Trilobites of New York: an illustrated guide

T Trilobites of New York

A N

I L L U S T R A T E D

Thomas E. Whiteley Gerald J. Kloc Carlton E. Brett with a foreword by Rolf Ludvigsen

Published in cooperation Paleontological Research

COMSTOCK

with

Institution,

PUBLISHING

CORNELL

UNIVERSITY

Ithaca

London

and

the Ithaca,

New

York

A S S O C I A T E S , a division o f

PRESS

G U I D E

C o p y r i g h t © 2002 by Cornell University

All rights r e s e r v e d . Except for brief quotations in a review, this book, or parts thereof, must not be r e p r o d u c e d in any form without permission in writing from the publisher. For information a d d r e s s Cornell University Press, Sage House, 512 East State Street, Ithaca, N e w York 14850.

First p u b l i s h e d 2 0 0 2 by Cornell University Press Published in c o o p e r a t i o n with the Paleontological Research Institution, Ithaca, N e w York

Printed in the United States of A m e r i c a

Library of C o n g r e s s Cataloging-in-Publication Data Whiteley, T h o m a s E. ( T h o m a s Edward), 1 9 3 2 Trilobites of N e w York : an illustrated guide / Thomas E. Whiteley, G e r a l d J. Kloc, a n d Carlton E. Brett, p.

cm.

Includes b i b l i o g r a p h i c a l references and index. ISBN 0-8014-3969-9 (acid-free paper) 1. Trilobites—New York (State)

I. Kloc, Gerald J.

II. Brett, Carlton E. (Carlton Elliot)

III. Paleontological

Research Institution (Ithaca, N.Y.)

IV. Title.

QE821 .W397

2002

565'.39'09747—dc21 2001054767

Cornell University Press strives to use environmentally r e s p o n s i b l e suppliers a n d materials to the fullest extent possible in the p u b l i s h i n g of its b o o k s . Such materials include v e g e t a b l e - b a s e d , low-VOC inks a n d acid-free papers that are r e c y c l e d , totally chlorine-free, or partly c o m p o s e d of n o n w o o d fibers. For further information, visit our website at www.cornellpress.cornell.edu.

Cloth printing

10

9 8 7 6 5 4 3 2 1

Contents

Text Figures vii

Chapter

Text Tables ix

THE

Foreword xi

NEW YORK

Preface xv

4

PALEOZOIC

GEOLOGY

OF 43

Overview 4 3 C a m b r i a n Period 4 6

Chapter

1

Ordovician Period 1

BACKGROUND INFORMATION

Silurian Period 81 D e v o n i a n Period

Historical Notes 1

56

95

Trilobite Names 2

Chapter Chapter

2

THE T R I L O B I T E S 4

THE B I O L O G Y OF T R I L O B I T E S Exoskeleton Ontogeny

5

117

O r d e r Redlichiida

4

118

Order Corynexochida

13

Soft B o d y Parts

O r d e r Agnostida

117

O r d e r Lichida

17

124

Order Phacopida

L i f e - M o d e 21

O r d e r Proetida Evolution and Cladistics 30

O r d e r Asaphida

128 148 157

O r d e r Ptychopariida

Chapter

118

163

3 32

TAPHONOMY

Appendix A: Trilobites and T h e i r E n v i r o n m e n t s

Death, Decay, and Disarticulation 32

Appendix B : T h e P h o t o g r a p h y

Transport and Reorientation

Glossary

35

172

Fragmentation and Biased Preservation 36

References

Abrasion, C o r r o s i o n , and E n c r u s t a t i o n

Trilobite Index

37

Fossil Diagenesis: G e o c h e m i c a l Processing of Potential Fossils 37

168

170

177 191

Index 201 Plates

204

Trilobite Taphofacies 4 0 Trilobite Lagerstatten

40

v

Text Figures

2.1

Trilobite structure using Eldredgeops rami using Kettneraspis

5

2.2

Trilobite structure

2.3

T h e structure of the trilobite c e p h a l o n using Calymene species

tubercidata

6

2.4

Trilobite eyes 9

2.5

Cephalic sutures 9

2.6

Hxoskeletal pits or circular perforations

2.7

Ventral a n a t o m y of the exoskeleton

2.8

O n t o g e n y of the trilobite

2.9

Trilobite exoskeletons with attached fauna or injury

2.10

Trilobite appendage reconstruction and n o m e n c l a t u r e

2.11

Ventral a n a t o m y and appendages 20

8

11

12

14

2.12

Internal a n a t o m y of the trilobite 22

2.13

Trilobite shapes and functions 23

18 19

2.14

Trilobite traces 25

2.15

Trilobite injuries 27

2.16

Cryptolithus, the most-studied trilobite genus f o u n d in New York

3.1

fossil assemblages reflecting various c o n d i t i o n s and t i m i n g of burial

3.2

C o n d i t i o n s for the f o r m a t i o n of pyritized, well-preserved fossils 39

28 34

4.1

T i m e scale for Earth history and for the Paleozoic rocks in New York 44

4.2

P r e c a m b r i a n Grenville ( 1 . 0 B P ) m e t a m o r p h i c / i g n e o u s rocks 4 6

4.3

M a p showing the extent of the Grenville belt in eastern N o r t h A m e r i c a 47

4.4

Paleomagnetic reconstruction of the supercontinenl Rodinia

4.5

Position of the Laurentian plate and n e i g h b o r i n g Baltica and Avalonia

48

terranes from the C a m b r i a n to the Devonian 49 4.6

C a m b r i a n rocks in New York 50

4.7

New York in the C a m b r i a n 52

4.8

C l o s e - u p o f Upper C a m b r i a n Potsdam S a n d s t o n e 5 3

4.9

Upper C a m b r i a n limestones 54

4.10

Simplified stratigraphy of the C a m b r i a n - O r d o v i c i a n rocks in the T a c o n i c allochthon

55

4.11

Lower C a m b r i a n a l l o c h t h o n o u s beds of the low T a c o n i c M o u n t a i n s

4.12

Stratigraphic chart of the Ordovician exposures in New York 57

56

4 . 1 3 A - C New York during the Early and early M i d d l e O r d o v i c i a n 58 4.13D-F

New York during the Middle O r d o v i c i a n 59

4.14

Details of the stratigraphy of the Chazy G r o u p in northeastern New York 63

4.15

Flute casts on Austin Glen graywacke 65

4.16

Black River limestones 66

4.17

Middle Ordovician Black River G r o u p 67

4.18

Close-up o f sharp Black River/Trenton ( W a t e r t o w n - N a p a n e e ) c o n t a c t 6 8

4.19

Close-up of storm beds in the Middle Ordovician Kings Falls L i m e s t o n e 69

viii

TEXT 4.20

M a p s of New York during late Middle Ordovician times 70

4.21

M i d d l e Trenton at Trenton Falls 72

4.22

M i d d l e Ordovician Trenton G r o u p limestone 7 3

4.23

Trenton at Trenton Falls 74

FIGURES

4.24

M i d d l e O r d o v i c i a n Dolgeville and Utica rocks 77

4.25

New York maps during the late M i d d l e Ordovician and the Upper

4.26

Ordovician/Silurian u n c o n f o r m i t i e s

4.27

Stratigraphic chart of the Silurian rocks in New York 82

4.28

O r d o v i c i a n - S i l u r i a n ( C h e r o k e e ) u n c o n f o r m i t y / O r d o v i c i a n - L o w e r Silurian

4.29

M a p s o f New York during W e n l o c k times

4.30

I r o n d e q u o i t - R o c h e s t e r b i o h e r m at the upper part of the Lower Silurian

