused at the base. They are long and pointed in males, and shorter and more rounded in juveniles and females. The surface of the bone is full of canals for blood vessels, suggesting that the horns had some sort of skin covering, as giraffe horns do. There was also a tiny pair of horns behind the first large pair. The teeth have unusually high

crowns, suggesting that Arsinoitherium ate very tough vegetation. More than half of the 47 known individuals of Arsinoitherium from the Fayum are juveniles or young adults. This is an unusally high proportion of immature animals. It may reflect a population that had more juveniles than normal, or possibly that juveniles just happened to be fossilized more often than adults (for whatever reason). Even though paleontologists had a pretty good idea of what Arsinoitherium looked like and how it lived, no one was sure what it was. Was it related to elephants, or rhinos, or something else? For lack of a better place, Arsinoitherium was made the sole member of its own order, the Embrithopoda. In mammal classifications, the Embrithopoda sat in splendid isolation, an enigma unconnected to anything else. In textbook after textbook, the author would put it at the end of the chapter, puzzled as to what to do with it. Ironically, the solution to the puzzle was lying in museum drawers for a long time, but no one put all the pieces together for over fifty years. In 1925, William Diller Matthew and Walter Granger of the American Museum of Natural History described a bizarre lower jaw from the Paleocene of Mongolia (Fig. 7.3). They called the beast Phenacolophus, but they had no idea what it was. Forty years later Malcolm McKenna was visiting the Soviet Academy of Sciences in Moscow, and looking at their Mongolian collections. There he found another jaw fragment of the mysterious Phenacolophus. What was even more surprising was that this fragment looked like it was part of the specimen in New York. On his second trip to Moscow, McKenna brought a cast of the American Museum specimen with him. Lo and behold, the two specimens fit together perfectly! The back half of the jaw had been collected by American Museum scientists in Mongolia in 1923, and Soviet scientists had collected the front half in 1948, presumably in the same spot. The two halves remained separated in New York and Moscow until McKenna realized that they were parts of the same specimen. Once the complete Phenacolophus jaw was put together, McKenna was able to determine what kind of animal it

OUT OF AFRICA

Figure 7.3. The back half of this jaw of Phenacalaphus was found in Mongolia by American Museum scientists in 1923. The fronthalf was found 25 years later by Soviet scientists, and in 1965 Malcolm McKenna was able to show that they belonged to the same jaw. (Photo courtesy M.G. McKenna).

was. Shortly afterwards, Rumanian paleontologist Radulesco found specimens from the late Eocene in the Hateg Depression in Rumania. Before publishing a paper about them, Radulesco sent pictures to McKenna in New York, who realized they were similar to Phenacolophus and Arsinoitherium. The Rumanian beast was described as Crivadiatherium in· 1976, and in 1977, McKenna and Earl Manning began to straighten things out. Crivadiatherium, Phenacolophus and Arsinoitherium were all arsinoitheres, and arsinoitheres occurred from Mongolia to Rumania to Egypt during the Paleocene and Eocene, a truly Tethyan distribution. McKenna and Manning suggested, based on the teeth that were then known, that arsinoitheres might be closely related to elephants and sea cows, but did not classify them as Tethytheria. Other primitive arsinoitheres turned up in the late Paleocene of China, and the late Eocene of Turkey. As this book is being written, new research on the original material of Arsinoitherium reveals many shared specializations in the skull and skeleton that clearly show that arsinoitheres are actually closely related to proboscideans. If this is true, then arsinoitheres are tethytheres, too.

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MERMAIDS We have seen that arsinoitheres are tethytheres, and in the next chapter we will discuss the mastodonts and elephants, the best-known tethytheres. However, among the typical fossils at the Fayum are the remains of a third group of tethytheres, the sirenians (better known as the manatees and dugongs, or sea cows). Like whales, their external body form is completely adapted for life in the water, with a fishlike body, front flippers instead of feet, no external hindlimbs, and a paddle-like tail. Unlike whales, however, sirenians are the only aquatic ungulates that feed on plants. Manatees (Fig. 7.4A) belong to the genus Trichechus (which includes three species). They live in the coastal waters, estuaries, and rivers of Florida and the Caribbean (Trichechus manatus), the Amazon basin (Trichechus inunguis), and West Africa (Trichechus senegalensis), and weigh up to 3500 pounds (1600 kg). A slightly smaller sea cow, the dugong (Fig. 7.4B) (a single species, Dugong dugon) lives in the Indian Ocean and South Pacific, and weighs up to a ton (900 kg). Both animals are docile, slow-moving animals that swim slowly in the water, grazing on· sea grasses and other water plants. They are fat, with thick layers of blubber covered by leathery skin. They have a walrus-like face (minus the tusks) and small eyes. It seems incredible that this ugly mug could be mistaken for a beautiful mermaid resembling Daryl Hannah in the movie, Splash. Yet most scholars agree that dugongs had something to do with the origin of the myths about creatures which were half human and half fish. Greek, Phoenician, Egyptian, Dutch and Scandinavian mariners all had versions of myths about creatures which were half-man, half-fish (such as tritons and mermen), and half-woman, half-fish (sirens and mermaids). At first it is hard to see how seafarers could have turned the ugly, slow, docile dugong into a mermaid. Their active imaginations required only a few human-like characteristics to build a myth that became more exaggerated with each telling. Mariners said that dugongs stuck together in mated pairs, with one trying to rescue its mate if it was harpooned, although modern observations have never substantiated this. They "cried tears" of a secretion when they were out of the water. Finally, the mother

Figure 7.4.A. A female manatee and her calf swimming in the shallow lagoons of Florida. Note the distinctive rounded tail fin of the manatee (Trichechus manatus). B. The dugong (Dugang dugan) is slightly smaller than the manatee, with a triangular tail. (Photo courtesy P. Rose).

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Figure 7.5. Daryl Damning and the reconstructed skeleton of the walking sirenian Pezosiren. (Courtesy D.P. Damning.)

Figure 7.6. Manatees are constantly feeding on water plants, such as this water hyacinth. (Photo courtesy P. Rose).

would supposedly suckle the young at her breast, cradling it against her body with' her flipper while she floated in an upright position. (Recent observations have never substantiated this; instead, the baby feeds while swimming horizontally, side by side with its mother.) To mariners who had been at sea without women for a long time, this was all they needed to spin elaborate yarns about beautiful aquatic women. Sirens occur in many myths, especially the famous passages in The Odyssey where Odysseus is tied to the mast to prevent him from being lured by their beautiful "siren songs." The mythical sirens gave us the zoological name for this order, the Sirenia. They were described by the Roman poets Horace and Ovid and portrayed in countless Renaissance paintings. The legend was well established when Columbus, on his first voyage, sighted the American manatee. He wrote with disappointment, "In a bay on the coast of Hispaniola, I saw three sirens; but they were not nearly as beautiful as old Horace's." Many more descriptions of manatees followed during later explorations, although most were highly inaccurate and contained many mythological embellishments. Two Frenchmen fishing off Martinique in 1671 gave the following description:

sea grasses draped over their heads might have looked like hair from a distance. But during the age of scientific enlightenment specimens were captured and examined, and the myths began to disappear. When Linnaeus constructed his 1758 classification he realized that sirenians were not halfhuman, and placed them in a group with elephants, sloths, and anteaters. Except for de Blainville in 1816, most zoologists of the next century classified them with the whales because of their aquatic body form. However, the discovery of the most ancient sirenians at the Fayum, along with archaic proboscideans, tipped the balance in favor of sirenian-proboscidean relationships. Although living sirenians and elephants look about as different as two animals can be, in the Eocene they were not that different. One of the most ancient proboscideans, Moeritherium (discussed in the next chapter), had many primitive similarities to sirenians. In addition, a number of anatomical specializations support this relationship. Tethytheres have a single pair of teats on the breasts (like humans and apes), not on the belly or groin as in other mammals. They also have a heart that is subdivided at the bottom, eyes which are shifted far forward on the skull, cheekbones which contain a broadly expanded pOl1ion of the rear skull bones, and a number of other features in common. Their most unusual specialization, however, is in their teeth. In most mammals (including humans), when the baby teeth eventually drop out, they are replaced by adult teeth erupting from below. Elephants and manatees, on the other hand, replace their teeth from the back of the jaw, pushing the old teeth out the front of the jaw in a sort of "conveyor belt" replacement. This "horizontal tooth replacement" mechanism is a specialization developed independently in elephants and sirenians, since it is not found in their ancestors, or in other tethytheres. As this book went to press, the most startling evidence for the ancestry of the sirenians came to light. Daryl Domning described a fossil of a sirenian from the Eocene of

"Down to the waist it resembled a man, but below this it was like a fish with a broad, crescentshaped tail. Its face was round and full, the nose thick and flat; black hair flecked with grey fell over its shoulders and covered its belly. When it rose out of the water it swept the hair out of its face with its hands; and when it dived again it snuffled like a poodle. One of us threw out a fishhook, to see if it would bite. Thereupon it dived and disappeared for good" (Wendt, 1959: 215). Since manatees are vi11ually hairless, it is hard to imagine what these men saw, although some have suggested that

OUT OF AFRICA Jamaica he named Pezosiren portelli, or literally "Portell's walking sirenian" (Fig. 7.5). Most early sirenian fossils consist only of skulls and jaws, but Pezosiren was the first known from a decent skeleton. It was about the size of a pig, but it still had well developed legs and feet, rather than the flippers and reduced hip and leg bones of all other sirenians. Yet the skull and the teeth are unquestionably like those of other sirenians. Domning speculates that it swam by dogpaddling, rather than by undulating its body up and down like later sirenians (and whales, seals, and otters, among other aquatic mammals). The occurrence in marine rocks, and the fact that it still had the thick, heavy ribs that sirenians use for ballast, shows it was primarily aquatic. Its well developed limbs and shoulder and hip bones show that it was fully capable of walking on land. Like the walking whale Ambulocetus (discussed in Chapter 6), it is a perfect transitional form, showing that sirenians (like whales) evolved from terrestrial anilnals, and that there were intermediates which could still walk yet were also aquatic. Sirenians are herbivores, but they do not have a multichambered stomach to digest the plants they eat (Fig. 7.6). Instead they have intestines over 150 feet long, with bacterial digestion of cellulose concentrated near the end. Compared to cud-chewers, their digestion is so inefficient and the plant material they eat is of such low quality that they must eat huge amounts to get the proper nutrients. Some sirenians eat up to 8-15 percent of their body weight daily, which can be as much as 400 pounds (180 kg) of seagrass or freshwater plants in 24 hours. Since these plants are so low in nutrition, sirenians sometimes root in the mud and eat the roots and stems, which have higher concentrations of carbohydrates. Many of these plants have abrasive materials, or mild toxins, to discourage plant eaters. Sirenians have bacteria in their gut to break down these toxins, and continual horizontal tooth replacement in manatees keeps up with their abrasive diet. Because of their large body size and layers of blubber, sirenians conserve energy well, especially since most of them live in the tropics. They do not need to expend much energy, so they move very slowly and have a low metabolic rate. Sirenians rarely move faster than 6 mph (10 km/hr), and stay submerged for five minutes or more; on occasion, they will not come up for air for fifteen minutes. They have almost no natural predators except humans, so they do not need great speed or defenses. The fat and blubber also serves as a food reserve, so they can fast for over six months if plants are not growing during a lean season. Their eyesight is adequate, but their hearing is better, although they have no sonar mechanisms like those used by whales and dolphins. Frequently, they will bump into objects in the murky water. They can produce a range of chirps, snuffles, and squeaks. Sirenians have a sense of smell, but they swim with their nose valves closed, so they seldom use it. Instead, they have an excellent sense of taste, not only to recognize food plants, but also to "taste" scent marks left by other sirenians. Manatees are inquisitive. They investigate oddities

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encountered in the water by nudging, nuzzling, or taking them in their mouths. One manatee was seen chewing on a Coke bottle, another carrying a beer can around, another nudging a log, and so on. Manatees nibble at frogmen's flippers and munch on anchor ropes. Their gentle slow-motion lifestyle was beautifully described by Faith McNulty in "A Swim with a Manatee": "I floated face down on the water of the Crystal River in Florida, looking through a mask into a shadowy world through which sunbeams cut bright pathways and clouds of silt swirled like smoke. Beside me I could see the shiny black frog feet of a biologist named Daniel Hartman and his assistant, James Powell, Jr. Hartman was trailing a white belt of foam rubber, to which an ultrasonic transmitter, or pinger, had been attached, and which he hoped to fasten around a manatee's tail. Beneath us, gliding in and out of the darkness, were two manatees-long gray shapes that looked as big as one-man submarines. I had a good view of the manatee directly beneath me. It glided easily, stroking the water with a tail flattened horizontally, like a beaver's, but shaped more like a Pi~g­ Pong paddle. Its hide had a mottled look and etched on its back, like graffiti scratched on stone, was a series of white lines-healed scars of wounds inflicted during an encounter with a motorboat propeller. Nearly every manatee Hartman has encountered in his study of the species is thus marked; besides making clear the danger that boats pose to manatees, the scars have incidentally served as identifying symbols, enabling Hartman to distinguish fifty individual manatees. One manatee slipped away into the gloom, but the other turned and hung in the water facing Ha11man, swaying gently, its flippers held out like arms akimbo, and looking disarmingly like a captive balloon. Seen full-face, the manatee is so homely of visage, its expression one of such innocence as to be utterly beguiling. Its head is small compared with the inflated bulk of its great round body; there is no neck to speak of and no external ears. This manatee's small, deep-set eyes stared steadily at the swimmers with an expression of simpleminded curiosity mixed with surprise, while its long, bristly muzzle had a despondent, hounddog droop. Hartman swam closer to the manatee, and still she didn't flee. ( I say "she" because Ha11man later told me that he recognized this manatee as a female he had named Piety, one of the half dozen or so with whom. he has been able to make particular friends.) For an instant, the man and the manatee hung face to face. Piety stared steadily and then, with what can only be described as a look of tender affection, swam forward, reached out with

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Figure 7.7. Manatees swim slowly close to the surface, so they are frequently hit by speedboats and show numerous scars from propellers on their backs. (Photo courtesy P. Rose). her flippers as though to embrace Hartman, and bestowed a bristly, nuzzling kiss full on Hartman's face mask. Hartman reached out and stroked Piety's huge, rubbery back. Piety revolved, presenting her round flanks and even rounder underside. For the next three or four minutes, I watched a slow-motion ballet as Hartman, assisted now by young Powell, tried to slip the belt around Piety's ever-waving tail. Powell took over rubbing the front end of Piety, holding her attention, while Hartman maneuvered for position at the tail end. The belt was bulky, and he found it difficult to move it quickly through the water. To fasten it, it would be necessary to encircle the narrow part of Piety's tail (the handle of the Ping-Pong paddle) and press together the two ends of the belt, which were covered with self-gripping fabric. Several times he came tantalizingly close to success, but Piety invariably swished out of reach at the crucial moment. Then, suddenly, he came closer than ever. Piety must have felt the belt grip her tail. She gave a great, convulsive, indignant flap and shot out of sight in the dark water, leaving Hartman and Powell and me in the swirling silt stirred by her abrupt departure. We were not able to find Piety again, or another approachable manatee, that day. That night, the weather turned warm, and the manatees disappeared. from the area, riding down the river and out into the wider waters at the river's mouth, in the Gulf of Mexico, where it would be impossible to find them... Perhaps the greatest flaw in what is otherwise a design for an idyllic life is in the sex lives of manatees. Male manatees are very sexy and female manatees are not. As a cow comes into estrus, there is a long period during which she is intensely attractive to males but is quite uninclined to mate. Consequently, she collects a train of increasingly frantic suitors, who pester her relentlessly.

Hartman guesses that things are arranged this way so that a herd will gather and there can be selecti ve competition for the privilege of mating. This is the only time there is anything like aggression between manatees. The males jockey for position near the female, colliding and bouncing off each other like living beach balls. The males probably enjoy the chase, and from time to time relieve their feelings with homosexual embraces, but the female shows no pleasure as she flees, dodges, and as a last resort, rolls on her back to frustrate their advances. Hartman saw one female followed for days by a herd of amorous males-almost the whole male population of the bay at that time. They gave her no peace until at last some mysterious clock within her ticked to the right second and she decided to submit, allow herself to be embraced, with the male lying on his back beneath her, and accepting one lover after another. Even when there is no cow in estrus, male manatees are always hopeful, constantly searching for sexual possibilities, and easily excited. If there is nothing better around they engage in homosexual play. Females never do" (McNulty, 1980: 49-51, 56-57). Like other large-bodied mammals, sirenians have a relatively slow reproductive rate. They live for decades (a manatee in his forties is still doing well in an aquarium). The females do not reach sexual maturity until they are 4-8 years old, and gi ve birth to a single calf after over a year of gestation. The calf may be weaned after 12-18 months, but stays with the mother for 1-2 years. Although the calf can use its teeth to feed within a few weeks of birth, it stays with the mother long after it is weaned, probably to learn migration routes, food and preferred feeding areas. This low rate of reproduction means that sirenians cannot replenish their numbers rapidly after heavy poaching, and consequently, all sirenian species are on the endangered list. For years, fishermen hunted dugongs and manatees for their blubber, oil, hides, and meat, and so they are nearly extinct in many parts of the world where they were once abundant. Commercial dugong fisheries once operated in Sri Lanka and Australia, and Asian cultures prized dugongs for their supposed aphrodisiac and medicinal properties. It doesn't help that they are also very slow and docile, and unafraid of people or boats, either. In addition to hunting, manatees are threatened by pollution in their waterways, and are often hit by speedboats. It is not unusual to see manatees with their tails and backs shredded by propellers (Fig. 7.7). They are particularly vulnerable when they collect in large numbers in warm lagoons or rivers, or in the warm water vent below a power plant during spells of cold weather (Fig. 7.8). It is estimated that there are still 100,000 dugongs off Australia. As recently as 1950 over 2,000 manatees were killed for commercial purposes in the state of Amazonas, Brazil, alone. Although they are strictly protect-

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Figure 7.8. During the cold snaps in the winter, manatees flock to sources of warm water, such as natural hot springs, or this cooling outlet for a power plant in Florida. (Photo courtesy P. Rose). ed in Florida, there may be fewer than 2000 manatees left in the United States, and they are declining rapidly elsewhere. The African species has been wiped out of most rivers except the lower Niger and lower Congo. It is truly sad that these harmless, docile, fascinating animals that have no effect on humans or their crops are now so close to extinction. Sadly, this fate has already overtaken a third type of sirenian. In 1741 the Czar of Russia sent Vitus Bering on his second great exploration of Siberia and the Arctic Ocean. His ship's doctor, the. German naturalist Georg Steller, was one of the few survivors of this expedition. When he returned to civilization, he reported a gigantic marine sirenian living around the Commander Islands in the Bering Sea between Alaska and Siberia. This animal was over 25 feet (8 m) in length, and weighed over four tons (Fig. 7.9). The mouth was completely toothless, and the animal fed entirelyon seaweed. Steller's descriptions are remarkably perceptive, and show that he realized that it was more like land ungulates rather than whales. He wrote: The animals live in herds like cattle in the sea. They eat like ruminants, moving slowly forward; they scrape the seaweed from the stones with their feet and chew it incessantly. They move their head and neck as they eat, like an ox; and every few minutes, they raise their heads out of the water and inhale

fresh air with a snuffling and snorting, in the manner of horses. Looked at superficially, the bones of their skulls are almost indistinguishable from those of a horse. While still covered with skin and flesh, the head bears a distant resemblance to that of a buffalo, particularly as regards the lips... (Steller, 1751) Steller made many other observations on the anatomy and biology of this curious beast. Many other interesting mammals and birds were described by Steller as well, including a giant sea lion, sea otters, and several species of cormorants, puffins, and ducks. Unfortunately, Russian fur trappers found the news of abundant sea lions, seals, and sea otters irresistible. Not only did they nearly wipe out these animals for their furs, but they also hunted the helpless Steller's sea cow for its flesh and fat, which, according to Steller, tasted "like the best Dutch butter, like sweet almond oil and very sweet-smelling, so that it can be drunk by the bowlful." As the fur traders pulled into Bering Island for fresh meat, the slaughter continued. Only 27 years after it was first discovered, the last giant sea cow was exterminated in 1768. It was the last of the great Ice Age mammals to die out. It almost survived long enough to be appreciated by conservationists who might have saved it. Steller's sea cow (now known as Hydrodamalis gigas) was not the only sirenian to suffer this fate. In fact there are many extinct sirenians, which have quite a good fossil

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Figure 7.9. Steller's sea cow was a gigantic sirenian living in the Bering Sea until 1768, and driven to extinction only 27 years after its discovery. (From Savage and Long 1986; courtesy Natural History Museum, London). record. This is partly because their bones are so durable, especially their ribs, which are very thick and made of dense bone so that they can serve as ballast. The earliest known sirenian comes from the early Eocene of Jamaica. By the middle Eocene, they are abundant in Egypt and Libya, and also known from Alabama, Florida, Jamaica, Somalia, Romania, France, Hungary and India. Several species are known from the late Eocene of the Fayum, Java, Italy, and the Caribbean. Clearly, once sirenians arose during the late Paleocene, they spread from the Tethys of the Old World across the Atlantic to the Caribbean. During the Oligocene, their fossil record is sparse since epicontinental seaways retreated due to a global drop in sea level. During the climatic warming in the Miocene, sirenians di versified further, giving rise to the manatees in South America. They also occurred in the northern and eastern Pacific, where they grew to the size of the giant Steller's sea cow. Desmostylians (Fig. 7.10) are completely extinct now, but at one time they were found around the entire North Pacific, from Japan to Alaska to Mexico. They had heavyset, hippo-sized bodies, with broad, heavy, hooved feet. Their heads were long and shallow, with a shovel-like snout that contained huge upper and lower tusks like a hippo. The most bizarre feature of Desmostylus is the teeth, each of which is made up of a series ofdentine tubes surrounded by a cylinder of enamel, all connected together. These teeth look more like a series of volcanoes than normal teeth with cusps and crests! Although it is difficult to tell the life habits of a completely extinct group with no modem analogues, Daryl Domning suggests that they lived something like sea lions do today, swimming in coastal waters to feed, and pulling up on the shore to breed. They may also have walked

in shallow water, as hippos do. The teeth and jaws of desmostylians most closely resemble those of hippos, and it is likely that they fed on sea grasses and their stems, or on algae, especially in the intertidal zone. Some scientists have suggested their cylindrical teeth were used for mollusc crushing, .but there is no detailed evidence to support this. One of the most complete specimens of a desmostylian was discovered during the excavations for the foundation of the Stanford Linear Accelerator in Palo Alto, California. It was called Paleoparadoxia ("ancient paradox") because of its puzzling combination of features. For a long time, one of the biggest paradoxes about desmostylians was what they were related to. They were frequently put in with the sirenians or proboscideans when only their jaws and teeth were known. In 1953, they were placed in their own order and were thought to be very unusual sirenian relatives. However, all the recent discoveries have shown quite clearly that they are closer to proboscideans. In 1986 Domning, Ray and McKenna described a very primiti ve desmostylian, and showed that both proboscideans and desmostylians had a common ancestor similar to the Chinese Paleocene mammal Minchenella. Since this animal comes from the same deposits as the oldest arsinoitheres and the oldest perissodactyIs, this suggests that both tethytheres and perissodactyls evolved during the Paleocene in Asia, possibly along the Tethys seaway (since their closest relatives also occur in the Eocene of India and Africa). By the middle Eocene, however, Africa became isolated from the rest of Eurasia, so that it was dominated by its unique tethytheres (especially arsinoitheres and proboscideans) which were extinct elsewhere in the world because of competition with typical Eurasian mammals.

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Figure 7.10. Desmostylians look vaguely like large hoofed sea lions, except that they have large tusks and peculiar molars (right) that resemble a bundle of volcanoes. (From Savage and Long 1986; courtesy Natural History Museum, London). THE "FEEBLE FOLK" Although they are unfamiliar to most of us, one group Ii ving today did particularly well in Africa. These are the hyraxes, also known as the conies, damans, rock badgers, or dassies. Found in rocky areas in the Middle East and Africa, they were familiar to the Old Testament Hebrews. Proverbs 30:24, 26 says, "Four things on earth are small but exceedingly wise...The conies are but a feeble folk, yet they make their house in the rocks." They are also mentioned in Psalms 104: 18, "The high hills are a refuge for the wild goats, and the rocks for the conies." In Phoenician and Hebrew, they were known as shaphan, the "hidden ones," for their habit of hiding in rocks. Three millennia ago, Phoenician sailors in the western Mediterranean found a land with what they thought were many hyraxes, and named it "Ishaphan"Island of the Hyrax. The Romans modified the name to "Hispania," which became "Spain." Ironically, there are no hyraxes in Spain. The sailors must have actually seen rabbits, and so Spain got its name from a zoological mistake. It is not surprising that hyraxes might be mistaken for rabbits at a distance (Fig. 7.11). Even close up, most of us would be reminded of a woodchuck, and swear that this small, furry beast was some kind of large rodent. They have a stumpy, marmot-like body with a short tail, and short ears and snout. Indeed, for most of their history, hyraxes were mistakenly classified as rodents. Even their names reflect this confusion. The name "hyrax" is Greek for "shrew mouse," and their family name, the Procaviidae, means "before the guinea pigs." However, the great French anatomist and paleontologist Baron Georges Cuvier took a closer look at some specimens

in 1800 and realized these similiarities were purely superficial. Not only did they have hooves like other ungulates, but they had features in the skull that were very similar to perissodactyls; their teeth were very similar to those of rhinos. When Richard Owen created the Order Perissodactyla in 1848, he included hyraxes. Later in the nineteenth century, however, their relationships became more controversial. Some have argued for a relationship with perissodactyls, others with tethytheres, still others have no opinion as to what they are related. The case is still not closed, but we think that the best evidence favors the idea that hyraxes are perissodactyIs. As detailed by Mat1in Fischer, they have a number of unique characteristics shared with perissodactyls that occur nowhere else in the mammals. These include a number of features in the skull and arteries in the ear region, details of the hoof structure, muscles of the limbs, and arrangement of toes and bones in the front and hind feet. The iris of the lens of the eye has little pendulous fleshy lobes that are seen also in perissodactyls. Their most bizarre feature, however, occurs in the Eustachian tube. This is the connection between your throat and middle ear that causes your ears to "pop" when you go up in an airplane. Hyraxes, horses, tapirs, and rhinos all have a strange, inflated area of their Eustachian tube, which has no obvious function and is unique to these animals. It is well known to horse doctors, since it is commonly a site of ear infections. Whatever this feature means, it is hard to imagine it (and all the rest of this anatomy) evolving twice independently. Either hyraxes are most closely related to perissodactyIs, or else all these features were found in the common ancestor of perissodactyls

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Figure 7.11. A. Hyraxes look somewhat like marmots, only they are hoofed mammals, not rodents. Two rock hyraxes (Procavia johnstoni) huddle on either side of a slightly smaller bush hyrax (Heterohyrax brucei) . B. This rock hyrax can fight viciously if cornered, biting savagely with its incisors (hyraxes have no canines). Hyraxes have no front cropping teeth, so they eat with the side of their mouths, nipping off vegetation with their molars. (Photos courtesy H. Hoeck). and tethytheres and lat~r lost in tethythere evolution. Although textbooks almost always state without discussion that hyraxes are related to elephants as a hypothetical grouping called "Paenungulata," the evidence is ambiguous. This is a case where the morphology and molecular information about their affinities provides many contradictions. Final resolution of this problem will require much more research, but for now we favor the evidence for perissodactyl-hyrax affinities. In our book (The Evolution of Perissodactyls, 1989, Oxford University Press) we classified them as perissodactyIs. Whatever hyraxes are related to, they are fascinating beasts. There are eleven species in three genera living today, found in central, southern, and eastern Africa and the Near East. The largest rock hyraxes reach about two feet (60 cm) in length and weigh up to 12 pounds (5.4 kg); the smallest tree hyraxes may be a third that size. Rock hyraxes (genus Procavia) and bush hyraxes (genus Heterohyrax) (Fig. 7.12) live in rocky outcroppings (kopjes) and cliffs, primarily in South and East Africa. Tree hyraxes (genus Dendrohyrax) are found in forests throughout central and eastern Africa. All hyraxes are herbivores, feeding on a variety of plants. Rock hyraxes eat mostly grass, so they have highercrowned teeth to cope with the gritty abrasi ve material that wears their teeth down. Bush hyraxes and tree hyraxes consume leaves and shoots, so they do not need such durable teeth. Hyraxes do not have specialized cropping teeth in the front of their mouths, like most herbivores. Instead, they crop food with the side of their mouth, using their cheek teeth to "eat sideways." When they chew, their jaws move in a manner very similar to cud chewing. Hyraxes do not ruminate, but they have a unique complex gut with three areas for microbial digestion. Apparently, their plant-processing efficiency is nearly as-.gl~_o(~t.__ as that of ruminant artiodactvls. They have highly efficient kidneys that conserve water, a valuable feature for animals living in dry rocks. They also

have a capacity to concentrate urea and electrolytes, and excrete large amounts of lime (calcium carbonate) without wasting water in their urine. For some reason, they all urinate in the same place, so some parts of the cliffs become "latrines," encrusted with white crystals of lime. These crystals were used as medicines both by South African tribes and by Europeans. Hyraxes do not regulate their body temperature well, and have a low metabolic rate. Consequently, they spend much time huddling together (Fig. 7.13), or basking in the sun. The famous zoologist Clive Spinage described his encounter with them thus: "During the morning and afternoon, but not the hottest part of the day, they lie out sunning themselves on the rocks. In quiet areas where they are little disturbed they are extremely inquisitive and most amusing to observe. If you climb into their rocky retreats they wait until you are within a few feet of them before running squeaking into the crevices. When they have all disappeared the thing to do is to hide in the rocks and wait. One by one they quietly creep out again to see what you're up to, the large old males first. I well remember when I first did this. Hiding in a crevice, I began almost to feel that I was being watched and occasionally I heard a strange little scuftle or a muftled squeak. When I thought that I had waited long enough, I poked my head up and almost fell over backwards. I was completely surrounded by hundreds of them, all staring at me intently. Of course, when I showed myself there was great consternation and, with squeaks and cries, many of them bolted immediately into their holes again. You never knew where they we.r~~.Qjn.g to appear next: every now and then a big old male would creep up to within about six feet of my back and I would suddenly turn around

OUT OF AFRICA

Figure 7.12. Hyraxes, such as this bush hyrax (Heterohyrax brucei) , live not only in rock outcroppings, but can climb trees with great agility. They can even rotate their hands at a special joint within the wrist to grasp a limb. (Photo courtesy H. Hoeck).

to find him quietly watching me. It is the curiosity of the hyrax which unfortunately makes it so easily trapped by the natives. Another amusing habit of the old males was to sit on a rock watching one and then draw back their lips, exposing their long incisor teeth. I presume that this was meant to frighten me, but it actually looked as if they were grinning!" (Spinage, 1963: 144-145). Although they are only active for short periods of time, when they move around, they can move very fast. Their feet have both small hooves and well-developed pads, which can develop a suction. These suction pads give them extraordinary agility in rocks and trees, so they can move around in environments where only monkeys (with grasping hands) or rodents (with claws to grip bark) would be expected. The suction is aided by a sweaty secretion, and the muscles in the center of their foot pads create a cup-like shape which generates true suction. As a consequence, it is not unusual for a hyrax that has been shot dead to remain clinging to a perpendicular surface. Like all other ungulates whose limbs were originally designed for running, hyraxes cannot rotate their lower arm. To compensate, they have developed a unique pivot joint within their wrist, so they can literally turn their hand without moving their arm. This allows them to climb branches almost as well as a monkey can. This quickness and agility is critical, since they have few defensive weapons. If cornered, they can stand and fight with their sharp canine teeth, but more often they try to dive

151

Figure 7.13. In most environments, two closely related species exclude each other from the same habitat, so they are seldom found together. However, the rocky kopjes of east and southern Africa support populations of both Procavia johnstoni and Heterohyrax brucei, living side by side, or huddled together for warmth (as here). However, they have some differences in behavior and sexual anatomy that prevent interbreeding, and they exploit different resources: Procavia feeds mainly on grass, while Heterohyrax browses on leaves. (Photo courtesy H. Hoeck). for a rock crevice. Once inside, they inflate their bodies and wedge themselves into a crevice, so they are impossible to pull out. They have excellent hearing and sight, so some of the colony will always be on the lookout for rock pythons, eagles, jackals, and leopards, their main predators. Once the lookout gi ves a sharp alarm whistle, they all dive for cover. In addition, rock hyraxes make a variety of whistles, screams, and chattering noises as they move around their rocky homes. In some cultures, they were known as "pigcrickets" for the noises they make. Tree hyraxes, which come out at night, are famous for their eerie, penetrating frog-like croak which used to unnerve explorers in the African jungle. Both bush and rock hyraxes are best known from the rocky kopjes of eastern and southern Africa. Unlike most other mammals, it is not uncommon for two species of hyrax to share the same rocks (Fig. 7.11A, 7.13), and even huddle together in mixed species bands for warmth. Normally, two closely related species will strive for different ecological niches to minimize competition. The fact that rock hyraxes prefer grasses and bush hyraxes prefer leaves probably allows them to cohabit without conflict. To prevent interbreeding, the two species have totally different mating behavior, and the territorial males have different warning calls, so that they only drive off their own species. These hyrax colonies are usually composed of family groups of 530 individuals, with one territorial male defending several females, their offspring, and assorted immature individuals that have not yet left their parent colony. Since the kopjes are limited in area, there can be densities of 40-50 animals per

152

HORNS, TUSKS, AND FLIPPERS northern South Africa, and even the island of Zanzibar. They feed on leaves, twigs, fruit, and bark, mostly from the upper canopy of the forest. However, they frequently descend and move around on the ground when necessary. Most of their activity takes place just after dark and just before dawn. They are famous for their piercing cries, which seem to take place right after feeding activity. The male's cry is much more powerful, and probably serves both a territorial and sexual function. One of the best descriptions of tree hyrax behavior was written by F.W. Fitzsimons, former director of the Port Elizabeth Museum of South Africa in the 1920's: "Its diet consists entirely of the vegetation of the native forests, including the plants which grow upon the ground, for the tree dassie, although it subsists largely on the leaves and tender shoots of the trees, freely descends to the ground in search of food, but will never venture far from the bush, to which it instantly runs on the slightest sign of danger. On moonlit nights the tree dassie ventures forth, and at these times, and during the early morning, their squalling cries, which begin with a clucking sort of noise, can frequently be he
Figure 7.14. The rarely photographed, nocturnal tree hyrax (Dendrohyrax arboreus) shown giving its eerie screeching call from a baobab tree. (Photo courtesy H. Hoeck).

hectare, comparable to the density of herds of wildebeest. Territorial males usually keep watch over their groups as they feed, sounding their territorial calls, and also sounding the alarm call if a predator is sighted. They become very aggressi ve in the breeding season, when the weight of their testes increases twenty times. A number of peripheral males hover around the group, waiting for the territorial male to be dethroned. The peripheral males live alone, with the highest ranking of them taking over if the territorial male is gone. Juvenile males leave their birth sites after they reach sexual maturity, 16-24 months after they are born. They have been known to migrate across the plains for over a mile, although their chances of dying from predation or exposure are very high. Females become receptive once a year, usually at the start of the rainy season. Within a group, nearly all the pregnant females then give birth in a span of three weeks, bearing between 1 and 4 young. The young are born fully developed, and they assume a strict teat order on the mother. They are weaned after 1-5 months, and reach sexual maturity in 16-17 months. The young females then join the adult females in their home group, but the young males leave before they reach 20 months of age. Not surprisingly, males have much shorter life spans than do females. Tree hyraxes (Fig. 7.14) are not as well studied as bush or -rG'ck-~B7raxes, !J1_ostly becal!se they· are·,·:e1usive at night and hard to study. They inhabit tropical rainforest from Gambia, Angola, and Zaire to Uganda, Kenya, Tanzania,

.

In addition to servaIs, tree hyraxes have many other predators. These include cats such as the caracal and the Kaffir cat, the eagle owl, and the python. Fitzsimons d€'"51~>:?'}~S how a python c~n;.,eve.n ..Q.a~t.\lre hyr.axes withi~ their dens in hollow tree trunks, and "should the cavity be large, it enters and forthwith proceeds to swallow every

OUT OF AFRICA dassie in that particular lair." Although hyraxes do not make good eating and are seldom hunted for food, at one time they were hunted for their pelts. It took 20 to 30 pelts to make one fur coat, and 48 animals for one rug. The most serious threat, however, is the rapid deforestation of the central and west African rainforest. The tree hyrax is rapidly moving to the endangered list, along with many animals in tropical rainforests around the world. Tree hyraxes occur in groups of two or three related indi viduals, .which live in a small area of the forest centered around a single tree. They usually mate and give birth during the dry season, which varies from place to place in Africa. A single precocious baby is born after a gestation of 8 months, and they reach adult size after only 120 days. They reach sexual maturity after about a year, and are known to live at least 5-6 years. They have a dorsal gland, whose function is unknown, in the middle of their back. When excited, tree hyraxes tum their rumps to a threat and stiffen the white hairs around the gland, which form a white ring. It is not certain whether this gives a visual signal to the predator, or whether it is connected to a skunk-like smell. This diversity of three genera and seven species in limited habitats is a pitiful remnant of their diversity in the geological past. There were at least 19 extinct genera in the last 40 million years, and they were adapted to a tremendous range of ecological conditions. Some were small and ratsized, but others were gigantic forms (Fig. 7.15), with impressive-sounding names like Titanohyrax, Gigantohyrax, and Megalohyrax. Some of these animals had skulls over 2 feet (60 cm) long, and were as large as modem rhinos. This wide range in size was accompanied by a wide range of adaptations, as they converged on the body forms of pigs, tapirs, horses, and a number of extinct animals, such as chalicotheres (discussed in Chapter 13). Apparently, hyraxes lived in Africa without competition from typical Eurasian mammals during much of the Eocene and Oligocene. Since there were no animals occupying the tapir niche, or the pig niche, for example, hyraxes evolved shapes to replace them. The oldest fossil hyraxes are known from the Eocene of Algeria. The five species include the rabbit-sized Microhyrax, which has very primitive, low-crowned rounded teeth suitable for browsing, and the huge Titanohyrax, which had teeth with sharp crests for grazing. Thus, when hyraxes first appear in the fossil record, they have already started their ecological differentiation caused by isolation in Africa. In the Oligocene deposits of the Fayum, they make up more than half of all the mammals found in the Lower Fossil Wood Zone. There are at least eight hyrax genera in the Fayum, three of which retain low-crowned rounded teeth like pigs, and probably ate a pig-like diet of roots, fungi, seeds, and fruits. The remaining genera had teeth with high shearing crests, adapted for a browsing diet of leaves, like the modern tapir. The largest of these was again Titanohyrax, one species of which was larger than the primi~~'{e prohoscideans foundln the same.clep9sits..The early

153

Oligocene of Africa was certainly the heyday of hyraxes. The same Fayum deposits record their decline as well. In the Upper Fossil Wood Zone, only 16% of the mammals are hyraxes, and only two lineages are left. They apparently encountered increasing competition with Eurasian mammals (the hippo-like anthracotheres, discussed in Chapter 2, had been there since the Eocene). Their diversity in Africa was even further reduced during the Miocene when they came into competition with ruminants (primitive antelopes, goats, and cattle) and with pigs. One of these survivors was Megalohyrax, which was not only large, but developed long, specialized limbs for efficient running. Apparently some hyraxes became even more specialized in their attempt to compete with immigrant Eurasian artiodactyls. The exchange and competition eventually went both ways. By the late Miocene one group of hyraxes, the pliohyracines, migrated into Eurasia. They spread along the Mediterranean from Spain to Turkey, through Afghanistan and the Soviet Union, and were especially common in the Pliocene of China. The pliohyracines were horse-sized animals whose teeth looked almost identical to those of the chalicotheres (discussed in Chapter 13). This convergence was so complete that they were not recognized as hyraxes for 37 years after they were discovered. They had a short skull, with eyes and nose high on the top of their head. These features, as well as the rest of the skeleton, suggest that they were aquatic forms, spending much time partly submerged in swampy lowlands feeding on aquatic plants. Pliohyracines became extinct at the end of the Pliocene, probably in response to the climatic changes at the beginning of the Ice Ages. Meanwhile, the African lineage that led to modem hyraxes was still evolving. Although they did not become as peculiarly specialized as pliohyracines in Eurasia, they were still abundant and showed great ecological diversity. There were still large hyraxes with high-crowned grazing teeth, such as Gigantohyrax, which was three times the length of living rock hyraxes. Hyraxes were particularly common in the Plio-Pleistocene cave deposits of South Africa which have yielded some of the earliest human fossils. For example, the famous Taung cave deposit, which produced the first specimen of the early hominid Australopithecus africanus in 1924, is dominated by the remains of baboons and hyraxes. This deposit has been interpreted as the lair of a leopard, with most of the fossils dragged there as prey. If so, then leopards preyed on hyraxes and baboons much as they do today. Undoubtedly, hyraxes were familiar to our earliest African ancestors, and they may have even been an important food item. In summary, hyraxes seem to have diversified from a common ancestor with the earliest tethytheres (including arsinoitheres and proboscideans) and non-hyracoid perissodactyIs in the late Paleocene of Eurasia (especially China) and along the Tethys shoreline. The earliest sirenians were also diversifying by the late Paleocene, because by the early Eocene, theyhad.spr~ad along the4~thY'd-~~'2:\t~.ay:and all the

154

HORNS, TUSKS, AND FLIPPERS

Figure 7.15. Comparison of the skull of a modern Heterohyrax brucei (small specimen) and the giant Oligocene Megalohyrax eocaenus from Egypt. (Photo courtesy D. T. Rasmussen).

OUT OF AFRICA way to the Caribbean. However, hyraxes, arsinoitheres, and proboscideans became restricted to Africa in the Eocene and Oligocene, where they developed into a wide variety of ecologies that completely dominated the environment in the absence of competition from Eurasian perissodactyIs or artiodactyls. By the late Oligocene and Miocene Eurasian immigrants (anthracotheres, ruminant artiodactyls, cats and dogs, and many others) began to invade the African sanctum. As a result, the arsinoitheres became extinct, the hyraxes were greatly reduced in diversity and became more specialized, and the proboscideans became more specialized as the large-bodied herbivore. Throughout the Miocene, more

155

and more Eurasian mammals invaded, and Africa lost many of its peculiarities. One group of hyraxes, the pliohyracines, successfully invaded Eurasia, where they became specialized large-bodied aquatic browsers that were long confused with chalicotheres. Since the extinction of pliohyracines at the end of the Pliocene, however, only a pitiful remnant of hyrax diversity survives in Africa. The sirenians, too, are being pushed to extinction in many parts of the world. The arsinoitheres and desmostylians have long been extinct. Sadly, this fate also seems to be pressing upon the most successful, widespread and popular of the tethytheres, the elephants.

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8. The Origin of Jumbo

GIANTS IN THE EARTH The giant bones that kept turning up in the New World Most cultures around the world have a mythology that were also a source of much mystery and consternation. The includes legends about giants. Typically, the legends hold Indian tribes usually attributed them to giant monsters that in the dark, mysterious past, gigantic races of humans fought by their ancestors, and incorporated them into their lived on Earth. They may have fought the gods, or been folklore. When these bones were first seen by white settlers, destroyed by floods. These legends were reinforced by the they were thought to be the bones of gigantic humans that discovery of gigantic bones, much larger than those of any had roamed Earth in Biblical times. Others thought the giant living human, all over the Mediterranean and Europe. The tusks so revered by the Indians were works of Satan, placed Greek philosopher Empedocles (492-432 B.C.) reported there to tempt the believer. In 1519 Cortez received the bone gigantic bones from Sicily, supposed remnants of a race of of a "giant," a gift from the friendly Tlascalan tribe of giants. The Roman historian Pliny mentioned fossil ivory in Mexico, during the conquest of the Aztecs. He sent it back the ground, and according to the historian Suetonius, to the King of Spain as proof that giants had once lived in Emperor Augustus (63 B.C.-14 A.D.) owned a collection of the New World. In 1706 the Reverend Cotton Mather of the huge bones that had been found on the island of Capri near Massachusetts Bay Colony pronounced them to be "the Pompeii. The skulls of elephants, with their huge central remains of godless giants drowned in Noah's Flood." He opening in front (for the trunk), were often thought to be the sent some bones to the Royal Society in London to have skulls of the one-eyed cyclops. them certified as evidence of this "wicked giant," since During the Middle Ages the huge bones were again some Biblical scholars were calculating Adam's height at attributed to gigantic humans or other monsters, supposedly 123 feet 9 inches. The Royal Society never pronounced its drowned in the Noachian Deluge. According to Genesis 6:4, opinion on the bones, although many members were becom"There were giants in the Earth in those days" [before ing skeptical of literal interpretations of Genesis. The blinding effect of religious dogma about giants and Noah's flood]. Giant tusks from Siberia were thought to be the horn of the mythical unicorn, or the tusks of dragons. In the Flood was complicated by another idea: the notion of some places, gigantic teeth or vertebrae of mammoths were Divine Providence. An omnipotent, benevolent God would revered as the relicts of saints. Nearly every possibility was never allow any creature to become extinct. As the poet suggested except that these were the bones of extinct ele- Alexander Pope wrote in Essay on Man, "Who sees with phants (Fig. 8.1). equal eye, as God of all, a hero perish, or a sparrow fall." In the early seventeenth century some giant bones dug The prevailing concept was that of a "Great Chain of Being" up in a sandpit near Langon in southeastern France became linking the animals to man to the angels to God. Breaking very famous. They were exhibited around France as -the any link in that chain implied the destruction of the whole remains of the gigantic Teutons, Germanic tribes which had chain. In the same poem, Pope also wrote, once roamed Gaul and been defeated by the Romans in 101 "Where, one step broken, the great scale's B.C. But in 1613 the famous anatomist Riolan attacked the destroy'd: prevailing interpretation, and suggested that the bones were From Nature's chain whatever link you strike, from an elephant. This generated a raging controversy Ten or ten thousandth, breaks the chain alike." between the physicians and anatomists, who thought they were elephant bones, and the barber-surgeons, who called By the late 1700s, however, it was becoming more and them gigantic human bones. Others thought that they were hoaxes, or generated by mysterious "plastic forces" which more obvious that many of the recently discovered fossils 'percolated through the earth. Still others attacked the had no living counterparts. The remote corners of the world anatomists for questioning the Biblical account of giants on were being explored, and although many new and surprising Earth. The controversy died down in 1618 without being beasts were discovered, clearly the gigantic mammoths were - _:fesQl:v~d~and_for the next two ceJJ,t~"~:::~~~_,most_J~~?pl~.c()!1_~_ not hiding in South America or Africa or the East Indies. -'Many stran-ge- fossils, such as the bones of hippopotami in tinued to interpret new finds as gigantic humans.

158

HORNS, TUSKS, AND FLIPPERS

Figure 8.2. The "American incognitum ," a mastodon tooth from North America that puzzled scientists for over a century. This illustration is from Button (1778). Paris, were clearly related to tropical animals, but it was assumed that the bones had been washed out of the tropics during the Great Flood. The notion of extinction was still blasphemous. The New World soon provided unequivocal evidence that these large bones were not simply gigantic humans. In 1739 Charles Ie Moyne, the second Baron de Longueil, left Montreal with French and Indian troops to fight the Chickasaw Indians along the Ohio River. Somewhere along the Ohio, he found the remains of what appeared to be three elephants. When the war ended in 1740 he collected them and shipped them to New Orleans, and ultimately to Paris, where they came to the attention of French naturalists. In the 1740s and 1750s English settlers in the region sent more of these bones from Big Bone Lick, Kentucky, off to England and also to Benjamin Franklin in America. Most of the bones (especially the tusks) were clearly like those of elephants and mammoths-but the teeth were puzzling (Fig. 8.2). They were clearly unlike any living elephant, yet they were part of an animal of elephantine size. [We now know that these were specimens of the American mastodon]. Franklin speculated that the teeth were reminiscent of a carnivorous animal, although he and others later decided it was a vegetarian. In 1769 the famous British anatomist William Hunter took the camivory suggestion seriously, and suggested this was not a true elephant, but a "pseudelephant" or "American incognitum" [Latin for "unknown"] which had independently developed ivory tusks. "This monster, with the'agi,l,i4'YJ'aIr~·Jerocityof:a,:tig. ill=-=-;.<~ruelas the bl%~4¥~J)an­ ther, swift as the descending eagle, terrible as the angel·()f right. ... And if this animal was indeed carnivorous, which I

believe cannot be doubted, though we may as philosophers regret it, as men we cannot but thank Heaven that its whole generation is probably extinct." This very precocious suggestion was still not accepted by naturalists of the time. Nevertheless, remains of the "incognitum" and also of the Siberian mammoth (including frozen carcasses with hair and skin) were turning up again and again. Georges Louis Leclerc, the Comte de Buffon (1707-1788), concluded in his Theorie de fa terre in 1749 that although most of the supposedly extinct animals were hiding somewhere in an unknown region, it was likely that the large terrestrial mammals such as the mammoth and "incognitum" had actually perished. By 1778 Buffon was relating their disappearance to his ideas of violent cataclysms in Earth's early history. During this time, the climate was warmer, so that polar regions had once been tropical, and elephants (meaning mammoths) could live in Siberia. This implied a non-Biblical Earth of much greater antiquity. Buffon suggested it was as much as 75,000 to 3,000,000 years old, rather than the 6,000 years demanded by most literalist Biblical scholars. Naturally, such revolutionary ideas were not popular with the theologians in the Sorbonne. Buffon was protected by the King, however, so he was not persecuted for his heresy, although his ideas were not widely accepted, either. Thomas Jefferson was a firm believer in the Great Chain of Being. As he wrote in 1799, "The bones exist: therefore the animal has existed. The movements of nature are in a never-ending circle. The animal species which has once been put into a train of motion, is probably still moving in that train. For if one link in nature's chain might be lost, another and another might be lost, till this whole system of things should vanish by piecemeal ... If this animal had once existed, it is probable on this general view of the movement of nature that it still exists." He was convinced the incognitum was still living out in the unexplored Northwest. As he wrote in 1781, "It may be asked why I [list] the mammoth as if it still existed? I ask in return, why should I omit it, as if it did not exist? Such is the economy of nature, that no instance can be produced of her having permitted anyone race of her animals to become extinct; of her having formed any link in her great work so weak as to be broken. To add to this, the traditional testimony of the Indians that this animal still exists in the northern and western parts of America, would be adding the light of a taper to that of the meridian sun." . When delayi,qpr2v~j*1led Lewis. and Clarl< from le(;iving until 1804, President Jefferson instructed them to go to Big

THE ORIGIN OF JUMBO Bone Lick and collect some more of the mysterious beast. When he received some gigantic claws from some cave deposits, he instructed Lewis and Clark t
159

~".M~·~~. Figure 8.3. Restoration of the primitive proboscidean Moeritherium,' from the Eocene beds of the Fayum in Egypt. (From Fenton and Fenton 1958). gypsum deposits of the Paris Basin, and the first pterodactyls. Although his notion of catastrophist geology was gradually replaced by the uniformitarian ideas of James Hutton and Charles Lyell in the 1830s and 1840s, his proof of extinction was never challenged. Indeed, more and more bizarre beasts, including the first dinosaurs, were described in the 1840s, driving home the reality of extinction beyond any doubt. EARLY TUSKERS Although mammoths and mastodontswere clearly related to elephants, they did little to show from whence elephants came (Fig. 8.1). They are so late in the evolution of the Proboscidea that they are virtually modern in the development of tusks, or trunk, or size. The origin of the Proboscidea was first detected by C.H. Andrews when he studied the fossils of the Fayum deposits of Egypt, discussed in Chapter 7. Among the peculiar Fayum mammals was a boar-sized beast that Andrews called Moeritherium. [Lake Moeris was the old Greek name for a dry lake basin in the Fayum Depression]. About a meter high at the shoulder, Moeritherium had a very pig-like appearance (Fig. 8.3). It had a large head with ears located high on the side of the skull, a long body, and very short slender limbs. It probably weighed about 500 pounds (225 kg). Although Moeritherium did not have a full-fledged trunk, its nasal bones are far back on the skull, suggesting a fleshy proboscis. However, the upper and lower jaws both have prominent short tusks. Indeed, in most features Moeritherium is very similar to the living pygmy hippopotamus, and it may have lived in ancient marshes and river banks, feeding on vegetation. It is almost always found in deposits of ancient river deltas, consistent with the amphibious mode of life. But the rest of its anatomy, especially the skull bones, clearly shows that it is a tethythere, not a pig or a hippo. In 1986, Daryl Domning, Clayton Ray, and Malcolm McKenna listed at least ten proboscidean specializations that establish beyond a doubt that Moeritherium is related to elephants. Its teeth are not yet specialized in the elephant mode of erupting from the ba~k ..~.and:tHlsbjnQ: out-the front (ho~i~9nt(lJt9()th replacem~11!., __~1~:a.::;; ~ ....: .... ....,-'-'-." ,.' .