Ordovician

succession

79 81

84

Clinton Group

87

88

4.31

M i d Silurian successions 91

4.32

Silurian c a r b o n a t e s 92

4.33

D o m a l stromatolites

4.34

C o m p o s i t e stratigraphic chart for the n o r t h e r n and central parts of the

4.35

N e w York during the Early D e v o n i a n 97

Appalachian Basin

94

96

4.36

Upper Silurian/Lower Devonian rocks

4.37

New York during the early M i d d l e D e v o n i a n

99

4.38

Upper Silurian/Onondaga Limestone

103

104

4.39

M i d d l e D e v o n i a n rocks

4.40

New York d u r i n g the Middle D e v o n i a n H a m i l t o n deposition

4.41

Devonian successions

4.42

M i d d l e D e v o n i a n / U p p e r Devonian successions

4.43

Stratigraphy of the Upper Devonian and the upper Middle Devonian of New

5.1

Lichids from the lower and lowest M i d d l e Devonian of New York

125

5.2

Key cephalic differences between D a l m a n i t i d a e and Synphoriidae

136

5.3

Trilobites of the families D a l m a n i t i d a e and Synphoriidae

5.4

Lower D e v o n i a n and lower Middle Devonian p h a c o p i n s

5.5

Features of New York Cryptolithus

York

106 108

113 114

115

164

138 143

Text Tables

5.1

Trilobites of the suborder Agnostina

118

5.2

Trilobites of the suborder Eodiscina

119

5.3

Defining features of the New York asteropygins

5.4

Features of the genera Bellacartwrightia and

129

5.5

Features of the Lower Devonian phacopids f r o m New York

5.6

Features of the Middle Devonian phacopids of New York

5.7

Features of the genus Odontocephalus of New York

5.8

Features of the described proetids of New York

Greenops

153

130

147

141 142

Foreword

T o m Whiteley, a n accomplished a m a t e u r paleontologist, has

" l o v e r " ) are those who pursue an activity out of interest instead

taken the lead in c o m p i l i n g a m u c h - n e e d e d popular a c c o u n t

of financial gain. A m a t e u r s , like professionals, tend to specialize.

of the trilobites of New York.

S u m p t u o u s l y illustrated with

In New York, as in O n t a r i o , O h i o , I n d i a n a , O k l a h o m a , and

generous photographs of c o m p l e t e s p e c i m e n s of New York trilo-

U t a h — r e g i o n s that have a lot of fossiliferous Lower Paleozoic

bites, this b o o k is m o r e than a regional field guide. It also testi-

o u t c r o p — m a n y a m a t e u r s and fossil collectors c o n c e n t r a t e their

fies to G e r r y Kloc's expertise in preparation and Carlton Brett's

efforts on trilobites. T h e y have collected and prepared trilobite

keen insight about the rocks and c o m p l e x facies of the state. In

s p e c i m e n s that, in quality and c o m p l e t e n e s s , rival those described

essence, the b o o k reprises the w o r k of Charles Walcott, a n -

by a c a d e m i c paleontologists. T h e extent of p o p u l a r interest in

other accomplished a m a t e u r paleontologist of a c e n t u r y and a

trilobites is exemplified by h u n d r e d s of websites on the Internet,

quarter ago.

almost all of t h e m hosted by a m a t e u r s .

T h e technical literature on trilobites is vast. It is dispersed

T h e p h o t o g r a p h s in this publication reveal why trilobites have

through n u m e r o u s paleontological j o u r n a l s , in specialized b o o k s ,

long been considered to be a m o n g the m o s t desirable and curious

and as century-old m o n o g r a p h s . Even a dedicated trilobite pale-

of fossils. A late Paleolithic h u n t e r in w h a t - i s - n o w central France

ontologist with access to a university library would have difficulty

carried o n e a r o u n d his neck as a p e n d a n t suspended from a

retrieving all of it. T h e popular literature on trilobites is a lot

leather t h o n g . A n c i e n t C h i n e s e philosophers called t h e m " s t o n e

easier to access, if only because there is so little of it. Few profes-

s i l k w o r m s " and " b a t s t o n e s . " T h e Pahvant Ute tribe of western

sional paleontologists have considered it i m p o r t a n t to write field

Utah knew t h e m as timpe khanitza pachavee, m e a n i n g "little water

guides to fossils along the lines of the popular regional guides to

bug like stone house." Strung as amulets, they were thought

flowers, m u s h r o o m s , trees, insects, and birds that are available in

to possess magical powers. In 1 6 9 8 , Edward Lhwyd, c u r a t o r of the

every bookstore across A m e r i c a . Fewer still have written b o o k s

A s h m o l e a n M u s e u m in O x f o r d , included in the pages of the

exploring the natural history of fossils.

Philosophical

Trilobites of New York is a lavishly illustrated bestiary of New

Transactions of the Royal Society a

plate with

a

finely

lined oval fossil f r o m the shales exposed near Llandeilo in south-

York trilobites in which o n e can sense the spirit of S a m u e l Latham

ern Wales. He t h o u g h t it was a "flat fish." In nearby areas in Wales

Mitchill's m o n o g r a p h , The Fishes of New York, published in 1 8 1 5 .

suffused with the legend of King Arthur, such fossils are called

Both books are basically encyclopedic and scientific in their

" s t o n e butterflies" and are widely believed to have been e n t o m b e d

approach, but each includes snippets of practical i n f o r m a t i o n .

in rock by spells cast by the wizard Merlin.

Mitchill advised fishermen that the blackfish will run in the spr-

European naturalists were fascinated by these fossils. Although

ing when the dogwood b l o s s o m s o p e n . W h i t e l e y suggests that a

they described and figured t h e m in considerable detail, they

3 5 - m m T I F F c o l o r image of a trilobite is a b o u t 25 megabytes

had great difficulty in d e t e r m i n i n g what they were and how they

in size and should be stored on a C D - R O M . T i m e s c h a n g e !

should be

Here is a s u m m a t i o n of nearly two centuries of discovery and

applied

classified.

the

term

The

great

Entomolithus

naturalist paradoxus

Carolus

Linnaeus

("paradoxical

stone

study of New York trilobites by a succession of paleontologists

i n s e c t " ) to such fossils f r o m Sweden; others t h o u g h t they were

and as an exposition of the natural history of these fascinating

fossil crabs or possibly weird mollusks.

fossils. T h e b o o k will be w e l c o m e d especially by A m e r i c a n pale-

W i t h their evocative and disparate n a m e s , these stony objects

ontologists, professional as well as amateur, and by anyone who

were corralled in

delights in the exquisite beauty of these ancient fossils.

Ernst

Professional paleontologists working on New York fossils have

Immanuel

Naturgeschichte

der

1771 Walch

w h e n the G e r m a n naturalist lohann published

Versteinerungen

the

third

[Natural

volume

History

of Der

of Petrifac-

always been greatly o u t n u m b e r e d by a m a t e u r paleontologists and

tions]. In it he proposed a collective n a m e derived f r o m the most

avocational fossil collectors. Although often ( a n d mistakenly) dis-

obvious f e a t u r e — t h e i r t h r e e - l o b e d appearance. Eventually natu-

missed as dilettantes, amateurs ( t h e root is the Latin amator, for

ralists studying fossils ( w h o were now b e g i n n i n g to be called pale-

XI

FOREWORD

XII

ontologists) accepted that trilobites c o m p r i s e a distinct group of

support from the state legislature to prepare a single volume on

fossil a r t h r o p o d s .

the fossils of the state. Hall had greater a m b i t i o n s , and entirely

By the early years of the n i n e t e e n t h century, trilobites of m a n y

due to his s t u b b o r n d e t e r m i n a t i o n and ability to browbeat legis-

different types had been d o c u m e n t e d f r o m Britain, G e r m a n y ,

lators, this v o l u m e b e c a m e the first of no fewer than 13 quarto

Scandinavia, and B o h e m i a . T h e n , as now, they attracted attention

volumes of the m o n o g r a p h series Palaeontology of New York. T h e

because of their peculiar shape, their striking o r n a m e n t a t i o n ,

series c o m p r i s e d thousands of pages and m a n y hundreds of plates

and their great age. A m o n g the m o s t ancient of fossils, they were

published over the next half century. To pursue his work, Hall

f o u n d mainly in the sectors of Earth history s o o n to be n a m e d

amassed

the C a m b r i a n and Silurian systems.

Beaverkill in Albany. Of Hall it can truly be said that he never met

huge fossil

collections at his laboratory along the

Trilobites are the most lifelike of f o s s i l s — m a n y well-preserved

a fossil he didn't covet. He hired a succession of assistants to

specimens belie their great antiquity and seem almost ready

collect, prepare, describe, and draw the specimens. Hall h i m s e l f

to arch their bodies, peer a b o u t with their c o m p o u n d eyes, and

described m a n y trilobites from the state in his Palaeontology, but

crawl forward as if to c o n t i n u e a j o u r n e y that was interrupted

independently o n e of his assistants m a d e the class Trilobita

hundreds of millions of years ago. A trilobite is an ancient a r t h r o -

his o w n .

pod, but it is certainly not a lesser a r t h r o p o d .

Charles Doolittle Walcott was a young m a n of 26 when he

Trilobite discoveries in the New W o r l d followed closely on

started to work for Hall in 1876. B o r n at New York Mills in the

those in the Old. By 1832 so m a n y different kinds of trilobites

M o h a w k Valley, he had little formal education but a wealth of

had been collected that J a c o b G r e e n , a professor at Jefferson

practical knowledge about fossils. A few years previously he had

Medical College in Philadelphia, had sufficient material to write

sold a collection of trilobites he had compiled from Trenton Falls

a 9 3 - p a g e m o n o g r a p h detailing all the species then k n o w n . He

on West C a n a d a Creek to the M u s e u m of Comparative Z o o l o g y

might have titled it Trilobites of New York instead of A Monograph

at Harvard University for $ 5 0 0 0 . At night, after he had finished

of the

his w o r k for Professor Hall, Walcott polished sections of tightly

Trilobites of North America,

because

of the

32

species

he

dealt with, all but 7 c a m e f r o m that state.

enrolled s p e c i m e n s of the trilobite Ceraurus in an a t t e m p t to

New York was h o m e to the first A m e r i c a n s c h o o l of geology.

d e t e r m i n e the structure of its infolded limbs. This was e n o r -

1824 Stephen Van Rensselaer provided the funding that

m o u s l y difficult—akin to attempting the restoration of an orchid

allowed A m o s Eaton to start the Rensselaer S c h o o l in the town of

by slicing serially through a rolled-up f l o w e r — a n d , not sur-

In

Troy. T h i s school left a solid m a r k on early A m e r i c a n geology

prisingly, resulted in inaccurately reconstructed trilobite limbs.

and

of

Walcott also collected f r o m localities in New York where few trilo-

g e o l o g i s t s — o n e that effectively d o m i n a t e d A m e r i c a n geological

bites had been k n o w n b e f o r e . He m a d e large collections f r o m

paleontology.

It graduated

a

remarkable contingent

surveys—along with a few paleontologists who ensured that New

deformed

York remained the paleontological heartland of North A m e r i c a

and f r o m Upper C a m b r i a n limestones near Saratoga Springs.

for the rest of the nineteenth century. O n e of the Rensselaer

However, Walcott chafed at the treatment he received f r o m the

graduates was sure that he had f o u n d a living trilobite.

mercurial Hall, w h o after a few years dumped him for a younger

As a m e m b e r of the United States " E x p l o r i n g Expedition

Lower C a m b r i a n

rocks of the Taconic M o u n t a i n s

and m o r e c o m p l i a n t assistant. Walcott benefited by gaining a

o f 1830," James Eights o f Albany was the f i r s t A m e r i c a n scien-

position

tist to study the m a r i n e animals, l a n d f o r m s , and geology of

b e c a m e director of the survey, and rose to b e c o m e the secretary

in

the newly f o r m e d

U.S. Geological Survey, t h e n

Antarctica and its surrounding islands. A m o n g his discoveries

of the S m i t h s o n i a n Institution. Walch might have n a m e d it, b u t

from the shallow seas a r o u n d the bleak S o u t h Shetland Islands

it was Walcott w h o conceived the trilobite taxon. He was the first

was a peculiar creature that he n a m e d Brongniartia

trilobitoides

to suggest that the class Trilobita (or, as s o m e paleontologists now

Brongniartia

favor, phylum Trilobita) was a group of arthropods quite distinct

had

f r o m crustaceans.

and boltoni.

illustrated B.

alongside

boltoni was

a

its

large

presumed fossil

relative,

trilobite

that

been

described f r o m ancient Silurian shales scooped up by tarriers digging the Erie Canal near Rochester. And if B.

New York had to relinquish its primacy in matters trilobitic

boltoni was

in the early years of the twentieth century as the research focus

a stony extinct trilobite, then surely the lively trilobitoides m u s t

shifted to o t h e r parts of the c o n t i n e n t — t o the Great Basin of

b e living m e m b e r s o f that a n c i e n t clan. T h e Antarctic a n i m a l ,

Nevada and Utah, to N e w f o u n d l a n d , to Virginia, to the Upper

however, t u r n e d o u t to be a c r u s t a c e a n — a n isopod of the genus

Mississippi Valley, and to the southern C a n a d i a n Rockies. In the

Serolis.

But even today Serolis trilobitoides (Eights)

is cited as a

1960s a new crop of paleontologists applying m o d e r n paleonto-

t e x t b o o k e x a m p l e o f the convergent evolution o f isopods and

logical ideas sparked renewed interest in the New York trilobites

trilobites.

that had been described a century earlier. A m o n g these scientists

New York p a l e o n t o l o g y entered a new state-sanctioned phase

were F r a n c o Rasetti, the paleontologist/nuclear physicist from

in the early 1840s w h e n James Hall, the state paleontologist and

J o h n s H o p k i n s University w h o focused on C a m b r i a n trilobites

the b e s t - k n o w n graduate of the

from the tortured rock of the Taconic region; Harry W h i t t i n g t o n ,

Rensselaer S c h o o l , received

FOREWORD

XIII

the Woodwardian professor of geology at C a m b r i d g e University,

ing us full circle as they update and e n h a n c e the story of the trilo-

who restored the a n a t o m y of pyritized

bites of New York, bringing new visions and fresh perspective to

Triarthrus f r o m Upper

Ordovician shales near R o m e ; and Niles Eldredge, the p a l e o n t o l -

these wonderful creatures.

ogist at the American M u s e u m of Natural History in New York City, whose work ensured the centrality of M i d d l e Devonian Phacops

(now Eldrcdgeops)

in

the

new

evolutionary

model

of

punctuated equilibria. So the authors of this b o o k are to be congratulated for bring-

ROLF

LUDVIGSEN,

Head

D e n m a n Institute for Research on Trilobites D e n m a n Island, British C o l u m b i a , C a n a d a

Preface

S c i e n t i s t s estimate that life on Earth may have begun as early as three billion years ago. life

was

confined

to

For m u c h of its history, however,

single-celled

bacteria.

Stromatolites,

New York State is and has long been a m a g n e t for trilobite hunters. Historically, New York was of central i m p o r t a n c e in the study of Paleozoic fossils, and New York's trilobites were

layered m o u n d s of sediment trapped by mats of blue-green

among

cyanobacteria, are the p r e d o m i n a n t fossils for nearly two billion

York strata are the source of m a n y s p e c i m e n s accepted worldwide

years

as the best of their kind. T h e s e fossil

of geologic

history.