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cussed in Chapter 7). Nevertheless, its teeth have many features seen in later mastodonts. Contrary to many popular accounts, however, Moeritherium cannot be the ancestor of the Proboscidea. Domning, Ray, and McKenna found at least four unique specializations in the skull of Moeritherium that showed it is merely an extinct side-branch near the ancestry of proboscideans. In most features, however, Moeritherium gives us a good idea of how the elephants began. With just a slight lengthening of the tusks and the development of a short proboscis, an aquatic animal can live like a pygmy hippo, yet it has the rudiments of the long tusks and trunks of its descendants. Moeritherium was very widespread in North Africa and around the shorelines of the ancient Tethyan seaway during the middle Eocene. It is known not only from the Fayum in Egypt, but also from five other sites in North Africa, located in Libya, Mali, Senegal, and Algeria. There is even one occurrence in India that is supposedly Moeritherium, but this is based on some poorly preserved hip bones, and it may belong to ev~n more primitive proboscideans. Moeritherium gives us the first step toward animals with tusks and trunks, but where did it come from? How do we connect the Proboscidea with other orders of mammals? Until recently, there was little evidence for the origin of the Proboscidea. But the last decade has seen some remarkable breakthroughs. The story begins with an animal that has been known since 1940. First described by Guy Pilgrim and named Anthracobune, the specimens consisted of some confusing teeth that looked a little bit like very primitive artiodactyls to some scientists, a bit like primitive perissodactyls to others, and were once even assigned to the phenacodonts, an archaic ungulate group discussed in Chapter 1. However, Anthracobune came from the early and middle Eocene of Pakistan and India, so no one bothered to compare it to proboscideans, which were then thought to be restricted to Africa. Then~ in the late 1970s, Earl Manning of the American Museum of Natural History recognized its specialized similarities to Moeritherium. Additional primitive anthracobunids were described under the names Lammidhania, Pilgrimella and Jozaria, and by 1983 the proboscidean relationships of anthracobunids were becoming clearer. Although their molar teeth were much like Moeritherium, they did not yet have specialized tusks of any kind. Lammidhania was the smallest anthracobunid, weighing about 45 pounds (100 kg), or about the size of a large pig. Anthracobune weighed about 125 pounds (275 kg), about the size of a tapir. Proboscideans, like other tethytheres discussed in Chapter 7, once had a widespread Tethyan distribution in both Asia and Africa by thy early Eocene. But where were proboscideans in the late Paleocene? The final piece of the puzzle fell into place in 1978, when the doors to China opened. As discussed in Chapter 10, the years of Chairman Mao's Cultural Revolution had prevented Chinese paleontologists from publishing spectacular specimens that they were continuously unearthing from late Paleoeen~4eposits. These included RadinskY9 (discussed in

Chapter 10), and another specimen, originally called Conolophus by Zhang in 1978. Since that name had already been used for the Galapagos iguana, in 1980 Zhang replaced it with Minchenella in honor of Zhou Minchen, the patriarch of Chinese paleontology. Zhang originally assigned these few teeth to the phenacolophids, a group discussed in Chapter 7 and now recognized as representing primitive arsinoitheres. In 1981, Philip Gingerich and Don Russell recognized its similiarities to Anthracobune, and made the final connection. Domning, Ray, and McKenna also showed that Minchenella could be related not only to the anthracobunids and proboscideans, but also to the desmostylians (discussed in Chapter 7). However, we do not get another glimpse of the desmostylians until they reappeared around the Pacific Rim in the late Oligocene. In 1996, another key piece of the puzzle was found, when Phosphatherium was described from the upper Paleocene rocks of Morocco. Although it is known only from upper jaws, they already show the development of cross-crests that characterize the early proboscideans. Like the perissodactyls, sirenians, and hyraxes, the earliest relatives of the tethytheres clearly come from the Tethyan region, running from China to North Africa. By the early Eocene proboscideans had spread to India and Pakistan, sirenians into the shallow seas all the way to South America, and perissodactyIs had spread to all the northern continents. By the middle and late Eocene we find the hyraxes, arsinoitheres, and proboscideans dominating an increasingly isolated African continent, but extinct elsewhere in the world (except for the one isolated late Eocene arsinoithere from Rumania discussed in Chapter 7). Africa would remain virtually isolated for the rest of the Eocene and Oligocene, almost a 20-million-year span of time. During that isolation, both hyraxes and proboscideans diversified, and came to occupy most of the niches for large herbivorous mammals on the continents. Since the hyraxes were discussed in Chapter 7, we will now look at the early proboscideans. Moeritherium shows the earliest traces of enlarged tusks or a slight proboscis. The next step in the story was just recently discovered. In 1984 a partial skeleton of an animal from the early Eocene of Algeria was described, and in 1986 it was named Numidotherium. Although the specimens of Numidotherium are not very complete, we know that it already had a very high forehead like the more advanced proboscideans and unlike Moeritherium. The nasal opening is further back on the skull, indicating the beginnings of a trunk. The upper tusks are beginning to develop, but like Moeritherium, it had not lost the rest of its upper front teeth. Even more importantly, the lower front teeth are beginning to develop a broad scoop, which we shall see is common in nearly all the primitive mastodonts. The most surprising feature of Numidotherium was its size. It was only about 1 meter (3 feet) tall at the shoulder, smaller even than Moeritherium. Yet its limb bones were fully developed for bearing great weight, with limb segment p~~portions like that of later l?roboscideans. ClearlY,9ne

THE ORIGIN OF JUMBO

Figure 8.4. Deinotheres were an early side branch of the proboscideans, but they had spectacularly downcurved lower tusks and no upper tusks. (From Fenton and Fenton 1958). could not ask for a more perfect intermediate between moeritheres and later elephants. Since it is found in early Eocene deposits (even earlier than Moeritherium) it must have evolved from a common ancestor with moeritheres in the early Eocene, and Moeritherium persisted side-by-side with its relatives, the more advanced proboscideans, until the early Oligocene. The next step in the family tree is a peculiar, poorly known animal called Barytherium, whose name literally means "heavy beast." It, too, was one of the mysterious animals of the late Eocene of the Fayum first described by Andrews in the early twentieth century. Nobody had any idea what it was. Its huge molars had simple cross-crests like those seen in primitive proboscideans, but little else was known of the skull or skeleton at the time. For years, scientists didn't know where to place it in the classification of mammals, and sometimes created a whole new order, the Barytheria, for this one odd species. In the early 1970s, however, Robert Savage described new specimens of Barytherium from the late Eocene of Libya. Its skull turned out to be very elephant-like, with a high forehead and the beginnings of a trunk. The skull was almost a meter long, and the limb bones were heavy enough that it was approaching the size and proportion of typical mastodonts. Like Numidotherium and Moeritherium, but unlike later proboscideans, it still had two incisors in both the upper and lower jaws. Barytherium was not yet down to a single pair of tusks in the upper jaw only. The upper tusks were still short and pointed downward, wearing against the forwardpointing lower tusks (much like the modern hippopotamus). The next extinct sidebranch on the way to true mastodonts and elephants was a strange group of animals known (is deinotheres(FLg. ~.4). Their narnemeans "terrible

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beasts" in Greek, and indeed, they must have looked frightening and terrible. Although most of their anatomy is very similar to primitive mastodonts and barytheres, they have one very peculiar feature that stands out. Instead of having curved tusks arising from their skull, as in normal mastodonts and elephants, they developed giant tusks from their lower jaw which curve downward and backward. No one is sure what these odd tusks were used for. Some speculated that they used them for digging, or even swung down from branches by their tusks! John Harris studied them in detail and pointed out that the tusks have normal wear at the tips, indicating that they were rubbed and abraded during feeding. Harris speculates that they were used (as are normal elephant tusks) as a point of leverage for the trunk, and may have also aided in stripping off bark and vegetation with a downward movement of the head. There is no evidence from the tusk abrasion that deinotheres used their tusks for digging. The first known specimens of deinotheres consisted of their huge molar teeth, which are widespread in the Miocene and Pliocene deposits of Europe. These molars have extremely well developed cross-crests, so they look very similar to those of many other leaf-eating mammals, including tapirs, rhinos, and primitive proboscideans. Cuvier first described these teeth in 1799, considering them to be rhino teeth, and later deciding they were giant tapirs. Others thought they belonged to mammoths, sirenians, hippopotami, whales, sloths, and even marsupials! The great British geologist Sir William Buckland reconstructed Deinotherium somewhat like a walrus. The mystery was not solved until a skeleton was found in 1853 after the collapse of an embankment of the Paris-Brunn railway. From the rest of the skull and skeleton, it was clear that deinotheres were closely related to proboscideans. The most recent analysis points out that their teeth are extremely similar to those of barytheres, and not as advanced as true mastodonts. Unlike moeritheres or barytheres, however, deinotheres did not stay in Africa. The earliest form, Prodeinotherium, occurs in the early Miocene of Libya, and was about the size of a cow. Its skull does not yet show the extreme shortening and retraction of the nasal openings, indicating that it had a much flatter head and shorter trunk than typical elephants. Its lower tusks pointed downwards but not backwards. By the middle Miocene, Prodeinotherium was widespread all over northern and eastern Africa, and also spread to Eurasia. There it was followed by the best known form, Deinotherium, which reached true elephantine size toward the end of its evolution. Deinotherium was a fairly common inhabitant of the Miocene and Pliocene forests of Europe, Russia, the Middle East (Israel and Turkey), and Pakistan, but unlike true mastodonts, it never reached eastern Asia or North America. It was most abundant in the early Pliocene, and then rapidly disappeared from Eurasia. However, the last Deinotherium managed to hold on until the early Pleistocene in East Africa, were it was undoubtedly hunted by our early hoIllinidancesJoJ:S. It is foundcj,n,s;~ttfl~"cDftneclassic

162

HORNS, TUSKS, AND FLIPPERS

\~~~;:

Figure 8.5. Palaeomastodon, from the Oligocene of the Fayum, is often considered the ancestor of the main line of proboscidean evolution. It still had a short trunk and short upper and lower tusks. (From Fenton and Fenton 1958). localities, such as Olduvai Gorge and Lake Turkana, where the best hominid specimens occur. By the middle of the Ice Ages, however, it became extinct, along with many of the large mammals of Africa. Certainly the rapid climatic changes between wetter and drier climates had much to do with their extinction, although it is possible that when our ancestors first became hunters, they pushed deinotheres even faster to the brink of oblivion. The moeritheres, barytheres, and deinotheres were all early experiments in proboscidean evolution that no longer survive (although deinotheres almost made it to our modern zoos). By the early Oligocene, however, the ancestors of the major groups of mastodonts and mammoths are known from the Fayum. These include animals such as Palaeomastodon beadnelli and Phiomia serridens, which had much larger tusks, and a significant trunk. Palaeomastodon stood about 6 feet (2 m) high at the shoulder, and probably weighed as much as a small rhinoceros (Fig. 8.5). Its upper and lower tusks were oval in cross-section, the cusps on the molars were already arranged in pairs so they formed v cross-crests. Phiomia was about 4.3 feet (1.3 m) at the shoulder. It also had short upper tusks with oval cross-sections, like Palaeomastodon, but the lower tusks were flattened into a spatula-like shape. The cusps on its molars were not arranged in pairs, but staggered in two rows. As the main cusps and their small side cusps wore down, they formed looping "three-leaf clover" patterns. Both of these animals were well suited to browsing leaves in the dense forests of North Africa about 33 million years ago. Palaeomastodon and Phiomia represent almost perfect intermediates between Numidotherium and advanced elephants. They had moderate (but not long) trunks, short upper tusks (but still retaining lower tusks), and were intermediate in body size between the pig-size moeritheres and typical elephants. At this point, however, there is much controvers:)""among'eiephant specialists. Some scientists, such as Heinz Tobien and Cary Madden, think that Palaeomasto-

don is ancestral to the true mastodonts, and Phiomia is ancestral. to the rest of Proboscidea, including mammoths and elephants. They base this belief on the cross-crest arrangement of molar cusps in Palaeomastodon, which is developed even more strongly in true mastodonts. Pascal Tassy, on the other hand, considers the similarities in molars between these groups to be outweighed by the other anatomical features which argue that Palaeomastodon is not ancestral to mastodonts alone, but to all other proboscideans. In either case, there is no dispute that by the late Oligocene, the Proboscidea had split into two major groups: the true mastodonts (Family Mastodontidae) and a group including the gomphothere and shovel-tusked "mastodonts," the mammoths and the elephants (Fig. 8.1). Unfortunately, we have almost no middle or late Oligocene deposits in Africa to record this transition. In the early Miocene, about 22 million years ago, both of these groups made their escape from Africa, along with hyraxes and our anthropoid primate ancestors. The reason for this has now become clear. Africa and India were once part of the southern supercontinent, Gondwanaland, that had persisted for over 600 million years. It began to break up about 100 million years ago. As it did so, both Africa and India moved northward on a collision course witll Eurasia. The great Tethyan seaway which once separated them was confined between the colliding continents. The collision also pushed up great mountain ranges, such as the Alps, the Caucasus, the Zagros Mountains of Iran, and the Himalayas, into gigantic folds, like a wrinkled rug. As we have already seen, during the Eocene (55-34 million years ago), Africa and India were getting close, but still remained somewhat isolated from Eurasia. Consequently, the Tethyan seaway was still dominant, and we find many kinds of animals widespread along its shores from Africa to eastern Asia. Africa had still not docked with Asia during the Oligocene, so most of its mammals were unique inhabitants: proboscideans, hyraxes, arsinoitheres, anthropoid primates, and peculiarly African rodents and artiodactyls. By the end of the Oligocene, however, Africa was so close to Europe that animals could hop between islands or walk across dry land between the two continents in the region that is now the Middle East. The Tethys seaway was permanently closed off in the middle, and its western half was about to become the MeditelTanean. Africa's isolation as an island continent, with its own peculiar mammals, had ended. From now on, its natives would have to compete with Eurasian mammals. The proboscideans were probably the most successful of the immigrants from Africa. We find them in the middle East and Pakistan about 22 million years ago, in western Europe and China by about 18 million years ago, and all the way to North America by 16 million years ago. From the middle Miocene on, both the mastodontids (true mastodonts) and the other elephantoids (gomphothere '"'fuastodonts," mammoths, and elephants) wandered freely among the continents, including even South America (but

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Figure 8.6. Exhuming the First American Mastodon by Charles Willson Peale. These excavations, near what is now Newburgh, New York, in 1799-1801, were among the first major scientific excavations of fossils. To retrieve the bones from the pit, water is lifted out in buckets on a human-powered treadmill, and mud is shoveled onto a series of platforms to be removed. (Neg. no. 310511, courtesy Department of Library Services, American Museum of Natural History). not Australia) at the end of the Pliocene. Before we review the long complex history of the elephantoids, let us look at the true mastodonts. THE "GREAT MISSOURIUM" The American mastodon was the first extinct animal collected and described from the New World. Since it had the bones and tusks, but not the teeth, of living elephants, it was a great mystery. Many prominent Americans, including Benjamin Franklin and Thomas Jefferson, puzzled over the "American incognitum. " Since it apparently lived in marshy habitats and was abundantly preserved in ancient bog deposits, eighteenth-century Americans occasionally discovered its bones when draining a swamp or excavating for peat. The Big Bone Lick,. near the OhioRiv~tin eastern Kentucky, was a common source for these mysterious bones. Apparently mastodonts were concentrated there by a

natural salt lick which attracted them, along with other wild animals. The most famous find, however, was made in the Hudson Valley, near Walkill, New York. In 1782 the Reverend Robert Annan found some gigantic teeth and bones while digging an irrigation ditch. He sent· them to General Washington, who at the time was preoccupied with the Revolutionary War. They eventually reached the hands of Charles Willson Peale, the famous American artist, who was asked to draw them. These bones, along with numerous paintings, stuffed animals, and wax figures, became part of the first natural history museum in the United States, Peale's Museum of Natural Curiosities in Philadelphia. When the fossils were sold to a Dutch professor in 1787, Peale needed something to rephlce_th~m. He got his chance in 1801, when another farmer in the Walkill area found giant bones in a peat bog about four miles

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HORNS, TUSKS, AND FLIPPERS

from the Reverend Annan's farm (Fig. 8.6). The farmer and his helpers had broken up the ribs badly as they dug, but the huge thighbones were intact. Peale and his sons rushed to the scene, where they purchased the rights for "one hundred dollars in silver or ,gold." They excavated from July to September, rigging up a water wheel to keep pumping out the copious groundwater. After all that digging, they had plenty of leg, backbone, and rib pieces, but no skull or jaws. They tried several other places, and just as they 'were about to give up, they found an excellent skull and two sets of jaws. (Today, the site is covered by a Winnebago lot). Wrapped in canvas, the bones were carted to Philadelphia, where the Peales put together one of the first skeletal mounts of an extinct animal in history. It was a huge success, pronounced by the press to be the "Ninth Wonder of the World." However, the level of anatomical understanding in this country was still abysmally low, and few in America had ever seen an elephant. In fact, black slaves were adept at recognizing mammoth teeth, since they closely resembled elephant teeth they had seen before their captivity. Most people interpreted the strange bones as remains of a gigantic carnivorous beast. After the Peale Museum's success, other places began to collect and exhibit mastodon skeletons as well. Some reconstructions were so poor, however, that they seem laughable today. In 1841 a mastodon found in Gasconade County, Missouri, was exhibited as the "Great Missourium," or the "Leviathan Missourium." Reconstructed by the showman Albert Koch (Fig. 8.7), it was supposedly large enough that (according to the London Times) "a mammoth would have strutted with ease between its legs ... the animal is supposed to be aquatic in its nature. This we

should have inferred from the anatomical structure of its neck." The Philadelphia editor James Pedder was·convinced Koch's reconstruction was wrong, but his idea was even more fantastic (Fig. 8.8). "I have been led to conclude that the animal was a Monster of the Tortoise Tribe 32 feet long and corresponding width, with a power of withdrawing its head within its shell; the tusks then forming a mail of defense around its edge to ward off obstruction ... [the tusks were] carried near the Earth, and resting upon it, at the will of the animal." Despite this confusion, the mystery of the mastodon was solved long before 1841. Cuvier, of course, realized that these animals were related to elephants. After seeing Peale's drawings of Mammut americanus, he decided that it was different from the frozen furry animal from Siberia. This beast had long been called mammot ("earth burrower" in Tartar) by medieval eastern European farmers who found the huge bones in their fields and thought they belonged to a giant burrowing beast. Since the American beast had conical cusps on its molars that resembled women's breasts, he called it le Mastodonte, or "breast-toothed." Eventually, the name "mastodont" stuck, and only the woolly Siberian animal was called the "mammoth." However, according to the rules of naming animals, the first scientific name applied to an animal must take priority, even if is inappropriate or forgotten in favor of a more popular name. Thus, zoologists must use the name Mammut for the mastodon, since it was first applied to that animal eighteen years before Cuvier

Figure 8.7. Many reconstructions of the American mastodon showed no understanding of anatomy, as shown by the incorrectly curved tusks and arched spine of this mount.

THE ORIGIN OF JUMBO

Figure 8.8. Even more odd, however, is Pedder's reconstruction of mastodon tusks as part of a giant turtle. renamed it "mastodon." The true mammoth is now known as Mammuthus, an unfortunate confusion since mastodonts and mammoths are not very similar, nor even closely related. An even greater confusion applied to the formal zoological name of the mastodont family. While Cuvier's term Mastodon, was still widely used, the family named "Mastodontidae" was coined by Girard in 1852. Eventually, when scientists realized that the correct name was Mammut, they changed it to Mammutidae, and so it is listed in nearly every book in print today. Cary Madden, who is convinced that Palaeomastodon is the ancestor of this family, used Palaeomastodontidae, since this family name was coined before Mammutidae. However, according to the International Code of Zoological Nomenclature, the first familygroup name applied normally remains valid, even if the genus on which it is based is later shown to be invalid. Based on priority, then, the correct name should be Mastodontidae. However, since the name Mammutidae is now so widely accepted, the Commission on Zoological Nomenclature may decide to suppress "Mastodontidae" in

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favor of the better known name, Mammutidae. Until that occurs, we will use "Mastodontidae" in this book. Since Cuvier's time much more has been learned about the American mastodon and its family, the Mastodontidae. This family diverged from the rest of the Proboscidea long before the rest of the elephants discussed in the next section. The earliest known mastodontid, Zygolophodon, first migrated from Africa to North America 16 million years ago, and the entire family remained very conservative throughout their long history. Although generally elephantlike in build, Mammut was only about 10 feet (3 m) at the shoulders, and had no great forehead or shoulder hump like true elephants (Fig. 8.9). It also had a longer skull, flatter brow, deeper chest, broader pelvis, longer back, and shorter legs. Tusks were present in both sexes, although those of males were larger, extending up to 10 feet (3 m) from the skull. These tusks projected forward from the skull, then curved outward and finally inward. The males also had smaller vestigial lower tusks that were lost in maturity. One tusk is usually worn shorter than the other, indicating that these animals were typically either right-tusked or lefttusked. Their tusks were probably used to pry off bark and branches, and break them up into pieces. During the Ice Ages mastodonts apparently preferred open spruce woodlands and spruce forests, where they browsed on leaves and vegetation. Although they were most common in the east, they were also found in forested valley lowlands and bogs in Florida, Texas, and the Great Plains. Their molars have even been found by fishermen on the Atlantic continental shelf over 250 miles (400 km) from the present shoreline. Apparently, they lived on conifer-covered shelf areas exposed during the glacial low in sea level

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HORNS, TUSKS, AND FLIPPERS

25,000 years ago. Stomach contents found in their ribcages included twigs and cones of conifers, leaves, coarse grasses, swamp plants, and mosses. They had coarse, brownish outer hairs about 3 cm long, and a fine woolly undercoat, much like aquatic and semiaquatic mammals. Given their preference for bog habitats, it is likely that they were as fond of water as the Ice Age moose. Mammut americanum was one of the most conservative and long-lived of all known fossil mammal species. It spread all over Europe and North America, and persisted without change for at least 4 million years. Surviving until the end of the last Ice Age, the best dates for its extinction range from 9,000 to 12,000 years ago. There are younger dates, but most of these appear to be due to contamination. However, many Native American legends describe a beast like the mastodont, so some scientists speculate that it survived much longer. It is clear that Paleoindians hunted the mastodont. The best known kill site is Kimmswick, about 20 miles south of St. Louis and close to the Mississippi River. Two mastodonts were ]<..illed at different times, and Clovis projectile points are found among the bones. It may be that Paleoindians were responsible for the extinction of mastodonts from overhunting them, but this is uncertain. Like the extinction of other large Ice Age mammals discussed elsewhere in this book, climate almost certainly played a role in the extinction of mastodonts as well. SHOVEL-TUSKERS AND GOMPHOTHERES By the early Miocene the Fayum palaeomastodonts had diverged into two major groups: the Family Mastodontidae (discussed above) and the main line of elephant evolution (Fig. 8.1). The most primitive members of the main line are known as the gomphothere (or sometimes "trilophodont") "mastodonts," although as we have already seen, the name

Figure 8.10. During the early and middle Miocene, the main line of proboscidean evolution was represented by the gomphotheres. They still retain the primitive low, long skull, and relatively long upper and lower tusks. (From Fenton and Fenton 1958).

Figure 8.11. Another side branch of proboscidean eVOlution were the shovel-tusked amebelodonts. (From Fenton and Fenton 1958). "mastodont" should only be applied to members of the Family Mastodontidae. The gomphotheres, howe~~r, looked much like primitive mastodonts (Fig. 8.10). They had long, low skulls (up to 2 meters long) with straight upper and lower tusks of about equal length, and short trunks not much longer than the tusks. Some reached up to three meters at the shoulder, approaching the size of the Asian elephant. Like Phiomia, they had flattened, spatula-shaped lower tusks, which showed a lot of wear from digging, and from stripping leaves and bark off trees. They apparently preferred forested habitats, which they pursued all over the northern hemisphere and Africa during the Miocene. The cusps on their molars were arranged in staggered rows (rather than in straight rows forming cross-crests, as in Palaeomastodon and mastodontids). These low blunt cusps were covered with a very thick enamel. When the teeth were worn, they typically showed a "three-leaf clover" pattern formed by the worn tips of the cusps and the tiny cuspules on the side. Like mastodontids, gomphotheres had horizontal tooth replacement, but unlike elephants, they had as many as three molars in each jaw operating at one time. Both mastodontids and gomphotheres escaped from Africa in the early Miocene, and Gomphotherium was soon widespread all over Eurasia. Both Gomphotherium and Zygolophodon migrated to North America in the middle Miocene, about 16 million years ago. From that time onward, proboscideans replaced rhinos as the largest land mammal in North America. One of the earliest and most unusual side branches of the gomphotheres were the "shovel-tusked mastodonts," or amebelodonts (Fig. 8.11). These animals had developed the flattened lower tusks of Phiomia or Gomphotherium into extremely broad, shovel-shaped scoops that made them look a bit like a duckbilled elephant. Like mastodontids and gom-

THE ORIGIN OF JUMBO photheres, they probably evolved in Africa during the late Oligocene gap in the fossil record, but first show up in Africa and Eurasia in the early Miocene. By the late Miocene, they were widespread all over Eurasia and North America. Some of them reached extremes in this development. The jaws of some specimens of Platybelodon were almost 9 feet (2.7 m) in length, and the two lower "shovel tusks" form a broad blade almost 2 feet (60 cm) wide (Fig. 8.12). The strangest of them all was Gnathobelodon, which developed its lower jaw into a long "spoon" over 5 feet (1.5 m) long with no lower tusks at all! In 1928 the Central Asiatic Expeditions of the American Museum of Natural History found the first jaw of a shoveltusker in Mongolia. As described by Roy Chapman Andrews, leader of the expedition, "Two years later we went back to Wolf Camp. We wanted to find out more about the great shoveljawed mastodons. Again our tents were pitched right on the edge of an old lake basin. The next day one of our scientists found a deposit of bones six miles away. There was every indication it had been a death trap. We began digging with great interest. At first, we did not know that we had discovered one of the world's most remarkable fossil deposits. I wish you could have been there with us. It was thrilling to open that ancient grave! Out there in the desert, the year 1930, we worked in the brilliant sunshine ... The mastodon's grave had been uncovered at least a century before we found it. Already the upper part of the deposit had disappeared in dust. Still, much remained. A mass of bones lay

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buried in hard, green clay. This was the mud that once filled the pit. The fossils lay like a huge pile of jackstraws. Great scoop jaws were heaped, one upon another, in every possible position. Some stood on end; others were at oblique angles; still others lay almost horizontal. Some of the jaws were perfect and nearly six feet long. The one we had found some two years before was considered to be one of the world's most extraordinary fossils. But now, we had a dozen better jaws right in front of us. Mixed with them were many other bones. Enormous flat shoulder blades, legs, pelvic bones and dozens of ribs lay in a seemingly hopeless jumble. It was difficult to take out anyone bone, for usually part of it ran under some other. Only by finding the topmost bones could we begin work. The bones were badly preserved. They were filled with only a little mineral matter and were soft as chalk. As soon as part of a bone was exposed, it had to be soaked with shellac. This hardened it. Then more of it could be dug out. Next, it was covered with Japanese rice paper and gum arabic, a kind of glue. The paper and gum held the loose bits in place. Then the whole surface must be bandaged with strips of burlap soaked in flour paste. In a few hours the paste dried and the bone was enclosed in a hard shell. For six weeks, ten men worked at the job! In another deposit just below camp, one of our men found the back part of a female mastodon. She had died lying on her side. Within the pelvis were

Figure 8.12. The spectacular bonebed of shovel-tusked amebelodonts excavated in Mongolia by the Andrews American Museum expeditions in 1928. Two jaws are shown in the foreground. (Courtesy Department of Library Services, American Museum of Natural History).

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Figure 8.13. Reconstruction of the long-tusked proboscidean Anancus. (Painting by Z. Burian). the skull and jaws of an unborn baby. The jaw of the baby was about twelve inches long" (Andrews, 1932). Most of the popular books state that shovel tuskers used their "scoops" like a duck to feed on swamp vegetation. However, a study by David Lambert showed that the wear on their lower incisors was caused by shoveling, scraping, and stripping. On some animals the wear shows that the lower tusks were used primarily for cutting vegetation. Shovel-tuskers must have fed much like other proboscideans, stripping bark and slicing vegetation with their

lower tusks used like lawn mower blades. If this was so, then they also had a well-developed trunk for manipulating the vegetation, and not the short flap-like trunk shown in most standard reconstructions. Another side-branch of the gomphotheres were the anancines (Fig. 8.13). These animals were distinguished by their enormously long, straight tusks-more than 10 feet (3 m) long! They had exaggerated gomphothere proportions, with very short legs, and a very long face, but they completely lost their lower tusks. Apparently this feature evolved in parallel with the loss of lower tusks and the short lower jaw found in true elephants. Anancines evolved in

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Figure 8.14. Diagrammatic representation of the change in proboscidean skull shape. The long, low skull of gomphotheres (left) became shortened and more vertical in stegotetrabelodonts (center), shifting the center of gravity (Ctg) and putting different stresses on the occipital condyle (oc) at the back of the skull, and the nuchal muscles (nm) that hold the head up. Further shortening of the skull in elephants and mammoths (right), along with the downward shift of the upper tusks, forced the occipital condyles to become taller. In addition, the insertion point of the nuchal muscles shifts above the center of gravity to counterbalance the weight shift. (From Maglio 1973). Eurasia during the late Miocene, and were widespread over Eurasia and Africa during the Pliocene. They became extinct, however, when the Ice Ages began. By the late Miocene this variety of archaic proboscideans-deinotheres, mastodontids, gomphotheres, and amebelodonts-had reached the peak of their evolution in Eurasia, Africa, and North America. Then, like the rhinos, horses, and many other large mammals, they suffered from severe extinctions at the end of the Miocene. As pointed out in Chapters 10 and 14, the probable cause of this extinction was climatic change triggered by the isolation and drying up of the Mediterranean Sea. This extinction event wiped out the shovel-tuskers completely, eliminated deinotheres from everywhere but Africa, and drove most of the gomphotheres to extinction. Only some of the conservative mastodontids (Pliomastodon) and the ancestors of the living family of elephants, the Elephantidae, survived into the Pliocene in the Northern Hemisphere. These are the subject of the next section of this chapter. ELEPHANT GRINDERS Gomphotheres and mastodonts had been very successful all over the world browsing on softer vegetation. With their simple teeth, however, they could not eat abrasive grasses very long before their teeth would wear out. Most proboscideans avoid this problem by continuously replacing teeth from back to front, but this was not enough for a very abrasive diet in such a long-lived animal. Elephants solved this problem by developing teeth which can wear continuously, and evolved a new mode of feeding. The first step in this direction was taken by the stegodonts (Fig. 8.1). These proboscideans first evolved in Eurasia in the late Miocene, were all over the Old World in the Pliocene, and persisted in many parts of Eurasia and Africa until the end of the Ice Ages. Like true elephants, they reduced their lower tusks to mere vestiges, and developed

long upper tusks (up to 3 meters long). This is similar to the anancines, but it is a clear example of parallel evolution, since in most features, stegodonts are much more advanced than anancines. In addition, stegodont tusks had. a "J"shaped curvature, and were so close together along the midline that the trunk could not slide between them, but had to drape over the side. The most elephantine feature of stegodonts, however, occurred in the molar teeth. They had only one huge molar on each side at a time, down from the three molars in simultaneous use by the gomphotheres. This molar tooth had the cusps merged into 14 transverse ridges, which were made of enamel bands that were deeply folded into the root of the tooth. In crown view this gave many cross-crests with deep V-shaped valleys in between. Like gomphotheres, however, the enamel was still very thick. The next step toward true elephants are the stegotetrabelodonts (Fig. 8.14 center, 8.15). They were like stegodonts in most features, but were more advanced in other parts of their anatomy. Their most progressive feature is change in the lower jaws. Although they still had lower tusks like gomphotheres, these were small and sloped downward, rather than forward. The entire front of the lower jaw became shorter and downturned. As this occurred, the face also shortened, so elephants began to develop their characteristic "forehead," so different from the low, flat head of mastodonts and gomphotheres. The shortened jaw with no lower tusks meant that the jaw could move in a front-and-back plane much more efficiently. As a result, the plane of the grinding teeth rotated upwards and backwards. In contrast, gomphotheres (like most other herbivorous mammals) moved their jaws in a complex rotatory motion. Beginning with stegotetrabelodonts, however, true elephants became specialized for front-and-back grinding, and soon developed huge, complex molars to accomodate this greater efficiency for grinding. This allowed them to eat not

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A

B

c

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Figure 8.15. Evolution of proboscidean molars, shown here in cross section. Enamel is shown in black, cement is heavily stippled, and dentine is lightly stippled. Gomphothere molars (A) had three rows of low, blunt cusps with thick enamel and a thin cap of cement. In stegotetrabelodont molars (8), the cusps have become three low, parallel ridges, with deep V-shaped valleys and little cement. The molars of Primelephas, the ancestral elephant (C), have an increased number of ridges and decreased width of the valleys which are partially filled with cement. Early Pleistocene Elephas planifrons (0) had molars with tightly compressed ridges and more of them; the enamel is thinner, the cement thicker, and the entire tooth is higher crowned. The living Indian elephant, Elephas maximus (E), like most late Pleistocene mammoths and elephants, has a molar composed of dozens of compressed folds of thin enamel, completely filled with cement to form a high-crowned prism. As this tooth wears, the enamel ridges stand out from the cement, producing a grinding surface. The front edges of the tooth wear off and some of the enamel prisms break away before the tooth is finally shed. (From Savage and Long 1986).

E

only the usual soft leafy vegetation, but also great quantities of gritty grasses without wearing their teeth down and starving to death. Once this feeding innovation appeared in stegotetrabelodonts, the true elephants (Family Elephantidae) could evolve into a great variety of forms. Living with Stegotetrabelodon in the late Miocene of Africa was one of the earliest true elephants, Primelephas gomphotheroides. Vincent Maglio considered this animal the ancestor of all later elephants. Primelephas took the tendencies seen in Stegotetrabelodon even further. The lower tusks are tiny, and the lower jaw is very short, but the molars are even more progressive. They have completely fused the cusps into simple cross-crests, and decreased the total number of crests to about eight. More importantly, they have filled in the valleys of the crests with a thick, hard substance known as cement, which is found on the teeth of horses, cattle, and other herbivorous mammals who use their teeth for grinding (Fig. 8.15). From this point on, most elephant molars evolved by increasing the number of thin enamel bands, and covering them with a thick coating of cement. Consequently, the typical elephant molar has a large flat grinding surface made of cement with many thin ridges of enamel (which do most of the grinding) sticking through. By decreasing the enamel thickness, the bulk of the tooth is reduced without decreasing the total shearing area of the surface. By adding more and more complicated enamel

ridges, the tooth can wear longer and longer before it is used up. Some mammoths had as many as 27 separate ridges of enamel on a single tooth! A complex pattern of elephant evolution and migration has been documented by Vincent Maglio. From Primelephas in the early Pliocene, all three major genera of elephantids soon diversified. The first to sl1lit off was Loxodonta, the genus of the living African elephant. The oldest known species is Loxodonta adaurora from the early Pliocene of East Africa. It soon spread throughout Subsaharan Africa, but Loxodonta apparently never managed to escape from Africa. Elephas ekorensis, the oldest known relative of the Asian elephant, also arose in East Africa in the early Pliocene. Several different species of Elephas evolved and spread throughout Africa in the Pliocene and Pleistocene. By the late Pliocene Elephas planifrons had escaped Africa and appeared in the Middle East, Pakistan, and India. Its descendant species then spread to China, Burma, and all the way to Java by the middle Pleistocene. The eventual descendant of this lineage is Elephas maximus, the living Asian elephant. A second invasion from Africa occurred in the early Pleistocene, when Elephas namadicus appeared in India and Pakistan. It also spread to many areas which had never seen elephants previously, including eastern and western Europe, and Japan. Then at the end of the Ice Ages Elephas became extinct in Africa, leaving the continent to Loxodonta. Elephas never spread into the northern glaciated regions, or managed to cross the Bering Strait to the Americas, however. This was left to its close relati ve, the mammoth. WOOLLY WANDERERS Schumachoff the fisherman had a hard life. He fished for sturgeon in the icy Lena River in northern Siberia, but usually he had little luck. Then he salvaged his fishing expeditions by collecting the mysterious chunks of ivory that showed up in the Lena River sands. However, during this particular trip in 1799 he proceeded a little further up the Lena than ever before. As he rounded a bend in the river, he suddenly came face to face with a huge hairy monster

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Figure 8.16. Artist's impression of the discovery of the mammoth frozen in the cliff on the banks of the Lena River in Siberia in 1799. The beast (which was actually encased in ice) appears to have just stepped out from behind the cliff, startling the fisherman Schumachoff who found it. (From Benkendorf 1846). standing upright, embedded in pure ice in the cliff face (Fig. 8.16). It appeared to have just stepped right out of the cliff and frozen in place. Schumachoff was so astonished and awed that he did not approach too closely, and he made several more trips over the years to stare at it in wonder. Finally, he summoned up the courage to approach it and touch it, but the monster made no signs of eating him up. His superstition and awe overcome by greed, he broke the baiTier of ice and chopped out the tusks. Soon the wolves and bears had eaten the flesh. Two years later a Russian scientist heard of the wonderful discovery and made a voyage to see it. Although most of it was reduced to a skeleton, the eyes and brain were still in the skull. As we saw earlier in this chapter, tusks and bones of the strange beast known as the mammot had been discovered all over northern Europe and Siberia since the Middle Ages. Enough bones and frozen hides with hair had been discovered by 1799 that Cuvier and others could distinguish the mammot from the "American incognitum. " But this frozen mammoth was the first instance of any long-extinct beast found completely intact after thousands of years of burial.

Many people did not believe the accounts, and when the first scientists arri ved on the scene too little was left to prove them. In 1846 the scientific world was stunned again with an even more spectacular find. A young Russian engineer named Benkendorf was surveying the coast at the mouth of the Lena and Indigirka Ri verso As he sailed up the Indigirka in a small boat, he discovered a truly remarkable sight. As he wrote to a friend later, "In 1846 there was uncommon warm weather in the north of Siberia. Already in May unusual rains poured over the moors and bogs, storms shook the earth, and the streams carried not only ice to the sea, but also large tracts of land, thawed by the masses of warm water fed by the southern rains ... We steamed on the first favorable day up the Indigirka; but there were no thoughts of land. We saw around us only a sea of brown water, and knew the river by the rushing and roaring of the stream. While we were all quiet, we suddenly heard under our feet a sudden gurgling and stirring, which

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HORNS, TUSKS, AND FLIPPERS betrayed the working of the disturbed water. Suddenly our hunter, ever on the lookout, called loudly, and pointed to a singular and unshapely object, which rose and sank through the disturbed waters. I had already remarked it, but not given it my attention, considering it only driftwood. Now we all hastened to the spot on the shore, had the boat drawn near, and waited until the mysterious thing should again show itself. Our patience was tried, but at last, a black, hOITible, giant-like mass was thrust out of the water, and we beheld a colossal elephant's head, armed with mighty tusks, with its long trunk moving in the water, in an unearthly manner, as though seeking for something lost therein. Breathless with astonishment, I beheld the monster hardly twelve feet from me, with his half-open eyes yet showing the whites. It was still in good preservation. 'Mammoth! A mammoth!' broke out the Tschermomori, ~nd I shouted, 'Here quickly! Chains and ropes ... ' We therefore fastened a rope around his neck, threw a chain around his tusks, that were eight feet long, drove a stake into the ground about 20 feet from the shore, and made chain and rope fast to it ... The position of the animal was interesting to me; it was standing in the earth, and not lying on its side or back as a dead animal naturally would, indicating by this the manner of its destruction. The soft peat or marsh land on which it had stepped thousands of years ago gave way by the weight of the giant, and he sank as he stood on it, feet foremost, incapable of saving himself, and a severe frost came and turned him into ice, as well as the moor which had buried him; the latter, however, grew and flourished, every summer renewing itself; possibly the neighboring stream had heaped plants and sand over the dead body. God only knows what causes had worked for its preservation; now, however, the stream had once more brought it to the light of day, and I, an ephemera of life compared with this primeval giant, was sent here by heaven just at the right time to welcome him. You can imagine how I jumped for joy ... Picture to yourself an elephant with a body covered with thick fur, about 13 feet in height, and 15 in length, with tusks eight feet long, thick and curving outward at their ends, a stout trunk of six feet in length, colossal limbs of one foot and a half in thickness, and a tail naked up to the end, which was covered with thick, tufty hair. The animal was fat and well grown; death had overtaken him in the fullness of his powers. His parchment-like, large naked ears lay fearfully turned up over the head; about the shoulders and the back he had stiff hair, about a foot in length, like a mane. The long outer

hair was deep brown and coarsely rooted. The top of the head looked so wild, and was so penetrated with pitch, that it resembled the rind of an old oak tree. On the sides it was cleaner, and under the outer hair there appeared everywhere a wool, very soft, warm, and thick, and of a yellow-brown color. The giant was well protected against the cold. The whole appearance of the animal was fearfully wild and strange. It had not the shape of our present elephants. As compared with our Indian elephants, its head was rough, the braincase low and narrow, but the trunk and mouth were much larger. The teeth were very powerful. Our elephant is an awkward animal, but compared with this mammoth it is an Arabian steed to a coarse ugly dray-horse. I could not divest myself of a feeling of fear as I approached the head; the broken, widely opened eyes gave the animal an appearance of life, as though it might move in a moment and destroy us with a roar... The bad smell of the body warned us that it was time to save of it what we could, and the swelling flood, too, bade us to hasten. First of all we cut off the tusks, and sent them to the cutter. Then the people tried to hew the head off, but, notwithstanding their good will, this was slow work. As the belly of the animal was cut open, the intestines rolled out, and then the smell was so dreadful that I could not overcome my nauseousness, and was obliged to turn away. But I had the stomach separated and brought on one side. It was well filled, and the contents instructive and well preserved. The principal were of young shoots of the fir and pine; a quantity of young fir cones also, in a chewed state, were mixed with the mass" (Benkendorf, 1846). Additional frozen mammoths were found in the next century, but the best studied was the Berezovka mammoth (Fig. 8.17). In the winter of 1900 a Cossack dealer of mammoth ivory bought some tusks from a Lamut tribesman who had chopped them out of a complete frozen animal. It took some time for word to reach scientists, so an expedition to study this find did not depart St. Petersburg until May 1901. By the time they reached it in September, much of the head had been eaten by carnivores during its two years of exposure. Nevertheless, most of the skin, tongue, and internal tissues were well preserved. Some of the braver scientists tasted the ancient meat, but most of it was fed to the sled dogs, who suffered no ill effects. The Berezovka mammoth had the woolly fur described by Benkendorf, and a short tail with hairs 10 inches (255 mm) long. Apparently it had fallen into some sort of hole or crevasse in the ice, because its death had been almost instantaneous. It had broken ribs, a shoulder blade, and its pelvis, and its viscera were wrenched to one side and filled with clotted blood. Then it was freezedried by the permafrost conditions in northern Siberia. There

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Figure 8.17. The Berezovka mammoth, more than 39,000 years old, as it was discovered in 1901. (Courtesy Russian Academy of Sciences).

Figure 8.18. Dima, the baby mammoth mummy, discovered in Siberia in 1977. (Courtesy Russian Academy of Sciences).

was still food between its teeth, including buttercups, and its stomach held grasses, but no pinecones or larch needles. It was apparently in good health at the end of a summer feeding season, because it had 3.5 inches (90 mm) of fat on its torso. The scientists collected it and brought it back to St. Petersburg (until recently called Leningrad), where it has been saved. Other partial mammoth mummies were found over the years, but the most significant find was in 1977. Placer gold miners, strip mining thawed soils from frozen ground in Magadan in the Soviet Far East, uncovered the frozen mummy of a baby mammoth. Nicknamed "Dima," it is by far the best preserved mammoth mummy ever unearthed (Fig. 8.18). The body had been frozen rapidly with little decomposition, and was found and collected rapidly before scavenging and decay could take place. Although most of its hair had fallen off, the preservation of the internal soft tissues was nearly perfect. Dima was truly a baby mammoth, only about a meter high at the shoulder; based on the stage of tooth eruption, it was about 4-8 months old. It was emaciated, starving, and completely lacking in body fat when it died, and suffering from parasites. Except for the colon, the digesti ve tract was nearly empty. The few plants preserved were mostly detritus of tundra grasses, and dirt was evidently inhaled and ingested as the trapped animal struggled. According to Dale Guthrie, Dima must have sunken into quicksand during a late summer thaw, struggling for days as it sunk in deeper and starved to death. Because of its small body mass, empty stomach contents, and low body fat, it froze rapidly once it died, resulting in excellent preservation. A unique opportunity is presented by such well-preserved organic tissues, which were not destroyed or replaced during the typical process of fossilization. The Russian cell biologist Mikhelson has attempted to produce a living "testtube descendant" of Dima, using these well-preserved cells.

By replacing the nucleus of an Asian elephant sex cell with that of Dima, Mikhelson hopes to clone this cell into many. Then it would be implanted into a living female elephant, who could give birth to an animal that has been extinct for over 9000 years! So far these efforts have not succeeded, but the possibilities are intriguing. Other efforts have been more successful. Jeheskel Shoshani and colleagues have done a nUluber of studies on the molecular biology of mummified mammoth and mastodont tissues, including blood cells, tissue proteins, and immune reactions of blood serum. All of these show that the woolly mammoth was closely related to the Asian elephant, as suggested by the fossil record. Mastodont tissues are much less similar to living elephants than are mammoths, as would be expected if mastodonts were only distantly related. A number of other less complete mammoth mummies have been found in Alaska and the Soviet Union. Along with cave paintings by prehistoric humans, they give us the most complete picture possible for any long-extinct species. Most fossil mammals must be crudely reconstructed from just bones; their hair and skin color are based on complete guesswork. Not so for these mummified Ice Age animals. The woolly mammoth, for instance, was the smallest and most specialized of all the mammoths. It was only about 9 feet (2.8 meters) at the shoulder, covered with long black hair and a woolly undercoat. Underneath that was an insulating layer of fat about 3 inches (80 mm) thick in a well-fed animal. Woolly mammoths had a high domed head, a strongly humped shoulder and sloping back, and a short tail with very long hairs. The ears were small and round to reduce heat loss, in contrast to African elephant ears, which are unusually large to aid heat loss. The trunk was short with two "fingers" at the tip for grasping bunches of grass, and had broad flaring flanges of flesh along the side for scooping up snow to drink. The long tusks curve backward into a semicircle, and the lower edges of the tusks show evidence of scraping.

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Figure 8.19. Reconstruction of the woolly mammoth (Mammuthus primigenius) using its tusks to scrape snow away to find food. (Painting by Z. Burian).

Figure 8.20. The Columbian, or imperial mammoth (Mammuthus columbi) , largest of the Ice Age mammoths. It was not as hairy as the woolly mammoth, and was widespread south of the glacial front, especially in the southern United States and Mexico. Here it is shown driving the sabertoothed cat Smilodon away from its young. (Painting by Z. Burian).

Apparently, they were used to scrape away snow to find vegetation, as many living tundra animals do today (Fig. 8.19). Analysis of the stomach contents show that the woolly mammoth was an opportunistic steppe grazer. During the summer, it ate a large percentage of grasses and tundra legumes (including buttercups). In winter, most of the diet was leaves, twigs, and bark. For this highly abrasive diet, the woolly mammoth has the largest and most complex teeth of any proboscidean, with many more enamel ribs and the highest crown height of all. Although the woolly mammoth (Mammuthus primigenius) is most familiar to us because of the many specimens and familiar drawings of them, it was not typical of mammoths. So far as we know, most mammoths did not have the long hair of woolly mammoths, but were thinly furred or bare-skinned like living elephants. Whether woolly or not, all mammoths can be distinguished from other elephants by their high, foreshortened skull and concave forehead, and highly complex, narrow molars. Most mammoths had tusks which curved backward and inwards in adults. Some even had a spiral twist, and their points may even cross in front of the head. The genus Mammuthus, like most extinct Proboscidea,

was once a mess of confusing names and invalid species. In Henry Fairfield Osborn's 1936 monographs, for example, the early mammoths were called Archidiskodon, the intermediate mammoths Parelephas, and only the late mammoths were Mammuthus. Vincent Maglio's 1973 classification (modified by Bjorn Kurten and Elaine Anderson) has reduced 16 invalid species in three genera to just one genus with five species. Mammuthus first arose in Africa in the early Pliocene, along with the ancestors of living Loxodonta and Elephas. From there it spread to N011h Africa and Europe in the late Pliocene, becoming the common species Mammuthus meridionalis, the "southern mammoth." In the middle Pleistocene, this ancestor evolved into two different lineages: the woolly mammoth, which dominated Siberia and eventually invaded North America; and the descendants of its earlier invasion of North America, the Columbian and Jefferson's mammoths. About 1.5 million years ago in the early Pleistocene the southern mammoth crossed the Bering land bridge into North America. Here it was able to spread out over the temperate and subtropical grasslands without competition from Loxodonta or Elephas, as it had faced in the Old World. (Mastodonts were already here, but they were woodland browsers and did not compete with mammoths). By the

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Figure 8.21. The amazing density of bones at the Hot Springs Mammoth Site, in the Black Hills of South Dakota. (Photo courtesy L. Agenbroad) middle Pleistocene the southern mammoth had evolved into the Columbian mammoth (Mammuthus columbi, also known as the imperial mammoth). As the second name implies, this was the largest of the mammoths, reaching 13 feet (4 m) at the shoulder (Fig. 8.20). It was widespread all over North America in the middle and late Pleistocene, and is particularly well known from the La Brea tar pits in Los Angeles. In the late Pleistocene the Columbian mammoth was replaced by the slightly smaller Jefferson's mammoth (Mammuthus jeffersoni). This animal was a highly specialized plains grazer, with complex teeth suited to abrasive grasses. The late Pleistocene also saw the migration of the woolly mammoth from its Siberian homeland into Canada and Alaska. Mammoth bones, because they are large and spectacular, have been found in Ice Age deposits all over North America. Some of the most spectacular and well-known Pleistocene sites are dominated by mammoths. There are river deposits in Alaska with the bones of hundreds of indi-

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vidual mammoths, and river deposits and ancient springs and ponds all over the west with dozens of individuals. The most spectacular of these sites was found near Hot Springs, South Dakota in 1975. A bulldozer excavating a housing development on the edge of town struck mammoth bones, and soon the importance of the site became apparent. Over thirty mammoths (the count increasing each year) were discovered in a small area less than 200 feet (60 m) across (Fig. 8.21). The locality turned out to be an ancient pond deposit, or sinkhole, caused by the collapse of an underground cavern. Mammoths waded in to drink, but could not climb out the steep banks, and eventually starved and drowned. Most of the bones were found within 20 feet (6 m) of the sinkhole bank, where they had been trying to climb out onto the bank of slippery red shale. Many nearly complete articulated skeletons were found, including very thin, fragile bones of the throat (the hyoids) that are rarely known in fossil organisms. Other indi viduals were disarticulated by the trampling of trapped mammoths, or by the circulating water in the natural hot spring. All of the individuals are Columbian mammoths, dated about 26,000 years ago, or near the peak of the last glacial maximum. Most are young adults or fully mature animals, and there are almost no juveniles. The mammoth fossils are found in many different layers of the deposit. This indicates that most were trapped as isolated indi viduals, wandering in and dying one at a time over a long period of time, rather than a single herd killed catastrophically. The site is so spectacular that it has been excavated each summer since 1975 and the proud residents of Hot Springs raised the money for a spectacular building to house the continuing excavation. It is a tourist attraction as visually spectacular and paleontologically significant as the famous "wall of dinosaurs" at Dinosaur National Monument. We think of mammoths as the giants of the Ice Age, but Pleistocene elephants also show some remarkable instances of dwarfing. Whenever mammals reach isolated islands where the ecology is entirely different, they frequently evolve into new species with unique adaptations. For large mammals like elephants, this means that island populations often become dwarfed. On the Channel Islands, just south of Santa Barbara, California, there were mammoths only 8 feet (2.4 m) high at the shoulder. In Malta and Sicily, cave deposits show elephants becoming progressively more dwarfed until they were only 3 feet high ( 1 meter) at the shoulder (Fig. 8.22). There were also dwarfed elephants in some of the islands of the East Indies. This was a common trend, since some Mediterranean islands and Madagascar had dwarf hippopotamuses, and during the Miocene, there were dwarfed rhinoceroses in North America (discussed in Chapter 14). By contrast, small mammals on islands tend to get large: there is an extinct island shrew that is almost 3 feet long! Why do animals change size when they reach islands? Several reasons have been suggested. For big grazing animals like elephants, a large area of open grassland is neces-

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HORNS, TUSKS, AND FLIPPERS particularly difficult (although they probably didn't do it often). Similar scenarios could apply to the elephants of Malta and Sicily, although the distances are greater.

Figure 8.22. Dwarf mammoths, such as this little fellow from the Spinagallo Caves of Sicily, were dogsized even in adulthood. (Photo courtesy University of Nebraska State Museum). sary. Most islands are much smaller and have a limited area of grassland, with a greater mixture of plants. Island dwarfs all seem to have reduced their need for large amounts of coarse, poor-quality grass, and shifted to browsing smaller amounts of high-quality leaves. We see something similar happening today, with the browsing forest subspecies of African elephant, Loxodonta africana cyclotis, which is much smaller than its grazing plains counterpart. The pygmy hippo is also a forest browser, rather than a grazer like the big hippo. In addition, most islands do not have the predators found on the mainland, so there is no need for the protection of large size. Such protection is costly in terms of energy needed and time for growth. By speeding up growth and stopping at a smaller body size, dwarf elephants reached a size suitable for their habitat and diet without excess energy devoted to growth. How did island elephants get there? Certainly, they were not carried there in canoes. Although some of these islands had direct land connections to the mainland when the sea level was lower in the Ice Ages, some did not. However, it turns out that elephants are excellent swimmers. Elephants have frequently been seen swimming very wide rivers, and in 1856 one elephant managed to swim to safety from a sinking boat thirty miles offshore! Donald Johnson has shown that during low sea levels, the distance between California and the Channel Islands was only 6.5 km (4 miles) at the narrowest point of the continental shelf. Waterloving elephants would smell the vegetation and see the dark shape of the island on the horizon, and find the trip not

THE MYSTERY OF THE MISSING MAMMOTHS During the peak of the last glaciation 18,000 years ago mammoths were found all over the Northern Hemisphere. Jefferson's mammoths dominated the temperate region in North America south of the ice sheet, and the ice-free regions of Siberia, Alaska, and n011hwestern Canada were a region Dale Guthrie calls the "mammoth steppe." It was a relatively dry, cold, windy region similar to the steppes of the high central Asian plateaus today. Nevertheless it was very fertile, with an enormous variety of grasses in a long growing season when the summer sun never sets. Consequently, there was an abundant fauna of woolly mammoths, large steppe bison, steppe horses (like Przewalski's horse, discussed in Chapter 11), hemionine asses (also discussed in Chapter 11), woolly rhinos, saiga antelopes, ibex, reindeer, camels, muskoxen, giant deer, elk, reindeer, lions, giant bears, sabertoothed cats, hyaenas, wolves and cheetahs. Likewise, the La Brea tar pits in Los Angeles show that 40,000 years ago, the region was temperate anti rich in wildlife, including Jefferson's mammoths, mastodonts, horses, camels, bison, antelopes, ground sloths, and many other herbivores. They were killed or scavenged by sabertoothed cats, dire wolves, giant lions, short-faced bears, and a variety of giant vultures. Similar abundant faunas of large mammals, or "megafauna," comparable to those seen in the East African savanna today, are found in many other localities throughout the world at the end of the last glacial episode. This megafauna then disappeared from the face of the earth between 12,000 and 9,000 years ago, and most of the animals became extinct between 11,000 and 10,000 years ago. Today only a pitiful remnant, such as bison and elk in North America, still survive. What caused this great extinction? Scientists have come up with a wide variety of possible explanations, but there does not seem to be any conclusive evidence yet. Most explanations fall into two categories: the effect of humans, or the effect of climate. The human hunting hypothesis, or "overkill" theory, says that the arrival of sophisticated hunting cultures wiped large mammals out within a few hundred years. Paul Martin, the chief advocate of this school of thought, points out that the mass extinctions occurred in Africa around 50,000 years ago, when sophisticated Paleolithic hunting tools appeared, and 32,000 years ago in Europe, when such cultures appeared there. Most archeologists believe that Paleoindians first crossed into North America about 13,000 years ago, slightly before the peak of the megafaunal extinction on this continent. Whenever humans reach islands, most of their endemic animals disappear, especially since they are unwary of human hunters. Mammoths are particularly well known as prey of these

THE ORIGIN OF JUMBO early hunters. A number of sites have been found all over North America, many with Clovis projectile points embedded between the bones, and butchering marks on the bones. At Lehner Ranch, near Hereford, Arizona, there were remains of at least eight mammoths, killed near an ancient watering hole. Thirteen projectile points were found among the bones, and a butchering site was found on a nearby ancient sandbar. Lubbock Lake, near Lubbock, Texas, has a mammoth kill site with Clovis points dated at 12,650 ± 350 years ago, and a bison kill site on a higher level dated 9,883 ± 350 years ago. Clearly Paleoindians had no inhibitions about hunting mammoths, and there is clear evidence they hunted mastodonts (the Kimmswick site mentioned above), horses, camels, and bison as well. However 32 other extinct large mammals, including ground sloths, have never been found with evidence of human hunting. If a human "blitzkrieg" occurred, we should see more evidence of hunting among the rest of the megafauna. Some animals which were clearly hunted (especially bison) survived in spite of the invasion of Paleoindians. Other critics of the idea are skeptical of the timing of these extinctions: if Paleoindian hunters were so efficient, they should have spread all over and wiped out the megafauna in a matter of a few hundred years, rather than over a thousand or more years. What about the many species of birds that went extinct, even though they were not obvious food for humans nor dependent on large mammals for carrion? Numerous other criticisms have been aimed at the overkill hypothesis, many of which are reviewed in Quaternary Extinctions, A Prehistoric Revolution, edited by Paul S. Martin and Richard G. Klein. Most of the critics of the overkill hypothesis favor climatic change as the primary cause of the extinctions. They point out that the beginning of the current interglacial period was a time of extreme climatic and vegetational change, and naturally the large herbivores (and their predators) were the most severely affected. There is abundant evidence from the pollen for this dramatic vegetational change, and it corresponds quite well with megafaunal extinctions. Critics, however, point out that throughout the Ice Ages there were many interglacials before the present one, and they did not result in mass extinctions. Only the interglacial associated with human immigration did. But it is becoming clear that the present interglacial was unlike any that had preceded it. The evidence shows that it was much colder and drier than any that had ever occurred before, with a great expansion of deserts. Both pollen and animal records show that plants and animals which now live apart once lived together. Ernest Lundelius and Russell Graham suggest that prior to 12,000 years ago, there was a greater mosaic of habitats, with a wide variety of animals overlapping in ranges. By contrast, today we have a few monotonous habitats which extend over long distances. Many animals living today have been driven out of certain

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areas and are now restricted to narrow niches, so they no longer overlap with other animals who once shared their habitat. This is particularly true of Dale Guthrie's "mammoth steppe" discussed above. Although these Arctic grasslands were cold and dry, they still managed to support a great variety of edible grasses. From examining food particles embedded in the crevices of their teeth, we can see that each large herbivore had a slightly different diet. By contrast, today's tundra has only a small variety of plants and many of these are new arrivals which have evolved toxins to make them inedible. Thus, it can support only a few muskoxen and caribou, not the great variety of megaherbivores once found in the "mammoth steppe." If the problem were the quality of the vegetation, then one would expect that only the most efficient herbivores would survive. Indeed, this seems to be true. The main survivors of the extinction event were cud-chewing ruminants such as bison, antelope, deer, and elk. By contrast, herbivores which use relatively inefficient hindgut fermentation, such as elephants, horses, rhinos, and sloths, are the main victims of the extinction. Critics of the climatic change hypothesis also worry about the lack of extinctions in the small mammals, particularly the rodents. If climatic changes were so important, wouldn't small mammals, which are much more sensitive to small changes in their habitat, show the most change? Instead, they seem to have responded mostly by changing their· ranges. Some are also puzzled by many instances of climatic changes that caused no extinctions, or extinctions that have no known association with climatic changes. In fact, to some authors familiar with extinctions throughout the entire Cenozoic, the late Pleistocene extinctions don't seem particularly remarkable and require no special explanation. In short, there is a tremendous diversity of explanations. Some scientists have cynically pointed out that with so many lethal events, it's a miracle that anything survived! As reviewed by Larry Marshall in the Martin and Klein book mentioned above, these explanations fall on a continuous spectrum, with human causes at one extreme and climatic causes at the other. It seems likely that both were important, and in some parts of the world one may have been dominant over the other; in many places both may have contributed simultaneously. Like many problems in science, the mystery of the Ice Age extinctions does not have a simple answer. Nevertheless, it was very effective because it left the world impoverished in horses, rhinos, and elephants, or other large mammals. In the next chapter, we will look at the two species of elephant that managed to survive to historic times. Unfortunately, they too are suffering now from humancaused "overkill" that threatens them with extinction as well.

Figure 9.1. The elephant-headed god of wisdom, Ganesha, is an important member of the Hindu pantheon. (Photo courtesy J. Shoshani.)

9. Kingdom of Ivory

BEHOLD THE BEHEMOTH And God said to Job, "Behold, the Behemoth, which I made as I made you. He eats grass like an ox Behold, his strength is in his loins, and his power in the muscles of his belly. He makes his tail stiff like a cedar; the sinews of his thighs are knit together. His bones are tubes of bronze, his limbs like bars of iron. He is the masterpiece of my animal creation; the One that made him furnished him alone with a sword! For the mountains yield food for him where all the wild beasts play. Under the lotus plant he lies, in the cover of the reeds and in the marsh. The lotus trees cover him with their shadow; the willows of the brook surround him. Behold, if the river overflows, he is not frighten~d; he is confident though Jordan swells even to his mouth. Can anyone capture him when he is alert, or snare him by his nose?" Job 40: 15-24 Nature's great masterpiece, an elephant, the only harmless great thing, the giant of beasts. John Donne, 1612 Since the beginning of recorded history, elephants have played an important role in civilization. They had been an important part of the lives of prehistoric humans, as we saw in the previous chapter. They were well known to the earliest Egyptians, who obtained ivory from Sudanese elephants up the Nile. The great civilizations of the Indus Valley had the elephant-headed god of wisdom, Ganesha (Fig. 9.1), deeply entrenched in their theology, and first used the Asian elephant as a beast of burden no later than 3500 B.C., and perhaps earlier. There are records of the Egyptian Pharaoh Thutmosis III, who conquered western Asia in the fifteenth century B.C., encountering the Asian elephant on an ivory hunt, and realizing for the first time that there were two kinds of elephant. Once elephants had become domesticat-

ed, though, they served several valuable purposes. In the Indus Valley they became important beasts of burden, although they were less important for this purpose in North Africa. However their most common use was as the tank of antiquity, a superweapon that could defeat armies of chariots and soldiers. War elephants were used this way in battles between armies of the Indus and Babylonia or Assyria, and especially by the Persians, who brought them into their own armies. King Darius III of Persia used elephants to fight Alexander the Great at the battles of Issus and Gaugemela, but he was defeated both times. Alexander had a l
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Figure 9.2. Artist's conception of the Battle of Zama in 202 B.C. Here the Romans under Scipio Africanus used tactics to panic and cripple the Carthaginian elephants under the command of Hannibal. (Courtesy J. Shoshani). civilization of North Africa, a group derived from Phoenican seafarers. Elephants were important in many battles with the Romans during the Punic Wars. In 255 B.C. the Roman general Regulus found his close-packed infantry beaten back by a steamroller of Carthaginian elephants. Hannibal engineered the greatest feat with domesticated elephants when he began his invasion of Rome with a contingent of 15,000 men and 37 elephants during the Second Punic War (219202 B.C.). Setting off from his base in Nova Cartago (now Cartagena) in Spain, he crossed the Pyrenees, southern France, and even forded the rain-swollen Rhone River on rafts without losing a single animal. But the most dangerous part lay ahead. Hannibal drove his men and animals over the cold, narrow, steep mountain passes of the Alps. Neither the African soldiers nor the tropical elephants were used to such conditions. Many froze to death or slipped on the ice into canyons and crevasses. Halfway across they were down to half their original numbers, and only twenty elephants. By the time they descended the Italian foothills to the valley of the Po River there were only 2,000 infantry, a few hundred horsemen, and eight elephants. However, Hannibal still had the advantage of surprise by attacking the Romans from their unprotected north, and the advantage of elephants, which Roman armies had still not

mastered. In a series of six victories he beat back much larger Roman armies and came within three miles of Rome itself. Each time the Roman horses panicked at the sight and smell of the strange beasts, and the Roman soldiers were too close-packed to avoid the onslaught. However, by the time he reached the Amo River his troops were exhausted and he was down to a single elephant, the one he rode himself. He abandoned his plans to capture Rome and returned to Carthage, victorious in battle, but unable to complete the conquest. In his final battle, however, Hannibal met defeat at the hands of a Roman army unafraid of elephants. During the Battle of Zama in North Africa in 202 B.C. the Roman general Scipio Africanus borrowed tactics from Alexander the Great (Fig. 9.2). He spaced out his ranks and ordered his archers to pick off the elephant riders. This caused the elephants to panic and turn, trampling their own men. The Roman soldiers charged in, hacking at the elephants' trunks and bowels, while armored horses and chariots rode in and inflicted wounds at close quarters. After Hannibal fled, the Romans forced the Carthaginians to pledge that they would never again train elephants for use in war. The Romans saw elephants as unreliable and obsolete weapons, but they did use them for entertainment in their

KINGDOM OF IVORY

Figure 9.3. African elephants (Loxodonta afrieana eye/otis) are smaller with slightly smaller, more rounded ears than the savanna subspecies. These rangers from the Belgian Congo in 1948 show how successfully they can be tamed, unlike their savanna relatives. (Photo courtesy J. Shoshani).

great amphitheaters. Elephants were frequently used in battles between animals, or between soldiers and animals, and the bloodthirsty Romans delighted in the slaughter of these great beasts. When Pompey dedicated his theater the cast included no less than 500 lions, eighteen elephants, and hundreds of armed men fighting to the death. In 54 B.C. elephants were opposed by Getulian archers, who blinded and tormented the great beasts. Some, however, retaliated by throwing shields with their trunks like deadly frisbees, or stampeding into the stands and killing hundreds of spectators. The Romans were so profligate in their wastage of elephants and most other wild animals that North African populations of elephants were wiped out very quickly (as were Mediterranean lions, giraffes, and zebras). By the third and fourth centuries A.D. there were no elephants north of the Sahara in Africa, and they were already a distant memory to the Romans of the late Empire. When Rome fell, the memories of elephants were lost in the barbarian invasion, and they were the stuff of mythology for over 500 years of the Dark Ages. The spread of Islam in the Near East and North Africa further prevented Westerners from any encounters with African or Asian animals. The arrival of an elephant in the court of Charlemagne in 802 A.D., a gift from Sheik Harun al Rashid, was the greatest zoological sensation in many centuries. Elephants began to be tamed and used in warfare by the Arabs, and by the sixteenth century they were reintroduced to European courts. As early as the seventeenth century Asian elephants were also introduced to the Chinese T'ang dynasty court. Most of the elephants in Europe were captured by the Holy Roman

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Empire during wars with the Turks and were Asian elephants. Consequently, Europeans thought there was only one kind of elephant, even when they hunted in Africa. The distinction between the Asian and African elephant had been lost. This was partly because most encounters with African elephants were on ivory hunts, and very few of the thousands that were slaughtered were exported alive to Europe. In 1825 a specimen reached the Jardin des Plantes (Botanical Garden and Zoo) of Paris where it was described by Cuvier as a species distinct from Elephas maximus, the Asian elephant named by Linnaeus. Reports from the ivory hunters led to accounts of the great pointed-eared elephant of the savannas, and another smaller round-eared elephant of the African jungle. There were also numerous accounts of dwarf elephants. The confusion was finally resolved by the zoologist Glover Allen in 1937. There was only one species in Africa, but there was a smaller forest subspecies, Loxodonta afrieana eyelotis, which is about 2 feet (60 cm) shorter than the plains elephant (Fig. 9.3). The supposed "dwarf elephants" were merely forest elephants with subnormal growth. As we saw in the previous chapter, there have been many instances of true elephant dwarfs in the geological past, but none are living today. African and Asian elephants are remarkably easy to distinguish, even to a casual viewer (Fig. 9.4A, B). The most obvious feature is the ears, which are large and angular in the African elephant, and smaller and more rounded in the Asian elephant. To some writers the shape of the ears of Loxodonta reminds them of the shape of Africa. African elephants also reach larger size and have a concave back and a broad sloping forehead; the smaller Asian elephant has a convex back and a more concave forehead, with more prominent knobby temples. The African elephant has four toenails on the front foot and three on the hindfoot, while the Asian has five and four respectively. At the tip of the trunk of the African elephantthere are two flexible "fingers" for grasping, and only one in the Asian elephant. Finally, all mature African elephants have tusks, but only some mature male Asian elephants are tusk-bearing. It seems surprising that such large and conspicuous animals would be so easily confused in people's minds until 1937. This is even more remarkable when we think of how long elephants have been part of our culture in zoos and circuses, as a symbol of the Republican Party, or in popular art and cartoons such as Dumbo. Perhaps the most famous of all captive elephants was a giant African elephant known as Jumbo. Imported to the Jardin des Plantes in Paris, and then the London Zoo in 1865, he was immensely popular in the press and with the Victorian crowds that flocked to the zoos in the heyday of natural history. Indeed, he was so familiar that "Jumbo" became almost a synonym for elephant in the popular mind. In the Zoo he was photographed again and again with people on his back and fed large numbers of sticky buns by the visitors. After almost twenty years, however, he became bad tempered, perhaps because of his boring life and too many buns. He was sold in 1882 for £2000

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Figure 9.4. Comparison of the African and Asian elephants. A. African elephants have larger, more angular ears, a rounded forehead, and a gently sloping back. (Photo courtesy A. Walker). B. Asian elephants have smaller ears, knobby temples, and a discrete hump on their shoulder. (Photo courtesy J. Shoshani.) to the circus entrepreneur P.T. Barnum who took him to America. This caused a great public uproar in England, where he was dearly beloved, but the Zoo needed the money and didn't need his trouble. Barnum then made Jumbo the centerpiece of his circus, displaying him all over the country to huge crowds. Tragically, Jumbo died in an undignified manner in a train wreck on September 15, 1885, when an unscheduled locomotive hit him as he was trying to cross the tracks. There was national mourning in both Britain and America. Barnum, however, was not one to throwaway an opportunity. Jumbo's stuffed body is now on display at Tufts University in Boston, and the skeleton is stored in the American Museum of Natural History in New York. BEHEMOTH BIOLOGY "There is an animal who laughs, weeps, gets drunk, plays practical jokes, falls in love, gets married, goes on honeymoons, doses himself with laxatives, poultices his wounds, pulls his aching teeth, and sometimes earns a living as lumberman, teamster, builder, postman, hunter, soldier, actor, acrobat, or even clever smuggler. Although he is not a man, he is recognized and

treated as another kind of human being throughout India, Ceylon, Burma, Siam, and other countries in the Orient. India's Brahmans even believe that the hathi, as they call him, prays at dawn and sunset when he stands in silence watching the sky with contemplative devotion. Buddhists and other Asiatics agree that this unique animal has a primitive religion of his own and thus treat him with respect and reverence" (Hallet, 1968: 82-83). Although they are a familiar cultural symbol to Westerners, we are still just learning about elephant biology. Surprising discoveries occur all the time. The best information comes from the African savanna elephant. Much less is known about the African forest elephant or the Asian elephant, because they are rarer and harder to study at a distance in the thick vegetation. Most of the peculiarities of elephant biology stem from their body size, which is the largest of any living terrestrial mammal (although not as large as some extinct rhinos discussed in Chapter 14, or many dinosaurs). The largest known elephant, killed in Angola in 1955 and now on display in the Smithsonian, weighed 11 tons (10,000 kg), and measured 13 feet (4 m) at the shoul-

KINGDOM OF IVORY der. Most male African elephants, however, weigh about 13,000 lb (about 6000 kg), and male Asian elephants weigh about 11,000 lb (5000 kg). Female elephants are even smaller, averaging about 6600 lb (3000 kg). Their scientific names are misleading. The Asian elephant was called Elephas maximus by Linnaeus because traditional lore held that they were the largest species. This may have been because the smaller forest elephant was the only known African elephant at the time. Because of their unusually large body size and tropical habitat, one of the biggest problems faced by elephants is keeping cool. They have such a large body volume compared to their surface area that they lose heat to the environment very slowly. Since they are warm-blooded they are already producing enough heat internally, and in their tropical habitat it is even harder to lose heat or avoid getting overheated. Thus, elephants must spend much of their time trying to keep cool, especially by swimming and taking mud baths. In addition, their enormous ears serve primarily as radiators of heat. Through their thousands of blood vessels and large, exposed surface area, they dump internal heat much more easily than does the skin of the body. These organs are remarkably efficient. lain Douglas-Hamilton recorded a 17°F (10°C) drop in temperature in the blood leaving the ears compared to the blood entering them. One healthy elephant reached a body temperature of 112.6°F (44.7°C) after running, the highest temperature ever measured in a healthy mammal. Most mammals die at temperatures even slightly higher than 100°F (37.7°C), and marathon runners can reach 105 OF before collapsing. Elephants also cool off by flapping their ears, and by sweating. Not surprisingly, the savanna elephant, which lives in the driest, most exposed habitat, has the largest ears. Those of the forest elephant and Asian elephant, who live with more shade and water, are smaller. Large body size has other tradeoffs. Once elephants have grown up they are protected from most natural predators by their size. As the head gets further off the ground it gives a better view of the horizon and potential predators, but also puts a distance between the mouth and the ground. Other large animals solved this problem with a long neck and an ability to stoop down (like giraffes do), but the large elephant head prevented developing a long neck. The unique proboscidean solution to this problem was the extension of the nose and the upper lip into a trunk. As we have seen, even the earliest proboscideans like Moeritherium had a tapir-like proboscis, and the earliest mastodonts almost certainly had short trunks. Once this feature had appeared, it proved versatile beyond helping with feeding off the ground. It also gives elephants the ability to reach the highest branches for food, or to reach in delicate places for fruits and leaves. It is powerful enough to uproot entire trees, but with over 22,000 muscles, it is also a very mobile, delicate organ. The prehensile finger-like tips of the trunk, equipped with fine sensory hairs, can pick up very tiny objects. It can serve as a snorkel when swimming and elephants are

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Figure 9.5. Cross-section of the skull of an elephant, showing the great number of spongy air passages, which lighten the skull. Note how deeply rooted the tusks, and the huge molar teeth are. (From Gregory 1951 ). famous for sucking water up into their trunks and then squirting it, either into their mouths or over them to· take a shower. The trunk has a capacity of over 2 gallons (8 liters). Trunks are used to throw dust over the body and reduce insect problems. They are important in social behavior for greeting, caressing and threatening, and for amplifying their vocalizations. Elephants have a keen sense of smell, both for recognizing other elephants and detecting danger. In thick brush, they raise their trunks like a periscope above the cover and sniff out the source of danger. They can detect some odors over 5 miles (8 km) away. With such long noses and large size, the elephant must have other specializations in the head as well. The huge skull is supported by very strong muscles and ligaments, and is full of hollow cavities of spongy bone to make it light but strong (Fig. 9.5). Most of the elephant's large skull is hollow and serves primarily to support the muscles of its neck and trunk. The brain is large, but buried deep inside the head, over a foot below the forehead. The brain size is slightly larger than would be predicted for an animal of such size and elephants have shown much evidence that they have complex social behaviors requiring great intelligence. Although it is not true that "an elephant never forgets," they

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Molar 3 is breaking up, near the end of its period in wear, while molar 4 is still not . fully in wear. Molar set 3 I

The molars develop in the angle of the jaw. They are laid down as individual lamellae that together make up the new tooth. As the lamellae are produced, they migrate forwards and upwards.

The crowns of the lamellae of molar 3 fragment and are spat out or swallowed. The roots are resorbed into the lower jaw.

Figure 9.6. The replacement pattern of teeth in elephants. The six molars in each side of the jaw erupt from the back in succession, and push the old teeth out the front. (From Eltringham 1991)

t A continuous remodelling of bone occurs in the lower jaw, allowing the molars to migrate forward through the jaw. This involves both the dissolution of old bone and the laying down of new bone.

do have an excellent memory, and circus elephants have been known to remember tricks after years of being out of practice. As we mentioned in earlier chapters, elephants have large, very specialized teeth which are replaced from the back of the jaw and pushed out the front as they wear away (Fig. 9.6). Although each side of the jaw ultimately has six teeth, only two or three are exposed at anyone time. The first two are small teeth, but the third molar is much larger and is dominant when the elephant is about seven years old. After about thirteen years the dominant tooth is the fourth molar, and the fifth molar does not appear until the elephant is in its mid-forties and in the prime of life and can pass on its genes to the next generation. By its fiftieth year the elephant is on its last set of teeth. As these begin to wear away the elephant has a harder time feeding and must rely on softer vegetation. In their sixties they are nearly toothless and usually die of starvation, although some may live until their seventies. The longevity record belonged to an Asian elephant named Rajah who died in 1988 at the age of 82. It served as the bearer of a sacred relic of the Buddha in Sri Lanka, a national treasure maintained in their holiest temple. As far as evolution is concerned, if elephants are past breeding age their fitness is no longer important. Hence, their teeth provide a natural timer on their lifespans (if poaching, accidents, or disease has not already killed them). Other than their molars, elephants have no other teeth in

their mouth except for one set of upper incisors, the tusks (Fig. 9.7). Tusks are made of ivory, which is a mixture of dentin (the soft pulp of your tooth) and cartilage fibers mineralized with calcium. They have no hard enamel surface like other vertebrate teeth, so they are relatively soft and easy to wear or break. However, they grow perpetually and very fast, so that wear or breakage is eventually replaced. This is important since elephants use their tusks for many purposes. They are most familiar as tools for fighting, but they are also used for digging and for clamping trees or other objects between tusks and trunk. They are almost certainly an indicator of age and social status, since males have the largest tusks which get even larger with increasing age and social dominance. The largest African males have tusks reaching up to 10 feet (3 m) in length and weighing over 200 pounds (90 kg) apiece. Female African elephants have smaller tusks. In the Asian elephants, most (but not all) males have small tusks, and females have tusks which do not protrude externally. The Sumatran subspecies lacks tusks altogether. To support these great teeth their heads are not only large, but have heavily reinforced sockets in front, and the tusk is usually embedded up to a third of its length. Given their huge heads and large body size elephants have surprisingly small mouths. This is even more surprising when one considers the enormous amount of food they must eat to stay alive. Unlike artiodactyls, but like perissodactyls, they have no special foregut chamber with bacteria

KINGDOM OF IVORY

Figure 9.7. The great bull elephant Ahmed became a symbol of conservation in Kenya. He died of natural causes in 1974 at age 55, and had tusks reaching 11 feet (3 m) in length, and weighing 150 pounds (68 kg) each. After his death, this fiberglass replica was built and now stands outside the National Museum of Kenya. (Photo courtesy J. Shoshani.) to break down cellulose and digest most of the vegetation. Consequently their digestion is very inefficient. Approximately 45% passes straight through without being digested, and they must eat about 16 hours a day, consuming about 300 pounds (140 kg) of food in that time. To avoid competition with other hindgut fermenters, like perissodactyls, they can eat just about any coarse vegetation, including roots, woody branches, and bark. Of course they prefer tender vegetation, new grass, flowers, and fruits when the rains make them available, but they can survive the dry season on coarse vegetation which is inedible to other mammals. Because of their large body size, elephants need considerable amounts of water. Most consume 19-24 gallons (7090 liters) of fluid a day. Consequently they spend much time around bodies of water, and during the dry season will dig holes in the river bed with their tusks to find water. However, their large body size also allows them to move long distances between their watering holes and the best feeding places in their daily cycle. Considering their size, elephants are surprisingly graceful in their movements. Their foot has a thick elastic fatty

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pad in the heel which allows them to move almost silently. Elephants literally walk on their toes. The pad also allows the elephant to cushion its great weight as it moves. They can negotiate steep inclines and rocky terrains because their foot flexes to meet the irregularities in the ground. However, their feet are tender and elephants do not like to move across sharp rocks. Their agility has been attested to by many people who have observed them move in and out of tent ropes without tripping or breaking them. Since they cannot see below them, they feel the ground ahead with their trunk before placing their feet. Their hind feet step exactly in the footprint of their forefeet. The normal walking pace is about 6 mph (10 km/hr), but elephants reach 15 mph (24 kmlhr) during a fast rolling walk. They can also charge for short distances at speeds of up to 18 mph (29 kmlhr). From all this it is obvious that most of the elephant's waking hours are spent eating, drinking or keeping cool. Most elephants spend only three to four hours a night sleeping, and a 65-year-old elephant will have spent 45 years of its life eating. Since they have no predators they feed continously both day and night. They sleep in short dozes, and are known to drop off to sleep while standing upright during feeding. During the heat of the day they will seek shade under a tree and get an hour or two of rest. But their bodies are adapted to almost continuous feeding, and sleep is less important. To sustain their need for food and water elephants have home ranges which cover 300-600 square miles, depending upon how rich the vegetation is. If there is a sudden rainfall they may travel as far as 20 miles (32 km) to reach a spot where an isolated shower has created temporary lush grass. The Asian elephant and African forest elephant have traditional pathways in their territories that are used by generations of elephants, called "elephant roads." These cut through the densest jungles and are used by all the other inhabitants of the forest. On the African plains elephants use traditional pathways to favored watering holes. Their most important effect, however, is in pruning back trees and beating back the growth of vegetation. Without elephant modification much of the savanna would become thickly overgrown with thorn scrub. The elephants open up the parkland and promote lower, more nutrient-rich vegetation, which in turn sustains a greater variety of wildlife. Norman OwenSmith has suggested that the loss of mastodonts and mammoths in North America at the end of the last Ice Age may have helped cause the extinction of the other large mammals, because their preferred vegetation was no longer maintained by elephant trampling. THE SISTERHOOD Elephants are very sociable herd animals. The main herd consists of ten to fifty animals ruled by the oldest female, or matriarch. She uses her years of experience to guide the herd to the best feeding grounds and is always responsible for keeping watch and frightening off threats. The rest of the

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Figure 9.8. A. Bull elephants in musth have a swollen temporal gland (between the eye and ear), which exudes a viscous liquid. Their hind legs are damp where urine has dribbled, and their penis is semi-erect. The curved trunk and the ears held high are also signs of musth. B. African elephants mating. (Photos courtesy J. Shoshani). herd will consist of her sisters, daughters and their immature offspring. On occasion gatherings of more than a hundred elephants are reported, but these are certainly temporary assemblages of smaller herds crowding together for a critical source of food or water. After the herd reaches a certain size, some of the subadult females might separate and form their own herd. As a result most of the elephants in a given area tend to be closely related. Because of this relatedness, there is strong social cohesion among elephant herds. In her book Elephant Memories, Cynthia Moss described how elephant herds show great excitement during reunions. The elephants run toward one another, touch trunks and click tusks. They rumble, snort, and make many other noises that Moss interprets as joy. Male elephants, on the other hand, leave their natal herd when they reach puberty and tend to congregate in small, ephemeral bachelor herds. Once males become mature they are driven further and further away from the herd until they are no longer part of it. Younger males tend to trail the herd at a distance, feeding on the periphery of the females. Although these bachelor herds are temporary and do not normally mix with the females, they do come to the aid of other elephants when threatened. Bull elephants have a condition known as "musth," when high levels of the male hormone testosterone trigger aggressive behavior and sexual activity (Fig. 9.8A). Musth is apparent from the secretions of the temporal gland under the eye, which swells during their periods of aggression. They also dribble urine during musth, and have a different posture and way of flapping their ears that signals their sexual state to other elephants. During mating season each female is in heat for only a few days at a time. Bulls must travel constantly to find the receptive females within their home range. Their large size allows bull elephants to travel long distances in search of receptive females, and once they arrive

they must compete with other males. After an initial threatening charge to scare off more timid males, bull~lephants will spar, shoving head-to-head and wrestling with trunk and tusks. Only the largest males have a good chance of copulating; the smaller and weaker males are left out. This selection of size is responsible for the much larger size of males. The males will approach a female herd, but if no female is in heat the matriarch will drive them off. The males go through a complex courtship ritual, gradually coaxing the female to allow them closer. The male may attempt to mount the female a number of times before copulation occurs (Fig. 9.8B). The male's penis grows to over 4 feet (1.3 m) in length during erection, and weighs over 60 pounds (27 kg). Its distinctive S-shaped curvature when erect is due to special muscles that allow it to move independently of the pel vic thrusts. This is necessary because the female's vulva is situated well in front of the hind legs. The male straddles the female's back, edging his hindquarters forwards until he is nearly squatting. The penis thrashes around, beating her belly until it finds the vulva. Then it hooks onto the opening, touching her 17 ~inch (43 cm) erectile clitoris. The pair may copulate only once or twice for a minute or so. After copulation they may spend a few more hours together, although eventually the male drifts off. Males have no part in raising their offspring, either. As they wander from herd to herd they prevent the populations from becoming too inbred, since the herds are composed of closely related females. Elephant populations have a reproductive cycle which is strongly controlled by the seasonal climatic cycle. During the dry season the population is under stress and the cows cease to ovulate. One or two months after the rains have returned the females have built up their body fat again and are ready to breed. By the latter half of the rainy season the females are in heat; they may continue in this condition during the early part of the dry season.

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Figure 9.9. Young elephants are closely protected by their mother, aunts, and sisters as the herd moves from place to place. (Photo courtesy A. Walker). Elephants have the longest gestation period of any mammal: 20-22 months, or almost two full years. This is much longer than it should be for animals of their body size, and even longer than the gestation of whales (see Chapter 6). Some have argued that this long gestation is necessary so that the young are born at the start of the wet season when they have the best chance of survival. However, most baleen whales compress their gestation time into twelve months, even though they may weigh one hundred times as much as elephants. Many of these whales (such as the gray whale) also have seasonal migrations, calving in the winter in warmer, temperate waters and spending summers in the rich polar feeding grounds. So the seasonal explanation for long elephant gestation does not completely explain why they take two years instead of one. Females do not reach sexual maturity until they are ten to twelve years of age, and this may be delayed by repeated droughts and bad conditions. Once she starts to breed she may produce a calf every three to four years, although bad times will space out the breeding further. Female elephants reach their peak fecundity between 25 and 45 years of age. This is the slowest reproduction rate of any living mammal, a disadvantage when their populations are under such extreme poaching pressure. It will take centuries to replace the elephants that have been lost in just the last few years, even if all poaching stopped immediately. When the female is in labor the other members of the herd assist her and even serve as "midwives," removing the fetal membrane. When the calf is born it is covered with fine brown fur that persists for six months. The mother, aunts and

sisters immediately use their trunk and tusks to lift the baby to its feet and help it stand and walk. They all watch over the young collectively, since the babies are very vulnerable to predators. Among Asian elephants almost a quarter of the calves are lost to tigers before they reach a year in age. At birth the African elephant weighs about 265 pounds (120 kg) and the Asian elephant about 220 pounds (100 kg). It is already over a meter in height, and after about 48 hours the calf is able to walk alongside its mother and follow the herd (Fig. 9.9). It is just tall enough to reach its mother's single pair of nipples which, like in humans and sirenians, are located just behind the front limbs. The calf does not use its trunk to suckle, but rolls its head back to suckle with its mouth. The mother keeps it close to her side, guiding it back to refuge under her belly and between her legs with her trunk. Occasionally another female will "babysit," and if she is also producing milk, suckle the calf as if it were her own. The young are so playful and carefree that the females have to keep constant watch over them and constantly steer them away from trouble. In this way the young are integrated into the social network of the herd. Elephants have such a complex social organization that it takes many years for the young to learn all they need to survive and fit into the network of relatives. Matriarchal females which have reached menopause continue to guard the herd, taking care of the young, and using their accumulated wisdom to ensure the survi val of their daughters. In his book Among the Elephants, lain DouglasHamilton describes the first hours of a newborn:

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HORNS, TUSKS, AND FLIPPERS "It wasn't until evening that I saw Leonora's family again. To my great delight Slender Tusks had with her a tiny blue-brown calf, covered in red wavy hair; it had not been there in the morning. The calf peered out at the unknown world from under her belly. His head had the elongated squashed look of newborn elephants with a short trunk, and his two ears which resembled maps of Africa hugged the contours of his body in a perfect fit. His toenails, five on each forefoot and four on each hindfoot, looked as if they had just been scrubbed. He was a male with clearly visible sex organs. No blood was visible on the calf or the mother, so I knew the birth must have taken place before a shower of rain which had fallen several hours previously. The calf still appeared to be very unsteady on his feet. His legs were weak and he placed the round soft pads gingerly as if they hurt when he walked. With eyep half shut, embedded in deep wrinkles, he moved his trunk up and down exploring for a place to suck. Eventually he found a teat between his mother's forelegs and made a hesitant attempt to suck, but every so often the effort was too much and he fell down. Each time Slender Tusks nudged him gently upright with her forefoot and trunk. The calf then wobbled over to his elder sister who was about four-and-a-half years old, and she turned towards him and extended her trunk. The calf nuzzled under her right foreleg for a nipple; evidently he was too young to know how to identify his true mother but he showed a strong desire to find a suitable object to satisfy his sucking instinct. His sister was sympathetic and spread her forelegs and tried to straddle him. The calf promptly collapsed, regained his feet and wobbled back to Slender Tusks, who paid little attention to him as he explored her underbody with his trunk held rigidly out in front of him. She walked on and he immediately collapsed. She turned round, extended her trunk and growled; Leonora and the others answered. The calf then stood still with his eyes closed, swaying gently for about ten minutes" (Douglas-Hamilton, 1975).

Within a year, the calf will be eating vegetation, although it may suckle for two or three more years if the mother will permit it. Once the calf is weaned it begins to play with other young calves and is not watched as closely by the mother, who may be pregnant again. Young elephants grow very rapidly, reaching the weight of 2200 pounds (1000 kg) after only six years. After about 15 years their rate of growth decreases, although they continue to grow throughout life. Males also undergo a spurt of post-pubertal growth between

20 and 30 years of age that builds them up to full breeding size. Although they can live 60 years, half of the elephants born in the wild die by 15 years of age, and only one-fifth survive to 30. This survival rate has declined due to extreme poaching. Elephants have very complex social behaviors, befitting animals of such great intelligence. They convey many visual messages with the posture of their head, ears, and trunk, and also communicate by touching each other with their trunks. Although it is harder to observe, they clearly recognize each other by smell as well, and use smell to determine many things about their herd and the environment. The mother-infant bond is communicated primarily by touching and caressing with the trunk. When elephants greet one another they often touch each other's mouths with the tips of their trunks. Elephants also communicate with a variety of sounds. Their primary noises are deep rumbling noises, two-thirds of which are below the capacity of human hearing. Recent research has focused on their use of extreme low-frequency sound to communicate not only with their immediate herd, but also with herds miles away. Low-frequency sound has a great advantage over higher frequency sound in that it travels the longest distances and is not audible to mahy predators. Elephants vocalize more frequently in thick bush where they cannot see one another and must use sound to keep track of the herd. Researchers have made sonograms of these calls and found that elephants have many complex subaudible vocalizations which convey a much richer language than was previously realized. In addition to these sounds elephants also bellow and scream, using their trunk as a resonating chamber. The loud trumpeting so familiar from movies is actually an alarm call, emitted only when the elephant is excited or threatened, or widely separated from the herd. Normally elephant herds move single-file, with the matriarch leading the way, and spread out when they reach feeding areas. At the first hint of danger the adult females all cluster together around the calves for protection, waving their trunks in the air to find the scent of the threat. Once they see the threat the matriarch will advance, threatening with her outstretched ears, pointing trunk, and dust-stirring feet (Fig. 9.10). Other adult females may do the same thing, and the sounds may bring males from the vicinity to help out. Only if the threat persists and the elephants become very agitated, or if the threat gets too near the young, do the elephants charge. Once they do so, they are capable of trampling or goring people or lions on the ground, or rolling and crushing a vehicle. However most of the time elephants are very docile and will ignore or flee from people if given the chance. Most instances of people being killed by elephants occur when they get too close, or ignore the fact that if they approach one "lone" elephant, there are many others nearby in constant communication with it to help out. People who are aware of the ways of elephants and exercise suitable caution are seldom in danger.

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Figure 9.10. (above) This matriarch is demonstrating the threat posture, with ears flared and head down, as she stirs up dust. Only if the threat persists does she charge. (Photo courtesy A. Walker). Figure 9.11. (right) Elephants inspecting the bones of one of their fallen comrades. They sniff and toss the bones around for some time, and may be able to pick up the scent of its owner from the tusks. (Photo courtesy J. Shoshani). The tales of big-game hunters are full of accounts of "rogue" elephants which attack humans without provocation. Most of these stories are myths, because it is rare for any elephant to be alone for long. Lone elephants are usually sick or diseased and their erratic behavior is often due to some nagging problem which causes them to go mad. Old elephants which no longer have functional molars, or who are too arthritic to keep up, may also be found alone, but they are seldom threatening. Another myth is the tale of "elephant graveyards." There is no scientific evidence to support the ideas that elephants migrate to a specific place to die. Large accumulations of bones are probably due to slaughter by ivory hunters, or due to flash floods washing large collections into a common area. It is also possible that a large concentration of elephant bones may be found around a dried-up watering hole, where starving, thirsty elephants all had to collect around the last water before they succumbed. However elephants do have a surprising fascination with death that has been documented by many observers. If they come upon the corpse or bones of a fallen comrade, they may spend a long time smelling and inspecting it (Fig. 9.11). lain Douglas-Hamilton described it this way:

"It seemed at first that they would pass the corpse. Then a breath of wind carried its smell directly into their trunks. They wheeled en masse and cautiously and deliberately closed in on the body. Shoulder to shoulder the front rank drew nearer, ten trunks waving up and down like angry black snakes, ears in that attentive half-forward position of concern. Each individual seemed to be reluctant to be the first to reach the bones. They all began their detailed olfactory examination. Some pieces were rocked gently to and fro with the forefeet. Others were knocked together with a wooden clonk. The tusks excited immediate interest; they were picked up, mouthed, and passed from elephant to elephant. One immature male lifted the heavy pelvis in his trunk and carried it fifty yards before dropping it. Another stuffed two ribs into its mouth and revolved them slowly as if he were tasting the surface with his tongue. The skull was rolled over by one elephant after another. To begin with, only the largest individuals could get near the skeleton, such was the crush. Boadicea arrived late, pushed to the centre, picked up one of the tusks, twiddled it for a minute or so, then carried it away, with the blunt

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Figure 9.12. Asian elephants loading lumber onto a truck in Sri Lanka. Note the mahout on its back, directing the elephant with the hooked stick. (Photo courtesy J. Shoshani.) end in her mouth. The rest of the group now followed, many of them carrying pieces of the skeleton, which were all dropped within about a hundred yards. Virgo was the last to leave, and catching sight of me she came close by with a rib in her mouth, and waved her trunk as she went past. It was an uncanny sight to see those elephants walking away carrying bones as if in some necromantic rite" (Douglas-Hamilton, 1975). Since the tusks are the only skeletal elements that other elephants could have touched or smelled when the owner was alive, perhaps the herd remembers the dead individual best from its tusks. Elephants are also known to bury their dead on occasion, piling them up with branches and sod. There are also rare instances of elephants burying dead predators, or even humans they thought they had killed. GOD AND SLAVE Unlike African elephants, which have rarely been domesticated and avoid human contact, the Asian elephant has long been a part of human society in southeast Asia and India. Amazingly detailed accounts of elephant life and habits can be found in the Rig Veda from 2000 B.C.

Elephants are revered and sacred in most southeast Asian societies, and one of the chief deities in Hindu mythology is the elephant-headed god Ganesha (Fig. 9.1). Ganesha guards the doors of the shrine to Shiva, since he has the power to remove obstacles (to true worship). He is the god of intelligence, and hence the patron of students and teachers. Next to domesticated cattle and water buffaloes, elephants are the most important domestic animal in this part of the world (Fig. 9.12). Yet unlike other domesticated animals, there have been only limited attempts to breed them in captivity. They have not been changed by selective breeding as have cattle, goats, or sheep. Most elephants destined for domestication must be caught in the wild. This has meant a diminishing supply of elephants, which ironically threatens the culture that is based on their labor. The use of elephant labor to bulldoze down the great forests has also diminished their habitat. But the biggest problem has been the population explosion in southeast Asia which has driven the elephants into smaller and more remote ranges. Even though it is considered sacred, the Asian elephant is now an endangered species, with fewer than 40,000 left in the wild. This is about a fourth of the approximately 150,000 found in the wild in 1940. Most live in India, Sri Lanka (Ceylon),

KINGDOM OF IVORY Myanmar (Burma), Thailand, Kampuchea (Cambodia), and Laos, with remnants in Nepal, Bangladesh, Vietnam, Malaysia, Indonesia, and southern China. The decimation of the herds has been most severe in southeast Asia. Laos and Cambodia once had about 20,000 elephants each; now they have no more than 2000, due to poaching by hunters with automatic weapons from southeast Asian wars. The Malay Peninsula had 5000 elephants in 1940, and now has less than 900. India once had 60,000 elephants, but the herds have now dropped below 20,000. Several methods of hunting and capture have been used. When elephants were more abundant thousands of men would be used to stalk them and encircle them in the forest, usually around favorite watering holes during the dry part of the year. A strong wooden fence in the shape of the letter'A' , called a keddah, was built around the watering hole. The men would slowly close their circle around the elephants, drawing in tighter day after day. It was important not to panic them, because they could tum and break through the lines if they were alarmed. When the circle had closed around the open end of the 'A' -shaped enclosure, the men would stampede the elephants into the opening. Once the elephants had reached the narrow funnel at the top of the 'A', a gate located at the crossbar of the 'A' would be dropped, and they were trapped. After celebrating the weeks of work on the elephant drive, the men would then begin to lasso individual elephants by the feet in preparation for training. In Laos, where the Suwei tribe still lives as an elephantbased culture, hunting is done differently. Elephants are too scarce now for a complex roundup. Instead the Suwei ride their own domesticated elephants and herd the wild ones like cowboys, using a long pole with a noose at the end to ensnare the elephants' feet with thick buffalo hide ropes. Once they are caught, they are tethered between domesticated elephants and brought back to camp. There, they are tied to large trees and the taming process begins. After several days of rage while the captive screams and pulls at its tethers, it begins to calm down. At this point, the men begin to approach it, touching and slapping it to get it used to human contact, and talking to get it accustomed to human voices. Soothing stroking, feeding, and watering alternates with pricking the tender trunk with a sharp pointed stick (the hawkus) to teach it to obey. After several weeks the elephant no longer needs to be punished, but responds to the positive treatment and goes along with its master, the mahout, willingly. The men pat and stroke the newly tamed elephant, chanting, "Good girl! Remember our lessons well, or we will feed you to the crows." When the elephant is about five years old and cutting its ties with its mother, the trainers can teach it to carry loads. With fruit and reassurance it is steered into a tight pen, like the bullrider chute in the rodeo. There the mahout climbs onto its neck and holds on tight as the elephant tries to throw him off. The tight enclosure, the presence of calm, tame elephants, and frequent food rewards gradually soothe it. After

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it has become used to the mahout riding its neck, the next step is getting it used to loads on its back. A heavy block of padded wood, heavier than the elephant can support, is gradually lowered onto its back. The elephant struggles, and the block is lifted away, but each time it is lowered, it struggles less and less until it is exhausted. This is repeated over a course of weeks until the elephant struggles no longer. Still, the training is not completed. It may take ten years of working with its mahout before it becomes completely tame and responds to dozens of verbal commands. The elephant also learns to respond to the pressure of the mahout's legs behind its ears to cause it to turn or to kneel. After a few years the elephant may be given light loads to carry, and these are gradually increased in weight. However the loads rarely exceed a few hundred pounds because elephants are not particularly strong at carrying things on their backs. Their main strength lies in pulling dead weights that dozens of men could not lift. After the years of training the elephant is put to work in the forests, felling and transporting huge logs of teak and mahogany. They may put in over thirty years during their working Iives. Since their lifespan is like that of humans, the mahout and the elephant may grow old together. They work nine months a year, resting during the hot months of spring. In a year a typical elephant could transport 100 tons of timber from stump to the floating-point in the river. Thus, in thirty years, a typical elephant will have completed over 20,000 hours of labor and removed about 3000 tons of wood. Sadly, this efficiency at timbering is the largest cause of deforestation in southeast Asia, which diminishes wild elephant habitat. Today the elephant is being replaced by mechanical methods. The diminishing numbers of wild elephants has meant that cultures dependent upon elephant labor are vanishing, along with the elephants they hunted and trained. In Thailand many of these tribes exhibit their elephants in the great Surin Roundup, held each November. This is a grand spectacle of elephant races, elephant soccer, simulated elephant hunts, and a tug-of-war between 100 soldiers and an elephant (which the latter always wins). Between the threeday roundup and the rides and pictures for tourists that accompany the trip, the elephant drivers earn most of their income for the year. Clearly, this way of life cannot sustain people much longer. The days of the elephant as the main workhorse in Asia are numbered. BLOOD AND IVORY Pound for pound, ivory is one of the most valuable natural organic substances known to mankind. It is hard and durable, but easy to carve and relatively flexible. It can withstand extreme changes in temperature, and polishes to a high gloss. Walrus ivory and other types have been used in some parts of the world, but elephant ivory (particularly the ivory from large tusks, which has the best grain and the largest quantity) is preferred. Some of the oldest known artworks are fertility symbols carved out of mammoth ivory by our

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Figure ·9.13. Carved ivory for sale in Douala Town, Cameroon, Africa. (Courtesy J. Shoshani). prehistoric ancestors. Ivory was carved and valued by the Egyptians, Phoenicians, Assyrians, Greeks, and Romans. With the spread of Christianity ivory was used to make ceremonial diptychs and triptychs, the intricately carved covers of ecclesiastical prayer books. It was particularly valued for lavishly carved boxes and caskets. Ivory carving reached its highest artistry in the Far East. For centuries the Chinese have carved a wide variety of remarkable objects, including the famous "Chinese balls," where two or three nested concentric balls were carved from a single piece of ivory. The Japanese ivory carvers are particularly famous for the little figurines known as netsuke, which were used as toggle fastenings for clothing. Ivory became valuable for inlay on tables, in billiard equipment (60,000 billiard balls a year in the 1920s), in piano keys, as well as in statuettes and jewelry (Fig. 9.13). In the 1970s, ivory's steady value was a hedge against inflation, stockpiled and traded like bullion. With such versatility and scarcity, it is not surprising that the price of ivory was as much as $114 a pound in 1989. With ivory's great appeal and value few people seem to think about its source. Each ivory object requires the slaughter of a majestic intelligent creature which may have lived for forty or fifty years and survived many natural disasters. Most of the ivory carvers are now in Japan or Hong Kong. Most have never seen a living elephant, and some are even unaware from whence ivory comes. Others believe that all their ivory was found in the fields of Africa in "elephant graveyards," or that elephants shed their tusks once a year like deer shedding antlers. Yet the effects of the demand for ivory are appalling, and

the worst decade of all was the 1980s. Gangs of poachers, armed with automatic weapons, strike across the borders of game reserves with ruthless efficiency, gunning down whole herds in a matter of minutes. They kill indiscriminately, including little calves with tusks only the size of your finger. Then they hack off the front of the head with axes or chain saws and leave the rest of the carcass to rot. They are finished in a matter of minutes, and they can smuggle the tusks to a number of countries and unscrupulous middlemen who operate on the scale of the cocaine barons of South America. The slaughter has gotten so bad that most parts of Africa are littered with the rotting carcasses of elephants, covered by vulture droppings (Fig. 9.14). In some game parks there are more carcasses than living elephants left, and the elephant has been wiped out from most areas not within game parks. lain Douglas-Hamilton estimates that of 1.3 million elephants in Africa in 1979, only 625,000 (less than half) remained a decade later. Kenya, a country which has strict ivory quotas and relatively strong game warden forces, has lost 85% of its elephants (from 130,000 in 1979 to about 16,000 in 1989). If the numbers were not appalling enough, one only need read Peter Beard's The End ofthe Game, with its pages after pages of photographs of elephant skeletons and carcasses, to realize the horror of the situation. It is made much worse by the fact that the poachers tend to kill mostly larger, older elephants with the most ivory. These are the older matriarchs whose accumulated wisdom and experience of 40 or 50 years guides and protects her herd of daughters and sisters. Because of competition from older bulls, males do not begin breeding until they are almost 30-but now nearly all the older prime bulls are dead. In most parts of Africa it is impossible to find an elephant over the age of 30. In Tanzania's Mkomasi game preserve a 1988 survey found no adult males, although they used to comprise almost half of the herd. Without these older individuals the social fabric of the herds is completely disrupted. The surviving elephants are extremely secretive and wary of humans, feeding mostly at night and hiding in dense forests in the day. The oldest female in the herd may now be only a subadult teenager. Breeding patterns are particularly disrupted. A recent study in Tanzania's Mikumi National Park showed that 72% of the elephant herds were without adult females or composed completely of young orphans. Besides the horrible impact this has on elephants, the impact on the entire African ecosystem is also severe. Because of their body size elephants have a dominant role in the ecosystem. It is well known that they are responsible for spreading seeds through their droppings. During droughts they dig out water holes with their tusks, which helps other animals survive. But their most important effect is their ability to open up the vegetation through their heavy feeding, trampling, and uprooting and toppling trees. In central and western Africa, this creates open spaces in the dense rain forest that allows different vegetation to grow. This, in turn, supports a much greater variety of wildlife, including

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Figure 9.14. Africa is now a killing field of poached elephant carcasses, with only their heads hacked apart to retrieve the ivory tusks. This cow is long dead and bloated and covered with vulture droppings, yet her orphaned calf still stays nearby, eventually to die of starvation. (Photo courtesy J. Shoshani.) rare antelopes and gorillas. In East Africa elephants tum closed woodlands into open brush, permitting grasses to grow and savannas to expand. This is largely responsible for maintaining populations of zebra, wildebeest, and gazelles, instead of having just a few forest antelopes. But economics, not conscience, dominates the market for ivory. The Africans who live among the elephants are under pressure from their own population explosion and threatened starvation to exploit any resource available. Five hundred years ago Africa had about 16 million people and 10 million elephants. Today the human population in Africa numbers over 740 million, and less than half a million elephants. The human population is growing in some countries at 4% a year, or about 50,000 new people every year, the fastest growth rate in the world. These people have settled and cultivated nearly all the once wild lands between the parks, and crowd out the wildlife. For most poor Africans who might make $20 a month (if they can find a job), a single tusk is worth $6 a pound, or about $120 per dead elephant. Since they have always viewed elephants as pests who raid their crops, few poor Africans shed a tear over the death of elephants. The economic and cultural incentive for poaching has been aided by Africa's political problems. Frequent African civil wars have flooded the continent with cheap AK-47 assault rifles and other automatic weapons so that gangs of ruthless poachers can gun down elephants or overpower the lightly armed park rangers. In Angola, the civil wars have even been financed by ivory smuggling. The genocide in Uganda caused by the madman Idi Amin and his successors not only slaughtered humans, but also reduced the elephant population from about 18,000 to fewer than 1900 in under a

decade. In some parts of Africa the rangers had to become small armies and operate on a "shoot to kill" policy. Political corruption is also a big problem in impoverished Africa. Many African government officials have been caught trading in illegal ivory, or accepting bribes to cel1ify it as legal. In Tanzania a member of the parliament, Alli Yusufu Abdurabi, was discovered with 105 tusks and is now serving a 12-year sentence in prison. Indonesia's former ambassador to Tanzania, Hoesen Yoesoef, was found trying to smuggle over 200 tusks out of the country. Other smugglers have included a Catholic priest, a leading local journalist, and officials of the Iranian and Pakistani embassies. When some countries crack down on ivory trading or increase their antipoaching efforts, the smugglers just shift to new places or new means of transport. For years most of the ivory poached in eastern Africa has been shipped through tiny Burundi (on the border of Tanzania and Zaire), a country that has no elephants and yet certifies the tusks as originating from that country. So much ivory was moving through that officials registering it had room after room filled to the ceiling with stacks of tusks. Fortunately the new government that came into power after a 1987 coup seems more sincere about halting additional imports. This only diverts the smugglers southward. Most of the ivory poached in southern Africa (Angola, Botswana, Zambia, Zimbabwe, Mozambique) goes through South Africa which has few elephants of its own. From there it is smuggled by any available means of transportation-merchant ships, jetliners, even single-masted dhows-to Singapore, Hong Kong, Taiwan, or Japan. Customs officials have found it in crates marked BEESWAX, BONE MATERIAL, MARBLE or even JEWELRY. When officials of the

194

HORNS, TUSKS, AND FLIPPERS

CITES (Convention on International Trade in Endangered Species) adopted a system of registering and marking tusks, they left a loophole for carved ivory. The tusks were then diverted through Dubai in the United Arab Emirates so they could be lightly carved and enter Hong Kong as legal ivory. Between 1979 and 1987, Hong Kong imported more than 3900 tons of ivory legally (representing the death of about 400,000 elephants), but this is only the tip of the iceberg. Much more comes through illegally. Hong Kong is the crossroads of the ivory trade. Government figures show about 675 tons of ivory stockpiled in about 375 shops. However most of it is controlled by about ten families or syndicates. The dean of ivory traders is K.T. Wang, who has never been to Africa, and has seen a live elephant only once in the Paris zoo. In February, 1989, he helped Tokyo's largest trader, Koichiro Kitagawa purchase five tons of Sudanese ivory (mostly poached from Kenya) at $1 million. In 1987 he arranged the sale of 26 tons of Congo ivory by the Osaka trader Kageo Takaichi, a $3.5 million shipment of 2052 tus~s. The day before the ban on ivory without CITES documentation, he shipped ten tons of ivory from Burundi on a Boeing 707. Officials examining the ivory found evidence of automatic weapon bullet damage, and many had bone attached, indicating that they had been rapidly hacked out of a carcass. Some even showed signs that they had been buried by smugglers trying to hide them. Once the ivory is obtained (legally or illegally), factories cut it down rapidly. The Kee Cheong Ivory factory has a brochure which claims that it produces 30,000 ivory bangles, 40,000 necklaces, and 100,000 rings every month. Its squalid sixth-floor shop hums with the sound of high-speed drills; the air is choked with ivory dust. Tusks registered in Singapore and Sudan are stacked up like firewood. In Japan 30,000 people draw their living from the ivory trade, although more than half of the trade is controlled by only two men. Before 1980 Japan was awash in illegal ivory laundered by bogus documents. But international pressure, and the realization that the extinction of the elephant would mean their own extinction, has reined in the Japanese ivory traders. Since 1985 Japan has complied with CITES rules. Its imports have fallen from 475 tons a year in 1983 and 1984 to 106 tons in 1988. Before the June 19, 1989 ban they impolted 29 tons, and have now agreed to a "zero quota" for ivory imports. However, the carvers have a stockpile good for several years. For years CITES has tried to restrict ivory trade with little success. Whenever regulations went into effect in one country, other countries with less scrupulous dealers and more corrupt officials took up the slack. Most of the funding for CITES has come from ivory trading countries, and some directly from ivory traders themselves. It was as if the fox were asked to guard the chickens! Some countries have had fairly effective protection of their elephants, and their herds are actually growing. These countries (Zimbabwe, Botswana, Mozambique) oppose a total ivory ban because they claim they must cull their excess elephants to keep popula-

tions under control. The culls bring much valuable revenue to their fragile economies. However, the exceptions from a total ban on ivory has simply let the smugglers claim their stocks were from countries where it is still legal. Political momentum to save the elephant has been growing, however. The year 1989 was a red-letter one for elephants. On June 1, Kenya and eight other African countries called for an international ban on all ivory trading, and on June 5 the United States banned all ivory imports. This was followed by bans by the European Economic Community on June 9, Japan on June 15, and Hong Kong on June 16. Finally, on October 17, CITES declared the African elephant an endangered species and banned all world trading as of January 18, 1990. Zimbabwe, Botswana, and Mozambique filed reservations to CITES's listing, so they plan to continue selling ivory-if any country will accept it. By 1992, the world market for ivory has collapsed. A survey of the 15 largest ivory dealers in the U.S. found no buyers for existing stocks, despite deep price discounts. Similar declines have occurred elsewhere. "In Africa, where ivory was selling for $200 a kilogram, prices have fallen to $2 to $5 a kilo," said Jim Leape, vice president of the World Wildlife Fund. Although this is extremely encouraging news, the war is not over. The short-term collapse of the ivory market may eventually break down the political will which led to the ban. In 2000, the southern African countries tried to have the ban loosened, and allow sales of their existing stocks of ivory to help fund their very effective anti-poaching policies. However, the rest of the African nations resisted this effort to weaken the ban, and it was defeated (Fig. 9.15). If ivory again becomes legal the same problems with poaching and corruption are sure to reappear. It is possible to have a legal ivory market relying only on elephants culled from oversized herds, or from natural deaths. As lain Douglas-Hamilton has pointed out, this would be the most efficient way to maintain a supply of ivory. The oldest tuskers have the largest amount of ivory, putting on the most each year, and many have outgrown their reproductive age and are reaching the age where they would starve from loss of teeth. The benefits of this system for the African countries are manifest: money for their local people, employment for game rangers, and tourists to see the wildlife, which are the steadiest source of income for many African countries. The fate· of the African elephant, however, finally boils down to one issue: human population control. No matter how efficient the ivory ban and the management of refuges becomes, the population explosion in most of Africa will wipe out nearly all the wildlife outside the parks. Since elephants are far-ranging beasts who often leave park boundaries, they are particularly vulnerable. Millions of starving Africans will not be satisfied by their meager incomes from tourism and safaris, and ultimately poaching and destruction of wild lands will be out of control. It's not surprising that African farmers, scrabbling to eke out an existence on marginal land, are angry when the government spends more on elephants than on people. In the next decade most of the

KINGDOM OF IVORY

195

Figure 9.15. A stockpile of ivory is burned to prevent its entry into the black market. Will the poaching cease before the elephant is wiped out in the wild, or will the demand for ivory finally drive elephants to extinction? (Photo courtesy J. Shoshani). African countries are expected to have severe economic difficulties. Their problems will be compounded by the AIDS epidemic in Africa, which is out of control, and slowly

killing off Africans. The health care system is in a crisis. Ultimately, only fewer human births will make it possible for both humans and animals to share the dark continent.

NORTH AMERICA

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Figure 10.1. Modern version of horse phylogeny, emphasizing the "bushiness" of their evolutionary past. Many side branches of horse evolution went extinct over the last 50 million years. Note especially the overlap between Mesohippus and Miohippus, and the placement of true Merychippus in the hipparionines. (Drawn by C.R. Prothero).

10. A Horse of a Different Color (and Shape)

THE ORIGIN OF PERISSODACTYLS To westerners, China has always been a mysterious and sometimes forbidding place. Now home to over a fifth of the world's population, China has gone through many periods of isolation and hostility to the west, as well as periods of exchange of people and ideas. China's political history has been no less turbulent in this century. Between the world wars westerners were welcomed, but after the revolution in 1949 China remained off limits for over twenty years. The brief periods of openness have proven to be exceptionally important to the study of prehistoric life. While the political climate was favorable during the 1920s, several major discoveries were made in China and Mongolia. The most famous finds were made by the American Museum of Natural History expeditions to the Gobi Desert of Mongolia. Originally the expeditions were mounted because Henry Fairfield Osborn, president of the Museum, thought that humans arose in Asia. He hoped that great expeditions would confirm this. They didn't, of course, because humans originated in Africa, as the last thirty years of discoveries in East Africa have shown. Nevertheless, their expeditions were successful in other ways. They discovered many early fossil mammals, including the gigantic hornless rhino Paraceratherium (or Indricotherium, discussed in Chapter 14) and many important fossil mammals from the Paleocene and Eocene. The most famous discovery was nests of dinosaur eggs, the first dinosaur eggs to be discovered. Roy Chapman Andrews, the expedition leader, made several trips to Mongolia and spent much of his life publicizing these important finds. However, by 1928 conditions for travel to Mongolia became impossible. Another important find was the discovery of the great caves of Zhoukoudian (formerly transliterated as "Choukoutien"). In these early Pleistocene caves were a number of unusual fossil mammals, including a giant tapir (discussed in Chapter 13), huge hyaenas, rhinoceroses, antelopes and cattle, and many mammals found nowhere else. More people were excited, however, at the discovery of fossils of Homo erectus, which at that time were known as Sinanthropus, or "Peking Man." These skeletons were the most complete Homo erectus specimens known at the time, and proved without a doubt that smaller-brained but upright humans lived about half a million years ago. This great

treasure of bones, however, disappeared during the Japanese invasion of China in 1941. A troop of U.S.· Marines tried to carry the fossils to safety, but somehow they were lost during the escape. Fortunately, we still have high-quality casts of the bones that were made before they were lost. In the last few decades the fossil sites have been reopened, and many more new specimens have been found. The Japanese invasion and the Second World War were just a few of the crises that prevented access to China and Mongolia. During the 1960s and early 1970s Chairman Mao's Cultural Revolution drove many scientists and intellectuals underground, and nearly destroyed universities and research institutions. Many Chinese paleontologists, cut off from the West, decided to keep a low profile and polish their English when they couldn't travel or read about the latest scientific discoveries elsewhere in the world. When China began to open up and welcome Western science and technology again, it was as if the floodgates had burst. Chinese scientists, who had been collecting spectacular specimens for years, could visit the West and present their ideas for the first time. Their presence at professional meetings was eyeopening. After an American paleontologist would finish talking about some scrappy fossils from Wyoming, the visiting Chinese scientist would show pictures of beautiful uncrushed skulls and skeletons of animals known elsewhere only from a few teeth. You could see the audience's jaws drop, eyes open wide, and hear their gasps of amazement! The Chinese had found high-quality fossils representing the earliest evolution of mammals in Asia, a continent that was very poorly known to the West before the 1970s. During the Paleocene and Eocene, China and Mongolia had been the home of many spectacular beasts. Some of these are found elsewhere, but many were unique to Asia. More importantly, the fossils were of such good quality that they allowed the first accurate reconstructions of many entire animals, and solved many mysteries about what kind of animals they were. From Chinese fossils, for example, we have solid evidence that rodents and rabbits are closely related, and that they evolved in Asia during the Paleocene. Rodents. then spread elsewhere in the early Eocene, and rabbits made it to North America in the late Eocene. The Chinese fossils revolutionized the study of hoofed mammals even more. Prior to the discovery of Chinese fos-

198

HORNS, TUSKS, AND FLIPPERS

sils, most Western paleontologists tried to trace the ancestry of perissodactyIs (Fig. 10.1) back to archaic ungulates found in areas they knew, like North America and Europe. Their best candidate was a group of ungulates called phenacodonts (discussed in Chapter 1), which have quite a few similarities to primitive perissodactyls. Some authors went so far as to identify a particular phenacodont species as "the perissodacty1 ancestor." Others could not find a continuous lineage between any known phenacodont and perissodactyls, so they suggested that perissodactyls evolved in Central America (where we have no Paleocene or Eocene fossils) and then migrated back to North America in the Eocene. All of these ideas went out the window just a few years ago. The Chinese found a spectacular skull of a small mam~ mal that looked very much like the most primitive Eocene perissodactyl-only it was even more primitive, and it came from the Paleocene of China! This specimen was described in 1989 by Malcolm McKenna and three Chinese coauthors, Zhou Minzhen, Ting Suyin, and Luo Zhexi. They named the animal Radinskya in memory of Leonard Radinsky, the foremost expert on perissodactyIs until his premature death of cancer in 1985. Although Radinskya had many similarities to perissodactyls, it was so primitive that McKenna and coauthors did not want to formally call it a horse, rhino, or tapir. Radinskya also looked much like certain phenacolophids, which were related to arsinoitheres (discussed in Chapter 7), and so McKenna and coauthors temporarily called it a phenacolophid. As we saw in Chapter 7, the Chinese Paleocene fauna included not only Radinskya and the oldest arsinoitheres, but also the most primitive tethythere, Minchenella. For this reason, it is now becoming clear that the entire tethythere-perissodactyl radiation began in Asia in the Paleocene, and spread to Africa and North America by the Eocene. All of those old ideas that perissodactyIs originated from phenacodonts in Central America are now obsolete. Perissodactyls appear suddenly in both North America and Europe in the form of Hyracotherium, the "hyrax beast." When they do appear, they become one of the most common mammals in Eocene beds around the world. THE "HYRAX BEAST" Collecting natural objects was a very popular pastime in early Victorian England in the 1830s and 1840s. As described by Lynn Barber, it was the "heyday of natural history." A hobby suitable for both gentlemen and ladies, it had the morally uplifting purpose of revealing God by studying His handiwork. Thousands of upper- and middle-class British with leisure time on their hands (particularly parsons and women) were running around the countryside collecting flowers, butterflies, fishes, ferns, and even fossils. Their interest and enthusiasm was so great that it was not unusual for people to spot a fly at dinner and argue about its correct scientific name. Among these enthusiasts was a gentleman named

Figure 10.2. Owen's (1840) illustration of the type skull of Hyracotherium leporinum, the "hyrax beast," which resembled a "Hare or other timid Rodentia." William Richardson, Esq., M.A., F.G.S. Collecting on the coast of Kent in 1839 he was concentrating on Eocene beds of the famous London Clay, looking about with "strong expectation for the evidence of some form of animal life, whether of beast or bird, destined to be sustained by so rich a provision." This time he was lucky, for he found the front half of a tiny skull (Fig. 10.2), as well as the remains of a bird. This little skull was given to Richard Owen at the British Museum, who was the foremost zoologist in England at that time. Indeed, Owen was justly famous for describing the first dinosaurs (he even coined the word "dinosaur"), as well as many other famous fossils (including the giant extinct ground sloths brought back from South America by Darwin on the Beagle voyage). The little skull, with large eyes and a short snout, looked more "like that of a Hare or other timid Rodentia." However the low, rectangular teeth with small cusps were clearly those of a primitive hoofed mammal, which most resembled the extinct Choeropotamus (a very primitive artiodactyl from the same beds). Owen correctly realized that the peculiar arrangement of cusps and ridges was even more similar to the living hyrax, so he called the animal Hyracotherium, or "hyrax beast." A few years later Owen was describing some more Eocene mammals, this time from the Isle of Wight. After describing the fossils he discussed some ideas first suggested by Cuvier in 1817 and de Blainville in 1816. Both of these French zoologists had argued that hoofed mammals could be associated by the number of their toes. Those with even numbers of toes were one group, those with odd numbers (usually three or one) were another. In 1848 Owen adopted de Blainville's association of horses, rhinos, tapirs, and hyraxes, and coined the name "Perissodactyla" for them. He did not put his little Hyracotherium in this group, because no foot skeleton had yet been found. Ironically, Hyracotherium turned out to be the most ancient and primitive perissodactyl fossil then known, but it was not recognized as such until the 1870s. Instead, the

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attention focused elsewhere. In 1859 Charles Darwin published On the Origin of Species by means of Natural Selection, and all of biology was turned upside down. As the debates in scientific circles became more and more bitter, critics pointed to the shortage of good examples of sequences of fossils that led to living animals. There were spectacular examples of transitional forms, like the halfbird, half-reptile Archaeopteryx (discovered in 1861), but the record of fossil mammal evolution was very incomplete in Europe. Nevertheless, some patterns were beginning to emerge. In 1872 Darwin's chief defender, Thomas Henry Huxley, pointed out that three fossil mammals from Europe, if placed in order of their age, seemed to form a sequence leading to modern Equus. There was the bizarre Eocene Palaeotherium, the early Miocene browsing horse Anchitherium and the late Miocene three-toed grazer, Hipparion (all discussed below). The following year the Russian paleontologist Vladimir Kovalevsky studied these same fossils, and was even more certain that these fossils represented the evolution of the horse. Both Huxley and Kovalevsky realized that the sequence was very patchy and incomplete-just four forms, with big gaps in between. Nevertheless, they correctly concluded that horses came from a more tapir-like animal with three toes and very lowcrowned teeth (Fig. 10.3). Unfortunately for European scientists, however, their sequence was not representative of the main line of horse evolution because that story took place elsewhere. Those European mammals were immigrant side branches from North America, where most of the history of the horse took place. Horse fossils from the Big Badlands of South Dakota were first described by Joseph Leidy in 1850. He first referred these fossils to Palaeotherium from Europe, and

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Figure 10.3. Gaudry's (1896) "pseudo-phylogeny" of horse evolution, based on a succession of European immigrants from the main horse "factory" in North America. This diagram shows the feet of two Eocene palaeotheres, Pachynolophus and Palaeotherium (not true horses), plus the Miocene browsing horse Anchitherium , the three-toed grazer Hipparion, and an Ice Age Equus.

then to the horse Anchitherium, not realizing that they were new forms unknown in Europe. By 1869 he had described quite a few fossil horses, found all over western North America. It was the Yale paleontologist, Othniel Charles Marsh, who took the next step. In 1871 and 1872 he began to find Eocene horses in the Rocky Mountains. He also found other horses which filled in some of the gaps, and began to work out the changes in their limbs and feet (Fig. 10.4) from his more complete skeletons (which neither Leidy nor any European paleontologist had seen). By 1874 Marsh boasted that "the line of descent appears to be direct, and the remains now known supply every important form." At the same time, his bitter rival Cope described specimens he had received from the early Eocene beds of Wyoming as Eohippus, or "dawn horse," in 1873. A few years later Cope realized that it was the American equivalent of Hyracotherium, and placed Eohippus at the base of horse evolution. When Thomas Henry Huxley sailed to America during its centennial year in 1876, he went there to give lectures on topics in natural history. He planned to give a learned discourse on the evolution of the horse in Europe, based on the work that he and Kovalevsky had done. However, he spent two days with Marsh in the collections at Yale, and found that Marsh's evidence was convincing. As his son and biographer Leonard Huxley wrote, "At each inquiry, whether he had a specimen to illustrate such and such a point or to exemplify a transition from earlier and less specialized forms to later and more specialized ones, Professor Marsh would simply turn to his assistant and bid him fetch box number so and so, until Huxley turned upon him and said, 'I believe you are a magician; whatever I want, you just conjure it up.' "

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Marsh later recalled of this encounter, "He then informed me that this was new to him, and that my facts demonstrated the evolution of the horse beyond question, and for the first time indicated the direct line of descent of an existing animal. With the generosity of true greatness, he gave up his own opinions in the face of new truth and took my conclusions." Huxley later wrote to Marsh, "The more I think of it, the more clear it is that your great work is the settlement of the pedigree of the horse." Huxley then rewrote his lecture, using diagrams supplied by Marsh to recant his old ideas and present the new evidence. Horses had evolved in America, and his European examples were occasional immigrants. Huxley was overjoyed with Marsh's evidence, for it showed not only the changes in teeth, but also in the skull, limbs and even the toes. It became one of his favorite examples of an evolutionary series (Fig. 10.5), and has been used almost exclusively in nearly every book written on evolution or fossils since that time. However, there were some problems with this example. In the 1870s the European sequence PalaeotheriumAnchitherium-Hipparion-Equus, or the American sequence Eohippus-Orohippus-Mesohippus-Miohippus-PliohippusEquus were good first approximations of horse evolution based on very incomplete samples (Fig. 10.6). They fit the

prevailing linear notion of evolution, with one lineage marching along from Eohippus to Equus. By contrast, the evolutionary history of the rhinoceros, or camel, which were much more complex and also less completely known, did not fit the simple linear "ladder of evolution" diagrams that were so easy to visually comprehend. So the linear picture of horse evolution became deeply entrenched in the textbooks for over a century, long after many more fossil horse specimens had made it obsolete. Indeed, it is still being reprinted in historical geology textbooks. Ironically, paleontologists have long realized that this simple "ladder of horse evolution" is a misrepresentation. The discovery of more and more fossil horses has made it clear that their evolution has many complications and side branches, just like rhinos and camels and most other mammals. The simple linear picture was both easy to understand and illustrate, and also fit the nineteenth century idea that life proceeded by a "ladder of evolution." However, it is becoming more and more apparent that life is not a ladder, but a bush (Fig. 10.1), with many side branches that are constantly pruned back by extinction. Of those many branches, one may succeed and give rise to the next major branching event, which is again pruned by extinction. So too with the horses. Early in this century, it became

A HORSE OF A DIFFERENT COLOR (AND SHAPE)

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Figure 10.6. Traditional portrayal of horse evolution, presenting a single linear series of horse skulls, teeth, and feet as they are found in ascending order in the Tertiary strata of the American West. Although correct in its details, it erroneously conveys the orthogenetic·impression that horses form a single unbranched lineage. (From Matthew 1926). obvious that there were many different genera of horses in the Miocene. Recent work on Miocene horses (discussed later in this chapter) has shown that there were many different genera living at the same time, and in some quarries as many as twelve different species found together. This is also true of horses in the Oligocene, as we shall outline below. In fact, there are even multiple species of horses in the Eocene, although they are usually placed in the same genus. Thus, the bushy pattern prevails throughout horse evolution. The "ladder of evolution" presented in most books is just a selection of a few of the many branches on the bush that happen to be well known. However, it gives a mistaken impression about horse evolution, which is neither that simple and linear, nor inevitably leading to one terminal lineage. If conditions had been different perhaps a three-toed browsing horse would be alive today instead of Equus. While these details ofhorse evolution got more complicated, the story of Eocene horses was also changing. As more and more specimens were found and described, there were dozens of names for various specimens that were slightly different from the rest. This type of taxonomic "splitting" was typical of the late nineteenth and early twentieth centuries when scientists were primarily concerned with naming and describing every new variation. By the middle of this century, however, zoologists were beginning to realize that populations varied in nature, and that most

variations seen in living populations were part of the same interbreeding species. In 1932 Sir Clive Forster Cooper of the British Museum compared European Hyracotherium with American Eohippus, and decided that they could not be objectively distinguished. By the rules of zoological names the first name proposed is the correct one, so Cope's 1873 name Eohippus became an invalid junior synonym of Owen's 1841 name. Unfortunately, the name "Eohippus" had become entrenched in the popular books on horse evolution so people are still using it today, even though it is incorrect and should be abandoned. George Gaylord Simpson suggested using it informally, as "eohippus," without the capital and italics to show it is not a valid zoological name. Ironically, just as both paleontologists and popular books have accepted Hyracotherium, the names may be changing again. In 1989 Jeremy Hooker of the British Museum was studying Hyracotherium specimens from the Eocene of Europe. Although they are practically indistinguishable in most features, to the trained eye it is possible to recognize several species. Hooker found that Owen's specimens of Hyracotherium had shared specializations that linked it not with American horses, but with European palaeotheres (a close relative of horses we will discuss below). This suggests that the original species of Hyracotherium was not a horse, but a palaeothere. According to

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HORNS, TUSKS, AND FLIPPERS

Figure 10.7. Restoration of Protorohippus (formerly Hyracotherium from the early Eocene forests of North America. (Painting by R.B. Horsfall, from Scott 1913). Hooker, the name Hyracotherium has become a taxonomic "wastebasket" for any primitive early Eocene perissodactyl, including some which are closer to palaeotheres, or even to tapirs, rhinos, and titanotheres. If Hooker is correct, and true Hyracotherium is properly a palaeothere, then what happens to the North American early Eocene forms (which are unquestionably horses)? It would be nice to revive the name Eohippus, but it appears that the specimen that first bore that name isn't a horse either. According to several people who have looked at it, it is probably a primitive brontothere or possibly a chalicothere. Although the formal decision has not yet been worked out, some other name (perhaps Protorohippus, coined by Jacob Wortman in 1896) may be the first valid name applied to the horse of the American early Eocene. This may cause a lot of paleontologists and textbook writers headaches, but those are the rules! What sort of animal was Hyracotherium (or Protorohippus, or whatever the correct name for the North American horse)? In most features, it was much like many other primitive mammals of the Paleocene and Eocene. If it were alive today few nonscientists would have guessed its relationship to horses. Owen certainly didn't when he saw the first fossils! It probably reached 10-20 inches (25-50 cm) at the shoulder, about the size of a beagle or terrier dog, and half the size of a Shetland pony (Fig. 10.7). It had a long, flexible back and a long bony tail, unlike the straight backbone and short bony tail (which appears long due to the tail whisk) of Equus. With its high hindquarters it looked very rabbit-like, and probably ran much like a rabbit. It had much shorter limbs than any later horse, with much longer segments near the body (the upper arm and leg). Instead of the long finger and toe bones found in Equus, it had relatively short toes and many more of them: four on the front foot, three on the hind foot. Also, it had a dog-like pad on the foot, which allowed it to run with the whole foot as a

dog does, rather than on the tip of one toe, as in Equus. It certainly didn't have a typical horse's head. The snout was very short, and the eye was much larger and further forward. It had no distinct muzzle, nor any gap between the front teeth and grinding teeth where we could put the bit of the bridle. Instead it had canine teeth of significant relative size, like most primitive mammals. In studying large population samples Philip Gingerich found that the canine teeth varied in size. The ones with larger canine teeth appeared to be males, and the smaller canines are found on the smaller females. In fact, the shape of the head is even different between males and females. The presumed males have a larger skull with a much more domed forehead compared to the females, which have a flat profile. Gingerich points out that this sort of difference in size and structure of the sexes is correlated with ecological differences. Eocene horses probably had a single male protecting a herd of females (as do modern horses, and most deer). According to Gingerich, the vegetation of the early Eocene was not a thick continuous forest as in the Paleocene, but a more open parkland. This kind of environment is typical of those inhabited by many of the smaller deer and antelope that live in herds with one dominant male. Horses seemed to have replaced the archaic ungulate Ectocion, which lived in great abundance during the more densely forested Paleocene. Early in their history they began to evolve away from primitive ungulates by having a different social structure, as well as a better running ability, correlated with the change in the environment. If this animal appeared more like a dog or a rabbit, how do we know it was a horse? The horse specializations are very subtle and not visible on the surface, but they are there. In the ear region of the skull there are a number of uniquely horse-like specializations in the canals that allow the nerves and blood vessels to pass through. In addition, their teeth are even more diagnostic. Although the molars and premolars are still very simple, with cusps and no crests, and very low crown height, the arrangement of the cusps is unmistakably that of a perissodacty1. However, only a few minor features in these teeth show that they belong to a horse. With very slight differences (such as in European Hyracotherium), they could be a palaeothere. With slightly more connection of the crests, they could be the most primitive common relative of tapirs and rhinos, Homogalax. To the untrained eye the teeth of these two animals are nearly identical, yet they represent completely different branches of the perissodactyls. As we have pointed out above, the teeth first named Eohippus are probably not horse either, but may belong to the most primitive brontotheres or chalicotheres. At this very early stage in the evolution of perissodactyIs the ancestors of each of the major groups are so similar in most features that they can barely be distinguished. It is only in hindsight, when we see how differently their descendants turned out, that we try to separate them. If you were to time travel back to the Eocene you probably could not have told them apart, let alone guessed what their descendants would look like.