Finally,

in

the

late

Precambrian

the

first

illustrated

fossils

in

North

America.

New

remains are actively

Ediacarian Period, about 5 7 0 million years ago, e n i g m a t i c soft-

sought, studied, and traded. W i t h its extensive shale deposits,

bodied forms of multicellular life first appeared as impressions in

New York is a particularly rich source of trilobites, m a n y of

sandstone.

which are shown for the first t i m e in this v o l u m e . M a n y out-

About 543 million years ago life m a d e a further p r o f o u n d

standing localities in New York State, from the majestic O r d o v i -

change in direction. A sudden burst of new o r g a n i s m s with hard

cian limestone bluffs of Trenton Falls to the Silurian beds in the

skeletons in the fossil record has b e e n called the " C a m b r i a n

great gorge of Niagara River to the D e v o n i a n shale cliffs of Lake

Explosion." T h e earliest fossil skeletons were simple tubes, p r o b -

Erie, c o n t i n u e to yield a b u n d a n t and spectacular trilobite fossils.

ably made by w o r m s ; shell material clearly m a d e by c o m p l e x

New York strata have also yielded m o r e trilobites with preserved

living creatures such as mollusks appeared a b o u t 5 4 0 million

appendages and o t h e r "soft p a r t s " than almost any other region

years ago. T h e n , beginning about 5 2 0 million years ago, highly

o f the world. T h e rarity and aesthetic beauty o f c o m p l e t e o u t -

sophisticated

stretched or enrolled trilobites gives trilobite fossils special value

skeletons

of trilobites,

early

representatives

of

Earth's most a b u n d a n t c o m p l e x a n i m a l s — t h e Phylum A r t h r o -

to

p o d a — a p p e a r e d in m a r i n e strata worldwide. T h e trilobites not

ranging f r o m a few millimeters to nearly a h a l f - m e t e r in length,

only appeared dramatically in the fossil record but for millions of

are featured in m u s e u m s all over the world; s o m e extraordinary

years they d o m i n a t e d it. Trilobites are the quintessential archaic m a r i n e animals. Few

collectors.

Spectacular,

ornate

trilobites

from

New York,

examples are prized by collectors and have been sold for t h o u sands of dollars.

if any other invertebrate fossils have attracted m o r e attention

Yet despite the f a m e of New York State's trilobites, no recent

from paleontologists and fossil collectors than these ancient

text has a t t e m p t e d to d o c u m e n t comprehensively these remark-

arthropods, distant relatives of today's crustaceans and insects.

able fossils. W i t h a little effort o n e can find trilobites in New

Paleontologists have learned a great deal about trilobites because

York State rocks ranging in age f r o m the t i m e of their earliest

they were ubiquitous in the oceans and seas of the early Paleo-

o c c u r r e n c e in the Early C a m b r i a n up to their last t i m e of

zoic Era and because they possessed readily preserved hard skele-

m a j o r a b u n d a n c e in the Devonian Period, a b o u t 3 7 0 million

tons. In the mid to late 1800s lithographed images of trilobites

years ago. T h u s , although New York strata do not d o c u m e n t the

became symbolic of the rapidly developing field of paleontology

entire evolutionary history of trilobites, the a b u n d a n t , high-

in New York State as well as in E n g l a n d , two hotbeds of early

quality material available in this area offers a rare o p p o r t u n i t y to

research by serious amateurs and professional scientists when

discover and study these intriguing representatives of early life

interest in the nascent field of geology was first b e g i n n i n g to

history.

burgeon. T h e beautifully preserved, segmented exoskeletons of

Trilobites of New York is

intended

to be a

nearly complete

trilobites—in shades of saddle brown and blue gray to b l a c k —

c o m p i l a t i o n of the trilobite species f o u n d in New York: a review

are truly spectacular o b j e c t s , but perhaps above all it is the well-

of the biology of the trilobite; insight into trilobite preservation

developed, c o m m o n l y c o m p o u n d eyes of trilobites that have

in the rocks; a s h o r t course on the Paleozoic geology of New York,

made them attractive to paleontologists and lay persons alike.

emphasizing trilobite-bearing strata; and a collection of high-

Trilobites were certainly a m o n g the first organisms to f o r m rela-

quality images of representative New York trilobites. T h e b o o k

tively clear images of their world.

is not and was never intended to be a field guide or identificaxv

PREFACE

XVI

tion m a t r i x to trilobites. As s u c h , there is no specific local-

the basis of quality, rarity, and representation of the material

ity i n f o r m a t i o n , although

present in the New York rocks.

tographs very useful

in

m a n y readers will

find

identification and in

the p h o -

differentiating

similar species.

Anyone w h o collects fossils of any kind understands that finding a c h o i c e specimen is only part of the process. Most trilo-

T h i s work started m o r e than 20 years ago as an attempt by

bites are e m b e d d e d in a m a t r i x of shale or limestone, and to really

T o m Whiteley to c o m p i l e illustrations of the trilobites found in

appreciate their quality o n e must prepare t h e m by removing the

New York. Although New York has a history of trilobite discov-

stone f r o m the part of the trilobite that is to be displayed. Most

ery and research since 1824, references on trilobites are scattered

of the illustrated s p e c i m e n s were prepared or " t o u c h e d u p " by

and often not available except in the libraries of large universi-

Gerald Kloc. Even s o m e m u s e u m specimens were worked o n ,

ties. T h e only collective works on New York trilobites were the

with the m u s e u m ' s permission, to bring out the details concealed

classic volumes by James Hall, and the last of these was published

by m a t r i x .

in 1888. It soon b e c a m e apparent that the New York Paleozoic

As work on this project progressed, it b e c a m e clear that to

exposures are too varied for o n e person to really understand all

c o m p i l e data and images on trilobites was not e n o u g h . A listing

the trilobites and their l o c a t i o n s . H e n c e , Gerald K l o c b e c a m e

of nearly 5 0 0 separate species, while interesting to a few special-

involved with this project for his knowledge of the Silurian and

ists, is not very helpful to the collector or the student. To be really

Devonian exposures and their trilobites and for his contacts in

useful, we needed to include i n f o r m a t i o n on why the trilobites

the amateur c o m m u n i t y .

are f o u n d where they are and how their preservation c o m e s

As in all research p r o g r a m s , b a c k g r o u n d literature is an essen-

a b o u t . To this e n d , Carlton Brett provided a review of trilobite

tial starting point. T h e r e are a few texts on trilobites that provide

t a p h o n o m y , as well as an overview of the geological history of the

m o r e in-depth i n f o r m a t i o n on the a n i m a l itself than we include.

New York Paleozoic.

T h e works

of Johnson

(1985),

Levi-Setti

(1975),

Ludvigsen

T h e r e m a i n i n g issue c o n c e r n e d the intended audience, or who

( 1 9 7 9 b ) , and W h i t t i n g t o n ( 1 9 9 2 ) are g o o d references for addi-

is expected to read the b o o k . Dr. Warren Allmon of the Paleon-

tional reading. Every trilobite publication has references, and

tological Research Institution suggested that high-school earth

these references lead to o t h e r p u b l i c a t i o n s , which in turn lead to

science teachers represented the right level for content, as this

m o r e references and s o o n . H u n d r e d s o f publications were e x a m -

level would provide i n f o r m a t i o n useful to the collector, teacher,

ined, and the relevant o n e s were put into a database. Fieldwork

and student. Dr. Allmon also made the first contacts with Cornell

was also carried out in the m o r e p r o m i s i n g exposures. However,

University Press.

this fieldwork resulting f r o m literature surveys was limited and

As already m e n t i o n e d , it was necessary in the course of this

nowhere near the h o u r s and days of work spent by m a n y p r o -

work to visit m a n y of the m a j o r natural history m u s e u m s in

fessionals and amateurs in the field collecting each individual

the northeast United States. T h e A m e r i c a n M u s e u m o f Natural

specimen. S p e c i m e n s of the quality illustrated in this b o o k are

History, M u s e u m o f C o m p a r a t i v e Z o o l o g y (Harvard), Peabody

u n c o m m o n , even rare. A n u m b e r of the trilobite s p e c i m e n s are

M u s e u m (Yale), New York State M u s e u m , National M u s e u m of

unique in their quality of preservation and preparation, and very

Natural History ( S m i t h s o n i a n ) , Rochester M u s e u m and Science

few like them exist anywhere.