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By the end of the early Eocene, however, Protorohippus and Homogalax had been replaced by more specialized forms that were beginning to diverge into distinct lineages. There were much more tapir-like animals, such as Heptodon, and titanotheres, such as Lambdotherium and Eotitanops. By the middle Eocene, there is a new horse on the scene, Orohippus. All three of these major perissodactyl groups continued to evolve primarily in North America for the next fifty million years, and we discuss them in more detail in later chapters. Meanwhile a different story was happening in Europe during the Eocene. CUVIER'S "ANCIENT BEAST" As we saw in Chapter 2, most of Europe was subtropical and under water in the middle and late Eocene, forming an archipelago of islands somewhat like Indonesia today. These European islands started out with mammals like the rest of the world in the early Eocene, but isolation had· its effects. Instead of becoming horses, titanotheres, and tapirs, European perissodactyIs developed in their own· unique way. Hyracotherium gave rise to a group of horse-like animals that are often mistakenly included in the horses, although they were only close relatives, not directly related to true horses (which were found only in North America). These are the palaeotheres (Fig. 10.8), which we have mentioned before. Some of these animals, such as Pachynolophus and Propachynolophus, remained so primitive that they are still mistaken for horses by some scientists. Others, however, became specialized in different ways. The most striking of these is Palaeotherium, which was the first to be described and gave its name to the entire group. Indeed, it was one of the first fossil mammals ever described, since it was found in the gypsum deposits around Montmartre in Paris and described by Baron Georges Cuvier in 1804. Its name is very appropriate, for it simply means "ancient beast." Since very few other mammal fossils were known at that time, there weren't many other "ancient beasts" that might usurp the name. Cuvier described the animal and pointed out that it was a curious mixture of tapir, rhinoceros and pig. In fact, this animal was so primitive compared to the more familiar Ice Age mammals that he began to speculate. Were animals of each more ancient stratum more primitive than those in younger layers? It seemed so. In his own words, "the most remarkable and astounding result" was that "the older beds in which these bones are found, the more they differ from those of the animals we know today." Cuvier went on to interpret this as evidence that a series of floods and successive creations had produced different animals on earth. Fifty-five years later this same evidence would be used to show that life had evolved. As we saw earlier, the horse-like features of Palaeotherium were emphasized by Huxley and Kovalevsky, who placed it at the base of their European "horse lineage." When Huxley saw true horses from the North American Eocene, he dismissed Palaeotherium as a horse ancestor. In general appearance Palaeotherium was less like a horse, and

Figure 10.8. Restoration of Palaeotherium, the tapirlike relative of horses which were common in the European archipelago during the Eocene. (From Parley 1837). much more like a tapir (Fig. 10.8). It was almost cow-sized with big, heavy bones and broad, three-toed feet with hooves. Its limbs were clearly too short and stocky for fast running, but suitable for walking about in heavy underbrush and wading through swampy ground, as the modern tapir does today. It was even more tapir-like in the head. There is a deep notch in the nasal bones, indicating muscle attachments for a tapir-like proboscis. The big molar teeth had crests suitable for browsing, and it still had a sizable canine tooth. If you were to see it in the flesh, you would probably first identify it as a tapir. However, the details of the tooth pattern clearly are closer to the earliest horses than they are to tapirs. As we shall see in Chapter 13, tapirs were excluded from Europe during its Eocene isolation. Hence, it is not surprising that ecological equivalents of tapirs evolved in a forested environment very suitable for their lifestyle. Not all palaeotheres were as big or as tapir-like as Palaeotherium. Some remained much like Hyracotherium. Others, like Plagiolophus, developed moderately highcrowned teeth with strong crests and a cement covering, suitable for eating coarse, gritty vegetation. In this respect they paralleled horses, rhinos, and other mammals which began to develop more durable teeth for eating gritty grasses. However, they never became as specialized for running and grazing as their New World cousins, perhaps because they died out at the end of the Eocene. The most spectacular specimens of these beasts come from world-famous deposits at Messel in Germany. Located about 20 miles (30 km) southwest of Frankfurt, this site was once a large open pit oil shale mine that has since been abandoned. When a sanitary landfill in 1975 was proposed for this location, an international scientific program saved it and began to restudy its classic fossils. Messel is virtually unique in the world of exceptional fossil deposits. Animals are found as complete articulated skeletons in death poses with every bone in its proper position. Even more remarkable is the fact that the outlines of their bodies are also pre-

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served as a black film on the shale surface. In a fossilized frog it is possible to distinguish the eyes, liver, and veins; in fossil birds, the detailed structure of their feathers is evident; in fossil bats, the complete wing membrane is still visible. The most remarkable thing, however, is that the stomach contents of the animals are still preserved, and in some fossil bats their diet was exclusively butterflies! Among the remarkable Messel animals was a complete specimen of Propalaeotherium). It was much more horselike and less tapir-like than Palaeotherium, so in some books it is actually called a horse. In its completely articulated death pose, it clearly shows the body outline and the delicate, seldom-fossilized bones in the throat and ear region. The best surprise, however, was the discovery of the remnants of stomach contents, a mass of leaves and fruit seeds that show conclusively what palaeotheres (and probably Eocene horses as well) ate. The detailed structure ofthe leaves they ate can be made out! Another specimen turned up with very tiny bones in the pelvic region. When "baby teeth" were also found, if confirmed that these were bones of an unborn embryo still in the mother! How did these remarkable fossils become preserved so exquisitely? The Messel deposits are shales formed in a very small (a few square miles in area) but deep lake in a fault valley. The very bottom of the lake did not have any circulation or overturn, so it was stagnant and without oxygen, preventing the usual scavenging fish and microorganisms from living there. In the warm, subtropical climate, frequent algal blooms even further depleted the oxygen at the bottom and increased its depth stratification. When animals or plants fell in or carcasses floated in, they sank to the bottom where they were buried before they could decay. The only scavengers were bacteria that live in oxygen-poor environments. The mysterious black outlines have been studied, and they were composed entirely of the mineralized remains of these bacteria. Thanks to the Messel deposits, we have a good idea of the animal and plant communities living in the European archipelago during the middle Eocene. Throughout the Eocene these islands increased their isolation, and their mammals became more and more peculiar. Instead of the horses, tapirs, rhinos, and brontotheres that were evolving in Asia and North America, the large mammals of Europe were mostly strange perissodactyls that lived nowhere else, like palaeotheres and the tapir-like lophiodonts (discussed in Chapter 13), or a wide variety of unique artiodactyls. However, this "Garden of Eden" was deteriorating through the later part of the Eocene. Climatic changes, triggered by the first glaciation in the Antarctic, were causing world temperature to cool. The vegetation, in turn, became less and less leafy and tropical, and more and more temperate, with more cool-weather plants. Ultimately, this affected the mammals. In North America and Asia tree-dwelling primates and multituberculates disappeared. Most of the leafeating mammals (particularly the archaic ungulates, tapirs and brontotheres) declined and went extinct.

In the European archipelago we see similar changes. Most of the characteristic archaic browsing ungulates, such as palaeotheres, lophiodonts, and the peculiar artiodactyIs, have nearly disappeared by the end of the Eocene. These changes in the mammal fauna were accelerated by another phenomenon as well. At the very end of the Eocene sea level dropped and many of the islands were reconnected with Asia. Asian mammals, especially rhinos, amynodonts, hyracodonts, chalicotheres (all discussed in later chapters), the pig-like entelodonts, peccaries, and anthracotheres, and the deer-like leptomerycids, swept across these former islands, driving their archaic competitors to extinction. A similar change can be seen in smaller mammals, such as the rodents, where archaic gnawers were replaced by members of the hamster family, and other typically Asian rodents. The difference between Eocene and Oligocene mammals is so striking in Europe that in 1909 the paleontologist Hans Stehlin labeled it la Grande Coupure (the "Great Break" in French). The subtropical island paradises of Europe were no more, and with their disappearance the strange and unique animals found on them disappeared too. HALFWAY HORSES During the fifteen million years of the early and middle Eocene horses such as Protorohippus and Orohippus had been small, primitive mammals that were barely distinct from primitive rhinos, tapirs, and brontotheres. By the late Eocene and Oligocene, however, horses became recognizably horse-like. The first of these "middle horses" was the late Eocene Mesohippus, whose name literally means "middle horse." Mesohippus was about two feet (60 cm) tall at the shoulder, or about the size of a German shepherd dog (Fig. 10.9). Its head was much more horsey than Orohippus, with a longer muzzle, eyes slightly further back on the face, and a larger brain. Its teeth were better adapted for coarser vegetation, with well-developed ridges and crests, but they still were not high-crowned as in later horses. The body was longer, with an arched back that was more flexible than in modem horses, but not as primitive as earlier horses. Its most striking feature, however, was its longer legs, with the upper arm and thigh segments much longer, and elongated toes as well. Most books describe Mesohippus as a completely threetoed horse, with the fourth digit of the hand (found in Orohippus) completely reduced to a vestige. However, specimens of Mesohippus have been discovered by Bob Emry which still possess a functional fourth finger (equivalent to our "pinky"), so the old idea is no longer valid. Later specimens of Mesohippus have completely lost this finger, so the change occurs during the evolution of the genus. Many books imply that this side toe gradually reduced through the evolution of the horses, but it is now clear that it disappeared rather abruptly in their history. The rapid disappearance of the "pinky" from horses seems to contradict the longstanding ideas about how horse feet gradually evolved in response to natural selection for

A HORSE OF A DIFFERENT COLOR (AND SHAPE) faster running. In fact, there is a better evolutionary explanation than slow, steady natural selection gradually reducing this finger. Neil Shubin has studied the embryonic development of the toes in horses. It turns out that each finger and toe is formed in a distinct branching sequence, with the innermost digits (big toe and thumb) formed first, and the outermost digits (pinky and little toe) formed last. The loss of the thumb or big toe thus requires major rearrangement of the embryonic development, and once it disappears, it never reappears. Archaic ungulates still retain this digit, but all perissodactyls are without it, and they never regain it, even in rare mutant freaks. The outer digits, on the other hand, are formed very late by the last branching sequence of cells (between the "ring finger" and "pinky," for example). It is relatively easy to "turn on" or "shut off' this path of development in embryonic history. Consequently, it takes only a slight mutation in the genes that regulate embryonic development to "shut off' the formation of the pinky, or "tum on" the suppressed genes again in animals without it. This not only explains its abrupt disappearance in horses, but also the fact that it reappears again in several fossil rhinos (which became threetoed as well). These rare fossil rhino specimens are single individuals in large population samples with normal toes, indicating that they were probably mutant throwbacks to their four-fingered past. We can also see the same phenomenon in living horses. Every once in a while a mutant horse is born with partially developed side toes (equivalent to your index finger and ring finger, for example). These so-called· "homed horses" were so unusual that they became Julius Caesar's mount of choice, and later were featured as circus freaks (Fig. 10.10). Unlike the mutant four-fingered rhinos and horses, these side toes have normally been suppressed in embryonic development. In rare individuals the genes that regulate the "shut off' command for side toes fail to operate, and the suppressed side toe genes are expressed again. The next time you see a horse, remember that they still have the genes in all their cells for three-toed feet, but have shut them off to reach the one-toed condition you see today. All of the traditional books and horse evolution diagrams show Mesohippus as one unbranched "trunk" of the evolutionary tree, followed by an unbranched late Oligocene Miohippus. Along with Neil Shubin, one of us (Prothero) has found that this traditional dogma is no longer true. By analyzing the huge collections of these fossil horses from the Big Badlands of South Dakota, and equivalent beds in Wyoming and Nebraska, we found that these "middle horses" had a very bushy "family tree," with multiple species of both genera living at any given time. The conventional diagrams show Mesohippus transforming gradually into Miohippus, and many scientists said that their change was so gradual that they could barely be distinguished. By contrast, we found that Miohippus arose much earlier than ever anticipated, and that the two genera lived side by side for almost five million years (Fig. 10.1). Both horses are

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Figure 10.9. Restoration of Mesohippus, a GermanShepherd-sized horse from the upper Eocene and lower Oligocene of the Big Badlands. It had three toes on both front and hind feet, and a slightly deeper, more "'horsey" skull. (Painting by R.B. Horsfall, from Scott 1913). very distinct, with Miohippus being much larger (about the size of a Great Dane), with more advanced feet and teeth. In one place in Wyoming there are three species of Mesohippus and two species of Miohippus living at the same time at the end of the Eocene. By the late Oligocene, however, Miohippus was the only horse present, although there are many species in this genus forming another "bushy" family tree. In addition to its slightly larger size, Miohippus was only a little bit more specialized than M esohippus. The most striking feature was again in the feet. As the side toes were reduced, the central toe (equivalent to your middle finger) became the main weight-bearing element of the foot. To support this weight it got progressively larger in horse evolution, crowding out the reduced side toes. One way of measuring this change in the middle toe is by the wrist and ankle bones which normally only touch the side toes. In Miohippus, an ankle bone known as the cuboid (which normally only touches the second toe) is in contact with the enlarged middle toe. In more advanced horses the middle toe enlarges to the point where all the wrist and ankle bones contact only the middle toe. Toward the end of the Oligocene a great evolutionary radiation took place in horses. Where there had been a number of species in only two genera (Mesohippus and Miohippus) , many more genera are clearly present in the early Miocene (Fig. 10.1). The first lineage leads to a conservative group of browsing horses, the anchitherines. The second is the progressive group that became grazers and eventually led to modem horses. These are the equines. BROWSING ANCHITHERES As we saw above, both Huxley and Kovalevsky thought that the early Miocene European horse, Anchitheriurn, was on the direct line of horse evolution (Fig. 10.11). As we have seen, however, it is merely an immigrant from the main line of evolution in North America. It is not surprising,

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Figure 10.10 (left) Marsh's 1892 diagram of the "horned horse" from Texas, showing the well developed side toes. Figure 10.11 (above). Anchitherium, a three-toed browsing horse of the early and middle Miocene. (From Savage and Long 1986).

however, that they thought so. In most features Anchitherium is only slightly more advanced than Miohippus. Although some species were about twice the size of Miohippus, they all retained very primitive low-crowned teeth, with no specializations for eating tough vegetation. They differ from more primitive horses only in that the crests on the teeth are more completely connected together and a little sharper. This indicates that their diet was little changed from that of their ancestors: browsing on leaves, along with some seeds and fruits. They also retained the three-toed feature of their ancestors, which indicates that they never specialized for high-speed running across open plains. Instead, they probably hid in denser forested patches of vegetation. The same could be said for the entire group of anchitherine horses, which became fairly successful and diverse throughout the Miocene. The Miocene was a time of climatic warming after the cooler, harsher Oligocene, and many land mammals show evidence of responding to the warmer climates and more abundant vegetation. In particular, they begin to specialize into different feeding types, and the anchitherines were forest horses that retained this ecology even as other horses tried new niches. Anchitherium became very successful at following forests, and eventually migrated to Europe and Asia in the early Miocene, where they were fairly common. In fact Anchitherium itself is so common in France that it was one of the first fossil mammals ever found, and it was described by Cuvier in 1822. It persisted until the late Miocene in Turkey, spanning almost fifteen million years with little change! This is one of the longest records for any fossil mammal, and even more remarkable for such a conservative horse.

Other anchitherines followed the basic browsing forest horse lifestyle, but divided the niche by body size. Presumably this meant that they could eat different types of forest vegetation, from low-growing leaves and fruits to the tops of bushes and lower branches of trees. The same specializations are seen in the many different types of antelopes living in East Africa today. Although there are dozens of species of antelopes living in the same environment, they subdivide the habitat by specializing on different types and levels of vegetation, so that they seldom compete. One anchitherine, Archaeohippus, was a dwarfed form, with a body size similar to late Eocene Mesohippus. It was found in the early Miocene from California to Florida, although it was never very common and never left North America. In contrast to the pygmy archaeohips, there were also giant anchitheres. These are usually called Megahippus ("big horse") and Hypohippus, and they are found in North America in the middle and late Miocene. These large horses evolved very rapidly from Anchitherium-size ancestors to reach up to 900 pounds (400 kg) in the largest Hypohippus. This is comparable to the size of many living species of horses, although not as large as draft horses. The large anchitheres were successful until the very late Miocene, when they lived together with a wide variety of grazing equine horses. In some quarries in Nebraska there may be two or three species of anchitheres found together with seven or eight species of more advanced horses. Anchitherium was not the only browsing horse to emigrate from North America. In late Miocene deposits of China a surviving descendant of large Hypohippus is also found. It is called Sinohippus ("Chinese horse"), and probably represents an immigrant from North America via the

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Bering land bridge. Like American anchitheres, however, it was outnumbered by hipparionine horses from the main line of horse evolution, the equines. GRAZING HORSES While some species of Miohippus seem to be closely related to the browsing anchitheres, other species show features that suggest they are more closely related to a different lineage of horses. These horses, the equines, show many of the classic trends that have made horse evolution so famous, such as increasing size, and greater specialization of the limbs for running. The most critical change, however, took place in the teeth. All the horses we have discussed so far (and most mammals in general) have "low-crowned" or "brachydont" teeth. Their teeth are like ours in that they have a well-defined root and crown, and cannot grow continually after they are formed and erupted. Very old individuals (or those with very gritty diets) wear down their teeth practically to the gums. If they survive long enough to do this, they may die of starvation. Some humans (such as Eskimo women, who use their teeth for softening leather) do the same, and old humans frequently lose their teeth for other reasons as well. In nature animals or humans with useless teeth would not survive, and this would be a problem if they were still breeding and had not passed their genes on to their offspring. If an animal tries to survive by living on a grittier diet that wears down teeth, it must adapt or die before it can reproduce. One of the grittiest possible diets is grass, which is full of little glassy particles that are as abrasive as chewing sand. In addition, grass often has dust or grit adhering to it, especially if it is cropped close to the ground. Before the Oligocene there were few grasslands anywhere in the world, and almost all herbivorous mammals were adapted to eating a diet of leaves, fruits, or nuts. Once grasslands began to appear and the woodlands shrank, some mammals had to change in order to survive. The shrinking woodlands were getting too crowded, and the grasslands represented an underexploited opportunity. Eating grass takes a toll, however. First of all, it is low in nutrition and full of less digestible cellulose, so you must eat much more of it to get the same energy. Secondly, it wears down your teeth rapidly, so you must develop teeth that can tolerate the wear, or else breed earlier before you become a starving "old gummer." A number of mammals found a solution to this second problem: make their teeth ever-growing, such that a new tooth surface is constantly replacing that which has been worn away. This means that the tooth is essentially one long prism, with no distinction between root and crown. The "root" can even be open at the base and filled with growing pulp cavity, so that new tooth is continually adding to the bottom as the top erupts and wears away. These teeth are "high-crowned" or "hypsodont." In a living horse, for example, the roots of the teeth penetrate almost to the bottom of the jaw, and well up into the facial region (Fig.

Horse

8 ysar.s

39 years Figure 10.12. Side views of modern horse skulls, showing how deeply the highcrowned cheek teeth penetrate into the skull and jaws. As the horse ages, it wears the teeth down further and further, until very little crown is left by old age. (From Gregory 1951).

10.12). A number of species of a11iodactyls (especially camels, deer, antelope, and cattle) independently developed high-crowned teeth as well, although constructed with a different pattern. As we shall see in Chapter 14, some rhinos became grazers, and their teeth were very hypsodont. This feature appears again and again in herbivorous mammals that took up eating grass. The great diversification of horses (and many other mammals with hypsodont teeth) in the early Miocene is probably a response to the expansion of grassland habitats. John Rensberger, Ann Forsten, and Mikael Fortelius found that middle Miocene horse teeth show specializations for a very gritty diet. The teeth of early Miocene horses such as

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Parahippus and Kalobatippus are already slightly highercrowned than Miohippus, and their crests are sharper and more connected for better shredding of vegetation. In addition, some of the advanced species of Parahippus and all later Miocene horses have an additional feature that made them more durable. This is cement, a bone-like mineral substance that forms a protective cap around the crown. Most mammal teeth are made of a soft, ivory-like substance called dentin in the core, with a hard outer layer called enamel. By adding cement to the tooth horses ended up with a large grinding surface composed of hard enamel ridges above softer, lower regions of cement and dentin. When teeth grind against each other the raised ridges become tiny shearing edges which efficiently chop the plant material into small pieces. This is much more efficient than having flat-topped teeth which can only squeeze or pound the tough, fibrous plant stems. Parahippus and later Miocene horses showed other features that were correlated with their move to the open grasslands. To accommoda\e their enlarged grinding teeth with deep roots, the snout region became longer and deeper. Since they were no longer protected from predators by hiding in the underbrush, they had to see threats stalking in the grass as soon as possible. Consequently, the eyes shifted further back and became larger to give them better vision. To escape stalking predators they also had features that made them better runners on hard, open ground. The legs became longer and more stilt-like, especially in the middle (lower arm and shin) and toe segments. In most mammals the lower arm and shin are composed of two equal bones which can rotate around each other. In your lower arm, for example, the two bones (radius and ulna) cross and uncross as you turn your wrist. If you grasp your lower arm where it meets your wrist, you can feel this when you turn your hand. However, specialized running animals no longer need to worry about turning their arms or wrists in order to grasp. Instead, their limbs need to be very efficient for moving only in the front-back direction. We have already seen that the ankle bone of artiodactyls and perissodactyIs is already specialized for this purpose. In Miocene horses the leg bones gave up any pretense of rotating out of the front-back plane. In the forelimb the radius becomes permanently attachedto the ulna, effectively making them one solid bone. In the hind limb the shin bone, or tibia, becomes the primary weight-bearer, and the other bone, the fibula, becomes a tiny splint which attaches to the tibia and nearly disappears. Finally, the story of side-toe reduction continues. In early and middle Miocene horses the middle toe was the primary weight-bearer. The side toes were very tiny, although they still bear hooves. There was no longer a pad on the foot, since the weight was being borne entirely on the tips of the toes. The side toes may have touched the ground briefly during part of the running motion, but they were no longer touching when the horse stood at rest. The side toes were not useless, however. They certainly gave the horse more trac-

tion on marshy ground (one-toed horses sink in too easily), and they probably prevented the foot from flexing too far when the main toe bent during the push-off phase of running. Three-toed horses were very successful, and there were dozens of species of them living for over fifteen million years during the Miocene, Pliocene, and Pleistocene. They should not be considered unsuccessful intermediate steps to the one-toed horse living today. Instead, they were the most successful and diverse horse type of all, and onetoed horses were a side branch that happened to survive until today. By the middle Miocene, equine diversification was at its peak (Fig. 10.1). The ancestors of over a dozen distinct late Miocene horse genera can be recognized. However, since in most features they are very primitive (Fig. 10.13) and look a lot like each other, these middle Miocene horses have traditionally been lumped in a wastebasket group called "Merychippus." A number of paleontologists working on Miocene horses have come to the conclusion that the "Merychippus" wastebasket needs to be broken up. Some species are related to more advanced later Miocene species, and should be put in those genera. According to Morris Skinner, Richard Hulbert and Bruce MacFadden, "Merychippus" coloradense and "Merychippus'" republicanus are actually related to Neohipparion (Fig. 10.14) or Pseudhipparion, "Merychippus" goorisi and "Merychippus" sphenodus to Cormohipparion, and "Merychippus" stylodontus and "Merychippus" carrizoensis to Pliohippus, Dinohippus and Equus. "Merychippus" isonesus, "Merychippus" sejunctus, and "Merychippus" insignis are also related to hipparionines. Only "Merychippus" primus and "Merychippus" gunteri cannot be clearly related to anyone specific late Miocene group of horses. This creates a severe problem for using the name "Merychippus." Only the last two species do not belong in some other genus, and their genus cannot be "Merychippus." This is because the original specimens on which the name "Merychippus" was based are very poor "baby teeth" which are not diagnostic of any particular species. Morris Skinner showed that these specimens compared well to more complete specimens from a population sample in Nebraska, so it may be possible to use the name for "Merychippus" insignis only. However, according to Hulbert and MacFadden, even this animal is related to hipparions, and is not "ancestral" to the radiation of Miocene horses. It appears that the name "Merychippus" will be restricted to just a few species of Miocene horses that are not ancestral to any of the later forms. Instead, the ranges of late Miocene horses like Cormohipparion, Neohipparion, Pseudhipparion, and Pliohippus will be extended back to the middle Miocene where their lineages truly first diverged. Isolated remnants of the old "Merychippus" wastebasket, like "Merychippus" primus and "Merychippus" gunteri , will need new names. Instead of the old, misleading "Merychippus" wastebasket, Skinner, MacFadden, and Hulbert recognize at least five major groups of equine horses diverging in the middle

A HORSE OF A DIFFERENT COLOR (AND SHAPE)

209

Figure 10.13. (left) Restoration of "Merychippus, " the wastebasket genus for most middle Miocene threetoed grazing horses. (Painting by Z. Burian.) Figure 10.14. (above) Restoration of the three-toed grazing horse, Neohipparion. Its relatives were found all over Holarctica in the middle and late Miocene. (Painting by R.B. Horsfall, from Scott 1913). Miocene. They include three groups called hipparions: 1) the Neohipparion-Pseudhipparion-"Merychippus" coloradense group; 2) the Hipparion-Cormohipparion-Nannippus group; and 3) an unnamed genus for "Merychippus" isonesus and "Merychippus" sejunctus. In addition, two other groups are closely related to later horses: 4) a ProtohippusCalippus group; and 5) a group leading to Pliohippus, Dinohippus, and one-toed horses. Some of these horses, such as "Merychippus" intermontanus, "Merychippus" primus, and "Merychippus" gunteri, remained relatively unspecialized. However, the first three groups formed one of the most successful radiations of horses ever seen: the wandering hipparions. THE HIPPARION CONTROVERSY Most of what people believe about scientists are myths. We associate the word "scientist" with white lab coats, bubbling beakers, electrical sparks, and a certain touch of madness. At the other extreme, much of the public associates science with incontrovertible truth, fostered by our tendency to treat scientific statements as authoritative and infallible. In most instances scientists have good reason to state their conclusions with greater confidence than do wild-eyed UFO freaks or ultra-mellow astrologers. However, good science is al ways conducted in an atmosphere of testing and criticism. The criterion of a good scientific idea is not its ability to al ways be right and avoid criticism, but its ability to be tested and possibly proven wrong. The best and most interesting ideas in science are furiously debated, not sober pronouncements of "truth" with no dissenting or testing by other scientists. In some cases this argumentation process brings out the human nature of the scientists. Debates not only become long and complicated, but the debaters may lose their tem-

pers. We have seen scientific discussions degenerate into shouting matches and even come to blows. More frequently, hot scientific debates are conducted by cutting words in scientific journals, but the wounds to one's scientific reputation and funding are much more painful than a black eye. The recent debate over the possibility of asteroids causing the extinction of the dinosaurs has resulted in much scientific name-calling and battles in the journals, with a Nobel laureate using intemperate words to insult the whole profession of paleontology. In the study of fossils one of the hottest debates still running is over the abundant, diverse groups of three-toed hypsodont horses known as hipparions (Fig. 10.15). These horses were so common in the Miocene and Pliocene in the northern continents and Africa that they were very popular for dating almost any deposit of that age. Their distinctive teeth, with little oval rings of enamel on the upper molars known as the isolated protocone, immediately identified them to even a casual collector. Since they were first described in 1832 dozens of species had been named and described, mostly on the basis of isolated teeth. Their classification was such a mess, however, that most authors could not make much sense of what they were seeing. In the 1920s Childs Frick, the son of the railroad and steel baron Henry Clay Frick, decided to spend some of his inheritance accumulating a collection of fossils of the ancestors of the big game mammals he used to hunt. He built a laboratory in New York, and kept crews of professional collectors working continuously in the High Plains and Rocky Mountains throughout the 1920s through the 1950s. By the time he died in 1965 Frick had amassed the best collection of Oligocene through Pleistocene North American mammals that the world had ever seen (Fig. 10.14). It surpassed all previous collections not only in quantity, but also in quality.

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HORNS, TUSKS, AND FLIPPERS

Figure 10.15. Dr. Morris Skinner examining just a small part of the fabulous Frick Collection of fossil horses in the mid-1970s. Here, the skulls of many critical specimens are arranged on a table in stratigraphic sequence to facilitate comparison. Skinner spent half a century collecting tons of fossil mammals for the Frick Laboratory, and much of his personal research was devoted to understanding horses. (Neg. no. 65476, courtesy Department of Library Services, American Museum of Natural History).

Where older collections had a few teeth or jaws from a given locality, the Frick Collection had dozens of skulls and skeletons. This collection became part of the American Museum of Natural History after Frick died, and was eventually housed in a new wing built especially for it. It is so immense that the fossil elephants occupy a whole floor, the horses another, the camels a third, the rhinos a fourth, and so on for seven whole floors. The collection was moved to its new wing and prepared for study in the early 1970s; some parts had remained virtually untouched by scientists for almost fifty years. One of Frick's best collectors was a young Nebraska farm boy named Morris Skinner. He had started out by collecting mastodonts and rhinos for the University of Nebraska in 1927, but eventually became a full-time

employee of the Frick Laboratory. He worked many fossil fields, particularly in north-central and western Nebraska, and was responsible for much of the best part of the Frick Collection. As he collected, he developed a fascination for fossil horses. While Frick was primarily interested in camels and carnivores, Skinner set aside the fossil horses when they came out of the crates fresh from the field. The Frick horse collection was superior to anything that had preceded it in many ways (Fig. 10.15). In particular, there were many complete skulls and skeletons of horses that had hipparionine teeth. From the skulls, however, Skinner could see that horses with similar teeth had many other anatomical differences in the rest of their anatomy. Clearly there was more than one kind of horse with hipparion-like teeth. Frick was very possessive of his private collection, so Skinner could not publish this work on Frick horses until after his boss had died in 1965. In the 1970s and 1980s Skinner, together with Bruce MacFadden, Michael Woodburne, and Ray Bernor, began to rethink hipparions based on this more complete material. In addition to features of the teeth, they also examined other parts of the skeleton, particularly the toe bones. A very useful part of the anatomy, which had seldom been used before, occurred on the face of the horse in front of the eyes. Many skulls had a pocket in the bone on the face, which varied from shallow to deep and had different shapes in different horses. Skinner, MacFadden, Woodburne, Bernor, and others found that these facial fossae were very useful features in sOlting out hipparion horses that had identical teeth. Since these horses are extinct, no one is completely sure what the function of this pocket was. It may have served as the attachment point of some facial muscles, or as a space for some special scent gland for recognition of other horses of the same species, or as a resonating chamber for their calls, or possibly it housed a branch of the nasal passages. Whatever its function, MacFadden showed with large population samples of horses that the fossa was as useful a character as the teeth. However, many European hipparion scholars were not convinced. The rearrangement of hipparion classification proposed by MacFadden and Skinner did not agree with their conception of European hipparions, based mostly on teeth. The scientific literature became full of papers arguing back and forth about the merits of the facial fossa in recognizing hipparions. In December, 1981, an extraordinary event took place. Most of the world's fossil horse specialists met together on the horse floor of the Frick Wing for a unique conference. There were representatives from the U.S., Germany, France, Italy, Spain, Holland, Greece, China and several other countries. They presented their arguments, sat down and agreed to standardized ways of measuring the bones, and tried to minimize the arguments due to poor communication across the barrier of oceans and languages. Although they could not agree on everything, many unnecessary problems were eliminated. Best of all, the scientists could argue their points with the finest specimens directly in front of them.

A HORSE OF A DIFFERENT COLOR (AND SHAPE) Since that time, much of the confusion about hipparions has been eliminated, and a clearer picture is beginning to emerge. No matter what one thinks of the facial fossa, there is no question that there were many different species and genera of hipparions in the Miocene and Pliocene and they spread almost worldwide in great numbers. At least six genera of hipparions were common in North America during the late Miocene, and all of them were living side-by-side about 8-10 million years ago, along with anchitherines, and horses such as Protohippus, Pliohippus, and Astrohippus (which are related to one-toed horses). Most were the size of "Merychippus" or Megahippus, or about the size of a Shetland pony. However, Nannippus and Calippus were dwarfed forms that weighed only 130 pounds (60 kg), about the size of a large dog. Like their predecessors, hipparions were three-toed, with well-developed side toes with functional hooves. However, some were stocky in build, with robust limbs, and others were delicate and gracile in their proportions. Whatever their shape, however, it is clear that horses were the North American Miocene equivalent of the great antelope fauna of East Africa today. Indeed, during the Miocene the North American plains were much like the East African savanna, except that the role of African antelopes and cattle was taken by horses and camels, with pronghorns and other deer-like animals being much less important. With so many horse species living side-by-side, they must have had different feeding strategies, and some differences in behavior and appearance that kept them as distinct species. Perhaps, like African antelopes, each horse specialized on different types of vegetation with some eating low, young green· shoots, and others eating the tops of bushes, and still others doing nothing but grazing. By the end of the Miocene, the great horse radiation was decimated. As we saw in Chapter 3, the great "Messinian crisis" triggered by the drying of the Mediterranean also changed the North American savanna into a dry, cold steppe. Most of the anchitheres and hipparions died out, leaving only a few surviving genera. However, hipparions did not die out everywhere at the end of the Miocene. For a long

211

time, it was thought that the first migration of hipparions from North America to Europe marked the beginning of the Pliocene in Europe. However that old dogma has also gone out the window with our new understanding of the complexity of hipparion evolution. According to Woodbume and MacFadden, there were at least two separate immigration events of hipparions from the New World to the Old World in the Miocene. About twelve million years ago Cormohipparion migrated across the Bering Straits, where it evolved into the middle Miocene hipparions known from the Mediterranean, western Europe, Pakistan, and China. A second immigration event brought Hipparion itself to the Old World about ten million years ago, and it became widespread and common all over Eurasia and even Africa. Some have suggested a third migration of Neohipparion about seven million years ago, although this is not universally accepted. The so-called "Hipparion datum" that was once the marker of the beginning of the Pliocene is no longer. There are two and maybe three "Hipparion datums," and all occurred in the Miocene. Hipparions had been around for over fifteen million years, one of the most successful groups of mammals that ever lived. The last of these three-toed horses existed in Eurasia and Africa until the middle of the last Ice Age, only a few hundred thousand years ago. The African hipparion evolved into a form with such distinctive, complex cheek teeth that it is often given its own name, Stylohipparion. During the Pliocene and Pleistocene, however, the stage was being taken over by a different branch of three-toed horses, unrelated to hipparions. In the Miocene they included Protohippus, Astrohippus, Dinohippus, Pliohippus, and the dwarfed Calippus. These horses had teeth which were specialized in a different way, and many lacked the facial fossa that is so characteristic of many hipparions. They also were developing higher-crowned teeth for even better grazing. Their most characteristic feature, however, was the further reduction of the side toes and expansion of the central toe. These horses were on the way to becoming one-toed, and eventually led to the living horse, Equus.

Figure 11.1. The plains zebra. (From the IMSI Master Photo Collection).

11. Equus

ONE-TOED HORSES "The year is 1924, the place the Staked Plains of the Texas Panhandle. W.O. Matthew and an eager but clumsy young assistant are prospecting for fossil horses in the blazing sunshine that beats down on the broken country around Mount Blanco. Their procedure is tiring and monotonous. They have no way of knowing where digging will reveal a fossil, except by finding a fossil before they start digging. There is no way of locating. a fossil still wholly buried. No dipping wand and no electronic instrument yet invented will reveal its presence. To dig at random is a hopeless task. Fossils are widely scattered, and a hundred holes might be sunk without hitting one... Among the fossils found by Cope [in 1892] were some horse teeth of a distincti ve type that he named Equus simplicidens. Later collectors found some more fragments of this species, but only fragments, and it remained very poorly known. Matthew recognized that this represented an important stage in the rise of Equus from its immediate ancestors and was anxious to learn more about the transition. He therefore decided to spend pal1 of the 1924 field season on the Blanco beds (so named for the nearby landmark, Mount Blanco), searching for better specimens of this horse and of the animals that Iived with it. After some days of prospecting, Matthew came to a place where several promising bits of bone were scattered down the slope. There was some chance that these were parts of a skeleton just starting to weather out. In that case, it might be possible to find other bones, perhaps most of the skeleton, still buried and not all broken up or washed away. He therefore worked up the slope carefully on hands and knees, picking up each piece of bone as he went. When no more scraps were to be found on the surface, he knew that the buried bones, if any remained, must be at or a little above this level. Looking about with even greater care, he saw with joy that there were indeed some bone ends sticking out of the uneroded white clay.

With a small one-handed pick he cut back the clay above the bones. Then, working with great care not to disturb the fragile and badly cracked fossil bones, he exposed them bit by bit, using small awls to work away the clay immediately around them. As this was loosened, it was brushed away with whiskbroom or smaller dust brushes. The bones tended to go to pieces as they were exposed, so they were hardened little by little with thin shellac. When this had dried, as it did very quickly in the hot, dry Texas air, the bone surface was further protected. and the fragments held together by covering with absorbent rice paper and another coating of shellac. In a couple of days the whole specimen was exposed, shellacked, and papered on top. With delight, Matthew noted that it was exactly what he most wanted to find: a skeleton of Cope's horse (Equus simplicidens), known until then from only a few separate teeth. There was, however, one bitter disappointment. The skeleton was practically complete, all but the most important part, the head. This had been weathered out and its fragments had been washed away beyond recovery. In the meantime, Matthew's assistant had been prospecting up a nearby draw, hoping to make some discovery to rival the boss's. He, too, found a lead to a partly buried fossil and breathlessly worked in to see what he had. Soon he was running back to Matthew, wild with excitement. He had a horse skeleton, too, a much less complete skeleton in all but one respect: his had the head still there! It was his first important discovery and the highpoint of his budding career. (No wonder I remember it so vividly a quarter of a century later!)" So wrote the greatest paleontologist of the twentieth century, George Gaylord Simpson, in his famous 1951 book, Horses. In fact, both Simpson and Matthew would become among the foremost students of fossil horses in this century, and both wrote popular books and pamphlets on the subject. The horses they were seeking on the Texas Panhandle were among the earliest and most primitive of the one-toed horses that are put in the modem genus Equus. Sometimes called

HORNS, TUSKS, AND FLIPPERS

214

A

PLIOHIPPUS

B

ASTROHIPPUS

10cm

MALAR FOSSA

C

DINOHIPPUS

o

EO.wJ.S.

Figure 11.2. Side views of skulls of late Cenozoic one-toed horses. Pliohippus (A) was long thought to be ancestral to Equus until more complete specimens showed that its preorbital fossa relegated it to a specialized side branch, along with Astrohippus (8). Dinohippus (C), on the other hand, has the appropriately shallow preorbital fossa for close relationship to living Equus (0). (From Woodburne 1989). Plesippus, or E. shoshonensis, E. simplicidens occurs in a number of places in North America with deposits of early Blancan age (about 3-4 million years ago). The most famous such deposit is a place known as Hagerman, about 30 miles downstream from Twin Falls, Idaho, on the Snake River Plain. This deposit contains a fine assemblage of early Blancan mammals, but its most spectacular yield is horses. One quarry worked by J.W. Gidley of the Smithsonian from 1930-1934, yielded over 150 skulls, 15 skeletons, and many other bones of this one horse! The Hagerman horse quarry is thus one of the richest fossil deposits in North America, comparable to the famous La Brea tar pits and the quarry at Dinosaur National Monument. In 1944 Paul McGrew of the University of Wyoming suggested that E. simplicidens was in fact a zebra (Fig. 11.1). Most recent analyses have confirmed this suggestion, since there are a number of specializations which it shares with the living Grevy's zebra, Equus grevyi. Like Grevy's

zebra, E. simplicidens stood about 6 feet (2 m) at the shoulders, with large ears like a donkey, and a long, narrow muzzle. It also had very primiti ve cheek teeth, and the splint . bones (remnants of the side toes) were still relatively large for a horse that runs completely on one toe. Bjorn Kurten called it the "American zebra," and it is clearly one of the most primitive species in the great Pliocene radiation of Equus. Other lineages of horses in this genus began to split at about the same time, leading to a number of extinct horses as well as to all the Ii ving zebras, asses, and wild horses. Older books state that the ancestor of the modem horse was the late Miocene horse, Pliohippus. Unfortunately, the name Pliohippus was based on some very poorly preserved fossil teeth, and for over fifty years paleontologists used the name "Pliohippus" as a wastebasket for any specimen with fairly advanced teeth. These animals were in fact so different that tremendous confusion resulted. In 1950 John Lance noticed that some specimens of "Pliohippus" were very different from the true members of the genus, but closer to Equus. In 1955 Jim Quinn formalized this distinction by creating the genus Dinohippus for these specimens which had erroneously been called Pliohippus (Fig. 11.2). Since then many scientists, especially Morris Skinner, have shown that Dinohippus and Equus not only have similar 'teeth (different from those of true Pliohippus), but Dinohippus and Equus are even more similar in their great reduction of the facial fossa (which is so distinctive in Miocene horses, as discussed in the previous chapter). This shared specialization is carried on in all Equus from the Pliocene onward. Pliohippus is thus an extinct side branch of Miocene horses which independently evolved a one-toed foot. Dinohippus and Equus simplicidens are the most primitive members of the living horse radiation. Some, like Debra Bennett, argue that Equus split into two great subdivisions during the Mio-Pliocene: the Equus asinus lineage (which includes most of the wild asses, as well as a number of extinct horses), and the Equus zebra lineage (which includes the modern horses and zebras). Other authors believe that the split did not occur this early, and still others argue that some modern horses are not descended from forms like Dinohippus. In this book, we cannot sort out all the controversies. Most of these horses are remarkably similar in their skeletal anatomy, so all of these distinctions are much more subtle than for almost any other mammal in this book. One of the biggest sources of confusion was the tendency to create a new species for nearly every new tooth or skull found. From 1842 until the present over 59 species of Equus were described from North American PlioPleistocene deposits. In recent years, however, scientists have come to recognize that natural populations are highly variable, even though they are a single interbreeding species. When the normal variations of teeth in natural populations are examined, then most of these "species" based on subtle differences of teeth are probably not indicative of true species differences. In 1980 Bjorn Kurten and Elaine Anderson, following Walter Dalquest, recognized only 15

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EQUUS

B 1

Figure 11.3. A. The late Miocene South American litoptern Thoatherium was remarkably convergent on living horses, as this reconstruction by R. B. Horsfall shows. (From Scott 1930). B. Convergence in the limbs was even more striking. Note the similarity between the three-toed horse Protohippus (1) and the three-toed litoptern Diadiaphorus (2). One-toed Thoatherium (3) has reduced its side toes even more completely than modern Equus (4). (From Colbert 1991). species of Equus in North America, and in 1989 Melissa Winans reduced this to five groups that can be objectively recognized (which may be species, or possibly subgenera). The classification of North American horses is still in flux, however, and there will probably never be complete agreement on how many species there were, or how they are related. After the appearance of the American zebra in the early Blancan, there was a much greater diversity of types of horses in the late Blancan and Pleistocene. Some retained the primitive large size and stout limbs of the American zebra, and these are usually known as Equus scotti. Others became quite small, with relatively short legs, and are often called Equus alaskae. The most specialized are the stilt-legged forms, such as Equus francisci or Equus calobatus; these ranged in size from that of a pony to a draft horse, and are clearly related to the wild asses. Still other horses are hard to distinguish based on their size, limb proportions, or other skeletal characters. If we knew more about their behavior or coloration, we might separate them further, as we do the wild horses living today. Clearly, horses were very successful during the Ice Ages in North America, since we find them in such great abundance and diversity all over the continent. As we saw in Chapter 8, however, the end of the last interglacial was a crisis for all of the large mammals on this continent. Although mammoths and mastodonts were among the most spectacular victims of these late Pleistocene extinctions, horses, too, were wiped out. The youngest dates on North American fossil horses are about 8150 years ago, although most of the horses were gone around 10,000 years ago. Once again it is not clear which explanation holds up best for this extinction. It is plausible to argue that mammoths and mastodonts were primary targets of those early Folsom hunting cultures, but the horses, too? Could hunters have completely wiped out

the great herds of horses found all over North America at the end of the Ice Ages? We know that Europeans hunted horses by stampeding herds off cliffs to their death, but there is no evidence for that kind of hunting in North America. The climatic explanation has some problems, too. Many mammals clearly lived in regions south of the glaciers where they thrived, and should have continued to do so after the last ice retreat 18,000 to 10,000 years ago. The great bison herds, which fed on the same plains grasses, did not disappear entirely. Indeed, when Europeans reintroduced the horse to North America, wild horses spread all over the plains and intermontane west; clearly the postglacial environment was suitable. Advocates of the climatic explanation point out that habitats were much more fragmented in North America, with no great southern refugium in Central America for grassland species. By contrast, the AfricanEurasian land mass had huge areas of similar vegetation arranged in latitudinal belts. Even when these belts shifted north and south due to glacial advances and retreats, they remained large and continuous. For this reason, the same habitats could extend continuously over large areas during climatic changes. Whatever the cause of these great extinctions, horses were not a part of the American fauna until 1493 when they were reintroduced from breeds domesticated in Europe during Columbus' second voyage. North America, which had long been the center of horse evolution, today derives all its horses from descendants that left the continent hundreds of thousands of years ago. During the Ice Ages there were actually several migrations of horses out of North America. Before about two million years ago there was no Central American connection between North and South America. As we saw in Chapter 1, South America had its own unique assemblage of mammals that had evolved in isolation for over fifty million years.

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Most of the South American natives were carnivorous mammals related to the pouched marsupials of Australia, or relatives of the living sloths and armadillos. However, some were members of uniquely South American groups that never occurred elsewhere. South American hoofed mammals, for example, separated from their Northern Hemisphere counterparts during the Paleocene and evolved in isolation from them. These "southern ungulates," or notoungulates, then developed forms through convergent evolution which were almost dead ringers for Northern Hemisphere horses, rhinos, hippos, elephants, tapirs, camels, and even rabbits. These animals filled the ecological niches of their northern counterparts, yet were completely unrelated. The most impressive example of evolutionary convergence is a South American ungulate known as Thoatherium (Fig. 11.3A, B). This animal independently developed a onetoed foot like Equus, but did even better: the vestigial side toes are completely lost! If you were to just look at the feet, you would be convinced that this is a true horse. One look at the skull, and the peculiar teeth, however, and it would be clear that this is no horse, but an animal unique to South America. These animals still had low-crowned browsing teeth. Unlike North American horses, they developed the one-toed foot without becoming grazers. They were at their peak during the Miocene, but were extinct before the beginning of the Pliocene. The great interchange with South America described in Chapter 1 gave horses a new realm to conquer. Ironically the first invading horse was not Equus, which spread so successfully over the Old World. Instead, some descendants of Dinohippus known from the late Pliocene of Arizona and Texas were the first invaders to head south. These horses, known as Hippidion and Onohippidium, were very peculiar (Fig. 11.4). They had very slender heads with small, low-set eyes, and relatively short legs. Their most peculiar feature is the bones that support the nose, or nasal bones. These are extremely long and slender, separated from the rest of the skull by a deep notch, so that they form very delicate splints. Although these nasal bones were probably supported and strengthened by cartilage, this peculiar feature is similar to that in tapirs and in some rhinos (to be discussed later). It is

possible that these horses had a more flexible snout or possibly a short proboscis, supported by the muscles that attached along this nasal notch. These peculiar horses were merely the first wave. During the Ice Ages Equus also invaded South America. They soon replaced the hippidions, and spread all the way to the Straits of Magellan. Unlike North American horses, however, they even survived the Ice Ages, and were doing well a few thousand years ago after Indians had migrated there. However, by the time that the Spaniards arrived they had mysteriously gone extinct, so that the horses used by Pizarro to conquer the Incas were brought from Spain. As in North America, these horses soon escaped and became wild, and were adopted by native tribes along with the Spanish culture. Some of the world's most famous horsemen are the gauchos of the Argentinian pampas who have carried the traditions of horsemanship to new levels. While native horses went extinct in both North and South America, they did not do so in the Old World. The first record of Equus is from deposits dated at about 2.6 million years, or late Pliocene, in both Italy and Pakistan. These first invaders were among the earliest members of the lineage of the modern domestic horse, Equus caballus, and are sometimes called E. bressanus. As in North America Equus continued to diversify in Eurasia, and there is much controversy over how many fossil species are truly valid. There, however, some of their descendants still persist to give us a picture of what true wild horses are like. STRIPES DO NOT A ZEBRA MAKE One of the easiest animals to identify in a zoo or an African wildlife film is the zebra. "Zebra stripes" have become part of our language. Some people call American football referees "zebras" because of their striped official's shirts. Most people think of "the zebra" as a single animal. However, there are three living species of zebra in Africa today (Fig. 11.5), one that went extinct at the end of the last century, and many more fossil species. Even more surprising, these three striped horses are probably not closely related. We have already seen that the earliest members of the genus Equus, E. simplicidens, are often considered the

Figure 11.4. Comparison of living Equus (right) with the South American Ice Age horse Hippidion. The extreme retraction of the nasal notch suggests that they might have had some sort of proboscis. (From Fenton and Fenton 1987).

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Figure 11.5. In northern Kenya, two species of zebra live side-by-side. On the left are Grevy's zebras (Equus grevyi), with their distinctive triangular striping pattern on their rumps. Behind the tree on the right is a plains zebra (Equus burchelli). (Photo courtesy C. Janis). "American zebra." This lineage of Equus is often put in a subgenus, Dolichohippus, although not all specialists agree with this name. By the early Pleistocene, a horse very similar to the Pliocene E. simplicidens appeared widely over Italy and France. This is E. stenonis, and some scientists consider it ancestral to Grevy's zebra. Some scientists also distinguish a northern species, E. robustus, from England, which was larger than E. stenonis or the Grevy's zebra. It apparently evolved into a species called E. suessenbornensis, the Stissenborn zebra, which lived side by side with caballine horses, such as E. bressanus. These zebras survived until about 500,000 years ago. They were apparently unable to compete with horses in the increasingly cold climate, and so died out in Europe. However, the Dolichohippus group was already established in North Africa by the late Pliocene. Known as E. numidicus, these horses are almost indistinguishable from early Pliocene E. simplicidens in North America or early Pleistocene E. stenonis from Europe. However, since zebras appear much later in Europe than in Africa, they must have migrated from North America via the Bering land bridge and Asia. Indeed, there are several of these Dolichohippus zebras in Asia during the Pleistocene. E. sanmeniensis, known from China, and E. cautleyi from India, were contemporaries of the European Ice Age zebras. E. valeriani Ii ved in central Asia as recently as 100,000 years ago, where its remains occur alongside Neanderthal man. However, these zebras too disappeared from Asia before the end of the Ice Ages, leaving only caballine horses. The predecessor of Grevy's zebra, E. oldowayensis, is common in middle Pliocene to middle Pleistocene deposits from Ethiopia to Tanzania. As the name implies, it is one of the common zebras in Olduvai Gorge where many of the

best early human fossils are found. In most respects it is almost indistinguishable from the living Grevy's zebra, which is known from Kenya and Ethiopia by the early Pleistocene. Grevy's zebra, Equus grevyi, once lived in Ethiopia, Somalia, and northern Kenya. It prefers deserts and steppes, as well as arid bush and grassland. Like its ancestors, it is a very large horse (the largest of the living wild equids, weighing up to 950 pounds, or 430 kg) with a relatively long, narrow skull, large mule-like ears, and primitive cheekteeth (Fig. 11.5). It is slender in build, with relatively long legs. Its color pattern is very different from most other zebras. The stripes are much narrower and closer together, and on the rear flank, they form a triangular arrangement of three sets of radiating arcs, rather than a single set of arcs around the hind leg found in other zebras. Unlike other zebras, Grevy's zebra does not form herds. Isolated stallions defend a territory of 1-4 square miles. The territorial stallion will tolerate other males unless a recepti ve female is present. Then he becomes very aggressive, and will fight off intruding males at the borders of his territory. These borders are marked by small dungheaps left at several spots along the border and periodically added to. When patrolling his territory the stallion may bray loudly to warn off other males. When an intruder challenges a territorial stallion who guards females, the territorial stallion extends his head, neck and ears forward. He then raises his head, flattens his ears, and bares his teeth, and both stallions then spar for position. If the challenger is serious, a fight will follow; if not, the challenger flees. The stallions fight with hooves and teeth, nipping at the flanks and rear of their opponent while jockeying for position. They also rear up and flail with their front hooves. They engage in shoving,

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Figure 11.6. The plains zebra is most easily recognized by the broad stripes which trend diagonally across its rump. (Photo courtesy A. Walker). rearing chest-to-chest, neck wrestling, and biting ears, neck, mane, or chest. If a leg hold brings both to their knees, they continue to wrestle. If one delivers a severe bite on the other, the bitten stallion will cease struggling until he is released, then he can either flee or resume fighting. Grevy's zebra seldom fights to the death; instead, the defeated male usually retreats. Ten-year-old stallions can have many scars and marks from numerous battles. The females and subdominant males, on the other hand, flock together in grazing groups, moving in search of food and water. Females are known to leave their foals for a full day in search of water, so the young are very vulnerable. In most details the social behavior of Grevy's zebra is more like some antelopes or asses, than it is like any other zebra. This is not surprising considering that it is not very closely related to other zebras. Grevy's zebra was the first zebra to be discovered by Europeans. The Romans exhibited them in circuses. However, they were forgotten for over a thousand years and not rediscovered until the King of Shoa (in what is now central Ethiopia) sent one to the Sultan of Turkey, and one to the Dutch governor of Jakarta during the seventeenth century. In 1882 Menelik II, King of Shoa and later Emperor of Abyssinia, sent one to the President of France, Jules Grevy. The French zoologist Alphonse Milne-Edwards recognized that it was different from the zebras from southern Africa, and it was named in honor of his president. During this time explorers seeking the source of the Nile in Ethiopia and Somalia continued to report this unusual zebra, but none has been observed in these areas since 1912. Somalis shoot them for food, and their unusual patterns make their hides very valuable, so Grevy's zebra is heavily poached. In addition

the frequent wars and famines in Ethiopia and Somalia have also contributed to its decline. Today Grevy's zebra is effectively confined to northern Kenya, along eastern Lake Turkana south and east to Samburu and Meru. It is estimated that of 15,000 Grevy's zebras that existed in the 1960s, only 1500-2000 still exist outside the reserves and national parks in Kenya. It is one of the most endangered of zebra species in the wild. The origin of the other group of zebras (placed in the subgenus Hippotigris) is less well known than the origin of Dolichohippus zebras (such as Grevy's). Debra Bennett argues that the three species have different origins within the caballine horses of North America and Eurasia. Rufus Churcher, on the other hand, thinks they are close relatives derived from a common ancestry in Africa. The earliest specimens come from the late Pliocene of North Africa, and they are known throughout Africa in the Pleistocene. All of these zebras are considerably smaller and shorter-legged than Grevy's zebra, with shorter, broader faces. The most familiar and common of the zebras in zoos and wildlife films is the plains zebra, or Burchell's zebra, Equus (Hippotigris) burchelli (Figs. 11.1, 11.6). These are the plumpest and smallest of the zebras, with very broad stripes. They range all the way from the rift valley in southern Ethiopia and Somalia through eastern and southern Africa. Their stripe patterns vary from north to south, leading some zoologists to subdivide them into subspecies and races. The races to the south tend to be less distinctly striped, with the stripes getting wider apart and receding up the legs. The northern races have shorter, scruffier manes than the southern ones, and some of the races in Somalia and Sudan have no mane at all. Most of these races interbreed freely, so

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Figure 11.7. All equines and many other ungulates raise their upper lips, exposing their vomeronasal organ to pick up pheromones in the air. This behavior is called Flehmen. (From Kingdon 1979). they are clearly not distinct species. Instead they are good examples of what zoologists call a geographic cline, or a single species that varies along a geographic gradient. If the e~tremes of this cline become isolated long enough, they mIght eventually form new species. However, as many of these races have already been wiped out by human activity, the:e is little likelihood of any new zebra species evolving before they are driven to extinction. As their name implies, plains zebras live in the open savannas and plains of eastern and southern Africa. They graze on older grasses that are too coarse for most antelopes, so they can coexist with a number of grazing species. They are most frequently mingled with herds of wildebeest (gnus). The size of their herd varies with the available vegetation and rainfall, but they seldom have more than 16 in a herd. Unlike the solitary, territorial Grevy's zebra, the plains zebra herds are stable units, composed of a stallion, a few mares, and their offspring. These herds are not territorial but migrate with the water and food supply. They recogniz~ each other, and if one is lost, they search for the stray. At times they may aggregate with other herds to form congregations of hundreds of zebras (especially during mass migrations), but when they split up again, the family groups remain together. The bachelor males also form small herds waiting for their chance to unseat a dominant stallion. ' Young females first become recepti ve after 13-15 months. They assume a receptive posture and attract a young male from outside the herd, who takes her away from her parental herd. The young female then passes from male to male until at about 2 years of age, when she begins to ovulate and stays with whichever male happens to be with her at the time. Mating and birth both occur between October and March, coinciding with the growing season for their food plants. Most foals are born in January after a gestation of 371 days, on the average. The foals can get up and run within an hour after they are born, yet there can be a very high death rate since zebra foals are the favorite food of lions, hyaenas, and jackals. The foals are weaned after 813 months, although they begin grazing just weeks after

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they are born. Females are capable of going into heat immediately after the foal is born, but they usually miss a year because of the strain of raising a foal. Like Grevy's zebra, the plains zebra shows a variety of fighting tactics between stallions competing for females. They also cement relations with members of their own herd by mutual grooming. Like other horses, they greet one another with pricked up ears, sniffing each other's bodies, especially the nostrils, neck, flank, and tail. Zebras, like rhinos, exhibit a distinctive behavior called flehmen, where they raise their upper lips and allow scent to reach the Jacobson's organ located underneath their upper lip (Fig. 11.7). This kind of behavior is particularly common when sniffing territorial markers of urine or feces of other zebras. Plains zebras apparently rely heavily on visual recognition, because they responded even to painted zebras and stuffed zebras! In fact, they did not respond to clean, bright stuffed zebras, but when the same specimens were rolled in dust, they elicited typical greeting behavior. Since most zebras are fond of rolling in the dust, it is not surprising that a clean zebra is something suspicious. This may also explain why the foals are a shaggy buff color with brown stripes when they are first born, and only develop black and white stripes after a few weeks. Although the plains zebra is not as threatened as the other zebra species, it has been wiped out in many parts of its former range by the expansion of human habitation. Plains zebras are particularly unpopular with natives since they are stubborn and hard to domesticate (unlike Grevy's zebra), and are also hostile to domesticated horses and donkeys. They will collect around a donkey pen and bray, trying to lure them out; when they do, the zebras attack the donkeys. Although still abundant, even plains zebras are declining rapidly in numbers in eastern and southern Africa due to the effects of poaching and homesteading on all of the land not in national parks. The mountain zebra, Equus (Hippotigris) zebra, is thinner and sleeker than the plains zebra, with narrower hooves (Fig. 11.8). It has slightly narrower stripes, and a white belly. In the middle of the throat they have a small, square dewlap. The vertical body stripes continue right to the tail, whereas plains zebras have fewer haunch stripes that do not continue to the tail. Mountain zebras also have separate ShOlt stripes along the backbone joined to the body stripes. At one time they were widespread in mountainous habitats in southwestern Africa. They are divided into two subspecies, Hartmann's zebra in Namibia, and the Cape mountain zebra in South Africa. Their social life is much like the plains zebra, although they live in rocky scrub, rather than open plains. They travel in single file along mountain tracks, with the stallion leading (the plains zebra herds are typically led by the mares). The stallion will go to a high point and look for danger, signaling "all clear" with a neigh so the rest can drink. Hartmann's zebra lives in a scrubby environment in the Kalahari Desert of Namibia, so it has many desert adaptations. The herd can go for three days without water,

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Figure 11.8. Hartmann's mountain zebra, Equus zebra hartmanni (PHoto courtesy C. Groves).