Center, Royal O n t a r i o M u s e u m , and Paleontological Research

T h e trilobite collections in a n u m b e r of m a j o r n o r t h e a s t e r n

Institution were visited, s o m e m a n y times, and their collections

United States m u s e u m s were e x a m i n e d carefully, and s p e c i m e n s

carefully e x a m i n e d . T h e c o o p e r a t i o n o f the m u s e u m s ' m a n a g e -

that were unusual or of high quality were p h o t o g r a p h e d and the

m e n t and their collections managers in particular was unreserved.

a c c o m p a n y i n g i n f o r m a t i o n recorded. T h e s e m u s e u m collections

W i t h o u t their help, this work would not have been possible.

represent the efforts of dozens of individuals over a period of

The

cooperation

and

assistance

of

Fred

Collier,

Jan

m o r e than 150 years. A n u m b e r of a m a t e u r collectors m a d e their

T h o m p s o n , Ed Landing, Niles Eldredge, Janet Waddington, T i m

s p e c i m e n s available for photography, which was helpful as the

W h i t e , Wendy Taylor,

best and most c o m p l e t e material is often n o t in a m u s e u m . In

Westrop, and G e o r g e M c i n t o s h were all i m p o r t a n t to this work.

Paul

Krohn,

Fredrick

Shaw,

Stephan

a few cases research paleontologists m a d e their p h o t o g r a p h s of

Fred Collier, in particular, while at the United States National

uncommon

M u s e u m , greatly influenced the early direction of these efforts

material available

for

reproduction.

The

photo-

graphic procedures are provided in A p p e n d i x B, b u t in general

with his professionalism and enthusiasm.

the p h o t o g r a p h s were taken in a m u s e u m or in a l a b o r a t o r y envi-

We gratefully acknowledge the collectors w h o m a d e their

r o n m e n t . O f t e n the s p e c i m e n s were whitened with a m m o n i u m

s p e c i m e n s available for p h o t o g r a p h y and in s o m e instances

c h l o r i d e to b r i n g o u t detail. T h e images were then scanned into

donated these s p e c i m e n s to a m u s e u m . T h e y are William P i n c h ,

a digital file, and all of the final preparation of images was d o n e

Kent S m i t h , Lee Tutt, Paul K r o h n , James Scatterday, Gregory

on c o m p u t e r . No i n f o r m a t i o n was added or subtracted from the

Jennings, Fred Barber, Kym Pocius, S a m Insalaco, Kevin Brett,

digital image at any t i m e . Of the thousands of p h o t o g r a p h s , o n l y

Steve Pavelsky, Tod C l e m e n t s , Douglas DeRosear, Fred Wessman,

a b o u t 2 0 0 could be selected for the b o o k . Selection was m a d e on

G o r d o n Baird, and William Kirchgasser.

PREFACE

xvii

Rolf Ludvigsen, Nigel Hughes, and G e o r g e M c i n t o s h read early drafts of the b o o k and m a d e m a n y valuable suggestions. Warren Allmon made the first contacts with

Sandoval, Lou R o b i n s o n , and C a n d a c e Akins also provided valuable assistance. To all we express o u r gratitude.

Peter Prescott,

science editor of Cornell University Press, w h o was i n s t r u m e n t a l

T h o m a s E. Whiteley

in giving the b o o k focus and helped turn what was a collection

Gerald J. Kloc

of information and pictures into s o m e t h i n g publishable. Alyssa

Carlton E. Brett

T Trilobites of New York

1

Background Information

Historical Notes

Lyceum of Natural History of New York was established in New York City, and in 1823 the Albany Lyceum of Natural History

E. Lhwyd provided the first record of trilobites in the litera-

was f o u n d e d .

Isotelus gigas was described

of Natural History (New Y o r k ) .

in

the Journal of the

ture in 1 6 9 8 , with the publication of plates depicting two Welch

Lyceum

trilobites, identified as fish. In 1 7 7 1 , J. I. Walch originated the

the Trenton L i m e s t o n e of central New York, particularly Trenton

T h e Isotelus fossils

from

use of the n a m e " t r i l o b i t e " as a distinct class of a n i m a l . L. D.

Falls, were long k n o w n and collected for sale by the local residents

H e r r m a n n , however, used the term trilobus as part of the n a m e

and b e c a m e part o f m a n y early natural history collections. T h e

for a trilobite fossil, as early as 1 7 1 1 . ( F o r the very early trilobite

Arctinurus s p e c i m e n described by Bigsby was first f o u n d during

references, see the publications by H. B u r m e i s t e r ( 1 8 4 3 , 1 8 4 6 ) . ) In 1822, C. Stokes was the first to describe North A m e r i c a n

the digging of the Erie Canal locks in what is n o w L o c k p o r t , New York.

from

In 1 8 3 6 , New York began a general natural history survey of

Canada. J. E. DeKay provided the first unequivocal description

the state, including its geology and mineralogy, and at the same

of a New York trilobite, Isotelus gigas from Trenton Falls ( n o r t h

t i m e f o r m e d the New York Geological Survey. T h a t same year the

trilobites,

with

Asaphus

(now

Isotelus)

platycephalus

of Utica, New York), in 1824. T h i s report was followed by that of

first state paleontologist was n a m e d , T. A. C o n r a d , a Philadelphia

Arctinurus

conchologist.

boltoni

by

Bigsby

in

1825.

Qf

the

40

trilobites

described in the classic works by the Philadelphia physician J. Green in 1832 and 1835, most were from New York. New York State

took an

early leadership

role

For the geological survey the state was divided into four districts, and the results from each district were published as sepa-

in

North

rate v o l u m e s . Starting in 1 8 4 2 , the first of these was published.

American Paleozoic invertebrate paleontology, in part due to

The

the n u m b e r of lower Paleozoic exposures within the state and also

b e g i n n i n g of the career of New York's s e c o n d and most well-

Geology of the Fourth

District of New

York

(1843)

was

the

to the history of the state itself. T h e early 1800s saw a general

k n o w n state paleontologist, James Hall. Hall was also the princi-

expansion westward within the United States. New York par-

pal a u t h o r of the e i g h t - v o l u m e Palaeontology of New York, issued

ticipated both by pressing settlement into the rich farmlands

between 1847 and 1 8 9 4 . V o l u m e s 1, 2, 3, and 7 (written with

of western New York and by aggressively seeking to b e c o m e the

J. M. Clarke) c o n t a i n significant trilobite i n f o r m a t i o n and are the

c o m m u n i c a t i o n route to the nation's Midwest. Roads, canals,

p r i m a r y references for early trilobite work in New York. Hall had

and permanent c o n s t r u c t i o n were all part of these goals, and

a n u m b e r of assistants w h o began their careers with h i m : F. B.