Figure 11.9. The quagga (Equus quagga), possibly a southern variety of the plains zebra with few stripes on the flanks, became extinct in 1883. (Photo courtesy Zoological Society of London)

and they can dig down nearly two feet into dry river beds to find water. Both subspecies of mountain zebra are seriously endangered. Their population has declined from 50,000-70,000 in the 1950s to fewer than 5,000 today. Because they compete with domesticated cattle for forage, their habitat is disappearing, and ranchers shoot them on sight. The Cape mountain zebra is one of the rarest of all large mammals. After extensive slaughter by Boer settlers, there were only a few hundred left in the 1920s. By the 1960s, only a few isolated herds of less than a dozen individuals could be found in the most remote mountains of South Africa. The largest herd, in Cradock National Park, contains only about 100 or so individuals. Although they are protected, their future is very uncertain with such small numbers of individuals in a few vulnerable places; extinction may not be far off. That fate has already overtaken the third species of this subgenus, the quagga (Fig. 11.9). Equus (Hippotigris) quagga was first discovered in South Africa in the 1770s. They OCCUlTed in large herds of over a hundred, and they were hunted easily because they were so tame. No one could imagine them disappearing. By 1823, however, they were rare in the wild, and the last known wild quagga was shot in 1861. They were kept in several zoos, and even used as spectacular animals to draw wagons. However, no attempt was made to breed them, and they gradually died off. The last known quagga died in the Amsterdam zoo in 1883. Occasional sightings in the wild have been reported since then, but none has been confirmed; they are probably hybrids between horses and zebras. The quagga was a little larger than the mountain zebra, with a long head and small ears like the plains zebra. Its most distinctive feature, however, was its stripes that were brown and occurred only on the head and neck. The body was brown and the belly and legs white. This parallels the

trends toward fewer stripes in southern races of plains zebras, and Colin Groves argues that they were just the southern subspecies of the plains zebra. Although" normally a plains animal, quaggas occasionally took to hilly country. Their name comes from their barking cry, which sounded a bit like "qua-ha," very similar to the "hee-haw" cry of plains zebras. Very little of their behavior was studied, however, before they went extinct. Of the four species that survi ved until recent times, then, the Grevy's zebra is clearly a distinct lineage with a different history from the other three. Debra Bennett thinks that all three Hippotigris zebras had different ancestries as well, and that quaggas and mountain zebras shared the closest ancestry with caballine horses. Either way, "zebras" are not a natural assemblage of animals, but at least two different lineages of horses that independently developed striped bodies. As Bennett says, "stripes do not a zebra make." At first, this may seem farfetched, until you recall that the details of the stripe pattern are very different in each species. Recent studies by the Scottish embryologist J.B.L. Bard have shown that all the striped color patterns have a similar embryonic origin, and vary only by differences in their embryonic history. The tendency for striping is actually in the embryonic potential of many horses, and occasionally stripes appear in asses, ponies, and mules. Thus many of the extinct horses we now call caballines or asses may have had stripes. The stripes are a primitive feature present in the genes of all Equus, and unstriped horses may be thought of as zebras which have suppressed their latent genetic potential for stripes. Instead of thinking of zebras as a group of striped horses, we should think of horses, asses, and onagers as unstriped zebras! These studies also answer the age-old question: is the zebra a black animal with white stripes (the African native view) or a white animal with black stripes (the conventional

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western view)? The white stomachs of zebras were long used as arguments for the black-on-white view, but recent embryological evidence clearly shows that the background color is dark and the white stripes are additions (along with the white stomachs). Indeed, every once in a while abnormal zebras are born. Their stripes are reduced to rows of dots and blotches, and they are clearly white dots and blotches on a black background. Why, then, did different horses develop similar striped patterns? Some striped animals camouflage themselves by breaking up their outlines in the view of a predator. However, zebras live mostly in large, noisy herds during the day, making little or no effort to hide from predators. Most of the other explanations do not stand up to close scrutiny either. The best hypotheses center on the fact that zebras are highly social, recognizing one another first by visual clues. They will even respond to a striped wall. The visual stimulation of stripes is deeply imbedded in their behavior. Zebras also enhance their social cohesion by grooming, and they prefer to be groomed around the mane and withers. Since these areas are frequently wrinkled whenever the neck bends, perhaps the association of grooming areas with vertically wrinkled (and eventually striped) parts of the body became part of the visual clues of zebras. Clearly there is strong selection pressure for striping in the zebras once it is attained. Rare abnormal black zebras are almost always shunned by the herd. Crisp, black and white stripes only make sense in large social herds in warm, tropical areas. They become unnecessary in animals with low densities living in deserts (such as many horses and asses), or inoperable in animals from colder climates with shaggy coats and annual shedding. This may explain the breakdown of striping in quaggas and most horses, which live in colder climates. The ecological motivation for stripes not only explains why they were retained independently in at least two groups of tropical horses, but it also has other implications. Many of the fossil horses that were related to modern zebras, but did not live in tropical areas, were probably unstriped or weakly striped. If you could take a time machine back to the Pliocene, you would probably not recognize the "American zebra," E. (Dolichohippus) simplicidens, as a zebra, since it probably didn't have stripes. WILD ASSES The wild asses form a second natural group, which diverged early from the lineages which became horses and zebras. This distinction is often recognized by placing them in their own subgenus, Equus (Asinus). As with horses and zebras, their earliest origins were with Dinohippus in the late Miocene of North America. During the Pliocene and early Pleistocene there were a number of fossil horses in North America which seem to be related to asses. These include the stilt-legged onager, E. calobatus, the pygmy onager, E. jrancisci, the stout-limbed Mexican horse, E. conversidens, and the large, heavy-limbed E. scotti. All of these asses share certain specializations in their teeth seen in

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Figure 11.10. The Persian onager, Equus hemionus onager. (Photo courtesy C. Groves). living asses, and most have relatively long limbs compared to other horses. Asses do not appear in Eurasia until the late Pliocene, where E. stehlini occurs in deposits along with the ancestral Grevy's zebra, E. stenonis. The separation between Asian onagers and African wild asses may have occurred overhalf a million years ago, since this distinction is already visible in E. sivalensis, an onager from the Pleistocene of the Siwalik Hills in Pakistan. By the middle and late Pleistocene most of the living species of asses and onagers can be recognized from their fossils. According to Bennett, each of the living species has a different North American ancestor. If this is so, then there must have been several independent migrations of asses and onagers from North America into Asia during the Plio-Pleistocene. Today there are three distinct groups of living wild asses. Most scientists place these in three different species, but some recognize only two: the African ass and the Asian ass. Almost all inhabit rocky highlands and lowland deserts of North Africa and southern and central Asia. Their narrow hooves are excellent for moving among rocks, and their light tan coats help both in reflecting heat, and blending in to their drab backgrounds. Most have large ears, which give them excellent hearing and long-distance warning of danger, and also serve to shed heat from their bodies. Their hindquarters are high and bony, and they tend to be skinnier than horses or zebras. They often have scraggly manes, but long tails. The commonest Asian ass is the onager, Equus hemionus, which was once found in almost all the Asiatic lowland deserts from Mongolia to Iran to Syria and Turkey (Fig. 11.10). The name "onager" is from the Greek word for the African wild ass, but it is now used for the Asian species. The Greeks called the Asian ass "hemionos," or "half.-~ass" (in other words, mule), and this is now used as the onager's species name. Although they were once widespread all over Asia, they too have been extensively hunted and driven out of their habitat by humans and their domesticated animals.

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Figure 11.11. The last known individual of the Syrian wild ass, Equus hemionus hemippus. It died in an Austrian zoo in 1927. (Photo courtesy C. Groves).

Figure 11.12. The kiang, Equus kiang. (Photo courtesy C. Groves)

At one time there were six subspecies recognized, but some of these are now extinct. The largest wild populations still thriving are found in Mongolia and adjacent regions in the steppes of Siberia and China, members of the subspecies E. hemionus hemionus. The smallest and most distinctive of the subspecies, the Syrian wild ass, E. hemionus hemippus, was only 3 feet (1 m) in height, and a very bright tawnyolive color. This is the wild ass mentioned in the Bible and familiar to many ancient Mesopotamian cultures. However, these were hunted out of existence by Bedouins and other local peoples, and were last seen in the wild by the archeologists digging in the ancient ruins of Assyria. The last one known to exist died in an Austrian zoo in 1927 (Fig. 11.11). Onagers are tolerant of extreme desert conditions. In the Iranian desert temperatures range from 136°F during the day to 59°F (57°-15°C) at night. It is so extreme and shadeless that there are almost no insects, nor birds, nor even scorpions. During the summer onagers stay within ten miles of the few watering holes, but they get most of their moisture from eating succulent plants and the moisture that condenses on them at night. They eat whatever succulents and grasses are seasonally available, and also must eat salty soil to get nutrients. Onager herds are led by an old female and consist of younger females and males. The adult males live apart for most of the year, until the mating season, which is in early summer. Gestation takes about 11 months, so that birth takes place in the following spring. This ensures at least 2 years between each foal. When due to give birth, the mares leave the herd to drop their foals, and return three months later. The young are weaned after about a year, but are not sexually mature until they reach two years of age, and mares are not ready to foal until their third year. At birth the sex ratio is nearly 1 male: 1 female, but female mortality is high in the first year, making a ratio of 1.6: 1. Then the trend reverses in favor of females, so that after a few years, the ratio is 1: 4.5.

Young onagers are born with long fleecy coats, which they shed after a few weeks. However, through their life they have a long coat in the winter, which is shed in the spring. The hairs of their winter coat can be up to a foot long, although it is usually much shorter. Like horses, onagers will mutually groom each other, standing parallel head to tail, nipping each others' flanks and necks. This grooming is particularly important during the molting season. The onager is legendary for its ability to run swiftly and tirelessly for long periods of time. In this respect, they can even outrun most horses. They have been timed at speeds of 30 mph (50 km per hour) for over an hour without sweating, and have been seen to jump a wall 7.5 feet (2.3 m) high. They are also extremely agile on rough ground, and climb much better than regular horses, so they are very difficult to capture. In captivity, they are very wild and restless, and seldom can be tamed. Luckily, they breed well in captivity, so many of the subspecies nearly extinct in the wild are being maintained in several zoos. A second Asiatic ass is the kiang, Equus (Asinus) kiang (Fig. 11.12). Some zoologists consider it a subspecies of E. hemionus, but most recognize it as a species different from the onager. Also known as the Tibetan wild ass, it is restricted to the Tibetan Plateau, along with a number of other mammals, such as the yak, the Tibetan gazelle, and the goa cattle. Kiangs typically live at very high altitudes, between 13,500 and 16,000 feet (4000-4900 m), where there are broad plains with low desert vegetation, and a growing season of only 2-3 months. Yaks live at even higher elevations, and the gazelle at lower elevations, so the high Tibetan steppes are often subdivided by elevation and called "yaksteppe" or "kiang-steppe." The kiang is the largest species of wild ass, weighing up to 800-1000 pounds (700-870 kg). They have a large head

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with a thick muzzle and neck and a convex "Roman" nose. Their bodies are short and robust, with long robust limbs and broad hooves. Their summer coats are red, and winter coats more brown and very shaggy. They have striking white underparts, especially on the belly, legs, haunches, the throats, sides of the neck, muzzle, and in rings around the eyes. They have thick lips and a horny palate to feed on tough swamp grasses and low-growing plants. These grasses are so tough and gritty they would cut the mouths of other horses. There is good feed only in late summer, and during that time they put on fat. Through the fall and winter, as it gets colder, they survive on this summer fat. They seek out unfrozen streams, but can live off the water in snow if they have to. By May the grass is beginning to sprout, and they begin to molt. They love to swim during the summer, and it probably helps them shed their long winter coats. Kiangs live in herds, which can range in size from 5-10 to 300-400. These herds wander over the wild moorlands, crossing over low rocky divides where they wear out narrow passes from their constant travel. The herds are led by an old female, and consist of females with their young, and immature males and females. Stallions older than 7-8 years tend to keep separate, living alone, or forming bachelor herds in the winter. Their herds are very well organized, and never become scattered. They will follow their leader single file, copying her every move. The members run, wheel and turn, sniff, graze, and drink in unison, although there is little mutual grooming like in the onager. They have very sharp senses, smelling humans at 500 meters and seeing them over a kilometer away. By late summer, the stallions begin to try to herd the females, and round them up, driving off rival stallions with bitter fights. The rut ends in late summer, and the gestation period is nearly a year, so that foals are born in July or August. The foals can run within 2-3 hours after they are dropped. They are born with fleecy gray-brown coats, and grow very rapidly. By the first winter they are half-grown, and by the end of the year they are independent. The name "kiang" is probably a corruption of the Tibetan word, "djang." The Tibetans consider them sacred, and were shocked when Europeans or Chinese tried to hunt them. The only natural enemy of the kiang is the wolf, which will chase herds and run down the sick or young ones. The kiang has never been domesticated, and like the onager, they are restless and aggressive when kept in captivity. The third species is the African wild ass, Equus (Asinus) africanus (Fig. 11.13). This species is much leaner than the Asian asses, with the largest ears, and it is the least horselike of the three. It is usually gray in color, with a white muzzle, and narrow vertical hooves for rocky deserts. Two subspecies are recognized. One, the Nubian wild ass, was once found near the Red Sea in Sudan and Ethiopia, and in isolated pockets in the Sahara Desert in Sudan. The other, the Somali wild ass, occurred in the Afar triangle of Ethiopia and Somalia. The Somalian subspecies is slightly

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larger, with a more yellowish, less reddish coat, than the Nubian subspecies. There are also differences in the skull, teeth and skin markings. Both subspecies are found in flat, stony deserts with little hills, which they use as lookout posts. The temperature may reach 122°F (50°C) in the daytime, so they feed in the morning, rest under the sparse vegetation during midday, and feed again from 5 p.m. until sundown. Since water is so scarce, they can go 2-3 days without drinking, and travel long distances at night to visit waterholes. When they spot humans they begin running while they are still a long way off, but stop frequently to look back. They have been clocked at 30 mph (50 km per hour). Their biology is not very well known because they are so difficult to study under such harsh conditions, and they are now so rare. A few hundred Somali wild asses live in the great Salt Plain, 400 feet (122 m) below sea level in the Danakil Depression, where they are protected by the Ethiopian government in land too inhospitable for humans or domestic stock. The Nubian wild ass, however, has rarely been seen, and was last documented in 1963. There are wild asses in their former habitat, but most of these are feral wild asses. It is very likely that the Nubian wild ass is actually extinct, even though it is supposedly protected by the Sudan government. The donkey, of course, is a domesticated descendant of the wild ass. They are probably descendants of the African wild ass, but it is difficult to tell exactly which subspecies is their ancestor. Some have suggested that there was an Arabian race of asses which is ancestral to the donkey. Indeed, in some of the Neolithic sites in Palestine, there are remains of a wild ass which differs both from the living African species and the onager. It may be an extinct subspecies that lived in the Near East, and may also be ancestral to the living donkey. If so, then donkeys were domesticated in. the Near East at about the same time that the first civilizations arose and when most other animals were also domesticated. WILD AND DOMESTICATED HORSES All living horses, both wild and domesticated, are members of the species Equus caballus. Equus was the Latin word for "horse," and caballus was the "slang" name for "horse" used by Roman soldiers in the provinces. Since the Romance languages (French, Italian, Spanish, Portugese) came from provincial Latin, their words for "horse" (cheval in French, cavallo in Italian, caballo in Spanish, cavalo in Portugese) are all corruptions of "caballus." The lineage which led to modem. horses is therefore called "caballine" horses. The oldest caballine horse fossils come from early Pleistocene deposits about 1.4 million years old in Nebraska. Like the ancestors of asses and zebras, caballine horses migrated to Eurasia via the Bering land bridge in the early Pleistocene. By about a million years ago the earliest fossils of caballine horses (sometimes called E. bressanus)

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Figure 11.13. The African wild ass, Equus africanus. (Photo courtesy C. Groves).

occur in the forest-grass terrains of east-central Europe. It lived side-by-side with the ancestral Grevy's zebra, E. stenonis. By about 900,000 years ago, caballine horses had begun to differentiate in Europe. One subspecies, E. caballus libycus, occurred in the arid hardgrounds of the deserts around the Mediterranean and Near East. It was adapted for arid climates, with smaller size, longer limbs, narrow body, and inflated sinuses for moistening incoming air. In northern Europe a different subspecies, E. caballus germanicus, became adapted to the colder bog country. It had a chunky, rotund body with short limbs and ears, ideal for conserving heat, and was about the size of a modern draft horse. Its nasal bones were long and arched, lengthening the nasal passages so that cold air would be warmed before it reached the sensitive lungs. In central Europe the common species through most of the Ice Ages was E. caballus mosbachensis. It was smaller than E. bressanus or the northern subspecies, but it did remarkably well through all the advances and retreats of the ice sheets. By the end of the last ice advance it had become extinct in Europe. Meanwhile another species was developing along the ice front in Asia, living in the tundra fringe. This was Przewalski's horse, E. caballus przewalskii, which

still lives in Asia today (Fig. 11.14). The oldest known Przewalski fossils occur in deposits about 200,000 years old, before the last ice age. They were the common horse in Europe during the last ice age, and they are well documented by our Cro-Magnon ancestors in the cave painting of Lascaux, France. We know that these people actively hunted horses, since we have found many of their kill sites. Most scientists believe that Przewalski's horse is the stock from which all domesticated horses are descended. Unfortunately, its genetic similarity to domestic horses means that it interbreeds freely, and many doubt that there are any pure Przewalski's horses left in either the wild or zoos. When supposed pure Przewalski's are crossbred, they continually show signs of some Mongolian wild pony heritage. At one time Przewalski's horses were widespread over the Asian steppes in Siberia, China, and Mongolia. By the 1920s, however, small herds of less than a dozen in the Gobi Desert of Mongolia were all that remained in the wild. The last individual to be caught alive was captured in 1947. In 1978 the Russians mounted an expedition to find if any more survived in the wild, without success. Although they are occasionally reported from time to time, most of these reports turn out to be wild asses or feral horses. Thus, all that

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Figure 11.14. Przewalski's horse, Equus przewalskii, is much like the Ice Age stock from which all living domestic horses were bred. Last seen in the wild in Mongolia in 1947, they are now restricted to zoos. (Photo by D. R. Prothero).

remains of the ancestral stock are probably the zoo populations, which are being carefully bred to increase their numbers and spread them around the zoos of the world. Whatever their genetic purity, there are some physical features characteristic of all Przewalski's horses. They tend to be reddish-brown, or "dun" colored, with light muzzles, narrow white rings around the eyes, and a dark stripe along their backs. They have a short, stiff mane with no forelock in front of the ears. The body is fairly stocky and heavily built, compared to most asses or domestic horses. It is capable of growing a shaggy coat in the winter, with a long "beard" on the throat consisting of hairs almost a foot long. It has a long tail, with both short hairs and very long, stiff hairs. The behavior of Przewalski's horse can no longer be observed in the wild, but apparently they behave naturally and maintain herd structure in captivity when there are enough of them in a large paddock. A Przewalski herd consists of a stallion and about half a dozen mares, along with their offspring. They move around single file, with the stallion bringing up the rear, or leading if there is danger. When the stallion snorts in alarm, the herd flees single file with the foals in the center. The stallion is very active in controlling

the herd, circling with an exaggerated trot, head held high, neighing and swishing his tail. He will round up mares by chasing and biting them, and when they lash out, he can turn and kick. Occasionally, a mare will be inj ured or killed if he bites too hard. Like many other hoofed mammals, Przewalski's horses display the characteristic ''jlehmen'' behavior. They sniff while pulling back the upper lip, presumably to bring scents to Jacobson's organ under their upper lip. Flehmen is often associated with sniffing the territorial scents of other males, and in Przewalski's horse, the stallion does it to detect the scent of estrus (probably traces of estrogen hormones) in the female's urine. He may hold his lip like this for almost a minute at the time of the rut. It is also performed by mares and foals as a kind of greeting behavior. During the rutting season the males become even more aggressi ve and restless, and readily threaten other males who challenge them for their herd. They adopt a threat posture, with ears laid back and head lowered, circling their opponent for an opening to bite and knock him down. Rutting stallions inflict serious bites upon one another, and apparently these battles are frequently fatal for the loser. This is surprising because in most large mammals (such as stags or rams), rutting behavior

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stops when the loser gives up and they seldom fight to the death. The female carries the embryo for about eleven months, so the foals are born just before the next rut. Most births take place in the spring, typically in May. The mare drops her foal in a quiet place at night, returning to the herd after about nine days. The foal can get up and run within an hour of birth, and suckle for brief periods of about a minute at a time. They weigh about 65 pounds (30 kg) when born, and double in weight in 4 weeks. They are weaned after about two years. Foals show the same playful behavior seen in domestic horses, and will become domesticated easily by their handlers. The mares defend them vigorously, kicking at all potential threats with their hind hooves, and urinating upon intruders. Stallions begin breeding in the fifth year, and mares in the fourth year, when they reach adult size. Some mares have continued to breed after 20 years of age. Males continue breeding much longer, and one stallion is known to have sired a foal at age 31. J:heir maximum known age in the wild is 34, although one domestic horse reached the record age of 61. However, the stresses of breeding are very severe, so males have a high death rate. During the breeding· season, stallions spend almost half their time running around, while the rest of the herd spends less than 10 per cent of their time in motion. Stallions sleep only 5 per cent of the time, while the rest of the herd spends 20 per cent of their time sleeping. Since herds consist of one male to 4-5 females, there are fewer males than females, even counting the solitary young stallions waiting to challenge for their own herd. Przewalski's horses have a wide variety of forms of communication, including posturing and vocalizations. Their neighs can convey a variety of meanings, and a rutting stallion will utter a laugh-like grunt toward a mate in heat or a rival stallion, squealing as he paws the ground and rears up. Mares also squeal when they refuse a stallion, or defend their foals. In short, their behaviors are very similar to those seen in the domestic horse, their descendant. In addition to Przewalski's horse, one other subspecies of wild horse survived until recent times. Known as the tarpan, Equus caballus ferus, it was once found in Poland and the Ukraine. It was first described by the naturalist Gmelin in 1769 as a smaller horse than Przewalski's, mousegray in color, with a thick head, long pointed ears, a short frizzy mane, and black shanks. Their fast-running herds were frightened by noise. Their stallions abducted tame mares, and killed a domestic stallion in the process. Later Russian naturalists described animals much like this, although some details of the description varied. Some of these horses apparently ranged to the Aral Sea in southern Russia, and apparently interbred with Przewalski's horse populations further to the east. If this is so, then the tarpan may have been a geographic variant of Przewalski's horse. Descriptions of this horse may go back even further. The Greek historian Herodotus reported gray wild horses from the marshy country of northern Europe, as did the

Roman authors Pliny and Varro. These horses apparently ranged widely through Europe in ancient and medieval times. As the steppes were plowed up, the forests cut down, and domestic animals released to compete for the grass, the wild tarpans began to disappear. The last tarpan outside Russia was killed in Lithuania in 1814. The last tarpan Ii ving in captivity died in 1918 in the Ukraine. All is not lost for the tarpan, however. Polish scientists have selectively bred Polish working ponies, which have much tarpan blood, and have reconstituted a breed of horses which look very similar. Zoo directors have tried breeding Ukrainian ponies with some other horse breeds which resemble tarpans, with results that also seem to be pretty close. In addition to the horses that have always been wild, there are domesticated horses which have been released and secondarily became wild. These are known as "feral" horses (from the Latin word "ferus," meaning wild). The mustangs of the American West, for example, are all descended from domesticated horses released from stocks brought by Europeans. A variety of other parts of the world are inhabited by feral horses, including the wild brumbies of Australia, the dark brown horses of the northern Swedish tundra, the famous gray horses of the Rhone Valley of southern France, and several types of wild ponies in the British Isles. Indeed, just about any habitat that once supported true wild horses, and is not yet overexploited by humans and their animals, seems to be occupied by feral horses. Finally, this brings us to the domesticated horses. For millions of years humans had hunted horses strictly for food. We have abundant evidence from kill sites and from the paintings on the walls of the caves at Lascaux, that horses were just one more prey item. No one knows what series of events suggested to our early ancestors that this animal might be good for more than just food. Perhaps they started by keeping horses around for food during winter, and began to get used to feeding them. For years archeologists thought that early Neolithic humans living in Kazakhstan in the Siberian steppe of central Asia about 5000 years ago were the first to domesticate horses. Recent discoveries, however, produced evidence of horse domestication in the Ukraine about 6000 years ago. These people were nomadic, and eventually became herders of sheep and goats. Perhaps they also herded horses, first for food, and eventually realized they could be harnessed for pulling their loads. Although one of the earliest cases of domestication took place in central Asia, there is evidence that domestication took place independently in China, Spain, Africa, and elsewhere at later dates. Domestication was so easy and useful that many cultures stumbled upon it. By about 4000 years ago horse bones are found in association with human settlements all over northern Europe. They were well established in the Near East around 2000 B.C., and were eventually put to use dragging war chariots for Babylonian and Assyrian kings and nobles. They appear in Greece around 1700 B.C., and in Egypt by 1600 B.C. Indeed, the mysterious Hyksos

EQUUS warriors, who thoroughly disrupted Egyptian civilization, had an advantage because of their horses. Similarly, the warlike Hittites of Turkey and Syria had an advantage in chariots, and eventually chariots became essential to the Pharaoh's warriors. Of all domesticated animals, Equus has perhaps had the most profound effects on humans. Although cattle, sheep, and goats made certain nomadic and civilized lifestyles possible, horses changed the tide of history. The introduction of chariots profoundly affected historical events in ancient Egypt and the Middle East, particularly when charioteers attacked armies which had never seen horses before. Later, the addition of cavalry gave armies further advantage over their opponents. The invention of the stirrup by the nomadic horsemen of central Asia further revolutionized human history. Repeatedly these fast-moving, agile mounted warriors struck out of the east as invading hordes of Tartars, Huns, and Mongols. They not only brought down Rome, but repeatedly scourged central and western Europe during the middle Ages. When Cortez brought horses to Mexico the Aztecs were terrified, and thought the horse and rider were one supernatural creature. As described by William H. Prescott in History of the Conquest of Mexico, the Aztecs

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"had no large domesticated animals, and were unacquainted with any beast of burden. Their imaginations were bewildered when they beheld the strange apparition of the horse and his rider moving in unison and obedient to one impulse, as if possessed of a common nature; as they saw the terrible animal, with 'his neck clothed in thunder,' bearing down on their squadrons and trampling them in the dust, no wonder they should have regarded them with the mysterious terror felt for a supernatural being." Horses became associated with wealth and power many times in Europe, and knighthood and chivalry (from cheval, "horse") were impossible without them. Indeed, the word for "men with horses" has often been synonymous with the wealthy class throughout history: the "hippeis" in ancient Athens, the "equites" in ancient Rome, the "cavalier" in England, "chevalier" in France, "caballero" in Spain, and "Ritter" in Germany. Throughout the last two millennia horses have been the chief animal players in human history, from Richard Ill's "A horse! A horse! My kingdom for a horse!" to the charge of the Light Brigade. Even though horses are now replaced by motor vehicles, they still retain an important role in our cultural heritage and in our hearts.

Figure 12.1. The culmination of brontothere evolution in the late Eocene is represented by these large, elephant-sized Megacerops. (Painting by Z. Burian).

12. Thunder Beasts

THE LEGEND OF THE THUNDER BEASTS In the plains and badlands of what is now South Dakota, Nebraska, and Wyoming, the Oglala Sioux made their home in the middle of the nineteenth century. Pressed into ever smaller territories, ravaged by smallpox, tuberculosis, alcohol, and other problems brought by the white settlers from the East, they witnessed their old ways slowly disintegrate. The Sioux depended on the buffalo, but buffalo herds were being diminished as millions of these magnificent animals were slaughtered. There was hope, though, in the mythology of the Oglala Sioux. According to their legends, mysterious, gigantic animals known as "thunder beasts" or "thunder horses" would jump from the clouds during thunderstorms (Fig. 12.1). The thunder beasts would drive herds of buffalo to the Sioux. And then, once the storm was over and their work done, the thunder beasts would disappear into the earth. Surely the thunder beasts were just legend, the figments of the imagination of a simple and primitive people. Or were they? In the 1840s Dr. Hiram A. Prout of St. Louis took an interest in science, including the legend of the thunder beast. A friend, possibly a trapper, who had business to pursue along the upper Missouri River in the Nebraska Territory (Dakota country) sent a piece of a huge fossilized lower jawbone (Fig. 12.2) to Dr. Prout for his inspection; this, it was said, was part of the remains of a thunder beast. Dr. Prout did not believe that it was a mythological beast; instead he interpreted the specimen as representing a distant relative of the horse, a "gigantic palaeotherium" that must have been found in some previously unknown (at least to the "palefaces") Teltiary fossil beds. Only one tooth was left in the jaw, the last lower molar (the wisdom tooth), and this single tooth measured nearly five inches (13 cm) in length. The complete jaw must have been at least 30 inches (76cm) long. Inquiring of his friend, Dr. Prout learned that the jawbone came from the vicinity of the White River in the Mauvaises Terres, the Big Badlands, of what is now South Dakota. (It was near here, at Wounded Knee Creek, that the heart of the American Indian was to be symbolically buried over 40 years later). Recognizing the importance of this find, Dr. Prout wrote a description of the jaw that he sent, along with a cast of the fossil, to Professors Dana and

Silliman at Yale University in New Haven, Connecticut. Being suitably impressed, these esteemed Eastern professors saw fit to publish Prout's announcement and detailed description of the "gigantic palaeotherium" from the American West in the prestigious American Journal of Science during the years 1846 and 1847. Soon more remains of similar beasts were discovered in 1849 when James Evans, an assistant to U. S. Government geologist Dr. David Dale Owen, undertook a reconnaissance of the Badlands along the White River. Joseph Leidy was entrusted with the scientific analysis and description of the fossils that Evans and Owen found, and in 1852 Leidy used the name Titanotherium (literally "titan beast," an animal of titanic size) to refer to these extinct animals. Two decades later, Othniel Charles Marsh gave the name Brontotherium (literally "thunder beast"-not only alluding to the Indian legends, but also noting that this huge animal must have shaken the ground like thunder when it ran) to a closely related and very similar animal. Even though the names Titanotherium and Brontotherium are no longer considered valid by scientists, the group in general is still known informally as titanotheres or brontotheres. Even at this early date the magnificent extinct brontotheres were a subject of awe and speculation. As noted above, it was first thought that they were palaeotheres (see Chapter 10), but they also seemed to have characteristics in common with tapirs, rhinoceroses, and even hyraxes ("damons") and elephants. Owen's 1852 (p. 198) description of the brontotheres reads as follows: "Associated with these extinct races [here Owen is referring to the other fossils found in the Badlands] we behold also, in the Mauvaises Terres, abundant remains of fossil Pachydermata of gigantic dimensions and allied in their anatomy to that singular family of proboscidate animals of which the tapir may be taken as a living type. These form a connecting link between the tapir and the rhinoceros; while, in the structure of their grinders, they are intermediate between the damon and rhinoceros; by their canines and incisors, they connect the tapir withthe horse, on the one hand, and with the peccary and hog on the

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Figure 12.2. Original figures of Prout's "gigantic Palaeotherium," a fragment of a left lower jaw of a late Eocene brontothere from the Big Badlands. (After Prout 1847). other. They belong to the same genus of which the labors of the great Cuvier first disclosed the history, under the name of Palaeotherium, in publishing his description of the fossil bones exhumed from the gypsum quarries of Montmartre, near Paris, but are of distinct species; and one at least, of this genus, discovered in the Badlands (Palaeotherium proutii), must have attained a much larger size than any which the Paris Basin afforded. In a green, argillo-calcareous, indurated stratum, situated within 10 feet of the base of the section, a jaw of this species was found, measuring, as it lay in the matrix, 5 feet along the range of the teeth, but in such a friable condition, that only a portion of it could be dislodged; and this, notwithstanding all precautions used in packing and transportation, fell to pieces before reaching Indiana. A nearly entire skeleton of the same' animal was discovered, in a similar position, which measured, as it lay embedded, 18 feet in length, and 9 feet in height. But here, as in the former case, the crumbling condition of the bones rendered it impossible to disinter them whole; and the means of transportation to the Missouri were insufficient, even if these interesting remains could have been extracted in good condition."

BONE RUSH When the articles on Prout's jawbone and the finds that Evans had made were published, the New York paleontologist and geologist James Hall immediately recognized the importance of collecting more specimens from the Big Badlands. To this end, Hall recruited a young medical student, Ferdinand Vandiveer Hayden, who also happened to be a boarder in Hall's house. In 1853, after graduating from Albany Medical College, Hayden took his first geological excursion, a fossil collecting trip to the badlands of South Dakota under the auspices of Hall. Later in life this same Hayden (Fig. 12.3) would prove to be one of the foremost mid-nineteenth century geologists: he conducted early geological surveys in the western territories, he was instrumental in the establishment of both Yellowstone National Park and the U. S. Geological Survey, and he was a professor of geology at the University of Pennsylvania. In addition, he served as a Union Army surgeon during the War between the States. But in 1853 Hayden was an ambitious young man willing to collect fossils without pay, his only reward being the experiences he would acquire. Once in the Badlands Hayden found thousands upon thousands of fossil bones and teeth, many of which gave the appearance of being only a few years old rather than the millions of years old that they actually were. Not only did Hayden find numerous specimens of thunder beasts, but also oreodonts and other artiodactyIs, carnivorous forms such as saber-toothed, wolf-like and hyena-like animals, and the shells of ancient turtles ranging in length from a few inches to several feet. Hayden corresponded with Joseph Leidy about his finds, and sent a number of the vertebrate fossil specimens to Philadelphia for scientific study. (James Hall, Hayden's sponsor, was primarily interested in invertebrate fossils such as ancient shellfish.) Over the next several years Hayden continued to return to the Badlands to collect fossils and study the geology. He was so single-minded concerning his purpose in this forbidding land that the local Sioux named him "He Who Picks Up Stones Running." After this tlUlTY of interest in brontotheres in the 1840s and 1850s, relatively little work was pursued concerning the group until the arch rivals Edward Drinker Cope and Othniel Charles Marsh entered the brontothere scene in the 1870s. As a result of the Cope-Marsh feud (discussed in Chapter 1) a number of fine brontothere specimens were collected, which they then named. Hoping to outdo his archrival, Marsh determined to amass the largest and most complete collection of brontotheres, capping his proposed project with a large-format monograph on the group. Although he never lived to complete his monograph, Marsh did gather an enormous quantity of brontothere specimens, published several important papers on these animals, and in anticipation of his monograph prepared 60 lithographic plates illustrating the dentition and osteology of the brontotheres. In the autumn of 1874 Marsh was out west collecting fossils, particularly eager to expand his collection of bron-

THUNDER BEASTS

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Figure 12.3. Photograph of Ferdinand Hayden and his 1870 geological survey in Wyoming. Hayden is seated at the far end of the table, facing camera. (Courtesy U.S. Geological Survey). totheres from the Badlands. This particular trip was not actually initiated by Marsh; rather, he travelled west at the insistence of the army officers Col. T. H. Stanton and General Ord who reported that a very promising fossil collecting region had been located in the Big Badlands near the Red Cloud and Spotted Tail Indian agencies. Marsh reached the Red Cloud Agency in early November, assembled his collecting party accompanied by an army escort, and proceeded to seek permission to travel and collect in the Badlands territory controlled by the Oglala Sioux, at that time led by Chief Red Cloud. In order to be able to collect safely within the Indian-controlled territory, Marsh needed to obtain the permission and cooperation of the Sioux, for according to the terms of the 1868 treaty that followed Red Cloud's War all the territory west of the Missouri River in the general area of present-day South Dakota belonged to the Sioux. To this end Captain James H. Cook, an experienced trapper and scout who resided in Agate, Nebraska, interceded. Cook knew and respected the Sioux, and in turn they trusted him as much as any white man. One day when Cook was talking with Red Cloud the subject of the thunder beasts came up. Cook was introduced to this mythology, and even shown a petrified jaw bone that was said to have come from the thunder beasts. Of course, this was a brontothere jaw. When Marsh appeared on the scene shortly thereafter he met Cook and learned of the petrified thunder beast's remains-exactly what he was after! At first the Sioux were very wary of Marsh's intentions, thinking that he, like most white men, was after "yellow lead" (gold) rather than "stone bones." However, with the support of Cook, a meeting was

arranged between Red Cloud and Marsh during which the paleontologist was reluctantly granted permission to collect his beloved brontotheres. When it later appeared that the Sioux might withdraw their permission to enter their territories, Marsh gave the order for his party to depart shortly after midnight without the Indians' knowledge and without a single Indian scout, guide, guard, or interpreter. The fossil collectors and their army escolt literally sneaked past the sleeping Indians in the middle of the night and headed for the fossil fields. By the time they reached the Badlands collection sites they were under Indian surveillance, but at least temporarily the Sioux let them collect in peace. Winter was beginning, the weather was intensely cold, and fossils were collected quickly and piled in heaps. At least the vigorous activity helped keep the participants warm. Just as they were finishing up their collecting, but before they had a chance to pack the specimens, word came from friendly Indians (perhaps sent by Red Cloud) that hostile Indians to the north were planning an attack on the "Big Bone Chief' and his party. To top it all off, a snowstorm was on the horizon. Marsh was faced with a difficult decision. Should he simply remove himself and his party from the area as fast as possible, leaving the fossils behind? Or should he throw the specimens into the wagons unpacked and hope for the best? (At this point it was too late in the day to properly pack them and be able to leave.) If the specimens were not adequately packed and protected they would surely be jumbled and broken into thousands of worthless fragments by the time they got back to safety. It would be foolish to attempt to pack the specimens at night; that would mean

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lighting the tents that would then make perfect targets for Indian attack. Marsh took the gamble and won. He stayed one more day in order to see that the fossils were properly packaged and stowed on the wagons. Less than twenty-four hours after he left a large war party was at his former campsite looking for him. Marsh's 1874 trip to the Badlands yielded more than brontothere specimens. Marsh kept his word-he really was collecting stone bones and not yellow lead-and apparently a genuine friendship developed between Marsh and Red Cloud. Red Cloud bitterly related to Marsh how his people were being mistreated by corrupt government officials (particularly the Indian agent in charge of the Red Cloud Agency). Their land was stolen, treaties were broken, and crimes were perpetrated against them by the white prospectors, hunters, and trappers. He gave Marsh samples of the rotting food and other substandard supplies that were provided to the Indians by the corrupt Bureau of Indian Affairs. Marsh visited Washington, D.C., in April of 1875 to attend the meetings o~ the National Academy of Science. Armed with the information and evidence that Red Cloud had provided him, he made it a point to pay a visit to the current Commissioner of Indian Affairs, E. P. Smith. He brought Red Cloud's complaints to the Commissioner, described his own observations of Indian living conditions, and showed the Commissioner the substandard Indian rations. Feeling dissatisfied with the outcome of his discus- . sion with the Commissioner, the next day Marsh called on President U. S. Grant (the "Great White Father" himself) to relay Red Cloud's concerns. Shortly thereafter Marsh met with the Board of Indian Commissioners in New York City. The major newspapers, such as The New York Herald, Tribune, The Nation, and Boston Transcript picked up the story and throughout the summer and fall of 1875 Professor Marsh's continued dealings with the government on behalf of the Indians was big news. Indeed, the papers and public alike joined in the professor's crusade. The upshot was a bit of a shake-up in the government involving those who dealt with Indian affairs; among other things, Christopher Delano, the Secretary of the Interior, was forced to resign. By the time it was over O. C. Marsh was certainly the most famous paleontologist, and perhaps the best-known scientist (at least temporarily), in America. Unfortunately, Marsh's efforts on behalf of the Indians did not significantly improve their situation. Gold was discovered in the Black Hills of South Dakota, prospectors came pouring into the Indian territory, and in the summer of 1876 there was a bloody campaign against the Sioux in which George Armstrong Custer and five companies of the Seventh Cavalry were slaughtered at Little Big Horn. This was the last significant Indian victory. Within two decades the Native Americans were utterly defeated. Marsh's personal friendship with Red Cloud lasted for many years thereafter. Marsh displayed a painting of the Chief in full ceremonial regalia in his home. In 1877 Red Cloud sent his peace pipe to Marsh, and in January of 1883

Figure 12.4. John Bell Hatcher, the great collector of dinosaurs and brontotheres. (From American Geologist, 1907). Red Cloud was Marsh's guest in New Haven for three days. It is recorded that Red Cloud showed no interest in nor appreciation for the treasures stored in the Peabody Museum of Natural History or the Yale Art Museum. However, he is recorded as having smiled while visiting the local Winchester rifle factory, and he laughed with delight when he saw men slide down the firepoles at the local firehouse. Marsh needed more fossil specimens, especially good brontotheres for his proposed monograph, but after the middle 1870s he did little collecting himself. The Professor had to oversee the Peabody Museum (the actual construction of which began in 1874), the laboratory preparation and curation of specimens, and to do research and writing. Marsh had numerous individual collectors and collecting parties in the field working for him and shipping the field notes and specimens back to Yale. Occasionally the master might make brief forays into the field himself to check on the work. In the early summer of 1884, just after graduating from the Sheffield Scientific School at Yale, a twenty-three-yearold man by the name of John Bell Hatcher (Fig. 12.4) presented himself to Professor Marsh. When asked what his business was, Hatcher stated simply that he wished to collect fossils. He had worked in his youth as a coal miner in Iowa, and for his own personal enjoyment had gathered a small collection of Carboniferous fossils from the coal beds. Now he was willing to collect fossils for Yale; he would collect anywhere and at any salary. Marsh was impressed by the young man, and hired him. During his relatively short career (he would die but twenty

THUNDER BEASTS years later at the age of 43) Hatcher proved himself to be one of the best fossil hunters ever. He collected an enormous number of brontothere specimens (reportedly over 150 skulls and jaws) for Marsh; these specimens now reside in the National Museum of Natural History of the Smithsonian Institution (Washington, D. C.) since the expeditions were funded with Federal dollars. Notable among other types of fossils that Hatcher collected are horned ceratopsian dinosaurs and Mesozoic mammals. But Hatcher was not merely a field collector. He also became an outstanding scientist in his own right, authoring papers on brontotheres, extinct rhinoceroses, and a classic paper on recent and fossil tapirs (the subject of our next chapter). Hatcher was initially assigned to collect Miocene rhino bones from Long Island, Kansas, with the legendary fieldman Charles H. Sternberg. Within a few .days Hatcher's inherent traits began to manifest themselves: he was meticulous, dedicated (he would sometimes collect well into the winter, to the detriment of his health), somewhat of a perfectionist, at times brash and opinionated, and a bit difficult to work with-but an excellent collector. The young Hatcher, but a few days on the job, had the audacity to criticize Sternberg as a bit careless and in a hurry to remove and pack specimens, thus resulting in fossils being broken or missed. Soon Hatcher was excavating and collecting fossils on his own. Hatcher developed the modem technique of gridding off his bone quarry into numbered five-foot squares; using this grid he mapped precisely the original location of each bone he removed. This information would be of use later in attempting to reconstruct the animals and how they may have died and been buried. During the period 1886-1888 Hatcher spent much time collecting brontotheres from Dakota and Nebraska. The year 1886 was a banner one for brontothere collecting; between May and October of that year he shipped 118 boxes of brontothere specimens, weighing a total of 24,136 pounds, to Marsh. In later years Hatcher had a slight falling out with Marsh. Hatcher felt that Marsh was excluding him from the academic aspects of vertebrate paleontology in order to keep him a field man. Consequently, in 1893 he left Marsh's hire and took a position as Curator of Vertebrate Paleontology at Princeton University. While at Princeton Hatcher helped organize and lead an expedition to Patagonia (1896-1899). He then moved on to the Carnegie Museum of Natural History, Pittsburgh, leading fossil collecting expeditions to the West in the earliest years of the twentieth century. In 1904 he contracted a fatal case of typhoid. In 1890 Marsh purchased a beautiful lower jaw of a brontothere from L. W. Stilwell of Deadwood, South Dakota. Marsh paid the rather steep price of $100 for this specimen (remember we are talking about 1890 dollarsinitially Hatcher earned but $50 a month collecting for Marsh full time), but it was worth the expense. The jaw was almost identical to that of the genus Brontotherium, with one important exception. Whereas Brontotherium, Brontops, and

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similar forms had only four incisors between the canines, Stilwell's specimen had six incisors. Marsh anxiously acquired the specimen, and once he had it named a new genus and species for it-Teleodus avus. For over ninety years Teleodus was accepted as a valid genus. Then in the early 1980s Spencer Lucas and one of us (Schoch), at that time both graduate students at the Peabody Museum, were examining some of Marsh's original brontothere specimens when we made a surprising discovery. Looking at the famed original Teleodus specimen, we felt that the fossil originally had only four incisors, not six. It appeared to us that someone had added two extra incisors to the jaw. Could Stilwell have done this to increase its value? Alternatively, it was possible that the extra incisors were baby teeth that had not been lost in the adult animal. Either way, we were able to demonstrate that Teleodus, as an adult animal, had only four permanent incisors in the lower jaw. Further supporting our assertion, other than this single specimen of Teleodus, no brontothere lower jaw has ever been found in the Big Badlands with six incisors. It seems Marsh was fooled-perhaps purposely cheated out of $100. Given his greed for specimens, we have to wonder if Marsh might not have bought the jaw even if it had not had six incisorsbut perhaps for a lesser sum. OSBORN, ASIA, AND ORTHOGENESIS Marsh passed away in 1899, before he had a chance to write his brontothere monograph. It fell to Henry Fairfield Osborn (1857-1935) to finish Marsh's work (Fig. 12.5). One of the best-known names in American vertebrate paleontology in the late nineteenth and early twentieth centuries, Osborn was long associated with the American Museum of Natural History in New York (he served as its president from 1908 to 1933). After Marsh's death Osborn gained access to Marsh's brontothere material and the illustrations that Marsh had prepared. Osborn also had ready access to Cope's brontothere specimens since in 1895 he had arranged for· the American Museum to purchase Cope's collection of some 10,000 North American fossil mammals. Osborn added to the brontothere collections through his own collecting efforts, and the efforts of his staff and assistants. In particular, the American Museum's Central Asiatic Expeditions of the 1920s to the Gobi Desert uncovered a whole series of previously unknown brontothere forms. Led by the intrepid Roy Chapman Andrews, the Central Asiatic Expeditions of 1922 to 1930 were the talk of the paleontological world. In 1900 Osborn had proposed that many groups of animals had originated in the long distant past in Asia and thence spread out to the other northern hemisphere continents, namely North America and Europe. For instance, prior to the 1920s brontotheres were only known from the Rocky Mountain region of the United States and from a few meager remains presumably recovered from eastern Europe. Did it not make sense that they should also have occurred in the intervening area, Asia? The Asiatic expeditions uncovered a wealth of fossils, particularly

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HORNS, TUSKS, AND FLIPPERS "[I]n the summer of 1877 I saw in the Bridger Basin of south-west Wyoming my first fossil titanothere, and ten years later-namely, in 1887-1 began the series of seventeen papers and memoirs on the titanothere family (Brontotheriidae). This led to my appointment in the year 1900 as vel1ebrate palaeontologist of the United States Geological Survey and to twenty-nine successive years of as arduous intensive research as has ever been pursued in any central field of science, culminating in my Survey monograph No. 52 ... of 951 pages, 795 figures, 236 plates, by far the most profound study of a central family history [of animals] that has ever been made [Osborn never was one to be modest]; this monograph is entitled The Titanotheres of Ancient Wyoming, Dakota and Nebraska."

Figure12.5. Henry Fairfield Osborn, President of the American Museum of Natural History, and dominant paleontologist at the turn of the century. In this portrait, his aristocratic attitude and scientific arrogance are almost visible. Ironically, most of his voluminous scientific work on brontotheres, proboscideans, horses, rhinos, and other large beasts has been discredited by later paleontologists. (Courtesy Department of Library Services, American Museum of Natural History). Tertiary fossil mammals, and among the first and most common fossils they found were the remains of brontotheres! With confidence Osborn could now declare (in Chapman, 1926, p. vii-viii) that "Asia is the mother of the continents!" Asia was viewed as a veritable "palaeontological Garden of Eden," "the birthplace ... from which many kinds of reptiles and mammals spread westward and eastward." (Today not all paleontologists see it as clearly and simplistically as this, but it was an important idea at the time.) In 1929 Osborn's monograph on the brontotheres (which he generally referred to as titanotheres) was published. This, he hoped, would prove to be the definitive word on the subject. In fact, however, he was wrong (as will be discussed later). Osborn summarized his brontothere career in the following words (Osborn, 1930: 56-57):

Osborn's monograph stands as a monument to the man, but in science we are always adding to our knowledge and revising our theories, so it has not remained the definitive work on brontotheres. Even by the standards of Osborn's own time, his later work tended to be a bit idiosyncratic. He was a "splitter": he recognized over a dozen subfamilies of brontotheres, over two dozen genera, and over a hundred species. Recognizing so many subfamilies, genera, and species is not inappropriate if it is justified. The problem was that many of Osborn's taxa were not consistently distinguishable from one another. Furthermore, Osborn used his studies of the brontotheres as a backdrop to expound upon his own personal theories concerning the mechanisms and processes of evolution, dispersal, and extinction of organisms. By modern standards many of his ideas seem very strange indeed (although perhaps it is not fair to judge Osborn in this way sixty to seventy years later; Osbornian ideas were actually widespread among paleontologists of the time). As an example, Osborn espoused a type of orthogenesis-the idea that there was an intrinsic, direction-gi ving force controlling the evolution of brontotheres (Fig. 12.6). He maintained that animals such as brontotheres did not evolve simply via Darwinian natural selection. There were built-in progressive trends that controlled the evolution of organisms. As a result of these built-in trends driven by internal forces the brontotheres may have even evolved out of control. Perhaps they evolved horns and bodies that were so large as to· be counter-productive. This may have contributed to the extinction of the brontotheres, according to Osborn. The brontothere lineage over-shot its mark-it over-evolved-and the lineage lost its vitality and became "racially senile." Such ideas have since been discredited: there is no good evidence that even the latest brontotheres were not the result of natural selection. Still, they did go extinct, as have many other groups of animals throughout the history of Earth. Osborn's monograph (for the most part completed by 1920 although not published until 1929) was sent to press,

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intimidating, and there is an additional difficulty: most of the key specimens of Chadronian (late Eocene) brontotheres are still in their field wrappings and will require years to prepare. In the meantime new brontothere specimens have been uncovered (particularly with the renewal of interest in paleontology in China) and new genera and species have been named. At present Bryn Mader is attempting to sort out at least some of the confusion. Recently he published a review of the North American genera of brontotheres in which he recognized only eighteen genera (as opposed to twenty-four North American genera recognized in 1929 by Osborn), including several genera named since Osborn died (Fig. 12.7). However, Mader has yet to consider all named genera and species of North American brontotheres, and no revision of non-North American forms has been attempted.

~

~ Figure 12.6. Osborn's notion of orthogenesis in brontothereevolution, showing a linear array of specimens with the horns gradually getting longer. Ironically, most of the taxonomic names are now invalid, and many of these taxa were part of a "bushy" branching family tree, not a single unbranched lineage. (Compare with Fig. 12.7). (From Osborn 1929). and Osborn himself died, before the majority of Asian brontotheres collected by the Central Asiatic Expeditions were prepared and described. In a short paper published in 1943 the American Museum paleontologists Walter Granger and William King Gregory briefly described a dozen new Mongolian genera of brontotheres, a dozen and a half new species, and a couple of new subfamilies. As a result of the work of Osborn, Granger, and Gregory, the broad trends of brontothere evolution became clear, but the details needed to be resorted and revised. This would be a daunting task, and it is not surprising that no one since Osborn has attempted a complete revision and systematic study of the evolution of the brontotheres. Those two gigantic volumes of Osborn's monograph are pretty

THE BIOLOGY OF BRONTOTHERES When most people think of brontotheres, they think of the huge monsters that were the end result of the evolution of this lineage (Fig. 12.1). Certainly the late Eocene (Chadronian) brontotheres of North America were impressive beasts. Megacerops (formerly known as Brontotherium and Titanops; here we use the terminology of Mader's latest revision) stood 8 feet (2.5 m) tall at the shoulder, had a long skull that was elongated and high in the back behind the eyes, yet held only a small brain, and had a pair of horns growing from the nose area. These horns were made of bone and were probably covered with skin, analogous to the horns of the giraffe. In Megacerops they were long and flaring, with a circular cross-section. Another Chadronian brontothere, Menops (including Allops and Menodus) had horns with a more triangular cross-section. Mader recognizes only one more valid genus of Chadronian brontothere, Brontops (also known as Diploclonus), which had short, forwardpointing horns. The brontothere skeleton was very massive and almost elephantine. Based on the teeth, titanotheres must have fed on relatively soft, leafy vegetation. They may have inhabited both the forests and plains, and at times were extremely abundant. The horns of brontotheres (although not all brontotheres had horns, and horns were not identical in all forms that did possess them) have been a bone of contention ever since they were first discovered. Some scientists have speculated that the horns were used as protection against predators, although in fact there appear to have been few large carnivores living at the time that might have challenged them. One study suggested that the brontotheres used their horns in high impact head-on butting during intraspecific agonistic behavior, such as males fighting over females. More likely this was not the case. Instead, the horns were probably used in head wrestling between brontotheres, and in broadsiding each other by swinging the head side to side. Although the brontothere horns look very strong, massive, and impressive they were actually supported on the thin nasal bones of a skull that itself was relatively lightly built and full of cavities of open spongy bone. If brontotheres

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33 ......-

.....-..

Figure 12.7. Modern "bushy" version of brontothere phylogeny, based on the work of Mader (1989). Note that most of the brontotheres that were placed in an orthogenetic series by Osborn (see Figure 12.6) were actually contemporary side branches. smashed their horns into each other head-on they might well have shattered their skulls. Furthermore, in order for the horns of two brontothere individuals to meet tip-to-tip in head-on butting, the animals would have had to hold their heads at such an angle that they might not have been able to see in front of them. Supporting the suggestion that brontotheres may have hit each other in the sides with their horns, brontothere skeletons are known in which ribs were broken and healed during the lifetime of the individual (Fig. 12.8). Increase in horn size through evolutionary time, and how it mayor may not correlate with an increase in the body sizes of brontotheres through evolutionary time, has also been a topic of much discussion in the scientific literature. As noted earlier, Osborn used the brontotheres as a vehicle to promote his own views on evolution. According to Osborn, incipient horns (such as 5 mm high bumps) would serve no function and could not be accounted for by natural selection. Instead, the progressive (orthogenetic) development of horns in various lineages of brontotheres must have been due to internal forces that drive evolution regardless of natural selection. Since Osborn's time it has been convincingly argued that the development of structures, such as brontothere horns, can be satisfactorily explained by the

concepts of Darwinian natural selection in conjunction with studies of how the size and shape relationships of animal structures change as the overall body sizes of animals change. Mysterious internal forces that drive evolution need not be invoked. Even though a number of brontothere specimens have been collected in the last 150 years, it is rare to find a single quarry that contains several individuals of the same species that presumably all lived and died together. When such a quarry is found, however, it may help shed light on the living biology of the animals. In 1929 and 1930 the Carnegie Museum of Natural History in Pittsburgh uncovered and collected specimens of the late Eocene (Duchesnean) brontothere Duchesneodus (formerly known as Teleodus) from a single quarry outside of Vernal, Utah. From the Duchesneodus quarry eleven skulls were recovered: two juveniles, three that are thought to be males, and six females. The males have larger horns, generally heavier and more massive skull parts, and domeshaped convexities on the tops of the skulls. These features suggest distinct sexual dimorphism among these brontotheres. As is true for many other sexually dimorphic species, each male may have retained several females. Unlike many sexually dimorphic mammals, the canines

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Figure 12.8. A skeleton of "Brontotherium" (now called Megacerops) as it was mounted for display at the American Museum around the turn of the century. Note that one of the ribs just behind the shoulder blade is broken and rehealed with a thick mass of bone, probably from the blow of another brontothere horn during sparring. (Neg. no. 333452, courtesy Department of Library Services, American Museum of Natural History). appear to have been the same size in females as in males. The earliest known undoubted brontothere is found in the late early Eocene of North America and goes by the name of Eotitanops ("dawn titan") (Fig. 12.9). The genera Lambdotherium and Xenicohippus, from the same general area and time period as Eotitanops, may also be early brontothere relatives, but there is debate on this point. At this time no one is really certain whence brontotheres evolved, or what their closest relatives are among the non-hyracoid perissodactyls. For many years it was thought that brontotheres shared a common ancestry with the horse group (equoids) and/or with the chalicotheres (see the next chapter), but this is now open to considerable doubt. In the most recent detailed study of this problem the British paleontologist J. J. Hooker has concluded that there is no good reason to suggest that brontotheres are especially closely related to any other particular group of perissodactyls.

At any rate, the earliest known brontotheres come from the early Eocene of western North America, and on this basis they seem to have originated in North America (contrary to the opinion of Osborn that they arose in Asia). These brontotheres were relatively small, lacked horns, and resembled closely the horse-relatives of the time. Brontotheres quickly underwent a major evolutionary radiation, spreading into Asia and eventually eastern Europe during the middle Eocene. By the late middle Eocene they had become some of the largest land mammals in Eurasia and North America (Fig. 12.10), and then continued to evolve ever larger sizes and more impressive horns throughout the Eocene. At the end of the Eocene in North America they "suddenly" went extinct. European brontotheres are known from a few rare specimens found in Eocene deposits of Romania and Bulgaria. In Asia brontotheres appear to have also gone extinct at the end

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Figure 12.9. Reconstructions of the earliest brontotheres, the early Eocene Lambdotherium popoagicum (left) and Eotitanops borealis (right). (From Osborn 1929).

Figure 12.10. By the late middle Eocene, brontotheres were cow-sized, and included long-skulled varieties like Dolichorhinus (right) and small-horned Manteoceras (left). (Neg. no. 35835, courtesy Department of Library Services, American Museum of Natural History).

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Figure 12.11. The "battering-ram" brontothere Embolotherium, from the upper Eocene beds of Mongolia. (Neg. no. 312579, courtesy Department of Library Services, American Museum of Natural Mstory).

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of the Eocene. One of the largest and most memorable Asian brontotheres was Embolotherium from the late Eocene of Mongolia (Fig. 12.11). Instead of branched horns as seen in other brontotheres, embolotheres had a single, broad, blunt battering ram on their noses. Their battles must have been impressive to witness. Two angry males probably wrestled and battered each other with their enormous nose clubs, bellowing, snorting, and pawing the ground like bulls. At what appears to have been the peak of their evolutionary development (as judged by the sizes of their bodies and the sizes of their horns), brontotheres suddenly went extinct at the end of the Eocene (Chadronian time, formerly thought to be early Oligocene). Numerous explanations have been proposed for this extinction. Osborn thought that the brontotheres suffered from "racial senescence." Maybe brontotheres succumbed to a trypanosome disease epidemic-perhaps carried by an ancient ancestor of the tsetse fly. However, recent work by one of us (Prothero) has demonstrated that the extinction of the brontotheres coincided with the extinction of a number of archaic types of mammals at the end of the Eocene. This extinction event corresponded to a worldwide episode of glaciation, which caused a big drop in global temperature and a lowering of the sea level. Of more importance to brontotheres, the temperature and climatic changes affected the vegetation, and the forests of the late Eocene were replaced by savannas in the Oligocene. The forest vegetation on which the brontotheres and many other browsing mammals depended disappeared, and thus many of the mammals, including the brontotheres of North America, went extinct. Once brontotheres were gone, the rhinos and elephants were able to take over the niches of the giant herbivores.

Figure 13.1. The Brazilian tapir (Tapirus terrestris) , the largest American species, with its thick neck and bristly mane. It is found primarily in the Amazon Basin. (Photo by D. R. Prothero).

13. Proboscises and Claws

DRAGONS'TEETH For centuries the remains of the tin-schu, the subterranean dragons, have been highly valued among the Chinese for their strong medicinal properties. The Chinese dragon is considered beneficial, signifying wisdom (in contrast to the mythology of European dragons which are often depicted as creatures of terror). Even today one can buy fung-lungtschih (big, white dragons' teeth), tsing-lung-tschih (small, black dragons' teeth), and lung-ku (dragons' bones) from shops and pharmacies in China and those serving Chinese communities elsewhere. In the nineteenth century western scientists first acquired some of these dragon teeth and dragon bones for analysis. What were these dragons? None other than fossil mammal remains. For the European scientists this was both an exhilarating and saddening discovery. Certainly these fossils might shed much light on the history of life, but only if paleontologists could get to the specimens before they were ground up and ingested. For centuries the Chinese had been mining and destroying tons of fossils. And where were the actual localities from which the fossils came? The Chinese merchants, traders, and pharmacists were not about to tell. Dragons' teeth sold for high prices; such information was top secret. Still, since one could buy dragons' teeth on the open market, at least the western scientists could acquire specimens in this manner (as long as their money held out). Thus a few specimens purchased in Shanghai came into the hands of Richard Owen of the British Museum (Natural History). Owen described these specimens in 1870 and among the types of animals represented were a rhinoceros, a tapir, a chalicothere, and an extinct elephant relative (Stegodon). The appetite of the scientists for more of the dragons' teeth was whetted. During the period 1899-1902 the German scientist and physician Dr. Haberer acquired, through the Chinese drug vendors, a large collection of dragons'teeth and jaws which he turned over to his friend Dr. Max Schlosser, a vertebrate paleontologist working in Munich. Based on Haberer's collection, Schlosser was able to identify approximately sixty different species of Pleistocene mammals from China. Among these specimens was a tooth that Schlosser identified as a fossilized human molar; soon began the search for

ancient man in China, culminating a quarter-century later in the discovery of "Peking man" in the Zhoukoudian (formerly Choukoutien) caves near Beijing (formerly Peking). But that is the story of other books. In 1921 Walter Granger of the American Museum of Natural History in New York, a leading paleontologist of that museum's Central Asiatic Expeditions, went to the Szechwan Province of China in search of the dragons' teeth. Granger discovered that in this area the fossils were coming from Pliocene and Pleistocene fillings in limestone caves. During the winter Illonths the local farmers would collect the fossils and subsequently sell them to merchants who would in tum pass them on to various retail vendors and pharmacists. Granger short-circuited the process, by intercepting and purchasing the best fossils from the local farmers (who also could tell him exactly where they came from), and soon he had an outstanding collection. of dragons' teeth. When it came time to study these specimens, among the species represented was a tapir (Fig. 13.1). But this was no ordinary tapir. Although it looked very much like a modern tapir in many respects, its skull was 1.5 feet (0.5 m) long and it is estimated that the living animal may have weighed some 1700 pounds (800 kg), two and a half or three times the weight of living tapirs (Fig. 13.2). Appropriately, in 1923 William Diller Matthew and Walter Granger gave this new tapir the name Megatapirus.

Figure 13.2. Walter Granger compares the giant skull of Megatapirus with the skulls of living tapirs. (Neg. no. 250977, courtesy Department of Library Services, American Museum of Natural History).

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HORNS, TUSKS, AND FLIPPERS

HALL OF THE MOUNTAIN COW A century ago, so it is said, one might observe oddlooking, rotund, short-legged pig-like animals with short "trunks" (proboscises) placidly walking the streets of many South American towns. Easily tamed and capable of displaying great affection, these formerly wild tapirs would wander in the forest during the day, and then return to their human masters in the evening to be fed. Virtually "living fossils," modern tapirs are very similar (although in general a bit larger) than their Oligocene and Miocene relatives. Alas, the semi-noble tapirs (four species are extant) are now all classified as vulnerable or endangered species. The giant prehistoric tapir of Asia, Megatapirus, may once have coexisted with humans, but it is now extinct. The only tapirs living today are a few relict populations centered in Central and South America and Southeast Asia. The Asian, Malayan, saddle-backed, or banded tapir (Tapirus indicus) inhabits the primary rain forests of Burma and Thailand south to Malaya and Sumatra (Fig. 13.3). The Brazilian or South Amyrican tapir (Tapirus terrestris) lives in woody and grassy areas, near permanent water supplies, from Colombia and Venezuela southward to Paraguay and Brazil (Fig. 13.1). The woolly, Andean, or mountain tapir (Tapirus pinchaque) lives in the forests, and perhaps above the treeline, in the Andes mountains of Colombia and Ecuador, and possibly northern Peru and western Venezuela (Fig. 13.4). Baird's tapir (Tapirus bairdii) inhabits swampy or hilly forests from southern Mexico through Central America to Colombia and Ecuador west of the Andes (Fig. 13.5). Taking all four species of tapirs into account, the altitudinal range of tapirs is from sea level to about 14,700 feet (4,500 m). The head and body length of all species of tapirs is in the range of 70-100 inches (180-250 cm), they stand about 30-47 inches (75-120 cm) at the shoulder, and weigh in the range of 500-660 pounds (225-300 kg). Although rather stout-bodied with short but sturdy legs, tapirs actually have streamlined bodies (rounded in the back and tapering in the front) that are good for pushing through the dense undergrowth of the forest floor. Tapirs have short, strong necks and their nose and upper lip extend into a short fleshy trunk or proboscis (this is best developed in the Asian tapir). Their proboscises are extremely important to them; these they use to sniff their way through the jungles and woods, and they also use them as elephants use their trunks, to pull leaves and shoots into the mouth. The skull of a tapir has a long notch in the nasal region where the proboscis attaches, and this retracted nasal notch and modified nasal bones help us determine whether fossil tapirs also had a proboscis (Fig. 13.6). Tapirs also have good hearing, manifested by their protruding, erect, oval-shaped ears, but their vision is probably not particularly acute. This may be because they are primarily nocturnal animals. The head, neck, forelegs and hindlegs of the Asian tapir are black, but the middle part of the body is covered with a

white saddle. This coloration probably serves as protection against nocturnal predators (tapirs are hunted by big cats: the leopard and tiger in Asia and the jaguar in the New World); the black and white patches obscure the body outline of the tapir. The New World tapirs have dark brown to reddish coats, and the fur is often paler below around the belly and legs of the animal. The hide of tapirs is tough and only sparsely covered with short, slick fur, except in the mountain tapir which has a thick coat to protect it from the cold. Baird's tapir and the Brazilian tapir have low, bristly manes along the backs of their necks. The mountain tapir and Baird's tapir have white ear fringes; in addition the mountain tapir has a white chin. The forefeet of tapirs have four toes, and the hindfeet three toes. However, on the forefeet the fourth toe is slightly smaller and set higher than the other three, so the tracks of tapirs are usually only three-toed. The toes bear small hooves. Since tapirs can be shy and retiring in the wild, coming out primarily at night, often the tracks are the only evidence of tapirs that humans may see. The shy nature and nocturnal habits of wild tapirs may be why they eluded scientific discovery for so long, as described in the next section. Tapirs are solitary forest-dwellers, most active at night when they roam along river banks, "tapir trails," and forest clearings. They feed on leaves, sprouts, small branches, fruit, grasses, and buds; their preferred food seems to be green shoots. They are extremely selective, taking a wide range of leaves but only small amounts of a given species in a single feeding bout. They crush the seeds of some fruit, but others pass undigested through their gut, making the tapir the major dispersal mechanism for certain seeds. Staying relatively close to water, they are excellent swimmers. For relaxation they will wallow in the mud and splash in water. They are reported to be capable of staying submerged for several minutes at a time, and the Asian tapir may walk along river bottoms like a hippopotamus. They also tend to defecate in the water. Tapirs have also been reported to sleep on the banks of streams and lakes. On land, tapirs are good climbers (especially the mountain tapir), and can negotiate steep river banks and mountain trails with ease. Tapirs travel with the proboscis close to the ground, sniffing their way along. They also mark habitual daily routes with urine. If disturbed, tapirs may grunt like a pig, and defend themselves by biting, or will attempt to elude predators by seeking cover in thick underbrush. Large cats are the main natural predators of tapirs, although some bears may also prey on them. At the other end of the chain, most tapirs are parasitized by ticks; the mountain tapir in particular may, in an attempt to relieve the itching, scratch its rump until it develops bald and calloused spots. In the Barro Colorado Island reserve in Panama, tapirs were observed allowing male coatimundis (related to the raccoon) to glean bloodengorged ticks from their bodies. In a zoo, a peccary was observed to do the same to a tapir in its enclosure, but the tapir never reciprocated. Since both peccaries and coatis are

PROBOSCISES AND CLAWS

243

Figure 13.3. The Malayan tapir (Tapirus indicus), with its distinctive black and white banded body. (Photo courtesy Nova Development Corporation).

Figure 13.4. The mountain tapir (Tapirus pinchaque) , the smallest species with its thick brown woolly coat. (Photo by D. R. Prothero).

Figure 13.5. Baird's tapir (Tapirus bairdil) , the common lowland Central American species. (Photo by D. R. Prothero).

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HORNS, TUSKS, AND FLIPPERS

Figure 13.6. Diagram! showing the skull (top right) of a tapir, with the large notch in the nasal region, that serves as attachment for the flexible proboscis (bottom). (After Gregory 1951). known for reciprocal grooming, and tapirs are not, this may explain their selfish behavior. The famous zoologist Archibald Carr wrote of the zoology of Central America in his book High Jungles and Low. He described his encounters with the elusive Baird's tapir, known to the Nicaraguan Mosquito Indians as the "mountain cow." "APRIL 10... I believe I have conveyed something of my desire, amounting by now to an obsession, to see a tapir in the woods. With respect to my attitude toward varmints, I have always been afflicted with a Dr. Jekyll and Mr. Hyde complex-an altogether unresolved conflict between the instincts of a naturalist and the urge to shoot things. These dual drives have given me a lot of trouble from time to time, and today they did their worst. This morning in the rain I finally came upon a mountain cow that did not see, smell, or hear me first. The ponderous beast lay half sunk in a pool in the vine-grown floodplain of a little creek. I looked down on him from a curve in the trail that ski11ed a steep undercut bank. I could have stood who knows how long savoring the fulfillment of my desire to see a tapir, watching this one in his most private moments as he rolled and snorted and steamed himself in his oxbow bathtub, but I muffed the chance. Through inexorable reflex I raised my puny rifle and started shooting as fast as I could pull the trigger. I don't suppose the stream of hollowpoint bullets that rattled slantwise against his flinty thorax did the tapir any harm; I hope not. But they

put him in a great sweat to get out of the water and away from the neighborhood. He floundered out of the mudhole with the most incongruous agility. Ignoring in his haste the usual exit, he burst easily through the solid palisade of lianas and vine-strung saplings that enclosed his retreat. Heading straight for a bamboo thicket, he again sought no trail, but drove squarely into a dense strand of fishing poles, bending live canes and snapping dead ones that opposed him with the racket of a dozen rifles. He charged away through the brake with unabating fury, and I stood and listened in complete dejection as the noise of the popping canes grew feeble with distance... APRIL 22. . . On the trail this morning I came abruptly upon another tapir, evidently full-grown and much bigger than the one I shot. We met on a heavily wooded ridge, and the mountain cow heard or smelled me just as I saw it, and pivoted ponderously to face me with no show of fear, or of any other emotion. It stood no more than thirty feet away and looked straight at me for a long time. I was delighted at the encounter because it gave me a chance to confirm my notion that a tapir is precisely what one would expect of a cross between an elephant and a donkey. I suppose I made a poor impression, however, because the tapir began slowly to lift one forefoot and then the other and pound the earth with resounding strokes, uttering at the same time a whistling neigh a little like that of a startled buck deer but much louder. There was no way of knowing whether these sounds were intended to scare me off, to warn an unseen infant, or to call in reinforcements, but it was clear that the creature was growing dissatisfied with the tete-a-tete. When I moved a bit nearer it gave ground, which secretly pleased me, and when I pressed the advantage the mountain cow backed faster, and then wheeled and trotted slowly away, stopping several times, however, to turn and face me and make the wonderful drumming noisepom-pom-pom-pom-with its sledge-like front feet. From the tapir-lore that I have picked up around the campfire (Lord knows there's little enough in books) I lean to the theory that this was a female with a calf nearby, and it was mostly this feeling that kept me from shooting it, which I could easily have done. I also cite the abstention as atonement for my irresponsible attack on the first tapir of the ravine mudhole ..." (Carr, 1953: 162, 183-184). Tapirs are not territorial, although they do have general home ranges. Sometimes they travel in pairs through the tunnel-like trails that they beat through the jungles, following the same trails over and over again. In captivity, if kept together in the same pen or cage they tend to ignore each other most of the time. They do not have distinct breeding

PROBOSCISES AND CLAWS

245

Figure 13.7. Juvenile tapirs have patterns of stripes and spots that help conceal them in the jungle. (Photo by D. R. Prothero). seasons; rather, a female tapir may become sexually receptive approximately every two months. During the mating season they attract each other with shrill whistles and go through a noisy courtship characterized by high-pitched squeals, a sniffing of each other's sexual parts, moving about each other at increasing speed, nipping at the partner's feet, ears, and flanks, and prodding of the other's belly. Mating pairs may remain together for several weeks before separating. The gestation period for tapirs is 390 to 400 days. Just prior to giving birth, a female tapir will find a safe lair. Dsually a single young is born at a time; very rarely twins may be born. Newborn tapirs of all four species have reddish-brown coats that are covered with horizontal white or yellow stripes and spots (Fig. 13.7). This coloration pattern provides camouflage for the young tapir in the mottled shade of the jungle undergrowth. It is not uncommon to see reconstructions of long extinct fossil "tapiroids" given the coat patterns of living baby tapirs. At about two months this baby coat pattern begins to fade, and by the time the child is about half a year old it will have the adult coat coloration. To suckle, the mother and youngster both lie down as in pigs. Besides its mother, young tapirs have little contact with other tapirs. A young tapir may stay with its mother until it is nearly full-grown (they reach sexual maturity when they are about two and a half or three years old), but it will do some independent travelling when it is six to eight months old. A healthy tapir has a life span of about thirty years. Tapirs appear to have survived virtually unchanged for millions of years, but now due to the destructive forces of man all four species are considered to be endangered. Although some tribes of South American Indians do not kill

tapirs for religious reasons, in general tapirs have long been hunted for food (the meat is said to be rather tasty-but we do not know from personal experience), sport, and for their thick skins (although the skin is said to be thinner in mountain tapirs). Tapir skin makes a good quality leather that can be used especially for whips and bridles. In Mexico and Central America tapirs are sometimes regarded as pests because in searching for food they may damage young corn or other grains. However, all species of tapirs are probably most threatened by the encroachment of ci vilization. Although they tame quickly and easily adjust to life in captivity, in the wild they cannot tolerate disturbances and they do not adapt well to changed environments. Yet their native habitats are being destroyed at an alarming rate because of the clearing of land (deforestation) for agriculture, grazing, construction of roads and other man-made developments. Sometimes humans purposefully follow the tapir trails along the sides of mountains when constructing roads. The only chance tapirs may have of surviving in their natural habitats is if man can curb his destructive tendencies, possibly through the designation of major forest preserves. Although known to the native inhabitants of Central and South America (the name "tapir" comes from the Brazilian Tupi language) and of Southeast Asia, the woolly tapir, Baird's tapir, and the Asian tapir were not officially known to western scientists until relatively recent times. In fact the western "discoveries" and descriptions of these three species of tapirs shook to the roots one of Cuvier's contentions: that in all likelihood all of the living species of large mammals having been already recorded by science, it is unlikely that any new extant species of large mammals would be discovered in the future. Yet this is just what hap-

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HORNS, TUSKS, AND FLIPPERS

Figure 13.8. A. Von Humboldt's 1799 illustration of the Brazilian tapir. B. An early illustration of the Malayan tapir, which was not discovered until the nineteenth century. (From Wendt 1959).

PROBOSCISES AND CLAWS pened subsequent to Cuvier's pronouncement. The Asian tapir was not described and named until 1819, the woolly tapir not until 1829, and Baird's tapir had to wait until 1865 (over thirty years after Cuvier's death) to be recognized by science. Yet these animals might have been known to science earlier if the professional zoologists had placed a little more stock in the accounts of natives and travellers to distant lands. Ironically Baird's tapir, the last to be given a scientific name and thus recognized by the zoological community, was the first tapir to be recorded in European literature. Peter Martyr D' Angher collected information on various beasts that were seen by the earliest European explorers of the Isthmus of Panama. In a description written sometime between 1494 and 1504, and published in various editions from 1504 to 1516, he stated that Baird's tapir is a beast which "Nature created in prodigious form. It is as large as a bull, and has a trunk like an elephant; and yet it is not an elephant. Its hide is like a bull's and yet it is not a bull. Its hoof resembles that of a horse, but it is not a horse. It has ears like an elephant's though smaller and drooping, yet they are larger than those of any other animal" (quoted in Hershkovitz, 1954: 492). Certainly this description contains some exaggeration, but one has to remember that it is based on second- or thirdhand accounts by persons who were not trained mammalogists. In 1526 an accurate woodcut of Baird's tapir was published in Madrid, along with a description of how tasty tapir meat is, especially the feet, if they are slowly boiled. From then on Baird's tapir was often referred to, sometimes under the name tlacaxolotl, in the literature generated by travelers to the part of the New World that it inhabited. A major reason that it was not officially recognized until 1865 is that the European zoologists appear to have confused Baird's tapir with the common Brazilian tapir even though these animals are two distinct species. The Asian tapir (Fig. 13.8B) also escaped the notice of European zoologists for many years, and there is no other species of tapir now living in Asia with which to confuse it. In Sumatra the Asian tapir was known to the natives as the teuxon, and for thousands of years Chinese books, both serious adult zoology texts and children's books of animal stories, included descriptions of the "me." The me was described as a large black mammal with a white "saddlecloth," a small head, a trunk like an elephant's, a tail like a cow's, the paws of a tiger, and the eyes of a rhinoceros. Surely, reasoned the European scientists led by Cuvier, this was merely a fairy-tale animal. But the British naturalist Sir Thomas Stamford Raffles (1781-1826), who also happened to serve the crown at various times as lieutenant-governor of Java and British governor of Benkulen on Sumatra, thought

247

otherwise. Raffles set about recording and collecting all of the species of plants and animals from Sumatra. His ultimate goal was to write a massive and profusely illustrated natural history of Sumatra. Among his collections were a number of live birds and mammals, including a teuxon-theAsian tapir. He attempted to transport his collections back to England in 1824, but a fire on board the ship destroyed everything. In trying to bring the Asian tapir to the attention of modern science, Raffles had bad luck on that account as well. Two Frenchmen whom Raffles befriended turned out to be working for Cuvier; essentially they were scientific "spies." They sent notes and information on the Asia tapir back to Cuvier and as a result Cuvier's student, the French zoologist A.-G. Desmarest, became the first person to give the Asian tapir its scientific name, Tapirus indicus, in 1819. Even though the tapir that Raffles had tamed was burned to death in the ship fire of 1824, other travelers soon brought tapirs back to England and the European continent. But these tapirs were coming from Southeast Asia, not from China. What about the Chinese me? By the late nineteenth century dragons' teeth, some of which represented giant tapir remains, were reaching the European scientists. Is it possible that the tradition of the me was based, at least in part, on collective memories of the times when living tapirs still inhabited the forests of China? When it comes to the fossil forms, not everything that has been labeled a fossil "tapir" is equally a tapir. This is primarily a result of the fact that, as noted above, living tapirs are very similar to their close relatives in the fossil record. Modem tapirs seem to be characterized by many relatively "primitive" traits (of course tapirs have been evolving for just as long as anything else-they just have not changed as radically as some organisms have in the same amount. of time). As many early and primitive fossil perissodactyls were uncovered over the last two centuries, they were found to share a number of primitive traits with living tapirs. Accordingly many primitive perissodactyls were associated with the living tapirs in a wastebasket group (see Chapter 10) composed of both true tapirs and miscellaneous tapirlike forms. This group was generally referred to as the Tapiroidea. As it turns out, many of the so-called fossil "tapirs" are no more closely related to living tapirs than they are to living rhinos. Some of these so-called "tapirs" represent distinct evolutionary side-branches that are now extinct. Other fossil "tapirs" are most closely related to the peculiar chalicotheres, and some of the early fossil "tapirs" may be close to the common ancestry of Iiving true tapirs, rhinos, various tapir-like extinct side-branches, and the chalicotheres. Before tackling the evolutionary story of the true tapirs, the chalicotheres, and the various tapir-like forms, let us introduce you, the reader, to another set of actors on the stage of perissodactyl evolution-the extinct chalicotheres. CHALICOTHERES DON'T OBEY CUVIER'S LAW

248

HORNS, TUSKS, AND FLIPPERS

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Figure 13.9. Moropus , the early Miocene chalicothere from Agate Springs quarry in Nebraska. As reconstructed here by Margery Coombs and drawn by Henry Galiano, it lived much like a tree sloth, using its claws to haul down branches on trees and bushes. (Courtesy M.C. Coombs). It is common knowledge (at least among non-paleontologists) that somehow paleontologists have the magical power of being able to conjure up complete animals from only the slightest fragments, perhaps a single tooth, claw, or scrap of limb bone. This idea stems from the work of the French anatomist and virtual founder of vertebrate paleontology, Baron Georges Cuvier, whom we encountered in Chapter 8. Through his detailed studies Cuvier found that for vertebrates in general, and for mammals (such as perissodactyIs) in particular, from a single bone and tooth a good anatomist could identify precisely what species of animal was represented. Even in very closely related species (such as different species of tapirs) the comparable bones or teeth may be extremely similar, but they are not exactly identical. As a result, from a single bone or tooth (perhaps a fossil from the rocks) Cuvier could unambiguously identify the species of the animal. So far, so good. But Cuvier was not satisfied with merely putting names on animals, with simply identifying the species. Cuvier was also very interested in the ecology and functional morphology of the animals he studied: how they moved, ate, obtained their food, and in general made a living. In many cases the prime evidence we have for recon-

structing the lifeways of extinct animals is their skeletal remains. Certainly the skeleton bears on the lifestyle of its owner and, Cuvier reasoned (based on observing and dissecting living animals), skeletons must act as integrated wholes that work together. For instance, if an animal is a carnivore, a meat-eater, it must have knife-like teeth adapted to slicing flesh along with sharp claws for pouncing on and debilitating its prey. In contrast, a herbivore might have teeth adapted to crushing and grinding vegetation, hooves on its feet, and long legs that could be used to run away from predators. Thus, according to "Cuvier's Law of Correlation of Parts," certain types of teeth always cOlTelate with certain types of limb adaptations, and so on. Indeed, even from a single tooth or bone fragment of an otherwise unknown fossil mammal Cuvier thought he could reconstruct (at least in an approximate way) the entire animal. Or could he? Over the years the fossil record has continued to hold surprises for even the most knowledgeable paleontologists. In the early nineteenth century Cuvier was aware of funny fossilized teeth with "double V"-shaped crowns and also odd-shaped fossilized claws. Often these teeth and claws were found close to each other in the rocks, but obviously (according to Cuvier) the claws originated from some type

PROBOSCISES AND CLAWS of huge, extinct ant-eater ("un Pangolin gigantesque") while the teeth obviously belonged to an ungulate. It was not until the last two decades of the 19th century, especially with the work of the French paleontologist Henri Filhol, that it was definitively demonstrated that the claws and the teeth belonged to the same beast, a clawed perissodactyI! Cuvier's Law did not hold; even the best paleontologist cannot always reconstruct a complete animal from only a few bones, much less necessarily recognize which bones from a jumbled fossil deposit bearing many species should be associated in a single animal in the absence of articulated skeletons. Today these extinct clawed perissodactyls are commonly referred to as chalicotheres. They are probably the most bizarre, at least by modern standards (since there is nothing like them on the planet today) members of the order. Chalicotheres ranged from sheep-sized to horse-sized. Their heads were generally similar in overall shape and proportions to those of horses. As stressed above, they bore large claws on the feet and some chalicotheres could even retract their claws (similar to the way most house cats can). In some chalicotheres the fore- and hind-limbs were subequal in length (for instance, in the genus Moropus) and the neck was somewhat lengthened, but in other advanced forms (such as Chalicotherium) the hind-limbs were much shorter and stouter than the fore-limbs and the animal took on what appear to be gorilla-like proportions. It is generally thought that chalicotheres were browsers-their teeth appear to be designed to deal with soft plant material-feeding on high leaves and other vegetation. Why did chalicotheres have claws on the feet? It has been speculated that they used the claws for digging up roots, for plucking grass or other plants, or perhaps even to fight off predators. Based on the work of Margery Coombs and Helmut Zapfe, two of the foremost authorities on chalicotheres, it is now thought that Moropus and similar forms may have been predominantly quadrupedal tree browsers (Fig. 13.9), perhaps somewhat similar to the living Okapia (a relative of the giraffe), although sometimes standing erect on the hindlegs in order to reach higher branches. The gorilla-like Chalicotherium (which may have even knucklewalked somewhat like a gorilla) may have been a regular bipedal browser standing on its hindlimbs and using the forelimbs and claws to pull down branches or to support itself against the sides of trees while stretching the neck and head high above to reach succulent leaves (Fig. 13.1 0). In this respect, they converged on the giant ground sloths of the Ice Ages, which used their huge clawed forelimbs to haul down branches. Apparently chalicotheres were sexually dimorphic, with the presumed females being slightly smaller than the presumed males. Chalicothere specimens are generally rare in the fossil record, although a few large concentrations of these beasts are known (such as at Agate Springs, Nebraska, and at a site in Kazakhstan). Margery Coombs suggests that their rarity indicates that chalicotheres did not typically con-

249

A

Figure 13.1 O.A. Restoration of Chalicotherium grande, showing its gorilla-like stance due to its much longer fore limbs and short hind limbs. It apparently knuckle-walked, with its front claws pointed inwards. (After Coombs 1981) B. Chalicotherium feeding on leaves by pulling down branches with its long forelimbs and claws. (From Agusti and Anton 2002).

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HORNS, TUSKS, AND FLIPPERS

Figure 13.11. The dome-skulled Miocene chalicothere Tylocephalonyx. (From Coombs 1979).

gregate in large herds. However, their sexual dimorphism and their occasional large concentrations suggest that they may have been characterized by polygynous breeding habits. One genus of North American Miocene chalicotheres, Tylocephalonyx (Fig. 13.11), developed a peculiar domed skull which may have been used in head butting and other social displays (the domes may have been more prominent in males, although it is hard to tell since only three skulls are known). The relative scarcity of chalicothere remains may also be because they lived in relatively forested areas, and not on the plains where most fossilization takes place. When they are found, most chalicotheres are associated with other forest animals. Perhaps the reader has heard reports of sightings of the "Nandi bear" from the Kakamega forests of Kenya. The "Nandi bear," which most people put on a par with the Sasquatch ("bigfoot"), the Yeti ("abominable snowman") and the Loch Ness monster, is said to be gorilla-like with forelimbs longer than the hindlimbs, has the head of a horse, and claws on the feet. The English paleontologist R. J. G. Savage has suggested (in jest) that perhaps the "Nandi bear" is actually a living chalicothere that survived the Ice Ages when the last of its kind was thought to have gone extinct. JUST WHAT ARE CHALICOTHERES? For early paleontologists it was not only difficult to figure out what a chalicothere looked like (that it had ungulate teeth, odd limb proportions, and claws on its feet), but the evolutionary relationships of chalicotheres to other perissodactyls were very difficult to discern. Superficially, the teeth of chalicotheres look something like those of brontotheres. Thus, some early workers suggested that the chalicotheres evolved from primitive brontotheres in the Paleocene or early Eocene. Since brontotheres and horses were usually viewed as closely related, if chalicotheres were the descendants of brontotheres then all three groups could be associated together as a distinct suborder of the perissodactyIs

known as the Hippomorpha. In this scheme all other nonhyracoid perissodactyls (at this time hyracoids were generally not even considered to be perissodactyls), namely the tapirs, the rhinos, and their extinct relatives, were placed in the suborder Ceratomorpha. But not all paleontologists agreed with this scheme. The chalicotheres were so bizarre, with claws on their feet, that some scientists argued that even if they are perissodactyls they are surely only very distantly related to all other members of the order. Accordingly, these workers divided the perissodactyls into two groups: the suborder Chelopoda composed of the brontotheres, horse group, rhino group, and tapir group; and the suborder Ancylopoda composed of only the strange chalicotheres. Finally, some scientists effectively side-stepped the issue by pleading a level of ignorance pending the discovery of more fossils. If one cannot be sure of how all of the major groups of perissodactyIs are related to each other, then one should not attempt to group them into only two suborders. Following this line of reasoning, in perissodactyl classifications (which presumably reflect our knowledge of evolutionary relationships) the chalicotheres were maintained as a distinct order (Ancylopoda), the tapir group (tapiroids) and rhino group (rhinocerotoids) made up a second suborder (Ceratomorpha), and the brontotheres and horse group (equoids) made up a third distinct suborder (Hippomorpha). So things remained, in a state of relative ignorance, until just recently when various scientists began to reconsider how chalicotheres might be related to other perissodactyls. Once the topic was again opened up for discussion some interesting ideas began to emerge. Based on detailed analysis of the fossils, it turns out that the tapir group (the tapiroids) was not a natural group, but an artificial assemblage, a "wastebasket" taxon, composed of a heterogeneous mixture of animals that date from the early Eocene to the present. In general, they bear many primitive traits, which is why they were lumped together in the first place. Grouping all of these diverse, yet superficially similar, animals only led to confusion and obscured the true evolutionary relationships of these perissodactyls. The lophiodonts, a group of primitive "tapiroids" which since the time of Cuvier have been well known from the Eocene of Europe, have now been demonstrated (by the British paleontologist J. J. Hooker) to be not tapirs at all but close relatives of the chalicotheres. Currently the lophiodonts are classified, along with chalicotheres, in the Ancylopoda. Other animals traditionally classified within the wastebasket group of "tapiroids" are now acknowledged as more closely related to rhinocerotoids. Yet others of these "tapiroids" are related to true tapirs (living tapirs). Still other groups of tapiroids, the deperetelloids and lophialetoids (known primarily from Asia and discussed further below) are less closely related to rhinos than are true tapirs; the deperetelloids and lophialetoids are extinct side-branches that shared a common ancestor, probably in the Eocene, with the true tapirs and rhinos. Still other "primitive

251

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252

HORNS, TUSKS, AND FLIPPERS

tapiroids" may approximate the joint common ance~tor shared by lophiodonts, chalicotheres, deperetelloIds, lophialetoids, tapirs, and rhinos. In the early 1980s J. J. Hooker and one of us (Schoch) independently discovered (based on detailed analysis of the teeth and skeletons of the animals) that the chalicotheres (Ancylopoda) and the various "tapiroids" and rhinos are all more closely related to each other than are any of these groups to any other perissodactyIs. The various "tapiroids," the rhinos, and the lophiodonts and chalicotheres together form a natural subdivision of the perissodactyls. This group is now referred to as the Moropomorpha. Hooker also demonstrated, contrary to the older classifications discussed above, that there is no compelling reason to associate the brontotheres closely with the horse group (Hippomorpha). Thus the non-hyrax perissodactyls are currently classified, on the basis of their hypothesized evolutionary relationships, into three great groups: the Hippomorpha (horses and their close relatives, discussed in chapters 10 and 11), the Titanotheriomorpha (the brontotheres, discussed in the previous chapter), and the Moropomorpha (chalicotheres, tapirs, rhinos, and their close relatives, discussed ~n this an.d the next two chapters). The hippomorphs, tItanotherIomorphs (brontotheres), and moropomorphs represent three distinct radiations of perissodactyIs; these three groups probably shared their last common ancestor in the Paleocene or earliest Eocene. MOROPOMORPHS Now we are in a position to briefly discuss current ideas concerning the evolution of the moropomorphs from early Eocene time until the present (Fig. 13.12). The earliest known moropomorph was Homogalax, a small, relatively generalized animal found in early Eocene deposits of North America (where it is common) and Asia (where it is relatively rare). Homogalax was superficially very similar to contemporaneous horse relatives, such as Protorohippus or "Hyracotherium" (Fig. 10.7). The skull of Homogalax was approximately 6 inches (16 cm) long, and it probably had a body weight of about 22 pounds (10 kg). Compared to Hyracotherium, the molar teeth of Homogalax had developed higher and relatively unbroken crests that increased the shearing function and reduced the crushing function of the molars. Homogalax appears to have been relatively folivorous as compared to contemporaneous Eocene perissodactyls. By the late early Eocene and into the middle Eocene the early moropomorphs had spread into Europe and begun to diversify into a great variety of forms. In both North America and Asia there were close relatives of Homogalax that evolved along their own separate evolutionary branch only to go extinct well before the end of the Eocene (the isectolophids). On both of these continents during the Eocene there were also members of the family Helaletidae, close relatives of the true (as represented by Tapirus) tapirs. Beginning as Homogalax-sized creatures, the helaletids increased in size through evolutionary

Figure 13.13. Restoration of the head of Protapirus,. found in the upper Eocene-Oligocene beds of the Big Badlands of South Dakota. (Drawn by R. B. Horsfall, from Scott 1913). time and also developed tapir-like proboscises. Some scientists believe that certain animals commonly classified as helaletids actually gave rise to the true tapirs (a point we will come back to shortly). In addition, in Asia there were two independent indigenous groups of moropomorphs evolving during the middle and late Eocene: the deperetelloids and the lophialetoids. The deperetelloids included small and medium-sized forms (getting perhaps as big as a sheep) that molarized the premolars as in helaletids and true tapirs. The medium-sized lophialetoids reduced the size of the premolars and put m?re emphasis on the molars with large ectolophs (the outSIde crests of the upper molars that are parallel to the tooth row). Lophialetes independently developed a tapir-like proboscis. Unfortunately these interesting groups were extinct by the late Eocene or early Oligocene. The late American paleontologist Radinsky and the Soviet paleontologist Reshetov, two of the leading authorities on the deperetelloids and the lophialetoids, have suggested that these forms may have declined and gone extinct due to climatic changes and the rise of the ruminant artiodactyls and the rhinocerotoids which displaced and ecologically out-competed these moropomorphs. In the middle Eocene of Europe moropomorphs are represented by another distinct sidebranch, the lophiodonts, closely related to the true chalicotheres. A few rare and questionable lophiodonts are known from North America in the Eocene, but these animals were primarily European forms. Some species of Lophiodon, the best known genus of lophiodonts from Europe, evolved to cow size or possibly larger, developed teeth somewhat analogous to those of lophialetoids, and perhaps had the beginnings of a tapir-like proboscis. By the late Eocene lophiodonts had gone extinct. The earliest true chalicotheres (such as Eomoropus and Grangeria), very close relatives of the European lophiodonts, are known from the middle Eocene of Asia an.d western North America. In the Oligocene only the chahcothere Schizotherium is known, and this form is found only

PROBOSCISES AND CLAWS

Figure 13.14. Restoration of the primitive rhinocerotoid Hyrachyus, which is only slightly different from contemporary tapiroids. (Drawn by R. B. Horsfall, from Scott 1913). in Europe and Asia. By the Miocene advanced chalicotheres had divided into two groups: the chalicotheriines (represented by the genus Chalicotherium) and the schizotheriines (represented by the genus Moropus). From Eurasia the schizotheriines spread to North America in the late Oligocene, and in the late Miocene spread to Africa. Schizotheriines went extinct by the end of the Miocene in Eurasia and North America, but lasted into the Pleistocene of Africa. The chalicotheriines spread to Africa in the late Oligocene, but went extinct there by the middle Miocene. Chalicotheriines persisted, however, in China well into the Pleistocene. It seems that our early hominid ancestors shared the landscape with the last chalicotheres. Unfortunately these fascinating beasts did not survive into historical times. The true tapirs, family Tapiridae, are first known from the early Oligocene of North America and Europe, and by the Miocene had spread to Asia. As noted above, the tapirids are closely related to the helaletids and in fact these two nominal families should perhaps be combined as the single family Tapiridae. Helaletids are apparently merely primitive tapirids-thus another "waste-basket" group. From the Oligocene to the present tapirids have looked basically like modern tapirs. Protapirus (Fig. 13.13) of the Oligocene of Europe and North America had a well-developed proboscis,

253

and other than the fact that it was a bit smaller (by perhaps one-quarter) than modern tapirs it would probably be indistinguishable from Tapirus to the casual observer. This is why modern tapirs are often referred to as "living fossils." Tapirs existed at low diversity (in terms of numbers of species) and at relatively low numbers (in terms of numbers of individuals) throughout the Miocene, Pliocene, and Pleistocene. In North America, Europe, and Asia tapirs existed until about the end of the Pleistocene Ice Ages when they went extinct in North America and Europe. In North America in particular it has been documented, in a classic study by the late George Gaylord Simpson, that during the Ice Ages the tapirs were limited to that part of the continent that was south of the glaciated area. In China the huge tapir Megatapirus apparently evolved during the Pliocene and Pleistocene. Its bones and teeth are found in cave and glacial deposits (and are still sold as dragons' teeth). Megatapirus was extinct by historical times. In the New World the North American tapirs migrated along the Isthmus of Panama during the late Pliocene and thus became established in South America. By the end of the Pleistocene the once widespread tapirids were extinct except for the isolated species which remain to this day in Southeast Asia and Central and South Ameri~a. In the last few pages we have briefly reviewed the evolutionary history of a number of moropomorph lineages, such as the isectolophids, lophiodonts, chalicotheres, deperetelloids, lophialetoids, and tapirids (including the helaletids). But there is another lineage of moropomorphs that we need to mention. This lineage is represented by the genus Hyrachyus, a taxon that was widely distributed over Europe, Asia, and North America during the middle Eocene (Fig. 13.14). In some respects Hyrachyus is very similar to middle Eocene tapir relatives, and thus in the past it has even been classified as a helaletid. However, Hyrachyus did not have a proboscis, and in life it probably had very much the appearance of a small horse. Detailed analysis of Hyrachyus specimens demonstrates that rather than being an ancestral tapir, although it is more closely related to tapirs than it is to many other perissodactyls, it is actually even more closely related to rhinos. In fact Hyrachyus represents the earliest known and most primitive rhinocerotoid (the group that includes rhinos). The rhinocerotoids represent the largest and greatest evolutionary radiation of moropomorphs, and are the subject of our last two chapters.

AMYNODONTS

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Figure 14.1. Family tree of rhinocerotoids in North America. (Drawn by C. R. Prothero).

14. Rhinoceroses without Horns

"ANCIENT DACIANS" AND SIBERIAN MUMMIES Before the rise of modern comparative anatomy and paleontology, the giant bones found in the earth were a great source of wonder, mystery, and eventually legends. In Chapter 8, we saw how many of these "giants in the earth," interpreted as gigantic humans, were actually the remains of mastodonts or mammoths. The remains of fossil rhinoceroses (Fig. 14.1) were similarly misinterpreted. The horns of the woolly rhinoceros were thought by Siberians to be the claws of gigantic predatory birds and may have been responsible for the myth of the griffin (also spelled "gryphon"). The most amusing story of such myth-making was related in 1858 by the Finnish zoologist and explorer Alexander von Nordmann. In 1843 a number of large, mysterious bones were plowed up near the town of Kishinev in Moldova (now independent, but once part of the Soviet Union near the Romanian border). The Moldovan peasants lashed the bones together into an upright skeleton, and place the skull on top. In its "hand" was a staff with a colored rag tied to it like a flag. The local peasants flocked to see the wonder, which they considered one of their ancestors, the legendary ancient Dacian giants. They sang and danced around the skeleton, drinking plenty of the local firewater known as buza. When the Imperial Military Governor heard of this wonder he went to see it for himself. He decided it was not an ancient Dacian, but an "old Roman grenadier" (equipped with unusually large molars!). An "anti-geological priest" thought the object a monstrosity and ordered the supposedly "saintly" bones chopped into pieces and buried. When Nordmann arrived a few months later no one could find the burial site under the head-high wheat. However, an old medicine woman had hidden away a piece of the jaw to cure the ills of her patients. Nordmann obtained it and found that it was a jaw fragment (Fig. 14.2) of the extinct steppe rhinoceros of the Ice Age, Stephanorhinus hemitoechus. Fossil rhinoceroses had been found even earlier in many parts of Europe. The German naturalist Peter Simon Pallas (1741-1811) was invited to work for the St. Petersburg Academy of Sciences in 1767 by Catherine the Great. As a result, he was part of a long scientific expedition to Siberia between 1768 and 1774. When he published his

results in 1777 and 1779 he described fossilized and mummified "large animals of India, "including elephants, rhinoceroses, and buffalos [now recognized as extinct Ice Age woolly rhinos and mammoths, and bison]. His most spectacular find was a mummy of a woolly rhinoceros, found with its skin intact in the frozen ground on the banks of the Viloui (also spelled Vilyuy) River. To Pallas this was "convincing proof that it must have been a most violent and most rapid flood which once carried these carcasses toward our glacial climates, before corruption had time to destroy their soft parts." Pallas' insistence on the Indian origin of these Siberian mummies was a reaction to non-Biblical ideas proposed by Buffon in 1751. As we discussed in Chapter 8, Buffon regarded the presence of these "Indian" animals in Siberia, and similar animals in North America, as proof that Earth's climate had changed and elephants and rhinos had migrated in response. This implied that Earth was much older than orthodoxy was willing to admit, and that some of these beasts might be extinct. As we have seen, these heresies were not accepted until the nineteenth century, and most

Figure 14.2. This jaw fragment of the steppe rhino, Stephanorhinus hemitoechus, is all that remains of the "ancient Dacian" or "Roman grenadier" revered by Moldavian peasants in 1843. (From Kurten 1986).

256

HORNS, TUSKS, AND FLIPPERS

eighteenth-century scientists tried to find Biblical explanations for these mysteries. Pallas, like most of his peers, thought that the Great Flood of Noah had moved these "Indian" animals to the perpetually cold regions of Siberia, where they could never have actually lived (in his view). Along with fossil mammoths and mastodonts, fossil rhinos (especially the woolly rhinos) were described by many different scientists in Europe during the nineteenth century. Unfortunately, however, specimens from Oligocene and Miocene deposits tended to be very poor and incomplete, so very little progress was made in understanding rhinoceros evolution in Europe. Most specimens were simply isolated teeth and jaws, and these were usually assigned to one of the living genera. Not until 1832 did European scientists realize that some fossil rhinos did not have horns. Kaup created the new genus Aceratherium ("hornless beast") in recognition of this fact, and for the rest of the century nearly every hornless rhinoceros specimen was placed in this "wastebasket" genus. It soon turned out that through most of their history, rhinoceroses lacked horns. Only some of the lineages that started in the Miocene developed them, and by accident all of the species still living today have them. Most people think the horn is the characteristic feature of rhinos, but it is a late invention. Most extinct rhinoceroses were hornless. They can be recognized as rhinos by many other distincti ve features of the skull, teeth, and skeleton. Since horns are made of cemented hair-like fibers, and not cored with bone like artiodactyl horns, we seldom find them fossilized. We can only deduce their presence by the roughened attachment surfaces they leave on the skull. Because of the poor fossil record of European rhinoceroses, and the tendency to try to squeeze them into living genera, little progress was made in understanding their evolution in the Old World during the early nineteenth century. Ironically, it was scientists studying the excellent complete skulls and skeletons found in the western United States who were able to piece together their history and make sense of the Eurasian fossils. AMERICAN RHINOS One day early in December, 1850, Joseph Leidy received a surprising package in his Philadelphia study. Since 1847 Leidy had been receiving many shipments of fossils from the Indian Territories of Dakota and Nebraska out west, and his descriptions of these fossils had made him the foremost paleontologist in the country. Some of these fossils were of typically American beasts, such as dogs, cats, rabbits, peccaries, and deer, although they were of such archaic types that they could barely be recognized as related to their modern descendants. Other parcels held remains of animals (such as brontotheres) with no living descendants. Still other packages held the remains of animals never previously known from North America. He had already discovered that camels and horses had been all-American natives, but on this particular day he realized that he was looking at the first evidence of an American rhinoceros.

c Figure 14.3. Occlusal view of second and third left upper molars of (A) Amynodon, the amphibious rhino; (8) Hyracodon, the running rhino; and (C) Hyrachyus, the most primitive rhinocerotoid. Note how the second molars form the shape of the Greek letter Jt, and the third molars (the ones on the right) lose the back crest and become more V-shaped. (From Radinsky 1966).

A few days later Leidy described the specimen at a meeting of the Philadelphia Academy of Natural Sciences. He christened it Rhinoceros occidentalis, the "Western rhinoceros" (now known as Subhyracodon occidentalis). In the remaining twenty years of his career he described many more rhinos from the Dakotas, Oregon, California, Nebraska, Texas, and even Florida. Cope and Marsh also began to describe rhinos from their collections out west. By the turn of the century it was clear that rhinoceroses had not only lived in North America, but they were the commonest large herbivore on this continent for most of the last fifty million years. As we have seen in previous chapters, the oldest perissodactyls are known from the early Eocene. They include the first horse (?Protorohippus), and the most primitive relative of rhinos and tapirs, Homogalax. By the late early Eocene we find the oldest brontotheres and chalicotheres, as well as lophiodonts and palaeotheres. The diversification of the perissodactyIs was taking place at a very rapid pace in the early Eocene, although it was "rapid" only in the geological sense. After all, the early Eocene spans six million years. By the middle Eocene, the various lineages of "tapiroids," including the helaletids and isectolophids, diversified and became the dominant perissodactyls (see Chapter 13). The tapiroids already showed some of their characteristic specializations, such as strong cross-crests on the molars and a well-developed proboscis. Meanwhile, another lineage specialized in a different direction. This was the rhinocerotoids, the relatives of the true rhinoceroses, whose first representative is Hyrachyus (Fig. 13.14). Superficially, Hyrachyus is difficult to distinguish from

RHINOCEROSES WITHOUT HORNS

257

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8w ~

8

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Figure 14.4. (left) Evolution of skull shape in Eocene Mongolian amynodonts from Rostriamynodon (D) to Sharamynodon (C) to Amynodontopsis (8), and culminating in Cadurcodon (A) with its deep nasal retraction indicating a sizable proboscis. (From Wall 1982). Figure 14.5. (above) Restoration of Cadurcodon, the most tapir-like of all the amynodonts. (From Savage and Long 1986; by permission of the Natural History Museum, London).

some of its contemporaries among the horses and tapirs. It had a relatively slender body suited for running, and unspecialized features in the head and rest of the skeleton. But the teeth of Hyrachyus have already begun to show the hallmarks of rhino teeth. While both tapiroids and rhinocerotoids had strong cross-crests, the tapiroids began to reduce the ectoloph until only the cross-crests remain. Hyrachyus and later rhinocerotoids strengthen and straighten the ectoloph so that it joins with the cross-crests and forms the characteristic "pi"-shaped (n) upper molar (Fig. 14.3). Hyrachyus was very successful in the middle Eocene, spreading from Asia to Europe and North America and even to Ellesmere Island in the Canadian Arctic. From an animal like Hyrachyus, three major branches of rhinocerotoids split off in the middle Eocene (Fig. 14.1). In one branch, .the Family Amynodontidae, many species became specialized for amphibious life. Another branch, the Family Hyracodontidae, developed long legs suitable for running. The third, the Family Rhinocerotidae, was the lineage that led to the living rhinos. All three families can be distinguished by a number of skeletal features, but the quickest rule of thumb is to look at the last upper molar. In Hyrachyus the last upper molar has a very short crest in the rear outside corner of the tooth (Fig. 14.3). In amynodonts this crest is enlarged and points out and back. In hyracodonts the crest is enlarged, but points inward. In the true rhinoceroses this crest is lost altogether, and the last upper molar is triangular in shape. It seems like a subtle distinction to separate such different groups of animals, but it works. In this chapter, we

will first look at the two families which went extinct and did not lead to living rhinos. THE AMPHIBIOUS AMYNODONTS In the middle Eocene, one of the descendants of Hyrachyus migrated from Asia to North America over the Bering land bridge. This was Amynodon, a tapir-sized animal that superficially resembled many of the other large perissodactyIs (such as brontotheres and tapiroids) of the middle Eocene. However, it already showed some unique features that mark it for ancestry of a totally new group. Unlike most hoofed mammals, Amynodon had large canines, and these teeth became larger and larger until they formed a thick set of tusks in its descendants. There was a shallow depression on the facial region of the skull for attachment of the snout muscles. Amynodon probably had a prehensile lip like many modern rhinos. Finally, Amynodon had the square last upper molar characteristic of the group. From an animal like Amynodon two groups emerged. One, the cadurcodonts, remained in Asia and developed a more mobile face and snout. We can see the stages of cadurcodont evolution in Asia, from early late Eocene Amynodon to latest Eocene Sharamynodon and Amynodontopsis, and culminating with the end of the line, Cadurcodon itself. In each of these stages, the nasal notch grew deeper and the nasal bones retracted (Fig. 14.4). This indicated a more and more flexible snout and upper lip. Cadurcodon has such extreme nasal retraction, and such deep pits for muscle attachment that it must have had a trunk larger than a tapir's

258

HORNS, TUSKS, AND FLIPPERS

Figure 14.6. Reconstruction of Metamynodon in its typical hippo-like habitat, now represented by the lower Oligocene river channel sandstones of the Big Badlands of South Dakota. (Painting by R. B. Horsfall, from Scott 1913). (Fig. 14.5). Along with these changes, the front tusks grew larger and larger, and the cheek teeth become more massive and high-crowned for a more specialized diet. As the expanding trunk took over the front of the face, the eyes moved lower on the skull. While the cadurcodonts were probably forest dwellers that lived much like tapirs or elephants, the other group of amynodonts, the metamynodonts, were specialized for an amphibious lifestyle. They became massive animals built much like hippos, and reached sizes comparable to large hippos today. Like the cadurcodonts, most metamynodonts lived in Asia during the latest Eocene and early Oligocene. A few managed to migrate back to North America. The best known of these is Metamynodon itself, which was common in the early Oligocene ri ver deposits of the Big Badlands of South Dakota. So many of their bones have been found that they are known as the "Metamynodon channels." At first glance Metamynodon is very hippo-like (Fig. 14.6). It has both the broad, massive head and the stout, short-legged body that are associated with the hippo's amphibious existence. The eyes were high on the skull so it could see when its body and head were submerged. It had large tusks that the males must have used in combat. It also has impressively large, high-crowned molar teeth for grinding abrasive vegetation. It was probably a grazer. Modern hippos actually do most of their feeding in grassy meadows at night, and live in the water only when they're not grazing in the day. Metamynodon lived in the early Oligocene, just after the brontotheres had died out, and was the largest

mammal in North America at the time. When Metamynodon died out in the late early Oligocene no large amphibious plant eater evolved to fill its hippo niche in North America until the middle Miocene when another rhino, Teleoceras, appeared. After the early Oligocene, amynodonts became extinct in both Asia and North America. However, a metamynodont named Cadurcotherium survived in Europe in the late Oligocene, and in the early Miocene it is found in Asia. Its fossils have been found in early Miocene sediments of Pakistan and Burma. Cadurcotherium was truly a relict of the Eocene, surviving almost fifteen million years after all its relatives were gone. If we lived in the Miocene we would have recognized it as a "living fossil." Finally, it too succumbed to the competition from more advanced rhinos in Europe and Asia. About fifteen million years ago the last of the amynodonts joined its family in extinction. RUNNING RHINOS AND RHINO GIANTS While the amynodonts diverged from Hyrachyus in one direction, another group arose in the middle Eocene that was specialized for running (Fig. 14.1). These were the hyracodonts. Their earliest representati ves included Triplopus, an animal built along much more slender lines than Hyrachyus. The name Trip lopus refers to the three-toed front foot, since hyracodonts were quick to reduce digit 5 (the "pinky" finger). The amynodonts, on the other hand, retained the four-toed front foot, which must have been useful for traction in the mud. Triplopus and the hyracodonts

RHINOCEROSES WITHOUT HORNS

259

Figure 14.7. (above) Reconstruction of the GreatDane-sized running rhino Hyracodon, one of the commonest mammals in the Big Badlands. (Painting by C.R. Knight, courtesy Department of Library Services, American Museum of Natural History). Figure 14.8. (right) Life-sized fiberglass reconstruction of the gigantic hyracodont Paraceratherium, now on display in the University of Nebraska State Museum. Note its small relative Hyracodon to the right, and the living and fossil elephants for scale. (Courtesy University of Nebraska State Museum). not only lost the extra front toe, but developed much more slender limbs with a horse-like strong central toe. The late Eocene saw a number of small hyracodont genera in both Europe and Asia, but by the early Oligocene only a few remained. The best known of these is Hyracodon itself, which is very common in the Big Badlands of South Dakota (Fig. 14.7). It was about the size of a Great Dane, and only slightly larger than Mesohippus, the horse of its time. The head was slender and unspecialized, but the body and especially the legs clearly show that it was an efficient runner. It had a neck proportionally longer than the horses of the time, but stronger because it had a much larger head. In behavior it may have seemed more like a pony or donkey than like any modern rhino. Its teeth, however, are not very high-crowned or complex. It probably browsed on shrubs and bushes that were still dominant in the mixed forest-grasslands of the early Oligocene. By the late Oligocene the vegetation was changing to savanna grassland. There were fewer shrubs to browse on, and more and more animals that depended on them died out. Hyracodon survi ved until the very late Oligocene and then succumbed about 28 million years ago. It was the final member of its lineage anywhere in the world, surviving almost ten million years after the last of its relati ves had died out in Asia and North America. Like Cadurcotherium, it was a "living fossil" that did not survive quite long enough.

Neither hyracodonts nor amynodonts made it to our zoos. The third of the three families of rhinocerotoids, however, did make it (Fig. 14.1). They are the Family Rhinocerotidae. Before we take up the story of the Rhinocerotidae, we should look at one of the most fascinating offshoots of the hyracodonts, the giant indricotheres. One of the descendants of Triplopus was a much larger hyracodont known as Forstercooperia. Its cumbersome name is an accident. It was first named Cooperia by Horace Wood in honor of the British paleontologist, Clive Forster Cooper, who described many of the indricotheres. In 1939 Wood discovered that the name Cooperia had already been given to a genus of roundworm, so it could not be used again. The rhino was renamed Forstercooperia to avoid confusion and duplication, even though this made the name unusually long and clumsy. Forstercooperia was about the size of a cow, although there was also a dwarf species about the size of a sheep. It migrated back and forth between China and North America freely during the middle Eocene. By the late Eocene, however, it disappeared from North America and the rest of the indricothere story takes place in Asia. And what a story it was! Indricotheres quickly reached elephantine proportions with Urtinotherium, and then surpassed this standard. When they finished, they had produced the largest land mammal the world had ever known, Paraceratherium (or lndricotherium) (Fig. 14.8). This beast was almost 18 feet (6 m) high at the shoulder and probably

260

HORNS, TUSKS, AND FLIPPERS

Figure 14.9. The skull of Paraceratherium was immense, with molars the size of man's fist, and huge conical incisors. Otto Falkenbach, an American Museum preparator, stands in for scale. (Courtesy American Museum of Natural History).

weighed 40 tons (35,000 kg). Its head was so high off the ground that it browsed on the tops of trees over 25 feet (7.5 m) high. Today we think of elephants and giraffes as giants, but Paraceratherium dwarfed them in both size and bulk. Its head was over five feet (1.5 m) long, with enormous tusks at the front end of its skull. As big as its head was, it seemed ridiculously small on such a large body. In spite of these bizarre features, Paraceratherium still bears the hallmarks of its hyracodont ancestry. Its molar teeth show the same pattern as the hyracodonts, only they are enormous. Its incisors (Fig. 14.9), although large, are conical as they are in hyracodonts. Most importantly, its toe bones are still long and stretched out as if it were a runner. This is truly remarkable because most gigantic land animals, such as elephants and dinosaurs, shorten their foot bones until they are stubby, square blocks or even flattened like pancakes. The indricotheres outweighed any elephant, yet they retain the long toes as a hallmark of their running ancestry. An animal this large clearly had no need to run from any predator, and was much too large to run efficiently anyway. Paracera-therium is a good example of how animals can retain features of their ancestry long after they have outlasted their usefulness. The proper name for this beast is a great source of confusion. The first name given to these gigantic hyracodonts

was Paraceratherium, coined in 1911 by Clive Forster Cooper for specimens from Pakistan. Two years later Forster Cooper gave the name Baluchitherium to specimens of a large indricothere from the Baluchistan province of Pakistan. In 1915 the Russian paleontologist Borissiak described another giant rhino from the Turgai region of the Caucasus Mountains in southern Russia and called it Indricotherium. Although Borissiak's specimen is the most complete known, it was ignored because most scientists didn't read Russian and could not go to Russia to see the specimen during the First World War or the Russian Revolution. In 1922 the American Museum of Natural History made a highly publicized expedition to Mongolia where they found the largest and most spectacular specimens of a giant indricothere. It got enormous attention and was called Baluchitherium, since no one knew much about the Russian Indricotherium. As a result of all the publicity, nearly all the popular books have called this animal Baluchitherium, but this name is incorrect. This confusion over names is a good example of how politics and the sloppiness of popular science books can perpetuate names or ideas that are seventy years out of date. Scientists have long realized that Baluchitherium is a junior synonym of Paraceratherium, but are Paraceratherium and Indricotherium the same beast? Some scien-

RHINOCEROSES WITHOUT HORNS

Figure 14.10. The leg bones of this Mongolian Paraceratherium were found standing upright, just as they were left when the animal died in quicksand. Here, Walter Granger stands next to the four pits where the leg bones were uncovered. (Courtesy American Museum of Natural History). tists, such as Spencer Lucas, have studied all the large indricotheres called Paraceratherium, Indricotherium, and Baluchitherium, and have decided that they are all the same animal. The skull known as Indricotherium is thought to belong to the male and the skulls referred to Paraceratherium are thought to belong to females. If this is so, then the correct name for all these hyracodonts is Paraceratherium, the first name coined by Clive Forster Cooper in 1911, four years before Borissiak described Indricotherium. This reasoning makes some sense, since it is rare for such large animals to include many different species in a given area. Because of their large body size, their relatively small populations must have spread out over a large area, and there is not a lot of ecological space for such large animals to subdivide. On the other hand, very few specimens of these gigantic indricotheres are known, so it is difficult to tell if these skull differences are really due to differences in the sexes. We are divided over this dispute. One of us (Prothero) finds the argument convincing, but the other (Schoch) prefers to retain Indricotherium. In this book, we have followed the latter conservative course until some consensus is reached. The American Museum Mongolian expeditions of 1922 and later years made a number of spectacular finds, including the first dinosaur eggs. But the gigantic bones of Paraceratherium were among the most exciting. Roy Chapman Andrews, the leader of the expedition, described it this way: "The credit for the most interesting discovery at Loh belongs to one of our Chinese collectors, Liu Hsi-ku. His sharp eyes caught the glint of a white bone in the red sediment on a steep hillside. He dug

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a little and then reported to [Walter] Granger [the chief paleontologist of the expedition] who completed the excavation. He was amazed to find the foot and lower leg of a Baluchitherium, STANDING UPRIGHT, just as if the animal had carelessly left it behind when he took another stride [Fig. 14.10]. Fossils are so seldom found in this position that Granger sat down to think out the why and wherefore. There was only one possible solution. Quicksand! It was the right hind limb that Liu had found; therefore, the right front leg must be farther down the slope. He took the direction of the foot, measured off about nine feet and began to dig. Sure enough, there it was, a huge bone, like the trunk of a fossil tree, also standing erect. It was not difficult to find the two limbs of the other side, for what had happened was obvious. When all four legs were excavated, each one in its separate pit, the effect was extraordinary. I went up with Granger and sat down upon a hilltop to drift in fancy back to those far days when the tragedy had been enacted. To one who could read the language, the story was plainly told by the great stumps. Probably the beast had come to drink from a pool of water covering the treacherous quicksand. Suddenly it began to sink. The position of the leg bones showed that it had settled slightly back upon its haunches, struggling desperately to free itself from the gripping sands. It must have sunk rapidly, struggling to the end, dying only when the choking sediment filled its nose and throat. If it had been partly buried and died of starvation, the body would have fallen on its side. If we could have found the entire skeleton standing erect, there in its tomb, it would have been a specimen for all the world to marvel at. I said to Granger: 'Walter, what do you mean by finding only the legs? Why don't you .produce the rest?' 'Don't blame me,' he answered, 'it is all your fault. If you had brought us here thirty-five thousand years earlier, before that hill weathered away, I would have had the whole skeleton for you!' True enough, we had missed our opportunity by just about that margin. As the entombing sediment was eroded away, the bones were worn off bit by bit and now lay scattered on the valley floor in a thousand useless fragments. There must have been great numbers of baluchitheres in Mongolia during Oligocene times, for we were finding bones and fragments wherever there were fossiliferous strata of that age" (Andrews, 1932: 279-280).