all needed building stone to succeed. L i m e s t o n e was the ideal

M e e k , F. V. Hayden (future director of the United States Geolog-

material both for buildings and for the c e m e n t and m o r t a r to

ical Survey), C. A. W h i t e (future state paleontologist for Iowa),

hold them together. T h u s , small and large limestone quarries

W. A. G a b b , R. P. Whitfield, C. Calloway, C. D. Walcott (future

became c o m m o n along the H u d s o n - M o h a w k River corridor.

director of the United States Geological Survey and the secretary

T h e state government also was c o n c e r n e d about its knowledge

of the S m i t h s o n i a n I n s t i t u t i o n ) , C. E. Beecher (future professor

of the natural treasures c o n t a i n e d within its b o r d e r s . In 1818 the

at Yale University), and J. M. Clarke (future state paleontologist 1

BACKGROUND

INFORMATION

for New York). Hall was a difficult m a n to work with and c o n s e -

usually derived

quently had a high turnover in assistants. It is claimed that Hall

Greek, or I n d o - E u r o p e a n and are selected by the describing

t o o k on s o m e of his assistants to gain access to their personal

author. N a m e s are often latinized, and the gender of the species

fossil collections (Yochelson, 1 9 8 7 ) .

follows that of the genus. In other words, if the genus n a m e is

T h e turn o f the c e n t u r y introduced additional

important

c o n t r i b u t o r s to the knowledge of New York trilobites, such as R. R u e d e m a n n and P. R a y m o n d . By the early twentieth century,

from

Latin, ancient Greek, latinized ancient

c h a n g e d , the ending on the species n a m e must s o m e t i m e s change to agree with it in gender. G e n e r a , that are considered to be closely related on the basis

New York was no longer a m a j o r area for new trilobite discover-

of shared characteristics, are grouped into families.

ies, as the focus had shifted westward with the general expansion

families are larger and m o r e distinctive, it is often easier to deter-

of the United States. However, significant c o n t r i b u t i o n s are still

m i n e the family to which a new trilobite belongs than to deter-

m a d e today, for example, in the u n d e r s t a n d i n g of s o m e less well-

m i n e its genus. New genera are constantly being erected, and

described areas such as the Middle O r d o v i c i a n Chazy G r o u p and

trilobite species are frequently moved a r o u n d as descriptive

the C a m b r i a n in eastern New York. T h e general shift in e m p h a -

m e t h o d o l o g y b e c o m e s m o r e sophisticated and new classification

sis f r o m discovery to understanding still keeps New York trilo-

standards are adopted.

Because

bites in the limelight. In later chapters we will point out the

Families are further collected into orders, again based on

i m p o r t a n c e of New York trilobite beds in o u r understanding of

inferred evolutionary relationships. T h e r e are currently eight

trilobite biology and fossil preservation.

orders in the class Trilobita of the phylum Arthropoda (Kaesler, 1 9 9 7 ) . T h e r e are additional t a x o n o m i c relationships rarely used herein, such as superfamily and suborder. Family n a m e s always

Trilobite Names

have the suffix -idae; superfamily names, -acae; suborder, -ina;

Trilobites are n a m e d using the rules of zoological n o m e n c l a ture published in English and French in the International Code of Zoological Nomenclature ( I C Z N ) . T h i s c o d e is used worldwide by

and order, - i d a . * The common

New York trilobite

Eldredgeops rana

is taxo-

nomically described as follows:

all scientists irrespective of the language of p u b l i c a t i o n . In dealing with the names of trilobites ( o r any o t h e r kind of o r g a n i s m ) , it

phylum

helps to understand the basic rules, how n a m e s c o m e a b o u t , and

Arthropoda

how they can change over t i m e .

class

For example, and as m e n t i o n e d already, in 1824 J. E. Dekay first reported Isotelus gigas Dekay,

Trilobita

1 8 2 4 , a n a m e that remains

order

unchanged to this day. T h e first n a m e , with a capital first letter,

Phacopida

Isotelus, is the genus n a m e and refers to a group of a n i m a l s in

family

which similar characteristics indicate a close evolutionary rela-

Phacopidae

tionship. G e n u s names must be original and not used for any

genus

other grouping of fossil or living a n i m a l . T h e second mme, gigas,

Eldredgeops

which is not capitalized, is the species n a m e and ideally should

species

refer only to a coherent group of interbreeding populations.

rana

Species n a m e s do not have to be u n i q u e , except within the s a m e genus. T h e r e can be only o n e gigas within the genus Isotelus, but

To take a n o t h e r , s o m e w h a t m o r e c o m p l e x example, Eldred-

species n a m e s can and do reoccur in different genera (plural of

geops

genus). Accordingly there are seven different New York trilobite

(short for variety) rana by J. Green in 1832. (Green in the s a m e

genera with the species n a m e trentonensis.

T h e proper n a m e ,

rana

publication

(Green, had

1832)

described

was

first

named

Calymcne bufo

Calymene bufo from a

var.

poorly pre-

genus and species, is italicized in print. In descriptive literature

served phacopid s p e c i m e n in a float boulder. T h e c o n d i t i o n of

the n a m e of the describing author (Dekay in our e x a m p l e ) and

the fossil was too p o o r to use for determining clear relationships

s o m e t i m e s the date of publication ( 1 8 2 4 in o u r e x a m p l e ) follow

and the n a m e subsequently was a b a n d o n e d . ) In 1860 E m m o n s

the n a m e . C h a n g e s to the genus n a m e are not u n c o m m o n , and

changed the species to Phacops bufo because of the greater simi-

in these cases the n a m e of original a u t h o r and date are given in

larity of the genus to the European genus Phacops than to Caly-

parentheses.

mene.

T h e e t y m o l o g y of trilobite n a m e s often refers to a m o r p h o logical

feature.

Hall ( 1 8 6 1 ) first called the c o m m o n trilobite from the

Hamilton

shales

and

limestones,

Phacops rana.

Green's

name

Isotelus m e a n s " s i m i l a r " (iso-) " e n d " or " t a i l "

and publication date now appear in parentheses because of the

(-telus), referring to the similarity between the head and tail of

c h a n g e in his original genus designation. T h i s story is further

this species, a n d gigas m e a n s " l a r g e " or "giant," referring to the

complicated by the assignment of s o m e new phacopids to s u b -

large size of this species c o m p a r e d to most trilobites. N a m e s are

species of Phacops rana such as Phacops rana milleri Stewart,

1927

TRILOBITE

3

NAMES

and Phacops rana rana ( G r e e n , 1 8 3 2 ) . ( T h e designation of s u b -

representative, then this specimen b e c o m e s a lectotype. Other

species is not often used with trilobites because strictly speaking

s p e c i m e n s in the original series b e c o m e p a r a l e c t o t y p e s , and the

the term implies geographically separated populations that could

t e r m syntype can no longer be applied. If the species has no orig-

interbreed given the opportunity. T h i s is nearly impossible to

inal type s p e c i m e n s that can be f o u n d and a sufficient taxonomic

determine from fossils, and most authors prefer the single species

purpose is present, an a u t h o r may designate a specimen to rep-

names Mich as Phacops rami ami Phacops milleri.) Struve ( 1990)

resent the type for the species. T h i s specimen is called a neotype.

re-examined the New World "Phacops" species and f o u n d t h e m

If at all possible, the n e o t y p e should be from the same location

significantly different from the type species Phacops latifrons that

and horizon as the originally described material. T h e description

was originally described from the Devonian of Germany. ( T h e

and n a m e m u s t be publicly issued as a p e r m a n e n t scientific

type species is the single species used to describe and define the

record and available in multiple, identical copies. All these rules

genus.)

are t h o r o u g h l y spelled o u t in the I C Z N ( 1 9 8 5 ) .

He erected

a

new genus, Eldredgeops, with

Eldredgeops

milleri as the type species. T h e very familiar f o r m e r Phacops rana is thus now properly referred to as Eldredgeops rana.

O t h e r type designations are c o m m o n l y used in collections but do not bear I C Z N r e c o m m e n d a t i o n . H y p o t y p e is a specimen that

Species n a m e s are never changed by later a u t h o r s , not even to

was referred to, usually in publications, to extend or correct the

correct spelling errors. T h e exceptions to this are if the n a m e has

knowledge of a species. T o p o t y p e refers to a specimen from

already been used for a closely related animal in the s a m e genus

the type locality, and p l e s i o t y p e refers to s p e c i m e n s very close to

or if the same animal has been n a m e d by a n o t h e r person in an

the type. P l a s t o t y p e is an artificial cast of the original type.

earlier publication. In almost all cases, priority is with the n a m e given by the first author.

A difficulty o n e often e n c o u n t e r s with trilobites, as well as o t h e r fossils, is that species were originally n a m e d when only a

T h e n u m b e r of trilobite species and genera is constantly

partial s p e c i m e n was available. T h e r e are a n u m b e r of instances

increasing due to b o t h new finds and redescriptions of previously

where, for e x a m p l e , the pygidium of an u n c o m m o n trilobite bore

collected material. T h e r e are also differing a p p r o a c h e s to the

o n e n a m e and the c e p h a l o n a different o n e . Also in the 1800s

concept of species. S o m e authors view speciation on the basis of

trilobites were often identified with the s a m e n a m e s as species

small external changes and tend to propose new species based on

f r o m o t h e r locations but of the same geological age. A n u m b e r of

these differences. O t h e r s view m a n y small external differences

New York trilobites, for e x a m p l e , were given the s a m e names as

as

species from the Midwest, particularly O h i o , as well as s o m e from

within

the

normal

intraspecies

variation

and

include

a

wider variety of s p e c i m e n s within a single species. T h e concept

Europe. S o m e o f these n a m e s are o n l y n o w being corrected a s

of species is not u n a m b i g u o u s in extant animals, and in the case

careful studies are m a d e .

of fossils morphological features are usually all there is available

A n o t h e r interesting situation is that early in the twentieth

for evaluation. Statistical evaluation of fossils using m e a s u r e -

century, scientists going through m u s e u m collections saw differ-

ments of key features is often currently used to define intraspecies

ences in s p e c i m e n s and gave t h e m new n a m e s , or listed t h e m as

variability, and the c o m p a r i s o n of derived (uniquely shared)

subspecies, by n o t i n g the n a m e on a label and leaving it with the

characteristics between closely related species is used to deter-

s p e c i m e n . T h e s e " m u s e u m l a b e l " n a m e s are c o m m o n l y e n c o u n -

mine their evolutionary relationship. S y s t e m a t i c s is the study of

tered with the Ordovician trilobites at the National M u s e u m of

the similarities and differences in o r g a n i s m s and their related

Natural History ( S m i t h s o n i a n o r U S N M ) . M u s e u m label names

species. A. B. S m i t h ( 1 9 9 4 ) presented an excellent in-depth review

are not recognized by the I C Z N and have no priority or recogni-

of systematics for the fossil record.

tion, except when subsequent a u t h o r s c h o o s e to use t h e m to

T h e rules of zoological n o m e n c l a t u r e now require that an

name specimens.

Later a u t h o r s

recognized

these

unpublished

men that clearly exemplifies this new species. T h i s specimen

s c r i p t " ) . T h e official date for the n a m e is when it is published,

should then be deposited in an appropriate public collection,

however, not when the m u s e u m label was m a d e . An example of

such as a m u s e u m . T h i s o n e specimen is called the h o l o t y p e .

such a n a m e is Isotelus walcotti Ulrich in C. D. Walcott, 1918. In

Other specimens of a

reference g r o u p

this case E. O. Ulrich saw differences between the specimens from

hypodigm)

the

(the " t y p e series" or

n a m e s with

sometimes

author, when describing a new species, must designate a speci-

the designation " M S " (for " m a n u -

called

the New York Trenton L i m e s t o n e , which were being called Isotelus

paratypes. In the 1800s and early 1900s authors often illustrated

iowensis, and the a u t h e n t i c trilobite f r o m Iowa. He n a m e d the

their new specimens but failed to designate a single type speci-

New York species /. walcotti on a m u s e u m label, and C. D. Walcott

men and its repository. Later authors in referring to these speci-

recognized the n a m e in a subsequent publication in 1918. T h e r e

mens, provided they could be f o u n d , consider the m e m b e r s of the

is no specific rule or protocol for the recognition of m u s e u m label

from

which

holotype

was

chosen

are

type series to be syntypes. T h e term c o t y p e is also seen in c o l -

n a m e s , and it is solely to the discretion of the publishing author

lections; it is a synonym for syntype or paratype and its use is dis-

whether the n a m e is recognized or not. Walcott chose to recog-

couraged by the I C Z N . Should an a u t h o r need to c h o o s e a single

nize Ulrich; thus it is appropriate, but not required, to add his

specimen from the designated syntypes to be the single species

n a m e to the final f o r m a l trilobite n a m e .

The Biology of Trilobites

T r i l o b i t e s are the earliest u n a m b i g u o u s arthropods found in the

Exoskeleton

fossil record, evidently because they were the first a r t h r o p o d s to develop the mineralized skeleton necessary for frequent preser-

T h e word trilobite, freely translated from Latin, m e a n s " h a v i n g

vation. M o d e r n arthropods have o r g a n i c e x o s k e l e t o n s that are

the nature of three lobes." T h e n a m e refers to the three length-

often strengthened with minerals such as calcite. In contrast,

wise, lateral parts or lobes of the trilobite body (Figure 2.1 A ) , not

trilobites had an exoskeleton c o m p o s e d primarily of calcite,

the three parts m a k i n g up the b o d y — t h e cephalon or head

although it undoubtedly was modified with organic materials or

(Figure 2.1 D ) , t h o r a x (Figure 2 . 1 E ) , and pygidium or tail (Figure

other minerals. T h e appendages, legs, and a n t e n n a e were p r o b a -

2 . I F ) . T h e central of the three lobes is referred to as the axial lobe

bly an organic material like the chitin of extant a r t h r o p o d s , which

(Figure 2 . I B ) and the side lobes of the thorax and pygidium, as

is o n l y preserved when replaced by minerals under special c o n -

the pleural lobes (Figure 2 . 2 C ) .

ditions (see C h a p t e r 3 ) . N o n e of the organic skeletal materials

Trilobites

and

other

arthropods

probably

evolved

from

have survived directly in the fossil record. T h e word a r t h r o p o d

annelid wormlike ancestors. T h i s is reflected in their segmented

m e a n s " j o i n t e d foot or leg," and the phylum A r t h r o p o d a includes

b o d y and the observation that each segment, whether fused

trilobites, crabs, lobsters, spiders, horseshoe crabs, centipedes,

together or j o i n t e d , carries a pair of appendages. T h e segments in

millipedes, and the largest of all living a n i m a l groups, the insects.

the front of the b o d y are fused to form the cephalon, and those

T h i s large group includes animals with strong external skeletons

in the rear of the b o d y are fused to f o r m the pygidium. T h e

that must be shed periodically to enable physical growth. M a n y

central segments f o r m i n g the thorax or trunk were j o i n e d by flex-

also go through o n t o g e n e t i c phases in their growth, which can

ible tissue that enabled m a n y trilobites to flex inward to the point

include free-ranging n e a r - m i c r o s c o p i c larvae.