Paraceratherium was probably as large as a land mammal can become. Only the whales are larger, and their weight is carried by the buoyancy of the water they live in. Some people have suggested that indricotheres were also amphibious to help bear their enormous weight, although

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?

A

B

c Figure 14.11. The front teeth of rhinocerotoids are diagnostic of their family groups. Starting with Hyrachyus (A), hyracodonts develop more spatulate incisors (C, Hyracodon). Amynodonts (B), on the other hand, developed prominent upper and lower tusks. True rhinoceroses, such as this rhinocerotid Trigonias (D), have an upper incisor chisel which occludes against a lower incisor tusk. The remaining upper incisors are lost in later rhinos. (From Radinsky 1966).

Figure 14.12. Restoration of the late EoceneOligocene rhinocerotid Subhyracodon (once known as Caenopus), typical of the Big Badlands of South Dakota. (Painting by R. B. Horsfall, from Scott 1913).

their bones were certainly stout enough to carry them. In addition, their enormous height and long necks only make sense if they browsed on treetops, as giraffes do. Gigantic animals, such as elephants and dinosaurs, have to consume an enormous amount of vegetation to feed such a large body. Living elephants today have to eat almost constantly to survive. Jim Mellett has shown that Paraceratherium was probably a hindgut fermenter, like other rhinos and elephants, and therefore was not as efficient at digestion as cows or giraffes that are ruminants with four-chambered stomachs. Instead, it had to pass large amounts of relati vely low-quality forage through its gut quickly in order to get enough energy from its food intake. The largest dinosaurs, which were four times as big as Paraceratherium, all had peg-like teeth that cannot slice up vegetation. They had to swallow their food whole and digest large amounts of it quickly to survive. Paraceratherium was one of the few mammals that tried to make a living as the dinosaurs did. Not surprisingly, very few mammals have tried it before or since because it is a very difficult lifestyle in terms ofbioenergetics. Paraceratherium was the largest land mammal ever seen, and it is unlikely that any mammal will ever top its record. Another consequence of its large body size is that it has the same problems as elephants: its surface area for dumping heat is relatively small compared to its large volume, so it is always in danger of heat prostration. We have seen how elephants use the remarkable heat exchange network in their fanlike ears to dump heat, and must spend most of the hot parts of the day immersed in water or hiding in the shade. Indricotheres must have had the same problem, only more extreme, since they were about five times as large as an elephant. They certainly must have spent most of their daytime in the shade or the water, as elephants do, and fed mostly in the evening, at night, and in the morning. In addition, most reconstructions show indricotheres with fairly normal, relatively small ears. There is no bony structure to determine the size of the ears in extinct animals, but surely the indricotheres must have had much larger, almost elephantine ears, or some other fan-like structure in their body to help with dumping heat. The bony tubes at the base of the ear opening on the skull of indricotheres is very strongly reinforced, consistent with the idea that muscles and ca11ilages supporting a large fan-like ear must have attached there. TRUE RHINOCEROSES Life in the Oligocene looked very different from what we have seen in the Eocene. The climate was more temperate and arid than the subtropical world of the Eocene, with vegetation of mixed forest and savanna grasslands. These changes were effected by a number of causes we discussed in Chapter 12. Separation of Australia from Antarctica caused cold bottom waters to form and triggered climatic cooling. Rapid growth of Antarctic glaciers ultimately led to cooling and vegetational change, which caused the late Eocene extinctions that wiped out the brontotheres. Other

RHINOCEROSES WITHOUT HORNS animals felt the effects as well. The alligators, pond turtles, and other subtropical reptiles were replaced by land tortoises in great abundance. Tree-dwellers, such as lemur-like primates, vanished from North America as the forest canopy disappeared. Browsing animals with low-crowned teeth were becoming scarcer and were replaced by many modern groups of animals. These include shrews, squirrels, pocket mice and gophers, beavers, rabbits, dogs, camels, peccaries, elephants, true tapirs and rhinos, which first appear in the late Eocene. The grazing artiodactyls, especially the efficient ruminants, became more important, and most perissodactyl groups (especially tapirs and titanotheres) became scarce. The most common fossils in the Big Badlands of South Dakota are either artiodactyls (primarily oreodonts, deer, and camels) or tortoises. The only common Oligocene perissodactyIs are the horses and hyracodonts, and they are far outnumbered by artiodactyls. The role of dominant herbivore had shifted from the perissodactyls to the artiodactyls. Today the artiodactyls are by far the most abundant of ungulates. In the midst of this the true rhinoceroses (Family Rhinocerotidae) make their appearance (Fig. 14.1). They were first known from the middle Eocene of Asia and North America, and looked very much like hyracodonts. The oldest known species is Teletaceras radinskyi, recently described from the middle Eocene of Oregon. Two features distinguish true rhinoceroses from other rhinocerotoids. The last upper molar has completely lost the crest along the back (Fig. 14.3). In addition, the front teeth are no longer simple pegs or spatulas, but developed into a shearing upper incisor and tusk-like lower incisor (Fig. 14.11). This blade-tusk combination is not only efficient for feeding, but also served as an effective weapon. The living Indian rhino can use its tusks to slash very effectively, and elephants fear its tusks more than its hom. Trigonias typified the early Rhinocerotidae. Known from the late Eocene, it was cow-sized and· had a very saddle-shaped head. Although it had developed the advanced blade-tusk incisors, it still had the rest of the incisors and the canines in the upper jaw. Later rhinos would lose these useless, peg-like teeth, so that only the tusks and the cheek teeth remained. Although Trigonias died out by the early Oligocene, one of its close relatives, Subhyracodon survived until the late Oligocene and gave rise to later North American rhinos (Fig. 14.12). Subhyracodon is usually found in the ancient ri ver channel deposits, so it was probably semi-amphibious like Metamynodon. Apparently, the amphibious lifestyle was popular among the rhinos. The teeth of Subhyracodon are not so high-crowned as those of Metamynodon, so it was probably a browser, not a grazer. Subhyracodon is not often found with Hyracodon, which lived on the grassy, open floodplains. Incidentally, the name "Subhyracodon" has led to much confusion. First of all, it is a misnomer; the animal is a true rhinocerotid, not a hyracodont. It was the first American rhinoceros ever described (by Leidy in 1850), and he initially

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assigned it to the genus Rhinoceros, which includes the living Indian rhino. Secondly, most of the popular books incorrectly call this animal "Caenopus." The name Subhyracodon was proposed first in 1878, but the popular books have been unfortunately using the incorrect name for over a century. As we saw in Chapter 2, Europe was an archipelago in the middle and late Eocene, isolated from the rest of the world and its mammals. Until the end of the Eocene the dominant large mammals were endemic palaeotheres and lophiodonts, which evolved in isolation from their tapir, horse, and rhino relatives found elsewhere. But the end of the Eocene marked the end of European isolation, and a great break ("Grande Coupure") in the mammals. Invaders from Asia took over the European continent and drove many of the natives, including the palaeotheres and lophiodonts, to extinction. The largest of these invaders were the rhinos. These included the smaller, primitive rhino Epiaceratherium (much like Trigonias in many features), and larger, more advanced rhinos like Ronzotherium. In the late Oligocene the rhinos first developed horns. Rhino horns are nothing like the horns of deer, antelopes, or cattle. They have no bony core at all, but are made of a mass of hair-like fibers that is stuck together. They are attached to the skull at a roughened, raised area on the skull, and can break off. When they do so, they can grow back. Since rhino horns are made of hair-like fibers and not bone, they are very seldom fossilized. Paleontologists restore the size, shape and position of the horn based on the size and placement of its attachment point, but this is always approximate. The first homed rhino was the direct descendant of Subhyracodon named Diceratherium ("two homed beast"). Instead of the familiar single horn on the tip of the nose, it had small horns that were paired on the nose (Fig. 14.13A). These horns were supported by broad ridges that ran along the side of the nasal bones. Only the males had horns; the females were completely hornless. Presumably these horns were short and stubby, and may have served more for impressing females than for defense. Diceratherium is a characteristic animal of the late Oligocene of North America, and was the only rhinocerotoid left after the extinction of the amynodonts and hyracodonts. For almost ten million years, there were no other large mammals (including rhinos) to compete with it. It was the largest herbivore around in the late Oligocene. As a result, there were several species of Diceratherium living side by side, differing primarily in size. At 77 Hill Quarry in eastern Wyoming there are thousands of bones of both males and females of two species of Diceratherium. Diceratheriines were not restricted to North America. During the late Oligocene one of their descendants migrated to Europe, where it was named Pleuroceros. It too had broad flanges along the sides of its nasal bones, indicating broad paired horns. However, it was uncharacteristic of European rhinos. Instead, the ancestors of the dominant Miocene rhino groups were evolving in Europe. By the

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Figure 14.13. A. Front views of Menoceras arikarense (left) and Diceratherium armatum (right), showing the differences in their paired horns. The horns of Menoceras were supported by small, rounded bosses, while those of Diceratherium were underlain by long bony flanges. (Photo by D.R. Prothero). B. Restoration of Menoceras. (Painting by R. B. Horsfall, from Scott 1913). early Miocene they migrated out of Europe and spread to Asia and North America, driving endemic diceratheriines to extinction. MIOCENE INVASIONS By the early Miocene, about 22 million years ago, the climate and vegetation had changed in North America. Savanna grasslands were now widespread as the climate had become much more arid than in the Eocene or Oligocene. The animals reflected these changes. Most of the oreodonts had become runners with high-crowned teeth (Merychyus) or tapir-like or hippo-like amphibious beasts with a trunk (Promerycochoerus). Horses (Parahippus) had become more efficient runners, and also had higher-crowned teeth. A number of different types of camels had evolved, including a slender one more like a gazelle (Stenomylus). The piglike entelodonts that were important in the Oligocene had reached gigantic proportions. The early Miocene entelodont, Daeodon, was 7 feet (2.1 m) tall at the shoulder (see Chapter 2).

In the midst of all these native groups the first wave of immigrants since the early Oligocene gave the early Miocene mammals a new look. The chalicothere Moropus arrived from Asia. Musk deer, pronghorns, and dromomerycid cervoids all arrived shortly thereafter. A number of new types of carnivores, especially the bear-dog Daphoenodon, hunted the herbivores. Among these immigrants was a new rhino, Menoceras (Fig. 14.13B), which had arrived from Europe (Fig. 14.1) to challenge Diceratherium. Descended from the late Oligocene Protaceratherium, Menoceras also had paired horns on its nose, but it was not closely related to Diceratherium. Unfortunately, because both rhinos had paired horns, people have confused the two for years. Direct comparison shows that the two paired hom combinations are not the same. True Diceratherium had broad ridges that pass along the side of the nasal bones. Menoceras had horn bases that were rounded knobs at the

very tips of its nasal bones (FIg. 14.13A). The two animals are also very different in skull proportions, tooth features, and other features of the skeleton. Menoceras was much smaller, about three feet (1 m) high at the shoulder, or the size of a large hog. Yet many scientists today still refer to Menoceras as "Diceratherium." Most museum labels and popular books still have the name wrong, even though this mistake was corrected in 1921! The most famous find of Menoceras was made in 1885 by "Captain" James Cook, a pioneer scout and rancher. He established Agate Springs Ranch on the banks of the Niobrara in western Nebraska while it was still roamed by hostile Indians. Cook, however, was on good terms with them, and was a personal friend of the great Sioux chief Red Cloud, who visited frequently. Cook found many fossil bones weathering out of a small hill, consisting of the deposits of an ancient river channel, on his ranch. In 1891 he showed the specimens to Dr. Erwin Barbour of the University of Nebraska, who became the first paleontologist to see the fossils. The University of Nebraska began to work the small conical hill to the north, which acquired the name "University Hill" (Fig. 14.14A). In the summer of 1904 Olaf Peterson, one of the principal paleontologists of the Carnegie Museum in Pittsburgh, visited the Cook Ranch. Peterson described it this way: "A day or two later Mr. Harold Cook, the eldest son of Mr. James H. Cook, accompanied the writer to a small elevation some four miles east of the farm buildings and immediately beyond the eastern limits of the land belonging to the ranch. The talus of this low hill was discovered to be filled with fragments of bones, and was afterwards designated as quarry A. On our return to the ranch I reported to Mr. James H. Cook that the place which his son had shown me was of much interest and importance to me and that I wished to start the work of

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B

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excavation on the prospect immediately. This was entirely satisfactory to Mr. Cook and his family. In fact there was evident satisfaction on the part of Mr. Cook that I had found something which I regarded as of interest and importance near his farm, and I was accorded every civility which I could possibly desire. As I wished to be near my work, Mr. Cook invited me to camp in his "lower field." Accordingly our first camp was pitched on the south bank of the stream close to the hill and the operation of excavating in quarry A was begun during the last few days of July. We had worked three or four days in this quarry when I decided to visit the two buttes (since named Carnegie Hill and University Hill by Prof. E. H. Barbour) which lie about three hundred yards to the south of the place where we were working. One may easily imagine the thrilling excitement of a fossil-hunter when he finds the talus of the hillside positively covered with complete bones and fragments of fossil remains. It was with comparatively little effort that I was able to articulate portions of the feet of Diceratherium cooki [now known as Menoceras arikarense] and Moropus using the disassociated bones picked

Figure 14.14. A. Agate Fossil Beds National Monument includes two hills known as University Hill (on the left) and Carnegie Hill (on the right). (Photo by D. R. Prothero). B. Quarrying operations at Agate were extensive. This is Stenomylus Quarry, worked by the American Museum of Natural History. (Neg. no. 18357, courtesy Department of Library Services, American Museum of Natural History). C. A typical slab of bones from Agate. It contains about 4300 bones and skulls, mostly of the rhino Menoceras. (Neg. no. 5594, courtesy Department of Library Services, American Museum of Natural History).

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Figure 14.15. Side view of the skull of the Miocene aceratheriine rhinoceros Aphelops, showing the characteristic long nasal notch, and loss of the upper incisors. (From Cope and Matthew 1915).

Figure 14.16. The aceratheriine rhinoceros Peraceras was also common in the Miocene. Here are the skulls of Peraceras profectum (bottom) and the dwarfed species from the Texas Gulf Coastal Plain, Peraceras hessel (top). (Photo by D. R. Prothero).

up in great abundance in the talus. Here then was a veritable wonderland!" (Peterson, 1909: 70-72).

hole, possibly due to droughts. If they had been killed by a catastrophic flood, there would have been far more juveniles and adults in the prime of their lives, and fewer old individuals. The Agate bone bed records the first appearance of Menoceras in North America. Apparently it avoided competition with native Diceratherium, since quarries that contain one rhino in abundance have very little of the other, and vice versa. Soon afterward Diceratherium disappeared entirely, and Menoceras was the sole North American rhino. The early Miocene was a period of great mammal migrations throughout the world. For several million years many other mammal groups migrated back and forth between North America, Europe and Asia. Shortly after Menoceras arikarense appeared at Agate it evolved into a larger

Agate Springs bonebed was worked intensively by the Carnegie Museum from 1904 to 1908, and from 1911 to 1923 by the American Museum of Natural History in New York (Fig. 14.14B). Although only two small hills of the bonebed remained, an enormous number of fossil bones were concentrated there. One slab of sandstone with an area of 44 square feet contained 4300 skulls and separate bones (Fig. 14.14C). At that rate, one of the hills could contain 3,400,000 bones belonging to at least 17,000 skeletons! Over 16,000 of these belong to the little rhino, Menoceras. Since 1925 there have been only minor excavations. Most of the major American museums have large collections of Agate fossils. The entire area is now included in Agate Fossil Beds National Monument. How did such an incredible concentration of bones get there? The skeletons are nearly all scattered about, with very few bones still articulated. They show relatively little breakage and abrasion, although in some areas the bones are quite abraded. The most important line of evidence comes from determining the age structure of the population. By looking at the wear on the teeth, the approximate age of each individual can be estimated. Bob Hunt has studied the age structure of Agate Menoceras and finds that there are far more old individuals than could be expected if they were all killed by a single, catastrophic event, such as a flood. Instead, this kind of population structure occurs with normal attrition due to the death of older individuals, and so represents a long term accumulation of rhino bones around an ancient water-

Figure 14.17. (facing page) A. Panoramic view of the lava cliffs of the Grand Coulee region, where the lava cast rhino cave was found. (Photo by D. R. Prothero). B. Entrance to the lava cave, at the base of the lava flow to the right. C. Inside view of the lava cave, showing two cylindrical holes which are molds of the legs. D. Reconstruction of the lava cave, once on display at the Burke Memorial Museum of the University of Washington. E. Cast of the lava cave, showing the distinctive shape of the bloated rhino carcass floating upside down. (Photos B-E courtesy J. Rensberger, Burke Memorial Museum). F. Restoration of the Grand Coulee rhinoceros as it may have looked in life, and as a bloated carcass. (From Chappell et al. 1941 ; courtesy Geological Society of America).

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species, Menoceras barbouri. This last species of Menoceras ran into competition from a whole new set of immigrants. By the end of the early Miocene two lineages of rhinos had become established in North America. The first of these lines was the aceratheriine rhinos. These rhinos have long, straight skulls without any horns on the tips of the nasals. All of them have lost their upper incisors, so their lower tusks cut against horny pads on their upper lip. A few of them have secondarily regained digit 5 on the front foot, making them four-toed. Their long limbs and skeletal proportions are typical of most unspecialized rhinos. Aceratheriines are first recognized in the late Oligocene of Eurasia with animals known as Mesaceratherium and Alicornops. Two genera of aceratheriines appeared in North America in the early Miocene. Aphelops remained the generalized, long-limbed browsing rhino through 12 million years of the North American middle and late Miocene (Fig. 14.15). Aphelops started out small and generalized, but as time went by, it became· more specialized. Its teeth became higher-crowned and more complex, probably in response to tougher vegetation in the late Miocene. The notch below its nasal bones continued to retreat backward, indicating that it was developing a more flexible prehensile lip for browsing. By the end of its evolution the nasal notch was deeply retracted, and the last species of Aphelops was nearly, twice the size of the first species. The other North American aceratheriine was Peraceras, which diverged from Aphelops in the early Miocene. At first they are difficult to tell apart, but in the middle Miocene Peraceras begins to develop a broad, heavy skull common in hippo-like animals. Presumably, it followed an amphibious grazer lifestyle that we have already seen in Metamynodon and other rhinos. It soon came into competition with Teleoceras (discussed next) which perfected the hippo-rhino niche. Peraceras also evolved into a dwarf species, which is found primarily in the humid forests of the Texas Gulf Coastal Plain and not in the High Plains of Nebraska or Kansas, where other rhinos were abundant (Fig. 14.16). In this way, it is analogous to the dwarf species of many other large mammals living today, such as the pygmy hippopotamus, the dwarf Cape buffalo, and the smaller forest elephant. One ancient rhino was fossilized in an extremely unusual manner. About fifteen million years ago there were immense eruptions of lava in the eastern half of the state of Washington. These eruptions covered thousands of square miles, flowing at speeds of 60 mph (100 km/hour) and more. They came from deep fissures, or cracks in the earth, rather than from volcanoes. The eruptions happened again and again, with each flow covering the last. Between eruptions, enough time passed that soils could form and forests grow on the old flows. During one of these eruptions a bloated carcass of a rhino was floating in a small pond. Lava flowed into the water and immediately chilled into pillow-shaped blobs, j

which nestled against the carcass and compressed against it (Fig. 14.17). This made a natural mold of the rhino, preserving not only the bones, but the outline of the soft tissues of the body. Many more eruptions and millions of years later, rivers and glacial meltwater cut deep canyons into the flows, making the Grand Coulee. In 1935, three men were hiking along the steep walls of the lava-flow canyons near Blue Lake when they found an opening of a small cave. They crawled inside and recovered a jaw and a few leg bones in one of the side cavities. It seemed incredible, but they were crawling inside the natural mold of a rhinoceros! They must have felt a bit like Jonah, but in the belly of a rhino rather than a whale. The tubular side cavities which produced leg bones were clearly the impressions of the animal's legs. In 1948 several scientists returned and made a complete cast of the mold, so that it could be mounted for display. Using the cast, they also reconstructed the mold cave. From the cast it is obvious that the animal had died and become bloated well before it was covered in lava. The torso is unnaturally fat, the legs are distended, and the neck is pulled back in rigor mortis. The rhino was floating upside down, since its legs were at the top of the cave. There were also a number of molds of trees preserved in the same lava flow. The lava impression is not very detailed, but some areas were well preserved. The shape of the rhino's head, with its prehensile lip, is very clear. But the tip of the nose and the area of the horns were not preserved, since they were in the gap between two lava pillows. The feet clearly show three blunt toes and a thick pad on the heel of the foot. By putting all these features together, the appearance of the animal in life can be restored. Unfortunately, the most important features that would distinguish between Diceratherium, Menoceras, or the dwarf Peraceras are not preserved. The Blue Lake rhino ranks as one of the most unusual examples of preservation in the fossil record. It is one of the few exceptions to the rule that fossils are not found in igneous rocks. RHINOCEROS POMPEII Besides the two aceratheriines, Aphelops and Peraceras, one other early Miocene rhino immigrant was common in the middle and late Miocene of North America. This was Teleoceras, probably the most hippo-like rhino ever (Fig. 14.18). Teleoceras and its relatives, the teleoceratines, were highly specialized for an amphibious existence. They had a stout, barrel-shaped body with extremely short, stumpy legs. Teleoceratines first appeared in Europe in the late Oligocene with an animal known as Brachydiceratherium. This animal still had a very generalized skull that looked more like aceratheriines or diceratheriines in most features. The limb shortening had not yet fully developed, but these ·animals were still much more short-limbed than aceratheriines. By the early Miocene, Brachydiceratherium was joined by another teleoceratine, Diaceratherium (not to be confused with DiJ:..eratherium), a slightly more advanced

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Figure 14.18. (above) Reconstruction of Teleoceras, the most hippo-like and amphibious of North American rhinos during the middle and late Miocene. Note the barrel chest, the short, stumpy legs, and the broad skull with huge grinding teeth for eating grass. (Painting by Z. Burian).

Figure 14.19. A. (right) Excavation of the "Rhino Pompeii," as it appeared in 1995. Several complete articulated skeletons of Teleoceras major can be seen, some with calves nursing at their sides. (Photo by D.R. Prothero). B. (below) Reconstruction of the Ashfall Fossil Beds water hole as it might have looked 10 million years ago. In addition to the rhinos, there are numerous three-toed horses, giraffecamels, and other mammals. (Courtesy University of Nebraska State Museum).

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form with shorter, more massive limbs. Diaceratherium underwent rapid evolutionary change in the early Miocene, developing very shortened legs, very high-crowned teeth, and still retaining the four-toed front foot. It died out in the middle Miocene, but according to Kurt Heissig, it spread to North America where it evolved into Teleoceras. Another of its descendants was a dwarfed form, Prosantorhinus, which had a very strong hom, but died out at the end of the middle Miocene in Europe. Yet a third descendant is an Asian form known as Aprotodon. This rhino developed a very broad snout with long, outward-flaring tusks, and also developed a deep nasal notch for attachment of a prehensile lip. Thus, it has an interesting mix of features found in the hippo-like grazing rhinos, and the prehensile-lipped browsing rhinos. Aprotodon disappears from the geological record in the late Miocene, where its last fossils are known from the Siwalik Hills of Pakistan. By the middle Miocene Brachydiceratherium and Diaceratherium were replaced by a very successful animal, Brachypotherium. This ~teleoceratine was abundant and widespread throughout the Old World during the entire middle and late Miocene, and even managed to survive into the late Pliocene in East Africa. Although it had a huge, hippobody with shortened legs like most teleoceratines, it never developed the extremely high-crowned teeth found in the teleoceratines adapted for eating grasses. Nevertheless, its molars are very large and broad, even if they are low crowned, and it had a heavy massive skull and jaws. The early species of Teleoceras had relatively short legs already, but as they evolved, their legs became shorter and their limb bones became extraordinarily stumpy and compressed. The skull of Teleoceras was very large, with massive, high-crowned teeth that were almost certainly adapted for grazing on abrasive grasses. Unlike the aceratheriines, Teleoceras had a small horn on the tip of its nose, and still had its upper chisel-like incisors. The extraordinarily hippo-like body of Teleoceras suggests that it lived much like a hippo, wallowing in the water in the day and coming out at night to graze on land. Teleoceras bones occur in great abundance in Miocene river channels, especially in Nebraska, Kansas, Texas, and Florida. For this reason, it is probably one of the commonest and best known of the North American rhinos, and many museums have a mounted skeleton on display. Many river channel deposits contain quarries of bones of both Aphelops and Teleoceras, which often lived together even though they had different ecologies. From these large quarry samples, we have additional evidence that Teleoceras was a hippo-like grazer. The Love Bone Bed of central Florida contains both Aphelops and Teleoceras in great abundance. By determining the age of each individual (estimated from tooth eruption and wear), it is possible to reconstruct the age profile of the rhino population. Dave Wright found that the age structure of the Teleoceras population was more like that of living hippos than rhinos. The age structure of the Aphelops population, on the other hand, was more like that of the browsing

black rhinoceros. The most remarkable of all the Teleoceras discoveries, however, was made recently by Mike Voorhies of the Unversity of Nebraska State Museum (Fig. 14.19A). In 1977, he was prospecting around Verdigre Creek, near the tiny town of Royal, in northeastern Nebraska. As he followed exposures of a silvery gray volcanic ash from one bank of the creek to another, he found the skull of a baby rhinoceros sticking out of the streambank. The next day, he excavated further, and found that it was a complete skeleton of a baby Teleoceras. Voorhies and his crew continued to dig back, finding 12 more rhino skeletons in an area the size of a living room. In the summer of 1978, they brought in a bulldozer and cleared off the overburden above the ash layer. Then the University of Nebraska State Museum crews began the slow, painstaking excavation of the bed with delicate brushes and scrapers. As they exposed the rhino skeletons, they treated them with preservative to protecct the brittle bone from shattering. They marked off the entire excavation in meter-square grids, so that the precise position of every bone could be recorded. The work was hot, tiring and especially dusty, since the powdery vocanic ash was lifted by the slightest breeze, and everyone had to wear dust masks and goggles for protection. The crews began to know what those rhinos once felt, choking to death on fine volcanic ash. As they excavated further, the details began to emerge. Most of the skeletons were found intact, crouched down or lying on their sides in death poses. Even the most delicate bones of the throat and ear region (rarely preserved in most fossils) were in their correct anatomical position. Out of over 200 skeletons of Teleoceras major collected in the first few years, only 7 were adult males. The rest were adult females or their calves, many of whom were found in nursing position under the belly of their mothers. Some of the females had fetuses in their pelvic cavities. By studying the tooth wear, they found that most ofthe calves were in well defined age groups, as if they were born at the same season each year. Taken together, this suggests that Teleoceras formed large male-dominated herds, composed mostly of females and their calves, similar to many large ungulates today (Fig. 14.19B). The nature of the deposit indicates that the rhinos were buried by ash blown all the way from the Rocky Mountains, and filling a bowl-shaped waterhole, 3 m deep at the center and thinning toward the edges. Most of the rhinos are found in the center of the water hole, where they slowly died or suffocated after being buried in ash. Studies of the bone pathology indicates that many died from a disease caused when their lung tissues were lacerated by inhaling the razorsharp volcanic glass shards. Although most skeletons were buried intact, some of them were apparently exposed, and torn apart by scavengers. Others showed signs of rib cages that exploded when they died and became bloated. Subsequent research on the rhinos has revealed even more details. In the midst of the well-preserved throat bones samples of grass seeds were found. They turned out to be

RHINOCEROSES WITHOUT HORNS seeds of the Berriochloa, a common grass in the late Miocene of Nebraska. These seeds were found only in the oral cavities or rib cages of the rhinos, and not in the· surrounding ash, so they were unquestionably the "last supper" of this "Rhino Pompeii." This is the best possible proof that Teleoceras was a grazer, as its hippo-like build and population structure suggest. After the initial excavation concluded in 1979, the storage floors of the Nebraska State Museum were filled with over 40 tons (2000 casts) of jacketed fossils, most of which have still not been prepared for study years later. But the rhino quarry extended further under the landscape. So many skeletons had already been removed that Voorhies and his crew decided to leave the rest in the ground, partially excavated, as a permanent exhibit. In 1991, the region was turned into a state park, with a modern visitor's center that helps guests interpret the fossils. The main excavation is now housed in a large "rhino barn" (Fig. 14.19A), which protects the fossils (and the crews) from the sun in the summer, and can be opened at both ends to allow ventilation. Visitors can walk along the edges and on catwalks to view the excavation up close. When October comes and the park closes down, the rhino barn can be locked up to protect the delicate fossils from the weather and vandals. Ashfall Fossil Beds State Historical Park is one of the great paleontological meccas, worth going out of one's way to visit. As we saw in Chapter 3, the end of the Miocene was a period of great change around the world. In North America, oreodonts and the "slingshot-nosed" protoceratids were extinct, and horses, camels, mastodonts, deer, and pronghorns were reduced to a few species. As we discussed above, this great faunal change was caused by massive climatic cooling triggered by Antarctic glaciation and particularly by the Messinian drying of the Mediterranean. This Messinian event, which marked the beginning of the Pliocene, was also the beginning of the Ice Age world as well. Among the victims of the changes at the end of the Miocene were the rhinos. By the latest Miocene, Teleoceras is very rare where it used to be abundant, and a dwarfed species appears in the panhandle of Texas. By contrast, latest Miocene river deposits are full of bones of the largest and final species of Aphelops. At the very end of the Miocene, however, both rhinos were virtually extinct. Only one scrap of a rhino tooth is known from a single early Pliocene quarry. After almost fifty million years as one of the dominant large mammals on this continent, rhinoceroses finally disappeared from North America, and would never return except as zoo animals. In the Old World the crisis was just as severe. All the aceratheriines were decimated, with only a few species surviving into the early Pliocene of Asia. They were wiped out completely from Africa and Europe, as they were in North America. Teleoceratines disappeared entirely from Eurasia at the end of the Miocene, and only one lineage of Brachypotherium managed to persist into the Pliocene in Africa. The world of rhinos had been dominated by both aceratheri-

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ines and teleoceratines in the Miocene, but only a few straggled into the Pliocene before becoming extinct. They were replaced by three major groups which had arisen alongside them in the late Miocene: the dicerotines (the African black and white rhinos and their relatives); the dicerorhinines (the Sumatran rhino, woolly rhino, and their extinct relatives); and the rhinocerotinines (the Indian and Javan rhino and their extinct relatives). The first group came to dominate Africa, and the latter two were widespread in Eurasia, especially during the Ice Ages. HAIRY RHINOS AND GIANT "UNICORNS" As we saw at the beginning of the chapter, Ice Age rhino bones were responsible for many legends of "giants" and "dragons." Indeed, one of the earliest prehistoric restorations in sculpture was such a case. In 1590 the sculptor Ulrich Vogelsang built a huge winged dragon for the fountain in the main square in Klagenfurt, Austria. Although the body is conventionally dragon-like, with wings, scales, claws, and a long reptilian tail, the head looks peculiar. Disregarding the leaf-like ears, the head has the peculiar arched profile that can easily be traced to a skull of a woolly rhinoceros found in the area in 1335, and later placed on display in the Klagenfurt town hall. The woolly rhinoceros is one of the best known members of a long and diverse group of rhinos, the dicerorhinines. Almost all members of the group clung to the primitive forest browsing niche, so their skeletons and teeth do not show very many specializations. Indeed, the living Sumatran rhino, Dicerorhinus sumatrensis, still survives in dense forests today. Consequently, the lack of distinguishing features makes it hard to tell many of the species of dicerorhinines apart, even though they have a history going back at least 25 million years in Europe. Most of the extinct species are placed in the Sumatran rhino genus, Dicerorhinus. But this overextends the meaning of the genus, and turns the genus into a taxonomic "wastebasket" for animals which are not really Sumatran rhinos, but are called "Dicerorhinus" for lack of a better name. Most of the eighteen or more extinct species should not be referred to the living genus. Some of these species have been split off into new genera, such as Brandtorhinus, Lartetotherium, and Stephanorhinus, but most of the fossil species should eventually be placed in their own genera. Wherever possible, we will use these new genera in place of invalid uses of "Dicerorhinus." The earliest dicerorhinine is Lartetotherium tagicum from the early Miocene of Europe. It already had a small nasal horn like the living Sumatran rhino, and some specimens had a horn on the forehead as well. By the middle and late Miocene, Lartetotherium sansaniensis was widespread not only in Europe, but also in Africa where it evolved into Lartetotherium leakyi. In the late Miocene three different species of dicerorhinines coexisted in Europe, including the dwarf species "Dicerorhinus" steinheimensis, and the giant "Dicerorhinus" schleiermacheri and "Dicerorhinus" orien-

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Figure 14.20. (left) A close relative of the woolly rhino was the Etruscan rhinoceros, Stephanorhinus etrUSGUs. It lived in the early Pleistocene in southern Europe. (Painting by Z. Burian). Figure 14.21. (above) Restoration of the woolly rhino, Coelodonta antiquitatis , one of the commonest mammals of Eurasia during the Ice Ages. (Painting by Z. Burian). taUs. Asia was the home not only of "Dicerorhinus" orientalis, but also of "Dicerorhinus" abeli from the late Miocene of India, and "Dicerorhinus" ringstroemi of Turkey and South China. All of these rhinos maintained the forestbrowsing low-crowned teeth and long running limbs, but also had tandem horns on their noses and foreheads. In the Plio-Pleistocene dicerorhinines continued to flourish. One Ice Age lineage, Stephanorhinus, can be traced back to "Dicerorhinus" scheiermacheri and Stephanorhinus pachygnathus from the Miocene of the Mediterranean region. The Etruscan rhinoceros, Stephanorhinus etruscus, was a primitive browser from the early Pleistocene (Fig. 14.20). In the middle Pleistocene it was succeeded by Stephanorhinus hemitoechus, the steppe rhinoceros. This beast had a low-slung head and high-crowned teeth like the living white rhino, and must have grazed on grasses of the parklands and steppes during the interglacials. Unlike the woolly rhino, however, it did not manage to colonize the tundra during cold periods. During the late Pleistocene the forest habitat was dominated by Merck's rhinoceros, "Dicerorhinus" mercki. This beast was named after the German writer Johann Heinrich Merck (a friend of the great poet Goethe), who was so fond of finding extinct rhino and mammoth bones that he called himself "elephant hunter and rhinoceros shooter." These rhinos were so characteristic of steppes and forests that the fluctuation between glacials and interglacials in Eurasia can be identified by the presence of either the steppe rhino or Merck's rhino. The most successful of the dicerorhinines, however, was the woolly rhinoceros, Coelodonta antiquitatis (Fig. 14.21). This animal seems to have originated in the early

Pleistocene from Coelodonta nihowanensis of northern China, and then migrated westward. The woolly rhino arrived in Europe about 200,000 years ago. By doing so, it had the largest range of any rhino, from Scotland to Spain to South Korea. It was clearly a steppe and tundra grazer, with a broad front lip for mowing grasses. One of its most peculiar features was the horn, which is flattened like a saber blade. Mikael Fortelius has studied these horns (which were once thought to be "gryphon" claws) and found that they have scratches and abrasion surfaces on the front edge. Like the tusks of the woolly mammoth and the antlers of caribou, the woolly rhino used its blade-like horn to brush snow away in a side-to-side motion and find tender grasses underneath. With its short legs, however, it probably did not spend much time in deep snowdrifts. Unlike other extinct rhinos, we have an unusually complete picture of the woolly rhinoceros. A number of specimens frozen in permafrost have been found and they show that it had a thick woolly coat for protection against the Arctic cold. The most spectacular finds, however, were pickled in salty mineral wax, or ozocerite, in a natural seep near Starunia, Poland. Three complete carcasses, including the woolly hide, the flesh, the thick subcutaneous fat, and even the remains of the last meal, were found there in 1907 and 1929. The 1929 specimen had a last meal that included dwarf birches and small-leafed willows, typical of the tundra. This specimen has since been stuffed and is now displayed in the Natural History Museum of the Polish Academy of Sciences and Letters in Cracow (Fig. 14.22). In addition to pickled specimens, we also have eyewitness drawings. Some of the best cave paintings in Europe,

RHINOCEROSES WITHOUT HORNS especially at Font de Gaume and Rouffignac, portray the woolly rhino as it was seen and hunted by Ice Age humans. Paleolithic artists always show it with a distinct shoulder hump and a downward inclined head. Many drawings showed that they were very furry, especially along the lower jaw, the back of the head, and the belly. Like most other dicerorhinines, they had tandem horns, with the nose horn much longer and more curved, but there was great variability in hom shape (as there is in living rhinos). Upper Paleolithic people in Siberia were great rhino and mammoth hunters, with some sites containing 3-4% rhino bones. Some rhinos are shown being speared with javelins and arrows in the cave paintings of La Colombiere, France. Hunters may have also used pits dug across their habitual trails. Despite their success on the late Pleistocene tundra from Scotland to Siberia, woolly rhinos never crossed the Bering land bridge into North America. It is still a mystery why they did not do so when their fellow tundra dwellers, such as the woolly mammoth, bison, yak, saiga antelope, elk, and humans, all crossed successfully and spread through the Americas. The Siberian steppes were the home of another spectacular ice age rhino, Elasmotherium (Fig. 14.23). It was the true giant of the rhino family. As large as a living elephant, it had a huge skull almost 4 feet (1.2 m) long. Its most bizarre feature, however, was the horn. Instead of a typical nose hom, it had a gigantic horn over 6 feet (2 m) in length

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anchored to a huge bony boss on its forehead. In spite of the association of unicorn legends with other rhinos, Elasmotherium was more like the mythical unicorn in having a single hom on its forehead. Its cheek teeth were equally bizarre. They were rootless cylinders which had gotten so large that only a few were left in the jaw. As the tooth wore it became a thick cylinder of dentin surrounded by a thin layer of hard enamel. The worn surface of enamel formed a spectacular curlicue pattern that is totally unlike that of any other mammal known. These teeth, along with its steppe habitat, are clear indications of another great grazing beast. According to Kurt Heissig, this creature originated from a tiny rhino known as Caementodon of the early Miocene of Pakistan. By the middle Miocene, there was a great diversity of relatives of Caementodon, including Hispanotherium, and several species of Begertherium found from China to Spain. Another branch began with Iranotherium (first described from the famous late Miocene Iranian locality of Maragheh). Middle Miocene Beliajevina from Siberia and Turkey and Tesselodon from China already had the distincti ve elasmothere frontal horns and high-crowned teeth. In the late Miocene elasmotheres such as Ningxiatherium were restricted to central Asia, with lingering populations of Caementodon in Pakistan and Kenyatherium in Africa. Finally, in the Chinese early Pleistocene a beast known as Sinotherium gave rise to Elasmotherium. Elasmotherium was restricted to Siberia and eastern

Figure 14.22. (left) The mummified carcass of a woolly rhino, pickled in petroleum in Starunia, Poland. It is now on display in the Institute of Systematic Zoology in Cracow. (From Kowalski 1967). Figure 14.23. (above) Reconstruction of the elephant-sized rhino Elasmotherium, found in the steppes of Eurasia during the Pleistocene. Instead of a nasal horn, it had a single giant frontal horn. (Painting by Z. Burian).

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Figure 14.24. The living Sumatran rhino, Dicerorhinus sumatrensis, last of the lineage of the woolly rhino and its dicerorhinine kin. It is the smallest of living rhinos, and also retains the body hair typical of its tribe. (Photo by D. R. Prothero). Europe (primarily the drainages of the Black and Caspian Seas), although one specimen is known from the Rhine Valley of Germany. It is not as common or as well known as the woolly rhino, although they both roamed the steppes of Siberia and eastern Europe. Both Elasmotherium and the woolly rhino died out about 10,000 years ago, at the end of the last glacial episode. Like the other great Ice Age mammals, their extinction was probably due to the climatic changes that destroyed their habitat. As we have seen, however, the great extinctions of the Ice Age megafauna are controversial, and many scientists attribute them to human hunting. Woolly rhinos were hunted during the last glacial without going extinct, and there is no evidence of humans hunting Elasmotherium. Clearly, the climatic explanation makes better sense for Ice Age rhinos. Today the only remnant of the dicerorhinines is the Sumatran rhino, Dicerorhinus (formerly Didermocerus) sumatrensis (Fig. 14.24). In many ways it is a true living fossil. It retains the primitive forest browsing niche, and even has a significant amount of hair on its body (as most of the extinct dicerorhinines probably had). It is the smallest of the living species, weighing a little under a ton (about 550-750 kg). It is about 8-9 feet (2.5-2.8 m) long, and only 3-5 feet (1-1.5 m) high at the shoulder. Like other dicerorhines, it has tandem horns, although the forehead hom can be very small and give the impression that some individuals are one-

homed. Their horns can be used for sparring or defense, but they are also used for breaking down saplings to feed. Like the one-homed rhino, its skin folds give the impression of armor plating, even though it is covered with long brown fur over much of its body. Because Sumatran rhinos live in dense forests and are very secretive, very little is known about their biology. They spend most of the morning and evening browsing on leaves, twigs, bamboo shoots, and fruits such as wild mangoes and figs. With their prehensile lip, they are very adept at stripping off leaves and fruit. They will also eat lichens and fungus off a rotting tree, and occasionally eat grass. Dicerorhinus will step on a small tree and "walk it down" in order to reach fruit at the top. In the heat of midday, they sleep or wallow in the mud, and at night, they sleep in a concealed place. Male Sumatran rhinos are usually solitary and non-territorial, but females may live in a telTitory 1-2 miles (2-3.5 km) in diameter. These territories are criss-crossed with well established trails in the underbrush that resemble green tunnels. Paths are used year after year, so even the bedrock can be worn smooth by rhino abrasion. In some places, rhinos mark their paths with dung heaps almost 3 feet (1 m) high and 5 feet (1.5 m) across. Sumatran rhinos are very mobile, moving into the steep highlands during the rainy season and down to the lowlands when the floodwaters

RHINOCEROSES WITHOUT HORNS recede and the weather is cooler. They are excellent climbers, clambering about in terrain too steep for elephants or gaur cattle, up to elevations of 6500 feet (2000 m). They are particularly adept at plunging through the steepest, thickest, thorniest vegetation to avoid being followed, which is why so few people have seen them or been able to study them. They are also excellent swimmers, and have been known to swim in the sea. Their sense of hearing and smell is very acute, so it is very difficult to approach them although they have poor eyesight, as befits a forest animal with limited horizons. Dicerorhinus snorts when disturbed, brays like a donkey when alarmed, and squeaks when it is walking calmly. While it is wallowing it makes a variety of snorts, grunts, blows, and a low humming noise. Other than humans, Dicerorhinus is the only animal known to sing in the bath. Given their secretive habits, even less is known about their reproduction. Dicerorhinus is a slow breeder, raising only one calf at a time, with a gestation period of about 1518 months. One newborn baby was· 50 pounds (23 kg) at birth, with a 20 mm long horn, and short, crisp, black hair all over its body. Dicerorhinus appears to reach adult size after about 3 years, although their teeth will not have fully erupted until 9 years of age. Little is known about their lifespan in the wild, although a captive animal lived for 32 years. The Sumatran rhino is one of the most endangered of large animals. Although it once ranged all over southeast Asia, from India to south China to Sumatra and Borneo, today it is restricted to a very small portion of that original range. Poaching by humans seeking their horns is responsible for most of this decline, but today so few remain that they are only found in the densest forests, and are rarely seen

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by humans. The biggest threat to their survival is deforestation since they require large areas of dense forest and cannot be restricted to small reserves like other rhinos. Since they are so elusive, it is very difficult to get an accurate count of how many still survive. According to 2002 estimates, there are fewer than 300 left, a 50% decline in just the past decade. There are 15 now held in captivity (5 males, 10 females), mostly in Indonesia and Malaysia. Too few are left in the wild to risk capturing more. The Malaysian government has begun a captive breeding program at the Sungai Dusun Rhino Facility on peninsular Malaysia, and this may hold the best hope for successful captive breeding. Several of the captive pairs have been mated, and one baby Sumatran rhino has been born in captivity (although it was conceived in the wild). A Global Propagation Group for the Sumatran Rhino was formed in 1991 to plan a conservation strategy. In addition to captive breeding, a studbook is now being maintained and efforts are being made to determine the genetics of the few available animals and avoid inbreeding. For the long term, however, the survival of Dicerorhinus depends upon halting the destruction of their habitat. The Sumatran rhino, because of its status as an exotic large endangered animal, could serve as an "umbrella" species to generate political momentum and funding for the preservation of large areas of its habitat and all the other endangered animals that share it. Sadly, we know far too little about this fascinating Ii ving fossil which could give us a glimpse at the typical rhino of the prehistoric past. Yet our opportunities to learn more are rapidly diminishing. If deforestation is not slowed, captive breeding programs may not be enough to save this marvelous relict.

Figure 15.1. These two black rhinos were photographed in Ngorongoro Crater in 1973, and were poached soon afterwards. Today there are no rhinos in Ngorongoro Crater or most other East African national parks. (Photo by D.R. Prothero).

15. Thundering toward Extinction

Hearing and pre-eminently smell Make far better sense To rhinoceros, which sees dimly (And wears a nosehorn well). This all but hairless hulk So enarmored of thick skin with folds As to lack nonhuman predators of consequence Thunders toward extinction [Fig. 15.1] Blindly bold to man in self-defense. Preferentially it holds Itself apart, hoofing through reeds And high grass, browsing by dusk And dawn, solitary in its Territory save when it breeds. Communication faintly whiffs absurd: Movement is action Movements speak louder than words Territory marks are piled turds. (Burns, 1975) UNICORN, MONOCEROS, AND RHINOCEROS As we have seen in previous chapters, rhinoceros and mammoth fossils were responsible for many myths about great races of giants, or great extinct carnivorous beasts, or "ancient Dacians." The most persistent myth based on the rhinoceros, however, is the legend of the unicorn. A variety of one-horned beasts were common in ancient Chinese, Egyptian, Babylonian, and Assyrian mythology, and in the fables of the Greeks and Hebrews. In Job 39: 9-12, Yahweh asks Job, "Is the unicorn [re-em in Hebrew] willing to serve you? Will he spend the night at your crib? Can you bind him in the furrow with ropes, or will he harrow the valleys after you? Will you depend on him because his strength is great, or will you leave to him your labor? Do you have faith in him that he will return, and bring your grain to your threshing floor?" Herbert Wendt suggests that the familiar horselike unicorn was a combination of legends of the recently domesticated ox in Asia (known to the Babylonians as the rimu, and to the Akkadians and Ugarites as the remu), the oryx of the Egyptians (known in Arabic as the rim), the wild ass or onager of central Asia (famous for its strength and ferocity), and the one-horned Indian rhinoceros. Certainly, many ancient cultures were also aware of true

rhinoceroses. The Indian rhinoceros was described by the Greek historians Ctesias, Strabo and Agartharcides, and by the Roman poet Martial, who remarked on how it flung bears away in combat in the Roman circuses. In his Natural History, Pliny the Elder writes that the unicornis was "the born enemy of the elephant that sharpens its hom on a stone and in combat aims at the elephant's belly, knowing well that it is soft." Both the Greeks and Romans assumed that the mysterious horse-like beast of Asia (known as monoceros to the Greeks and unicornis to the Romans) was something different from the rhinoceros, especially since there was a big market for the medicinal properties of unicorn hom from China (almost certainly taken from Indian rhinos). In the Middle Ages, the lack of contact with Asia or Africa caused the classical knowledge of rhinoceroses to disappear into the unicorn legend. In almost all accounts, the unicorn is a powerful, wild beast, the size of a small horse but with a beard and cloven hooves. All were supposedly males. The unicorn was endowed with enormous· strength, but all of its strength was concentrated in its horn. It was said to precede other animals to water and render it pure by dipping its horn into it. It could only be captured by a virgin sitting quietly in the forest with one breast bared. When the unicorn came, it could not resist her, but placed its head quietly in her lap. Once she plucked the horn from it, it lost its strength and was quite tame. When mammoth tusks were dug up they were prized as the horns of unicorns, or unicornum verum. Sick people paid great sums to apothecaries for small shavings. Although most theologians discouraged this practice, fresh discoveries of mammoth tusks only perpetuated the myth. Even after the Middle Ages unicorns were illustrated and described in zoological textbooks by Gesner, da Vinci, Mercati, Leibniz, and even Linnaeus, none of whom doubted their reality. According to Leonardo da Vinci it was a mythical superbeast: "In its lack of moderation and restraint and the predilection it has for young girls, it completely forgets its shyness and wildness; it puts aside all distrust, goes up to the sitting girl, and falls asleep in her lap. In this way hunters catch it." By the seventeenth century it had become a bearded horse-like animal with cloven hooves and a long, straight

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Jfl.&' ~

R[IINOCERVS

15\

Figure 15.2. Albrecht DOrer never saw the Indian rhino on which he based this famous 1515 woodcut; nevertheless, it became the model for all rhino illustrations for over a century. The mythical element is still present in the unicorn horn protruding from the shoulder (From Wendt 1959). horn with a spiral twist on its surface. This idea of the hom probably came from the imported tusks of narwhals, a small Arctic whale related to the white beluga whale. Male narwhals have an enlarged left incisor that protrudes as a tusk, sometimes reaching 10 feet (3 m) in length, which is used for social dominance. When Scandinavian fishermen brought these tusks back from the Arctic they were greatly prized by apothecaries for their supposed miraculous powers as unicorn horns. They were so valuable that the apothecary kept it on a chain, and scraped off only a few grains for a high price. A prince of Saxony paid a hundred thousand thalers for a single "alicorn," and Emperor Charles V discharged his imperial debt to the Margrave of Bayreuth with just two narwhal teeth. Other "unicorn horns" were probably Indian rhino horns, powdered and used for medicine. Queen Elizabeth I had one in her bedroom in Windsor, and as late as 1741 unicorn hom was still officially recognized as a drug in England. Just before the French Revolution in 1789 the French court still used "unicorn horn" to test if the royal food had been poisoned. Pope Gregory XIV was offered some on his deathbed in 1591, although he died right after consuming a potion made of the powder. It was so widely regarded as a symbol of apothecaries that today the trade-

mark of Burroughs Wellcome, one of the world's largest drug companies, is a unicorn. Skeptics called the narwhal tooth the unicornumfalsum, and some even related accounts of a "toothed whale" from the Arctic. But the belief was so widespread that almost all accounts placed a long, straight narwhal tusk on their portraits of unicorns, the dominant image today. In the early nineteenth century, great anatomists such as Cuvier pointed out the biological impossibility of such a beast. No horselike animal had cloven hooves like an artiodactyl! The rediscovery of the rhinoceros after the Dark Ages caused almost as much excitement in Europe as the discovery of the elephant or giraffe. Instead of the delicate horselike beast they had come to expect, they found a large, ugly beast with armor. In 1292 Marco Polo returned from his seven-year voyage bringing reports of a two-horned beast he had seen in Sumatra (probably the Sumatran rhino). He saw "lion-horns, which, though they have feet like elephants, are much smaller than the latter, resemble the buffalo in which, however, they harm no one ... All in all, they are nasty creatures, they always carry their pig-like heads to the ground, like to wallow in mud and are not the least like the unicorn of which our stories speak in Europe. Can an animal of their

THUNDERING TOWARD EXTINCTION race feel at ease in the lap of a virgin? I will say only one thing: this creature is entirely different from what we fancied." Many of the European myths about rhinoceroses probably came from Chinese tales brought with the trade in rhino and elephant parts. These were liberally mixed with unicorn myths, and swallowed completely by credulous Europeans. The more ridiculous, the better. For example, rhinos supposedly had no joints in their legs and had to prop themselves against trees in order to sleep. If a rhino fell down it was helpless, so it could be captured by getting it to lean against a half-sawn timber. Once this collapsed it left the rhino immobilized on its side. Like unicorns, all rhinoceroses were said to be males. Rhinos were supposedly fond of music and perfume. To lure the rhinoceros a man should dress up as a virgin, reeking of perfume. If it charged, the man could climb a tree and drive the rhino off by urinating in its ear. Not until 1513 did Europe actually see a live rhinoceros. It was captured in India after the Portuguese conquered the coastal city of Goa. Sent by King Muzaffar of Cambray to King Manuel the Great in Lisbon, it caused a sensation. After the Portuguese king had tired of it, he sent it as a gift to Pope Leo X. It was harnessed with a green velvet collar, studded with gold roses and carnations, and tethered to a gilt iron chain. When the ship docked in Marseilles, Francis I of France bribed the captain 5,000 gold crowns to display it to the French crowd. On its way to Rome a storm wrecked the ship, drowning all aboard. The rhino carcass washed ashore, where it was collected, skinned, stuffed, and sent to the Pope. While it was in Lisbon it was described by the Italian naturalist Ulisse Aldrovandi, and a famous woodcut was made by the artist DUrer (Fig. 15.2) and copied by Gesner in 1551. The illustration emphasizes the folds of the skin, and showed horny spikes on the skin that were probably caused by the long confinement in the ship's hold. This early illustration was so influential that nearly every subsequent drawing of a rhino tried to show the same features, whether or not they were really there. When African black rhinos were found, they were shown with folded skin and armored spikes. Museum curators actually ironed some folds into their skins to make them "authentic." The influence of myth and hearsay upon even the most authoritative accounts is demonstrated by Edward Topsell's 1607 History of the Four-footed Beasts. It was one of the first English-language accounts of the natural history of beasts published since the Renaissance, and was copied without change for centuries. Along with descriptions of dragons, manticores, unicorns, and many real animals, he gives a complete account of the mysterious rhinoceros. "We are now to discourse of the second wonder in nature: namely, of a beast every way wondrous both for outward shape, quantity, and greatness, and also for inward courage, disposition, and mildness. For,

as the elephant was the first wonder of whom we have already discoursed, so this beast next unto the elephant fills up the number, being every way as admirable as he, if he does not exceed him, except in quantity or height of stature ... Because of the hom in his nose, the Grecians call him rhinoceros, that is, "nose-homed beast." Although there are many beasts that have but one hom, yet there is none that has one horn growing out of the nose but this beast alone. All the rest have the hom growing out of their foreheads. There have been some people that have taken the rhinoceros for the monoceros (the unicorn) because of this one horn, but they are deceived. In quantity, the rhinoceros is not much bigger than an oryx. Pliny makes it equal in length to an elephant, and some make it longer than an elephant but say it is lower and has shorter legs. A rhinoceros that was seen at Alexandria had a color like that of an elephant; his quantity was greater than a bull's, or as that of the greatest bull; his outward form and proportion was like a wild boar's, especially in his mouth, except that out of his nose grew a horn, which he used instead of arms. He had two girdles upon his body like the wings of a dragon, coming from his back down to his belly, one toward his neck or mane and the other toward his loins and hinder parts. To this we may add descriptions out of Oppianus, Pliny, and Solinus. The color of the rhinoceros is like the rind or bark of a box-tree. (This does not differ much from an elephant). On his forehead there grow hairs which seem a little red, and his back is distinguished with certain purple spots upon a yellow ground. The skin is so firm and hard that no dart is able to pierce it, and upon it appear many divisions like the shells of a tortoise set over the scales, and there is no hair upon the back. Upon his nose there grows a hard and sharp horn, crooking a little towards the crown of his head but not so high. The horn is flat and not round, and it is so sharp and strong that whenever he sets to it, he either casts it up into the air or else bores through it though it be iron or stone. It is apparent by the picture that there is another horn not upon the nose but upon the withers (I mean the top of his shoulder next to the neck). Oppianus says that there was never yet any distinction of sexes in rhinoceroses, for all that have ever been found have been males and not females. But from hence let nobody gather that there are no females, for it is impossible that the breed should continue without females. Pliny and Solinus say that they engender or admit copulation like elephants, camels, and lions. When they are to fight, they whet their hom upon a stone. There is not only

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HORNS, TUSKS, AND FLIPPERS discord between them and elephants for food, but there is also a natural enmity between the beasts. It is confidently affirmed that, when the rhinoceros which was at Lisbon was brought into the presence of an elephant, the elephant ran away from him. How and in what place the rhinoceros overcomes the elephant was shown already in the story of the elephant; namely, he fastens his horn in the soft part of the elephant's belly. All the later physicians do attribute the virtue of the unicorn's hom to that of the rhinoceros, but they are deceived. None of the ancient Grecians ever observed any medicines in the rhinoceros. The rhinoceros is taken by the same means that the unicorn is taken, for it is said that above all creatures they love virgins and that unto them they will come, be the beasts ever so wild, and fall asleep before the virgins, and so being asleep, they are easily taken and carried away" (Topsell, 1607).

As exploration continued in the following centuries rhinoceroses occasionally made their way into the hands of scientists. Their rarity and difficulty of maintenance and transp011, however, guaranteed that they were sensations fit for royalty. In the 1740s a Dutchman named Douvemont van der Meer took a rhino on a tour of the major European capitals, feeding it hay, beer, and wine. In Vienna, it received a full honor guard. It was so famous that Casanova mentioned it in his memoirs. Louis XV tried to purchase it after it had been to Versailles in a wheeled cage drawn by eight horses. But the owner wanted 100,000 ecus for his prize, a fee even the King couldn't afford. Madame de Pompadour had to settle for tossing orange peels into its mouth. BLACK AND WHITE By 1868 the great zoologist Sclater had published the first accurate, modern zoological account of the black rhino, which had just been acquired by the Regent's Park Zoo in London. The Indian, Sumatran, and Javan rhinos were also described about this time by Sclater and other scientists. The white rhino (Fig. 15.3), however, was known only from the accounts of the English traveler Burchell, who crossed South Africa in 1817. [The plains zebra, Equus burchelli, is named after him]. The Boers called it the wijd rhinoceros, or "big rhinoceros," and Burchell's knowledge of Afrikaans was so poor that he confused this with "white rhinoceros." The "white" rhino got its name from a mistranslation before anyone had seen it and realized that it is the same gray color as the "black" rhino. Since "black" and "white" are both misnomers, some zoologists prefer to call them the "browse" and "grass" rhinos, or the "prehensile-lipped" and "square-lipped" rhinos, in reference to their diet or their lip specializations for that diet. Either set of names would be preferable to the misleading color names, but "black" and "white" are so entrenched now that it is impossible to change them. Most of what people know about rhinos is

Figure 15.3. The white rhinoceros, Ceratotherium simum has a broad "Iawnmower" mouth for mowing down grass. (Photo courtesy Nova Development Corporation). wrong. In addition to the misleading "black" and "white" distinction, we saw in the previous chapter that horns are a late addition in rhino evolution. Popular books are full of myths of rhinos as terrifying, short-tempered beasts who eagerly gore and impale humans at any opportunity. Hollywood loves to portray them as dark terrors of Africa, the "horned fury," a dangerous and diabolic beast. But white rhinos are relatively docile and timid, and black rhinos can either charge or flee, depending upon what their poor eyesight tells them. As described by the Belgian zoologist, Jean-Pierre Hallet, "Africa's black rhino will, on occasion, "charge" a car without apparent provocation. He will also charge at tents, trees, bushes, rats, frogs, men, butterflies or grasshoppers. Sometimes he will even charge at the sound of his own dung dropping on a leafy scrub behind him. Much more often and for no good reason, he will flee from frogs, butterflies, and all the rest. There is no predictable pattern to his flights or aggressions; the same rhino who retreats in terror from a harmless native woman may gallop moments later toward a group of rifle-bearing white men. If the tourists hold their fire he will, almost invariably, come to a halt some twenty feet away, stare at them briefly, and then go trotting off to browse on a thorn bush. But they shoot, and most of them believe sincerely that they shoot and kill in self-defense.

THUNDERING TOWARD EXTINCTION Loud-snorting bluffer and titanic blunderer, more easily stalked and killed than any member of the hunters' Big Five, the black rhino is a rebel without a cause, a chronic but incompetent delinquent. He is, even from the animals' point of view, a bull in Africa's china shop, rushing from one messy disaster to the next ... What could be more frantic, more maddened by frustration, more suspicious and aggressive, than a three-thousand pound animal, nearsighted to the point of blindness, who searches constantly for something he cannot see? Insatiably curious, the black rhino is at the same time extremely timid and equipped with only limited mentality. His hearing and his sense of smell are superb, but his vision is abysmally defective. Each of his tiny eyes, set on opposite sides of his bulky, elongated head, gi ves him a different picture to look at; each picture is tantalizing in its wide-angle perspective but horribly frustrating in its perpetual fuzziness. An animal Mr. McGoo, nearsighted Kifaru [the Swahili name for the black rhino] cannot tell a man from a tree at distances of more than thirty feet, cannot see any object distinctly if it is more . than twenty or even fifteen feet away, and has to cock his head sideways to see, with one eye at a time, around the bulk of his muzzle and his massive front horn. Moving forward with horn lowered, he is running blind. By day as well as night, Kifaru hears and smells a whole world of fascinating objects which he cannot see. His curiosity drives him on to poke and probe among them, but his timid disposition makes him fear, and fear deeply, the very objects he wants to examine. He hesitates, agonized, while the two conflicting instincts boil within him. Usually he runs away but sometimes rushes forward to investigate with the world's most farcical display of bluff, noise, wasted energy, and sheer ineptitude-the notorious rhino 'charge'" (Hallet, 1968: 147-150). Hallet goes on to describe how easy it is to dodge a rhino "charge" if you do not flee or make noise to give away your position. After a week of futile charges, a captive rhino was even tamed and taught to play games, and was harnessed and ridden. Hallet compares the rhino to its skittish relative, the horse, which will also shy away from a fluttering bit of paper or a butterfly, and stampede when panicked by a startling sight or sound. The key to understanding rhinos is to realize that their senses are suited for dense vegetation, not the open savannas they now inhabit. In the dark forests where rhinos evolved, sight is nearly useless, and hearing and scent work at far greater distances. Douglas Adams made it clear in his description of a visit to the last remaining population of northern white rhinoceros in northern Zaire:

"You need to know something about the way that a rhino sees his world before we go barging in," [the guide] whispered to us. "They're pretty mild and inoffensive creatures for all their size and horns and everything. His eyesight is very poor and he only relies on it for pretty basic information. If he sees five animals like us approaching him, he'll get nervous and run off. So we have to keep close together in single file. Then he'll think we're just one animal and he'll be less worried." "A pretty big animal," I said. "That doesn't matter. He's not afraid of big animals, but numbers bother him. We also have to stay downwind of him, which means that from here we're going to have to make a wide circle around him. His sense of smell is very acute indeed. In fact, it's his most important sense. His whole world picture is made up of smells. He 'sees' in smells. His nasal passages are in fact bigger than his brain." From here it was at last possible to discern the creature with the naked eye. We were a bit more than half a mile from it. It was standing out in the open, looking, at moments when it was completely still, like a large outcrop of rock. From time to time. its long sloping head would wave gently from side to side and its horns would bob slightly up and down, as mildly and inoffensively, it cropped grass. This was not a termite hill ... The animal is, of course, a herbi vore. It lives by grazing. The closer we crept to it, the more monstrously it loomed in front of us, the more incongruous its gentle activity seemed to be. It was like watching an excavating machine quietly getting on with a little weeding. At about forty yards' distance, the rhinoceros suddenly stopped eating and looked up. It turned slowly to look at us and regarded us with grave suspicion while we tried hard to look like the smallest and most inoffensive animal we could possibly be. It watched us carefully but without apparent comprehension, its small black eyes peering dully at us from either side of its horn. You can't help but try and follow an animal's thought processes, and you can't help, when faced with an animal like a threeton rhinoceros with nasal passages bigger than its brain, but fail. The world of smells is now virtually closed to modern man. Not that we haven't got a sense of smell-we sniff our food or wine, we occasionally smell a flower, and can usually tell if there's a gas leak-but generally it's a bit of a blur, and often an irrelevant or bothersome blur at that. When we read that Napoleon wrote to Josephine on one occasion, "Don't wash-I'm coming home," we are simply bemused, and almost think of it as deviant behavior. We are so used to thinking of sight, closely followed

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by hearing, as the chief of the senses that we find· it hard to visualize (the word itself is a giveaway) a world that declares itself primarily to the sense of smell ... For a great many animals, however, smell is the chief of the senses. It tells them what is good to eat and what is not (we go by what the packet tells us and the sell-by date). It guides them toward food that isn't within line of sight (we already know where the shops are). It works at night (we turn on the light). It tells them of the presence and state of mind of other animals (we use language). It also tells them what other animals have been in the vicinity and doing what in the last day or so (we simply don't know, unless they've left a note). Rhinoceroses declare their movements and their territory to other animals by stamping in their feces, and then leaving smell traces of themselves wherever they walk, which is the sort of note we would not appreciate being left. When we smell something slightly unexpected, if we can't immediately make sense of it and it isn't particularly bothersome, we simply ignore it, and this is probably equivalent to the rhino's reaction to seeing us. It appeared not to make any particular decision about us, but merely to forget that it had a decision to make. The grass presented it with something infinitely richer and more interesting to the senses, and the animal returned to cropping it. .. The animal measured about six feet high at its shoulders, and sloped down gradually toward its hindquarters and its rear legs, which were chubby with muscle. The sheer immensity of every part of it exercised a fearful magnetism on the mind. When the rhino moved a leg, just slightly, huge muscles moved easily under its heavy skin like a Volkswagen parking ... The light breeze that was blowing toward us began to shift its direction, and we shifted with it, which brought us around more to the front of the rhino. This seemed to us, in our world dominated by vision, to be an odd thing to do, but so long as the rhino could not smell us, it could take or leave what we looked like. It then turned slightly toward us itself, so that we were suddenly crouched in full view of the beast. It seemed to chew a little more thoughtfully, but for a while paid us no more mind than that. .. For the rhino, the sight of us was simply a clue that there was something he should sniff for, and he began to sniff the air more carefully, and to move around in a slow, careful arc. At that moment, the wind began to move around and gave us away completely. The rhino snapped to attention, turned away from us, and hurtled off across the plain like a nimble young tank" (Adams, 1990: 97-101).

Although they are very different in their size and ecology, black and white rhinos are closely related. Members of the tribe Dicerotini, they first appear in the middle Miocene deposits of Ft. Ternan, Kenya (an important locality for the earliest fossil apes described by Louis Leakey, such as Proconsul and Kenyapithecus). Known as Paradiceros mukirii, the earliest dicerotin was a short-limbed browsing form with tandem horns, much like a small version of the black rhino. Paradiceros was not restricted to Africa, but is also found in middle Miocene deposits of Turkey and Greece. In the late Miocene the black rhino genus, Diceros, is widespread from Spain to the Middle East, as well as Africa. By the early Pliocene, dicerotines were restricted to Subsaharan Africa. According to Dirk Hooijer, the living black rhino species, Diceros bicornis, can be traced back to about 4 million years ago, making it one of the few living mammal species to last so long. The ancestor of the white rhino, Ceratotherium praecox, is found in southern and eastern Africa in late Miocene deposits about 7 million years in age. By about 3 million years ago the modem white rhino, Ceratotherium simum, could be found in Kenya. Like the black rhino, Ceratotherium simum has been around longer than just about,any living species of mammal. Both are truly living fossils. The white rhino is the second largest living land mammal after the elephant, reaching a weight of 5000 pounds (2270 kg) in males and 3750 pounds (1700 kg) in females (Fig. 15.3). Black rhinos are slightly smaller, weighing about 2100-3000 pounds (950-1370 kg). All dicerotins have tandem horns, one anchored on the nose, and the other on the forehead. Since these horns are made of compressed hair-like fibers, they grow continuously (at about the same rate as your fingernail grows), but are constantly worn by rubbing against the ground and trees. Occasionally they are torn off during digging, or during fights or other accidents. Then the animal must slowly grow another. The frontal hom is usually shorter than the nasal horn. Before heavy poaching, horns were typically 2-3 feet long, but are shorter in most living rhinos due to poachers. In the days before heavy poaching, the record holder had a horn 6 feet 6 inches (2 m) long, and it was probably a very old individual. The most fundamental distinction between the two dicerotins is in their diet and ecology. The "black" rhino, or "prehensile-lipped" rhino, is a browser, subsisting on bushes and small trees. Consequently, it has features that we have seen in extinct browsing rhinos (Fig. 15.4). Its finger-like upper lip is highly flexible for grasping twigs and stripping off leaves. The black rhino eats a wide variety of leaves and twigs of different shrubs in the acacia woodland community; it also pulls up tree seedlings, and will eat fallen fruits and even long grasses and clover when available. The lip and lining of the mouth cavity are so tough that black rhinos can eat acacia branches with three-inch thorns. Hallet notes that "while nipping off some three bushels of leaves and twigs every day, he ingests a large number of vicious, fleshripping thorns. They never seem to bother him at all.

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.

.

:

Dice~os bi~~~:1s;~i~

Figure 15.4. The black'rhinoceros, distinguished by its prehensile lip, which enables it to pull down leaves, branches and other browse. Here it is eating long acacia thorns without difficulty. (From Guggisberg 1966).

Appallingly, he eats the fat thorny leaves of the euphorbia bushes whose acrid, milky-looking sap blisters human skin; and he even dines on fallen branches of the candelabra tree, a species of euphorbia whose juice is used by East African tribesmen to poison arrows which they use to hunt ... rhinoceros. While toxic enough if it gets into his bloodstream, Kifaru's cast-iron stomach can digest the poisonous euphorbia; in fact, it forms the major part of his diet in regions where it is used also to kill him" (Hallet, 1968: 164). Like other browsers, black rhinos have relatively low-crowned teeth, and walk with their head held horizontally to reach vegetation at a variety of levels. Because of their diets, they prefer the edges of forests and open scrublands, and avoid the open grasslands favored by white rhinos. Since the African savannas are predominantly scrubland, black rhinos were once common in all of Subsaharan Africa except the Congo Basin rain forests. By contrast, the "white" rhino, or "square-lipped" rhino is a grazer, mowing grass with its broad, flat snout (Fig. 15.3). In addition to the broad snout it has a long, low-slung skull that always hangs down from the shoulder, so that it can feed easily on the ground. As we saw in other grazing mammals, they have very high-crowned teeth for chewing gritty grasses without wearing their molars down to the gums. Like other hindgut fermenters, they must eat enormous quantities of low-quality grass to make up for their inefficient digestion. During most of the year they feed almost constantly, with short periods of rest. During the wet season, they prefer the greener short grass, but they will settle for the medium-height (8 inches, or 20 cm) Themeda grass during the dry season, which they crop down to 1-2.4 inches (2-6 cm) in height. They feed by slowly swinging their head in a wide arc, cropping all the grass within reach as they step forward. In areas where they have been grazing, they manage to maintain the community of short grasses against invasion by other plant communities.

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Both species are heavily dependent on water holes, although they can go 4-5 days without drinking. Their traditional trails to the water hole are well marked, and the availability of water often limits the rhino population in a given area. With their great body mass, they must use every possible resource to keep cool, and wallowing in the mud or taking dust baths is one of their favorite activities during the heat of the day. The coating of mud also helps keep down the bites from flies. Ticks and lice tend to fall off when the mud dries. These parasites also entice oxpeckers, tick birds and cattle egrets to ride on the rhino's back, picking off insects as they find them. The rhino tolerates this, and often the birds serve as a warning for threats the rhino cannot see. Rhinos do not form large herds. Most often they travel alone, or females are accompanied by their immature offspring. Female black rhinos have home ranges covering 12 square miles in forest patches, and up to 35 square miles in arid territory. White rhinos occupy ranges of 3-6 square miles. The home ranges of individual females overlap completely, however, so they are not truly territorial. Their daily routine consists of traveling along well-worn trails within their home range between the water hole and the best feeding grounds. They spend the heat of the day in the water hole, or sleeping in the shade, and feed mostly in the morning and evening. Rhinos mark their trails with their urine and feces, and each rhino adds to the pile when it encounters the scent. These dung piles are particularly large along regularly used trails between their feeding areas and watering hole, and may indicate the population density in the area, or serve to mark a trail that is used once every few days. They also leave scent behind with the mud that constantly flakes off them. Males, on the other hand, are highly territorial, patrolling an area and attempting to dri ve off any other competing males. However, the territorial male will tolerate several subordinate males as long as they are submissive and do not challenge him. White rhino territories are quite small, covering 200-600 acres, since their prime pasture is relatively rich and predictable. But black rhino males must patrol about 1.5 square miles, since the richest bushes are unpredictable and less dense than grass, and in thick vegetation other males are hard to detect. They mark their territories by kicking over and spreading out the dung piles with their feet, and spraying urine on just about every available bush and tree on the perimeter of their territory (Fig. 15.5). When they encounter another male, they practice several rituals before they resort to combat. They stand showing their profiles to each other to gi ve their rival a sense of their size and maturity. (This behavior, which appears to be looking with one eye and then the other, has been misinterpreted to indicate that they do not have binocular vision). They may then stand horn to hom, staring each other down, and then back away to wipe their horn on the ground. This may be repeated for as long as an hour if they are at the boundary of their territory. If an intruding male does not back down, then they eventually get into a pushing match,

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Figure 15.5. Rhinos mark territory by spraying urine on bushes and trees around the perimeter. (Photo courtesy N. Owen-Smith).

wrestling with their horns, but they can get into serious fights that result in fatal injury, fighting with an upwards jab of their horns. Females and subdominant males will adopt a submissive stance to ward off the aggression of the territorial male, and utter loud roars and shrieks to indicate their submission. The resident male, on the other hand, utters a deep growl, which is replaced by a fierce bellow if the fight becomes intense. Recent studies have shown that rhinos, like elephants, communicate with low frequencies below the range of human hearing. This enables them to be heard over long distances, since low-frequency long-wavelength sound carries much farther than sounds we can hear. Females wander through the males' territories freely unless they are in heat. Then a male will try to consort with them, and attempt to confine them to his territory for as long as 1-2 weeks until they are ready for mating. However, if the female wanders into a neighbor's territory, the male will not trespass too far to keep her. Courtship is slow and cautious, taking 5-20 days to complete, since the female is frequently still with a possessive year-old calf, and can fight back herself. Once the male has overcome the female's reticence, he rests his head on her back, and then puts on a courtship display of brushing the ground with his horn, charging and shredding bushes, and darting back and forth on stiff legs, spraying urine. Eventually she allows him to mount her (Fig. 15.6). Copulation can take as long as eighty minutes, during which the male struggles to stay on top of the female as she walks along and ignores him. Birth can take place at any time of the year, but conceptions usually peak during the rains so that birth peaks occur from the end of the rainy season through the middle of the dry season. Gestation takes between 15 and 16 months (longer in white rhinos than in black rhinos). Females first come into heat at 5 years of age, and begin breeding at 6-8

Figure 15.6. During the many minutes of copulation, the cow walks around while the bull tries to stay mounted on top of her. Her calf from a previous mating sits nearby. (Photo courtesy N. Owen-Smith). years, and intervals between offspring are typically 2-4 years. When the mother is about to go into labor ~he seeks seclusion in the bushes. Rhino calves are small at birth, weighing only 4 percent of the mother's mass-about 143 pounds (65 kg) in white rhinos and 88 pounds (40 kg) in black rhinos. Within about three days they are able to keep up with their mother. If danger threatens, the mother stands protectively over the calf, or places her body between the calf and the predator. When several females and their calves are together they will form a circle with horns pointed outward, sheltering the calves within the circle. The calf stays with its mother constantly for two or more years until a new calf is born, at which time the older sibling is driven away and must fend for itself. Since the normal life span is about 40-50 years, a female could produce 10-11 calves in her lifetime. This slow rate of reproduction is one of the major reasons that rhinos are so vulnerable. ONE-HORNED RHINOS The only living beasts to bear the scientific name Rhinoceros are the two larger Asian species, the Indian rhino (Rhinoceros unicornis) (Fig. 15.7) and the Javan rhino (Rhinoceros sondaicus) (Fig. 15.8). They are also known as the greater and lesser one-horned rhino because they are the only living rhinos with a single nasal horn. However the majority of extinct horned rhinos had only a single nasal horn as well, and the tandem-homed condition seen in the dicerotines and dicerorhinines is an exception to the rule. The single horn of the Indian rhino tends to be a foot long or less, and they tend to use their sharp lower tusks as their principal weapon. The Javan rhino has even a smaller nasal horn, found only in males. Adult male Indian rhinos weigh about 4000 pounds (2000 kg) and females about 1600 kg, about the same as the white rhino, and the Javan rhino weighs slightly less. Both are distinguished by their distinc-

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Figure 15.7. The Indian rhino (Rhinoceros unicornis) has distinctive skin folds that were once thought to be "armor plating." They also have a single nasal horn that is somewhat shorter than the nasal horns of the African species. (Photo by D. Prothero).

Figure 15.8. The Javan rhinoceros (Rhinoceros sondaicus) is slightly smaller than its Indian cousin, with a smaller horn. It is one of the rarest of all endangered mammals, with fewer than 50 left in the wild. (Photo courtesy Alain Compost)

Figure 15.9. The genus Rhinoceros is descended from Gaindatherium, known from the Miocene of Pakistan (bottom skull). The Javan rhino (Rhinoceros sondaicus, middle skull) is a slightly more specialized version of Gaindatherium, and the Indian rhino (Rhinoceros unicornis, top skull) has the most extreme skull proportions. (From Colbert 1942).

ti ve skin folds that give them an "armored" appearance. This led many cultures to value rhino hide for making shields, although it is actually as soft and supple as any other large animal hide. The armor myth gave them their German name, Panzernashorn, and inspired the Ogden Nash rhyme:

that time Gaindatherium has been found in slightly older deposits in Portugal as well. Colbert showed that Gaindatherium already shows some of the characteristic features of Rhinoceros, including the arched nasal bones for the support of the horn, and the back of the skull is inclined forward. Fossils of these rhinos are rare in the late Miocene compared to dicerorhinines and relict aceratheriines and teleoceratines. By the Pliocene, they are represented by Rhinoceros sivalensis (also from the Siwaliks of Pakistan). Ironically, this animal is already more specialized than Rhinoceros sondaicus, the Javan rhino, which is built like a survivor from the late Miocene, but whose fossils are known only back into the early part of the Pleistocene. Several other species of Rhinoceros are also known from the Pleistocene of southeast Asia, including Rhinoceros sinensis from

I shoot the bold rhinoceros with bullets made of platinum, Because if I use leaden ones, his hide is sure to flatten 'em. The Rhinoceros lineage has been distinct since at least the middle Miocene, about 16 million years ago. In 1934 Edwin Colbert described Gaindatherium from the middle Miocene of the Siwalik Hills in Pakistan (Fig. 15.9). Since

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Figure 15.10. Like many other ungulates, Indian rhinos lift their upper lip to expose the vomeronasal organ in a behavior called Flehmen. This allows them to pick up faint scents of pheromones in the air. (Photo courtesy A. Laurie).

Figure 15.11. The Indian rhino cow protects her calf by hiding in the 25-foot-tall elephant grass during the daytime. (Photo courtesy A. Laurie).

China, and a number of places in Indonesia, Burma, and India. Since the middle Pleistocene, Rhinoceros unicornis has inhabited the Ganges floodplain of India and the Himalayan foothills until recent poaching has restricted it to a few tiny refuges. Unlike the browsing and grazing African rhinos, the Indian rhino is specialized for neither mode of feeding. Although it is mainly a grazer, it also has a flexible upper lip for grasping branches and bunches of grass. Andrew Laurie found 183 species of plants in its diet, but grasses accounted for 70-90%, depending on seasonal availability. The Indian rhino prefers swampy floodplains where it spends much of its time swimming and wallowing. Unlike the African species, the Indian rhino has a more leisurely daily routine, since water and shade are much more abundant in the forested floodplains of northern India and Nepal. From midday until late afternoon they remain almost completely submerged in their wallows, often in large, sleepy social groups. As evening approaches they move to their feeding areas and selectively pick out the youngest, greenest grasses in areas of recent grazing or burning, or along the edges of the river. Toward midnight they rest, with the adults sleeping wherever they feed, but females with young moving to the cover of the ten-foot tall elephant grass. In the morning, they continue to graze in more covered areas to keep cool, until it is time for their midday bath. Indian rhinos do not show the marked territorial behavior of African rhinos. There is no urine-spraying or aggressive patrolling of boundaries. They do produce a huge communal dung-heap, which they use as a register; by defecating and leaving their scent they update the "directory" of which rhinos are in the area. Instead of rigid territories, they divide their range into "public" and "private" areas connected by paths. "Public" areas include wallows and bathing

areas, which they share freely. Each rhino defends his or her own "private" area of about 5000 square yards of grazing territory for its own use, along with a private sleeping place in the elephant grass. When one Indian rhino intrudes on another's private grazing area, there can be conflict, although it is usually resolved by ritualized behavior, such as curling the lip to show their lower tusks, or advancing with head held low, snorting and honking. Sometimes they stand hom to horn and stare each other down, or exhibit close-up tusk displays. If these don't work in making one back down, then a charge can ensue. These fights can be severe, since their sharp lower tusks can slash through hide easily. Sometimes the victor will pursue the vanquished for kilometers, honking and bleating as it goes. Urine-spraying is used, however, during courtship. Once a female reaches sexual maturity at about 3 years of age she can come into heat for a 24-hour period every five to eight weeks. In addition to spraying urine (whose pheromones advertise her breeding condition), she also makes a strange whistling sound with every breath. When the male catches the scent, he curls his upper lip in the flehmen gesture also seen in horses (Fig. 15.10). This exposes his vomeronasal organ and allows him to pick up pheromonal scents more easily. Once the male locates a female in heat he may follow her around for several days, attempting to approach her. For quite a while the female ignores him, or repels his advances, and sometimes this can lead to severe fights. Often they will get into horn-to-horn pushing matches lasting for hours until both are tired. If the female turns and runs the male pursues, making a "squeakpanting" noise while the female honks and bleats. Eventually they exchange love-bites with their tusks, and the male rests his head on the female's back. After several attempts at mounting, the male will copulate for up to an

THUNDERING TOWARD EXTINCTION hour. The male may accompany the female for a few more days, probably to prevent any other male from mating with her. Pregnant females are particularly wary and aggressive, and frequently hide out in the protection of the elephant grass. Like the white rhino, gestation lasts about 16 months, and the calf weighs about 65 pounds (30 kg) at birth. Since it consumes about 6.5 gallons (25 liters) of milk a day, it grows rapidly and gains about 5-7 pounds (2.2-3 kg) a day. It has all the skin folds of an adult Indian rhino when it is born. Mothers are very protective of their calves, since they are vulnerable to tigers (Fig. 15.11). Once an Indian rhino reaches subadult size it has no natural predators. By two or three months the calves begin to eat grasses to supplement their suckling, and by 18 months they are weaned. Calves stay with their mothers for about three years until the cow becomes pregnant again. About a week before the mother gives birth she drives off her subadult young to fend for themselves. In contrast to the well-studied Indian rhino, the ecology of the Javan rhino is virtually unknown. This is largely because of their scarcity (only about 50-60 individuals are left), and to the fact that they inhabit the dense jungles of Udjung Kulon National Park on the western tip of Java. In the mid-1700s, they were so common in Burma, Thailand, Vietnam, the Malay Peninsula, Java, and Sumatra that they frequently damaged crops. Since that time, their numbers have been so reduced by poaching that they are the most endangered of all large mammals. Their decline was so rapid that once the Javan rhino was known to science, few were available even for museum collections, and none has been held in captivity in a long time. In addition to the smaller hom, Javan rhinos can be distinguished from Indian rhinos in several ways. Their skin lacks the knobbly surface that gives the Indian rhino its "riveted" appearance. Javan rhinos have much more complex skin folds in the neck, and their shoulder folds join in the midline of the back, giving them a segmented look like an armadillo. In most other features they are so similar to Indian rhinos that zoologists did not distinguish them until 1822. Their skulls look like a more primitive or immature Indian rhino, so most people cannot tell them apart. For years the American Museum of Natural History in New York had sent out expeditions to collect a Javan rhino, spending millions without success. Ironically, when Edwin Colbert was studying fossil Rhinoceros from China in 1942, he found a specimen of Rhinoceros sondaicus that had been purchased from the hunting trophies of Prince Maximilian zu Wied almost a century before. It had been mislabeled as an Indian rhino by less observant curators. No one realized that all those expedition dollars were being spent in vain until a paleontologist began poking around the museum's dusty attic! Like the Sumatran rhino, the Javan rhino prefers dense tropical jungles where it feeds on a variety of leaves and shrubs. It is restricted to the swampy lowlands, and appar-

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ently does not migrate to the higher regions of the Malay Archipelago like the Sumatran rhino. Javan rhinos are known to lean on a small tree and then "walk it down" to reach the leaves at the top; they are also known to eat bamboo, and stand in the ocean to eat mangroves. They create a series of green tunnels in the jungle with their preferred paths to food and water. Some of these are marked with urine spraying, and rarely they use a communal dung pile, although they are not territorial and do not use many kinds of scent marking. Their tracks were so well marked that many other animals and humans used them, and they eventually became the sites of roads; it is said that the roads of Java were originally surveyed and laid out by rhinoceros. Nineteenth-century explorers learned to follow a rhino track whenever they needed water. Even less is known of their reproductive biology. They are said to have reproductive ages and gestations similar to Indian rhinos, although very little data support this. The rut is said to occur sporadically and non-seasonally, and bulls are said to produce "frightful roaring and aggressive behavior." The cow remains with the calf for about two years. Since they are not territorial they are rarely aggressive, but flee at the first opportunity. In the dense jungle they are so secretive that they are usually gone before a tracker has spotted them. Occasionally they can be surprised if a human comes at them downwind. Under these circumstances, they were known to charge humans and trample or bite or toss them in self-defense. However, today they are so scarce and gun-shy from intensive poaching that they rarely allow humans to see them. This is particularly sad, since they are a true relict of the Miocene that could gi ve us much insight into what modem grazing rhinos evolved from. HORNS OF DOOM A rhinoceros hom is a wondrous thing (Fig. 15.12). Some can be 5 or 6 feet (1.5-2 m) long and weigh up to 12 pounds (5.4 kg). Unlike artiodactyl horns (which are made of bone), rhino horn is composed of compacted hair-like fibers made of keratin, the same protein in your own hair, fingernails, and skin. Like your fingernail, rhino horns grow continuously and are worn off during daily activities. They

Figure 15.12. Rhino "horn" is not made of bone like bovid horns, but out of thousands of tightly compacted hairlike fibers. (Photo courtesy E. Bradley-Martin).

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can also break off and grow back. Their size and shape is affected by the age of the animal, and daily wear and tear. As we have seen, they are used in defense and social interactions with other rhinos, although the rhino's body size protects it from most predation. Sadly, the size and shape of the horn has given them value in folk medicines and cultural traditions that have no basis in science. Because of their phallic shape, some cultures have thought they had aphrodisiac properties. Others connected them with power and masculinity, and have used rhino horn for all sorts of objects, especially weapons. In the Far East, rhino horn has been a major part of folk medicine, primarily for reducing fever. Pound for pound, rhino horn is far more valuable than gold. In some places, prices have reached $27,000 a pound ($60,000 a kilo). Its value is so great that it has generated its own "Medellin cartel" of smugglers who shoot to kill, and operate as viciously as any drug lord. Indeed, it is far more valuable than heroin, cocaine, or any other illicit substance. If that were not incentive enough, rhinos have the misfortune of inhabiting the poverty-stricken Third World where preserving wildlife has always been less important that feeding starving victims of the population explosion. Since rhinos require a lot of territory they do not do well in small reserves, and cannot be fenced in easily. Many African cultures view them as short-tempered, dangerous beasts who destroy their crops, and feel no remorse about killing them. Considering the fact that an African can make a year's salary from a single rhino horn, there are few taboos to prevent poaching. The rhino's biggest handicap is its total lack of fear. Until well-armed humans came along there was no predator that could threaten an adult rhino. However, evolution does not operate quickly enough to change fifty million years' worth of instinct overnight. Poaching has made most surviving rhinos extremely wary, but it is hard for a large, noisy, conspicuous animal with well-marked trails and dung heaps to hide from poachers for long. The consequences have been truly catastrophic. In the 1700s, there were hundreds of thousands of rhinos, freely roaming most of Subsaharan Africa and much of southeast Asia. Sport hunting and poaching began to take their toll in the nineteenth century, but the last thirty years have been a true holocaust. Since about 1970 the skyrocketing price of rhino hom and the easy availability of automatic weapons imported for use in Africa's civil wars have resulted in rhino genocide. In the past thirty years over 85% of the world's rhinos have been exterminated, leaving only about 16,000 left in the wild. Although 16,000 rhinos may seem sufficient, it is minuscule compared to their former numbers. It is even more alarming because those survivors are concentrated in only a few well-protected places, and most countries which once had rhinos in abundance now have none. On a species-by-species basis, the statistics are even more alarming. We have already seen how the Javan rhinoceros population is reduced to 50-60 individuals in the Udjung Kulon reserve on the western tip of Java. Although

they are very secretive and living in a protected area, they are still subject to poaching. This fragile population concentrated in a single reserve is very vulnerable to disease, or a local catastrophe such as a typhoon or volcano. Indeed, the 1883 eruption of Krakatoa Gust offshore) virtually wiped out the area, and it became a national park because humans were afraid to move back into the devastation. Luckily, the jungle and wildlife (including Javan rhinos) were not so reluctant. Some have suggested removing 30 animals from this population to start a captive breeding program. Unfortunately, so little is known about their biology that we cannot guarantee that captive breeding will succeed, or that capturing such a large part of the existing population won't cause the rest of the population to crash. In addition to the Udjung Kulon population, a small population of possibly 5-8 individuals was recently discovered near the Dong Nai River in Vietnam. It is amazing that these animals survived the devastation of the Vietnam war, but they may be survivors precisely because the war so greatly reduced farming and clearcutting of the jungle. Sadly, their limited population is very hard to study, and chasing them through the Vietnamese jungle with its live booby traps is dangerous. The situation for the Sumatran rhino is only marginally better. Once found all over southeast Asia, they are now gone from India, China, Bangladesh, Cambodia, Vietnam, Laos, and nearly wiped out in Burma and Thailand. Most of the remaining 250 animals are dispersed over the Malay Peninsula, Sumatra, and Borneo. They are too scattered in remote areas to build up a protected population in a national park. However, a breeding program in Malaysia is just now taking effect. About 100/0 of the population are lost each year to poaching, even though they have minuscule horns. The greatest threat, however, is the rapidly escalating deforestation of the Malay Archipelago that is destroying their remaining habitat. The Indian rhino has slightly better chances since its numbers are fairly stable in well protected reserves. At one time there were thousands of them along the Himalayan foothills from Pakistan to Burma. In the mid-1970s, its population was down to about 750 individuals. Since that time, however, aggressive protection (especially in the Royal Chitwan National Park in Nepal) has made a difference. As of 2002 there were about 600 in Nepal (mostly in Chitwan) and about 1800 in India (mostly in Kaziranga National Park), or about 2400 in the wild. There is also a zoo population of 140 individuals in 43 institutions, where there has been some success in breeding. However, poaching is still a serious threat. Indian rhino horn is typically valued at $20,000-$54,000 a kilo, more than twice the going rate for African horn. Apparently East Asian medicine considers Indian rhino horn to be more potent. A kilo of Indian rhino horn is also harder to obtain since they have smaller horns than African species. Consequently, the poaching pressure is tremendous-58 were killed in the northeastern Indian state of Assam in 1989. In recent years poachers have been resort-

THUNDERING TOWARD EXTINCTION

Figure 15.13. In the Arabian Peninsula, rhino horn is prized for use in the handles of daggers called jambias. Here a Yemeni craftsman is filing a piece of rhino horn into a dagger handle. (Photo courtesy E. Bradley-Martin). ing to a particularly gruesome method: electrocution. At one time, African rhinos were abundant all over Subsaharan Africa except in the Congo jungle. The southern white rhino (Ceratotherium simum simum) was the first to suffer from hunters. In the 1830s they were so abundant in southern Africa that they were at the limit of their food supply, and a single day's march typically encountered between 100-500. Over the next forty years the slaughter (mostly by white hunters) was intense, and by 1900 there were only about 50-100 in South Africa; at one point, they were thought to be extinct. Then southern Africa began to take conservation seriously, and the southern white rhino population has recovered somewhat. As of 2002 there were 10,400 individuals in the wild, mostly in South Africa, Namibia, and Zimbabwe (all countries where the British colonial conservation ethic has dominated for years). However in struggling countries such as Botswana, Kenya, Swaziland, and Zambia, the population is critical. As of 2001 the southern white rhino is extinct in Angola and Mozambique. The n011hern subspecies of the white rhino (Ceratotherium simum cottoni) is even more endangered. They were once found in a belt north of the Congo Basin including Chad, the Central African Republic, Sudan, Uganda, and Zaire. Most of these were wiped out during bursts of poaching in the 1950s and 1960s, so only about 400 were left by 1970. During the 1980s when civil war spread over the region, virtually all of these were destroyed. Only 30 individuals are left in Garamba National Park in northern Zaire. Thanks to the heroic efforts of Kes Hillman-Smith, their population is slowly increasing, although it requires a massive effort patrolling a park over 5000 square kilometers in

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area (about the size of Delaware). Fortunately, where the white rhino is protected, it is such a docile grazer that foot patrols can stand guard over them 24 hours a day. The saddest tale, however, is that of the black rhino. Before European exploration there were at least a million of them in Africa, inhabiting every country south of the Sahara. Due to their ecological versatility, they were found in more habitats than any other rhino. However, they were slaughtered for over a century, and by 1960 there were only about 65,000. They were still common enough, however, that they were regularly seen in the wild. Then because of civiI unrest in Africa, they went through the most alarming decline of all. Uganda, for example, was once teeming with wildlife. The depredations of Idi Amin, and the chaos that accompanied his ouster by the Tanzanians, led to anarchy, and thousands of heavily armed poachers slaughtered all wildlife indiscriminately. Today Uganda has no rhinos. Kenya's rhino population dropped 98% between 1970 and 1985. The poaching was similarly intense in most other African countries, especially in the 1980s, so that while there were less than 15,000 in 1980, today there are less than 3100. More than half of these are in Zimbabwe,· which has strong protection systems; the remaining populations are found mostly in Namibia, South Africa, Kenya, and Tanzania, where the European tradition of game parks is strong. However, black rhinos have been completely exterminated from Angola, Botswana, the Central African Republic, Chad, Ethiopia, Malawi, Mozambique, Rwanda, Somalia, Sudan, Swaziland, and Uganda. What can be done to stop this slaughter before it is too late? The alarming acceleration of poaching during the 1970s and 1980s produced more than 100 metric tonnes of rhino horn, which is equivalent to at least 40,000 dead rhinos. In 1979 Esmond Bradley-Martin began to study the rhino hom trade in order to determine how to stop it. Contrary to common belief, he found that most countries (except India) did not use rhino horn as an aphrodisiac. Instead the two biggest markets were Yemen (a tiny country on the southwestern tip of the Arabian Peninsula), where they were carved into dagger handles (Fig. 15.13), and the Far East, where traditional medicine relied on their alleged powers to reduce fever and for other therapeutic applications (Fig. 15.14). In addition, rhino hide, nails, penises, dried blood, and even urine were thought to have medicinal power. Many cultures used rhino-hom cups to detect poison. There may have been some validity to this practice, since the keratin in rhino hom would react to strong alkaloid poisons. The first crisis (and success) was in Yemen. Traditionally rich Arab nobles showed their wealth with a jambia, a huge curved dagger with a rhino-horn handle. When Yemenis became rich during the oil boom in the Persian Gulf, the demand for rhino hom increased. By the early 1970s they were importing three tons (equivalent to about 1000 dead rhinos) a year, more than 40% of the total market. A 1982 ban on rhino hom only increased the price

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Figure 15.14. A. A pharmacist cuts a piece of rhino skin in a traditional Chinese medicine shop in Southeast Asia. The customer was buying it to treat a skin problem. B. Packages of rhino products sold in Chinese drugstores, mostly for fever reduction. (Photos courtesy WWFI E. Bradley-Martin).

since bribery of corrupt customs officials resulted. Fortunately, the collapse in oil prices may have saved many rhinos, since most Yemenis could no longer afford rhino horn. In 1987 Yemen took steps to stop the flow of horns, and imports are now down to about 330 pounds (130 kg) per year. Water buffalo horn, camel nails, and plastic have been urged as a substitute, with great success. Similar pressure shut down the huge horn pipelines to Dubai, in the United. Arab Emirates on the Persian Gulf. The tiny central African country of Burundi, which has no rhino or elephant of its own, was once the main shipping point for smugglers for horn and tusks; it is also virtually closed down now. In 1987 the Convention on the International Trade in Endangered Species (CITES) banned all trade in rhino horn. International pressure began to take effect in Asian countries for the first time. By 1988 four major markets-Japan, Hong Kong, Malaysia, and Macao-were virtually eliminated by strong domestic enforcement policies. These successes, however, have been tempered by continuing difficulties in four other countries: China, South Korea, Taiwan, and Thailand. Because of the strong belief in rhino horn in Chinese medicine, it has been very difficult to close the market. Rhino horn is too expensive for most Chinese in the People's Republic now, but the Chinese government earned a record $700 million from exports of medicines in 1987. Although China joined CITES in 1981, it has not been very interested in controlling its trade. One of the sad consequences of this market fever is that priceless intricately carved rhino horn art objects from the Ming and Ch'ing

dynasties are now being ground down into powder for medicine. South Korea has been a difficult problem. Over 80% of its apothecary shops carry rhino horn products, even though the South Korean government outlawed them in 1983, and banned imports in 1986. The government has made no move to register their stock, so unregulated internal and blackmarket trading continues. They also refuse to join CITES, despite pleas from Britain's Prince Philip. Taiwan banned imports in 1988, but this raised the price to $54,000 a kilo for Asian rhino horn. Taiwanese self-made millionaires are notorious for their conspicuous consumption of endangered wildlife. The lack of enforcement made the ban meaningless, but there has been a recent movement to register their stocks. The worst offender has been Thailand. Traditionally a country where any substance-drugs, guns, illegal wildlife products-can be obtained legally and illegally, Thailand is second only to China in the trade of rhino horn. Although a member of CITES, it has never passed the necessary legislation or funded its officers to enforce the laws. Consequently, Thailand is the main shipping point for most smugglers today. Bureaucratic inertia and a long tradition of graft and corruption make it unlikely that Thailand will cooperate in the near future. Clearly, there have been some successes. There is also some hope of getting substitutes, such as saiga antelope horn, to replace rhino horn in Chinese medicine. But with demand from over a fifth of the world's population increas-

THUNDERING TOWARD EXTINCTION ing, it is not realistic to think that the entire market can be shut down completely. So most recent efforts have been focused on eliminating the supply. We have seen how the situation is already hopeless in most African countries. In some cases they have resorted to desperate measures. Namibia, for example, has tried dehorning rhinos to see if poachers would leave them alone. Aside from the problems this causes for rhino socialization and defense, this measure would not work in countries with vegetation denser than that of the Kalahari Desert of Namibia. Most poachers shoot at any sound, and in thick brush they would not check to see if a rhino had been dehorned before shooting. Besides, the horn grows back, so the rhinos would have to be captured and disturbed every two years for dehorning. The greatest successes have been in South Africa, Zimbabwe, and Namibia, where conservation enforcement and large national game reserves have been well funded for a long time. They now contain over 90% of the remaining African rhinos. These countries spend millions each year in salaries, guns, aircraft and vehicles, and in translocation efforts to move rhinos away from threatened border areas. Zimbabwe, for example, has captured hundreds of rhinos from the Zambezi River Valley where they were threatened by poachers from Zambia, and moved them into the country's interior. Rhino wars are costly not only in dollars, but also in human lives. The poachers are armed with automatic weapons and shoot to kill, so the rangers must do the same. Their efforts have been rewarded with growing populations in South Africa, so that some reserves now have a surplus of rhinos and are overgrazing their ranges. Even with these successes, there are setbacks. As this

Figure 15.15. Unless the appalling slaughter of rhinos is halted, few will be left in the wild by the next decade. Instead, future generations will find only skeletons covered by vultures, or bloated carcasses with the horns hacked off by poachers. (Photo courtesy WWF/E. Bradley-Martin)

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book went to press in 2001, four rhinos were killed in Tsavo National Park in Kenya, one of the most protected parks in East Africa. After years of unrestricted poaching that reduced their black rhino population from 20,000 in 1970 to 350 in 1987, Kenya focused on concentrating the remaining rhinos in a few well protected national parks. They had succeeded in getting the population up to 420 before this recent setback had occurred. Clearly, the ban on the sale of rhino horn and some of the tightest anti-poaching measures in the world were not enough to save these rhinos. At the International Rhino Conference in San Diego in 1991 controversy erupted between the representatives of the three successful southern African countries and the rest of the conservation community. Despite great effort and expense, most captive breeding programs have had limited success, and artificial insemination is still a long way off. The only effective use of conservation dollars is protection of wild populations. South African and Zimbabwean officials are faced with a dilemma: they have successfully increased their populations to the point of surplus, but cannot afford to continue with current conservation budgets. They argued that harvesting a few surplus rhinos and selling their horn legally would do more than anything to protect the remaining rhinos. The proceeds from a single horn would legally net $8000, and for a trophy-hunting" expedition produces over $30,000. This money would go far to supplement their stretched conservation budgets. This suggestion was met with horror by other conservationists and wildlife biologists. Although the idea sounds good in principle, they were concerned that releasing any legal horn to the market after the total ban in 1987 would make it easier for smugglers to operate. Once a rhino horn has been cut into shavings there is no way to identify where it came from. If all rhino horn trade remains illegal, then it is obvious that the hom is smuggled; poached horn could not be traded with forged documents as a legal horn. In addition, letting their guard down might discourage efforts to find hom substitutes in Asia, or to raise funds in the developed world. However, if conservationists are sincere about stopping the rhino horn trade, they must invest most of their dollars in South Africa, Zimbabwe, and Namibia to get the best results and decrease pressure for legal cropping and trade. The future is dim for these great beasts, magnificent relicts of fifty million years of evolution. After successfully occupying every major ecological niche, from giraffe-like indricotheres to hippo-like teleoceratines, to tapir-like cadurcodonts and aceratheriines, to running hyracodonts, they are meeting their final crisis. Zoos cannot preserve enough of them to make a difference, and the Javan and Sumatran rhinos may already be doomed (Fig. 15.15). Only extraordinary efforts on behalf of the successful reserves will provide healthy, growing populations of rhinos for future generations to marvel at.

In many areas of Africa, there are more carcasses and bones of elephants and rhinos than there are living animals. This "elephant graveyard" is typical of the carnage all over Africa. (Courtesy J. Shoshani).

Epilogue

"Elephants and buffalo had crowded the water hole and salt lick at Treetops, the famous game watchers' hotel on the southern slopes of Kenya's Aberdare Range. Visitors sat wrapped in blankets against the late afternoon chill as buffalo drank noisily or wallowed in mud and came out spotched and glistening. A herd of some 40 elephants, mostly cows and calves, had taken over the salty area. Now and then a baby crowded its mother's forequarters to nurse, its slender trunk curled above its head. Older animals squelched over the moist ground. At intervals one would drive back an intruding buffalo with irritable squeals. Suddenly one guest murmured, "It's prehistoric." He was right. Nearly everywhere in the world, until relatively recent times, giant animals roamed the countryside, hunted by Stone Age man. Some eight or ten thousand years ago on the American continent hunters used pitfalls and stone-tipped spears against the now-extinct mastodon. In Europe men of the Ice Age encountered the woolly mammoth and various kinds of rhinoceroses; during warmer interglacial periods, hippopotamuses flourished in the Thames and the Somme. In Asia, too, strange animals lived side by side with early man: elephants quite unlike those domestic in India today, and huge hippos. Africa had its giants too; and here, to a greater degree than elsewhere, some of them have survived" (Leakey, 1969: 29). So the famous anthropologist Louis Leakey described the prehistoric landscape that was once common in East Africa. Indeed, the same could have been said for most of the planet in the last 65 million years. Until recent times, hoofed mammals have been the dominant species on this planet. They have filled the large and medium-sized herbivore niche on this planet since the extinction of the dinosaurs, and exploited every habitat from mountaintops to jungles to great savannas to the open ocean. Different groups of hoofed mammals have come and gone, replacing each other as Earth's climate and continents have changed. Nevertheless, they were remarkably successful at adapting to mass extinction events and virtually anything else that nature could throw at them.

Then along came a global catastrophe known as Homo sapiens. For our first four million years, humans or their ancestors lived alongside hoofed mammals in the Old World, and hoofed mammals were among their chief sources of food and clothing. Although humans were destructive hunters, they did not push these species to extinction. Then came the great extinctions at the end of the last Ice Age, about 9000 years ago. The great mammoths, mastodonts, woolly rhinos, giant bison, horses, camels, and many other beasts disappeared from most continents, or vanished completely from the face of the earth. Although the climatic change at the end of the last Ice Age was an important factor, human hunting probably had a lot to do with the sudden extinction of many of these species. At the end of this blitzkrieg many of the continents were sadly depleted of large mammals. North America, for example, was once the homeof a great diversity of beasts, from the mastodonts and mammoths to horses and camels and bison. By 7000 years ago only bison still roamed the continent. The Great Plains are now remarkably barren, although they once supported a fauna that would put East Africa to shame. The second phase of human destruction came when hunting-gathering cultures were replaced by agricultural civilizations with domestic animals. As paleontologist Niles Eldredge puts it, sedentary agriculture-based humaninduced extinction is analogous to the great catastrophe (whether by asteroid or not) that wiped out the dinosaurs at the end of the Cretaceous. "We are like loose cannons, able to wreak great damage on our own, and particularly dangerous if our effects happen to coincide with physically induced changes that are also causing extinctions" (Eldredge, 1991: 217). Nowhere is this more vividly demonstrated than in our destruction of the last great refuge of species, the rainforest, home to most of the species on this planet. Yet each day 80 square miles of rain forest are lost, mostly in Africa, South America and southeast Asia. Each year an area of rainforest the size of Maine or Indiana is lost. The rainforest is cut down and burned, destroying the habitats of the vast majority of the earth's wildlife, and driving most to extinction. After the slash and burn is through, the land is briefly turned into pasture for cattle so that we can have more fast-food hamburgers. Yet the nutrients of the rainforest are not in the soil, but in the trees. When the trees are burned, the poor soil lasts only a few years before giving out and becoming bar-

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ren, brick-hard laterite. The land becomes a wasteland, shedding tremendous amounts of soil into the rivers due to uncontrolled erosion. And the pristine forest rarely grows back. Meanwhile, the poor subsistence farmers must move on to survive, slashing and burning more rainforest. In his book African Silences, the naturalist Peter Matthiessen surveyed tropical Africa, and came back shocked. Most of the great forests of West Africa are gone, replaced by barren wasteland and starving people. Senegal, Gambia, Liberia, the Ivory Coast, and adjacent countries were once covered by the famous West African rain forest, home to most of Africa's exotic wildlife. That forest is now almost completely gone, and even within the parks and wildlife refuges, most of the animals have been hunted out by poachers and starving people. As Matthiessen put it, "The great silence that resounds from a wild land without sign of human life, from which all the great animals are gone, is something ominous. Mile after mile, we stare down in disbelief." The same is happening rapidly in the Congo Basin, the true heart of the African jungle. The exotic Africa of Stanley and Livingstone, of Joy Adamson and Dian Fossey, full of jungle beasts we remember from Tarzan movies and Daktari, is almost gone. This kind of hunting and habitat destruction has been catastrophic for all wildlife. As we have seen throughout this book, many species of hoofed mammals have been wiped out by humans in just the last few centuries. The quagga, the aurochs, the Steller's sea cow, the blue antelope, and many other spectacular animals are no longer with us. Most of the beasts we have described in this book are in decline, and there are over 100 species of hoofed mammals (including another dozen species of whales, including the blue whale, largest animal that ever li ved) currently on the endangered list. These include all elephants, sirenians, rhinoceroses, tapirs, most wild horses and asses, pygmy hippos, babirusas, Chacoan peccaries, wild Bactrian camels and vicunas, and dozens of species of wild deer, antelope, and cattle. Most of these animals have not been replaced by other animals, wild or domestic. Instead, their habitat remains a wasteland. When they are replaced, it is by our domestic animals, particularly cattle, sheep and goats. Unlike wild grazers, which are adapted to selecti vely cropping certain vegetation and allowing it to grow back, domestic livestock are indiscriminate eaters. Goats and sheep crop plants right to their roots, and hungry goats will eat bark, limbs, and anything else they can reach. Typically, they are left in an area until they have overgrazed it, reducing the land to barren earth that cannot regrow. The results are familar to anyone who has seen pictures of a fenced pasture: barren on the overgrazed side, rich where Ii vestock cannot reach. The worst aspect of turning land over to livestock is that most of it is unnecessary. Animal foods are a very inefficient way for humans to feed themselves. For example, 12 pounds of grain can produce about 12 loaves of bread, but only about 1 pound of ground beef for hamburger. Thus, to raise the equivalent amount of food, we need approximately

twelve times as much land to raise animals as we would for a vegetarian diet. This is apparent to anyone who has traveled in the farm belt. Most of the land actually produces feed corn, alfalfa, hay, soybeans, oats-to feed to animals. In fact, 80% of our annual corn harvest, and 70% of our soy beans and oats are fed directly to animals, further wasting our precious food resources, making even greater demands on scarce water and soils, and increasing our needs for toxic fertilizers and pesticides which pollute the environment. Why do we do this? Because we Americans are addicted to our high-cholesterol diets of bacon and eggs, cheeseburgers and milkshakes, which ultimately kill us with heart disease and cancer. The saddest and most sickening form of destruction is the indiscriminate slaughter of these animals for some product of dubious worth. Whether it is the bison for their hides, elephants for their ivory, rhinos for their horns, saiga antelopes for Chinese medicines, whales for their oil and meat, or any of the many examples of poaching we have discussed in this book, this kind of killing is the cruelest and most wasteful of all. At one time it might have been possible to justify extensive hunting for the purpose of keeping humans alive. At the turn of the century, the herds ~f great game animals seemed so vast that sport hunters could not imagine their killing would make a difference. Yet now most of the earth's great mammals are holding on by a slim thread, and there is no justification for killing them. Justification or not, such killing will continue, no matter how enlightened our cultures become, no matter how much international pressure enforces wildlife protocols. The reasons are simple: population and economics. As of this writing, there are about 6.2 billion people on this planet, and we may exceed seven billion by the year 2015. This number is more staggering when one considers the accelerating rate of increase. For humankind to reach a population of one billion took at least 500,000 years. The next billion was added between 1800-1930, only 130 years. The third billion was reached in 1960, only 30 years later. The foulth billion came between 1960 and 1974, in only 14 years. The fifth billion was added by 1987, just 13 years later. By 1999, in merely 12 more years (a geological instant), the world population increased by another billion. As you read this, 14 to 15 babies are born every six seconds! Each hour there are nearly 8800 more mouths to feed; each year, more than 77 million more people than the year before. Naturally, such staggering numbers have a catastrophic economic effect. The reason for the growth has not been high birth rates so much as low death rates. Western medicine has succeeded in preventing much infant mortality, but the necessary birth control has not accompanied it. Most of this growth takes place in the Third World, where wealth and resources are limited, so more and more people are born with less and less to live on. The greatest moral dilemma is that about 30% of the world's resources are found in the Third World, which has 70% of the population; conversely, our wasteful industrialized society is only about 30% of the

EPILOGUE world's population, but uses 70% of the resources. We cruelly tantalize Third World countries with cars and televisions and other amenities that they cannot possibly attain with their population and economic problems. We would not have such wealth if we had not lived so wastefully at their expense (and at the expense of future generations), and exploited the bulk of Earth's scarce resources before the Third World (or our children) could get to them. Tragically, most of this growth takes place in Third World countries where much of the wild habitat still remains. In Africa, the last haven for the great beasts of the savannas that covered Earth in the late Miocene, the rate of population growth is faster than in any other place on earth. Much of the savanna outside the natural parks is now under the plow, or pasture for cattle. Extreme poverty, plus the political instability that puts automatic weapons in the hands of gangs of poachers, gives the local natives a strong incentive to poach elephant and rhino. We deplore these acts as barbaric and short-sighted, since we view these animals as part of their heritage to be preserved. But for starving Africans, this is all irrelevant when their own survival is at stake. Clearly, enormous efforts will have to be made, not only to protect the wildlife, but also to solve the far greater problems of overpopulation and all the destruction that it causes. The survival, not only of other animals, but of our own species, is at stake. Yet many short-sighted individuals continue to argue that this planet is made for human domination, and cannot see compelling reasons to prevent the slaughter. "After all," they say, "mass extinctions have happened in the past, and the planet has always rebounded." We find the words of zoologist Mark Carwardine (concluding his book with Douglas Adams on the "last chance to see" many endangered animals) answer them well: "Extinctions, of course, have been happening for millions of years: animals and plants were disappearing long before people arrived on the scene. But what has changed is the extinction rate. For millions of years, on average, one species became extinct every century. But most of the extinctions since prehistoric times have occurred in the last three hundred years. And most of the extinctions that have occurred in the last three hundred years have occurred in the last fifty. And most of the extinctions that have occurred in the last fifty have occurred in the last ten. It is the sheer rate of acceleration that is as terrifying as anything else. There are now more than a thousand different species of animals and plants becoming extinct every year.

There are currently fi ve billion human beings and our numbers are continually growing. We are fighting for space with the world's wildlife, which has to contend with hunting, pollution, pesticides, and most important of all, the loss of habitat. Rain forests alone contain half the world's species of animals and plants, yet an area the size of Nebraska is being destroyed each year. There are so many threatened animals around the world that, at the rate of one every three weeks, it would have taken Douglas and me more than three hundred years to search for them all. And if we had decided to include threatened plants as well, it would have taken another thousand years. In every remote corner of the world, there are people like Carl Jones and Don Merton who have devoted their lives to saving threatened species. Very often, their determination is all that stands between an endangered species and extinction. But why do they bother? Does it really matter if the Yangtze River dolphin, or the kakapo, or the northern white rhino, or any other species live on only in scientists' notebooks? Well, yes, it does. Every animal and plant is an integral part of its environment: even Komodo dragons have a major role to play in maintaining the ecological stability of their delicate island homes. If they disappear, so could many other species. And conservation is very much in tune with our own survival. Animals and plants provide us with life-saving drugs and food, they pollinate crops and provide important ingredients for many industrial processes. Ironically, it is often not the big and beautiful creatures, but the ugly and less dramatic ones, that we need most. Even so, the loss of a few species may seem almost irrelevant compared to major environmental problems such as global warming or the destruction of the ozone layer. But while nature has considerable resilience, there is a limit to how far that resilience can be stretched. No one knows how close to the limit we're getting. The darker it gets, the faster we're dri ving. There is one last reason for caring, and I believe no other is necessary. It is certainly the reason why so many people have devoted their lives to protecting the likes of rhinos, parakeets, kakapos, and dolphins. And it is simply this: the world would be a poorer, darker, lonelier place without them" (Adams and Carwardine, 1990: 210-211).

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Index

Aceratherium Aepycerotini Agate Springs quarry Alcelaphinae Alcelaphini Altungulata Ambulocetus amebelodonts amynodonts anancines anchitheres Andrews,· C.M. Andrews, R.C. Andrewsarchus antelopes anthracobunids anthracotheres Antilopinae Antilopini antlers archaeocetes arctocyonids arctostylopids arsinoitheres artiodactyls Ashfall fossil beds asses astrapotheres aurochs babirusa Baluchitherium Barytherium Basilosaurus bearded pig beluga whale bighorn sheep bison blackbuck blastomerycids bongo Boselaphini bovids

256 88-89, 103-104 247-258, 263-265 88-89, 100 88-89, 102-104 9 117-118,145 166-169 257-258 168 206-207 141-142, 159 118-120, 133,167-168 118-120 100-107 160 42-43 88-89, 100,104-107 88-89, 104-107 63,77-78 115-118 7 13-16 141-143, 159 8, 19-85 268-271 221-224 14-15 92-93, 97-98 33-34 260 161 115-118 34 131 111-113 86,94-97 105-107 73 92 88,90 87-113

Bovinae Bovini brontotheres buffalo Buffon, G.L. bushpig camels Bactrian dromedary giraffe Caprinae Caprini cattle cave goat Cenozoic Cephalophinae Cervinae Cetacea Chacoan peccary chalicotheres chamois CITES Condylarthra Cope, E.D. Cuvier, G. deer deinotheres desmostylians Diacodexis Diceratherium dichobunids didolodonts dik dik Dinohippus dolphins Domning, D. donkeys dromomerycids dugong duikers

88,90-98 88-90, 92-98 229-237 90-91 158 30-32 1,45-56,62 53-55 53-56 1,48-49 88-89, 1'07-113 88-89, 111-113 97-98 109 3 88-89, 98-100 80-81 8, 115-139 38-39 247-250 108 193-195,290-291 5 9-13, 199 149, 159, 165, 191,203,247-248 72-85 161 148-149 23-24 263-264 23-24 13 104-105 214 129-132 144-145, 148-149, 159-160 224 79-80 143-147 98-100

310 eland Elasmotherium elephant African Asian forest embolotheres entelodonts Eocene Eohippus Eotragus EQ (encephalization quotient) Equus Fayum Filhol, H. flehmen forest hog Frick, C.

HORNS, TUSKS, AND FLIPPERS 91 273-274 2, 9, 170-195 181-190 181-182, 190-192 181 239 26-27 3 200-201 87 125 210-227 141-143, 159-160, 162, 166 25 112,219,286 32-33 209

gazelle gerenuk giraffes gnu gomphotheres guanaco

1, 103, 105-1 07 105-107 1,67-72 102-103 166 51-53

hartebeest Hatcher, J.B. Hayden, F.V. hipparions hippidions hippopotamus Hippotraginae Hippotragini Homogalax horned horses horns horses Huxley, T.H. hyopsodonts hypsodonty Hyrachyus hyracodonts Hyracotherium hyraxes

102 232-233 12, 230-231 209-211 216 1,39-42,62 88-89, 100-102 88-89,101-102 202, 250-252 205-206 63-85 198-207 199-200 8 207-208 253, 256-257 258-261 198-202 9, 149-155

ibex impala indricotheres Indricotherium Irish elk ivory

111 2, 103-104 258-261 260 77-78 191-195

Janis, C. Jarman, P.

62-64,74 63-64,89

Jefferson, T.

158-159

kiang klipspringer kudu I ava cast rhino Leidy, J. litopterns lophiodonts

222-223 104-105 91

Mammalia mammoth manatees markhor Marsh,O.C. mass strandings mastodonts McKenna, M.C. Megacerops Megatapirus Menoceras Merychippus Mesohippus mesonychids Messel Messinian event Miocene Miohippus Moeritherium moose moropomorphs Moropus mountain goats mouse deer muntjacs musk deer musk ox Mylohyus Mysticeti narwhal Nebraska man Neotragini notoungulates Odontoceti okapi Oligocene onager oreodonts oromerycids oryx Osborn, H.F. Ovibovini Owen, R.

266-267 11-12,56-57, 199,256 13-14,215-216 252 5 2, 170-177 9, 143-148 111 9-13, 199, 229-233 126-127 2, 161-166 9,24, 142-143, 148-149, 159-160, 198 235-237 241-242 263-265 208-209 205-206 117-121 204 50,211 3 205-207 159-160 82 241-253 247-258, 263 108-109 65-66 80 72-73 109-111 37 122,133-135 131,278 36-37 88-89, 104-105 14-15 122-133 66-67 3 221-222 56-59 45 100-102 233-235 88-89, 109-111 115, 149, 198-202,241

INDEX Pakicetus palaeotheres Paleocene Panama land bridge pantodonts Paraceratherium peccaries Pere David's deer periptychids perissodactyIs Pezosiren phenacodonts Phenacolophus Phosphatherium pigs Platygonus Pleistocene extinctions Pleistocene Pliocene Pliohippus porpoises Powell, J.W. Proboscidea pronghorns protoceratids Protorohippus Przewalski's horse pygmy hippopotamus pyrotheres quagga Quercy Radinskya Reduncini reindeer rhebok rhinoceroses black Indian Javan Sumatran white woolly rhinocerotoids river dolphins ruminants Rupicaprini

117-118 197-204 3 50-51 16-17 260-261 2, 35-39 83-85 8 9, 20, 24-25, 197-202 144-145 9, 198 142-143 160 2,26-35,62 37 176-177, 215 3 3 214 129-130 12-13 159-195 1,73-76 45-47 198-202 224-227 41-42 14-15 220 25-26 198 88-89, 100-101 83 101 261-292 280-284 284-287 284-285 274-275 280-284 272-273 253-292 128-129 21-23,61-85 88-89, 108-109

sable antelope Saigini Samos Samotherium serow sheep sirenians Sivatherium Skinner, M.F. South America sperm whale springbok steenbuck Steller's sea cow stenomylines Subhyracodon takin tapirs Teleoceras Tethys tethytheres titanotheres Tragelaphini tragulids tylopods uintatheres ungulates unicorn vicuna warthog waterbuck whales baleen intelligence toothed whaling wild boar wildebeest wisent zebras zhelestids

311 101 88-89, 108 61-62 61-62, 69-70 108-109 111-113 143-148 68 209-210 13-17 131-133,136 105-107 104 147-148 48 256,262 109-111 241-253 1, 268-271 24-25 9, 141-195 229-237 88,90-92 65-66 45-59, 62 9-13, 15 6 277-279 50-51 28-30 100-101 8,115-139 122,133-135 124-126 122-133 135-139 34-35 102-103 93-94 1,216-221 6