of enrolling (Plate 1 0 9 ) , but probably did not allow for m u c h , if

T h i s chapter is divided into four parts: the external skeleton

any, sideway flexing. S o m e trilobites are found arched or flexed

or exoskeleton, the growth phases or ontogeny, the appendages

dorsally, which

and internal a n a t o m y ( t h e unmineralized or soft b o d y p a r t s ) , and

culation. For a m o r e detailed a c c o u n t of the elements of trilo-

indicates the flexibility of the trilobite arti-

the m o d e of life of trilobites. T h i s order roughly c o r r e s p o n d s to

bite articulation, see the publications by Whittington ( 1 9 9 2 ) ,

the level of knowledge about the biology of trilobites, as most is

B e r g s t r o m ( 1 9 7 3 ) , Levi-Setti ( 1 9 7 5 , 1 9 9 3 ) , M o o r e ( 1 9 5 9 ) , and

k n o w n a b o u t the exoskeleton and least is known about the life-

Kaesler ( 1 9 9 7 ) . T h e work by M o o r e ( 1 9 5 9 ) , Treatise on Inverte-

m o d e . T h e last part, l i f e - m o d e , is inferred from knowledge of

brate Paleontology, Part

trilobites in the fossil record and observations of living a r t h r o -

simply as the Treatise. Kaesler's publication ( 1 9 9 7 ) is the first of

O, A r t h r o p o d a

1, often

is referred

to

pods. All of the illustrations were c h o s e n from trilobite genera

a three-part revision in progress but only the first part has been

f o u n d in New York.

released. F o u r t e r m s are used repeatedly in describing trilobites. T h e s e are dorsal, m e a n i n g the uppermost surface of the body in the animal's life position; ventral, the lower surface of the body;

•1

FIGURE 2 . 1 . Trilobite structure using Eldredgeops rana (PRI 4 9 6 5 6 , w h i t e n e d ) . A. The three lobes from w h i c h the n a m e trilobite w a s d e r i v e d . B. The axial lobe. The axial lobe is s u b d i v i d e d into the thoracic axis a n d the p y g i d i a l axis. C. The pleural lobes. These may be further d e f i n e d as thoracic pleurae a n d p y g i d i a l pleurae. D. The c e p h a l o n or h e a d of the trilobite. E. The thorax. F. The p y g i d ium or tail. G. The glabella. H. The eyes. I. The p a l p e b r a l lobes on top of the eyes.

FIGURE

2 . 2 . Trilobite

structure

using

Ketlneraspis

tuberculata

(GJK

collection,

whitened).

A.

The

exoskeleton without the right free c h e e k . B. The genal spine e x t e n d i n g off the free cheek (arrow). C. Lateral thoracic pleural s p i n e s (arrows). D. Pygidial spines (arrow). E. Anterior c e p h a l i c s p i n e s (arrow). F. Axial n o d e s , raised areas on the thoracic axis (arrows). G. Axial o c c i p i t a l n o d e (arrow). H. Pustules, small, r a n d o m l y scattered raised areas (arrow).

7

EXOSKELETON a n t e r i o r , toward the front; and p o s t e r i o r , toward or at the rear of

T h e glabella is the dorsal covering of the s t o m a c h of the trilo-

the body part being described. Dorsal and ventral are absolute

bite. It usually has lateral grooves in its surface known as lateral

terms in the sense that the dorsal and ventral surfaces are the

glabellar f u r r o w s (Figure 2 . 3 G ) . T h e furrows rarely cross the

same regardless of the part being described or its o r i e n t a t i o n .

surface completely but can be deep, f o r m i n g p r o m i n e n t areas on

Anterior and posterior relate to the particular part or parts being

the glabella called lateral glabellar l o b e s (Figure 2 . 3 F ) or simply,

described. T h u s , a suture, or inflexible j o i n i n g , might be anterior

glabellar lobes. Because of the use of furrows and lobes in trilo-

to o n e body part and posterior to another.

bite identification, they are designated starting f r o m the occipital

T h e hard mineral exoskeleton, also called the c u t i c l e , is a

ring and occipital furrow. T h e furrow or sulcus separating the

complex structure. T h e external surface is variously o r n a m e n t e d

occipital ring f r o m the glabella is labeled S O ; the next most ante-

with ridges, terrace lines, n o d e s (Figure 2.2F, G ) , pustules (Figure

rior glabellar furrow is S I , a n d so o n . ( T h e O in SO and LO refers

2 . 2 H ) , tubercles, and spines (Figure 2 . 2 B , C, D ) . Terrace lines are

to " o c c i p i t a l " a n d is n o t a zero.) T h e lobes are similarly desig-

c o m m o n on the trilobite exoskeleton and are described in s o m e

nated, with the occipital ring called L O , the lobe directly anterior

detail by Miller ( 1 9 7 5 ) . Nodes are discrete, r o u n d e d , raised areas

to it L I , and so forth. It is not always easy to distinguish the most

on the dorsal exoskeleton, which are usually bilaterally s y m m e t -

anterior lateral lobes because the furrows can be very faint; thus,

rical (Plates 45 and 1 3 4 ) . Pustules, on the o t h e r h a n d , are raised

the most a n t e r i o r p o r t i o n of the glabella is called La, for anterior

areas that are m o r e frequent on the surface and also tend to be

glabellar lobe. T h e furrow separating the glabella from the cheek

more r a n d o m l y distributed (Plates 24 and 2 5 ) . Large pustules

area (Figure 2 . 3 H ) is the glabellar furrow. On m a n y trilobites the

are often called tubercles (Plate 2 7 ) . T h e r e c o m m o n l y are c h a n -

edge of the c e p h a l o n is distinctive (Figure 2.31) and is called the

nels from the surface of these structures to the interior, and it is

border.

believed

that

these

channels

served

for

sensory

capability,

T h e cheeks generally bear the eyes of the trilobite (Figure

enabling the trilobite to sense currents and chemical changes

2 . 1 H ) . ( T h e r e are eyeless, presumably b l i n d , trilobites but these

to the e n v i r o n m e n t (Figure 2 . 6 ) . S o m e of these perforations also

are an exception a n d will be n o t e d in the specific descriptions.)

may have been follicles for sensory hairs. Dorsal spines are the

T h e eye is often p r o m i n e n t l y raised, actually being on a stalk, in

physically extended equivalents to nodes (Plates 46 and 1 2 8 ) .

a few species. T h e area between the eye and the glabella is called

Spines, which extend or radiate from the edges of body parts, will

the palpebral area (Figure 2.11) and can have its o w n furrows and

be discussed later.

lobes.

T h e cephalon is the most c o m p l e x and the m o s t i m p o r t a n t

T h e surface of the eye has multiple lenses to form images,

part of the trilobite to be understood by the student or collector

a n d this surface can be very distinctive. Eyes with a closely

because it is often the m o s t easily recognized evidence for trilo-

packed optical structure a n d a s m o o t h , c o n t i n u o u s o u t e r surface

bites in the rocks.

The center of the cephalon is the glabella

( c o r n e a ) are called h o l o c h r o a l (Figure 2 . 4 A ) . Although they have

(Figure 2 . 1 G , 2 . 3 E ) , a raised p o r t i o n with characteristics often

a s m o o t h a p p e a r a n c e , these are c o m p o u n d eyes, similar to those

important to the recognition of trilobite species. Although the

in s o m e m o d e r n insects. Eyes with discrete individual lenses,

glabella is treated here as separate from the occipital ring (Figure

each with its o w n corneal surface, are called s c h i z o c h r o a l (Figure

2.3F, the lobe labeled L O ) , the t e r m i n o l o g y used in the Treatise,

2 . 4 B ) . In addition, the lenses in schizochroal eyes are separated

most trilobite workers today include the occipital ring as part of

by a thick interlensal sclera. T h e r e is a third type of eye, resem-

the glabella (this latter protocol is used in the Kaesler ( 1 9 9 7 ) . Lat-

bling the schizochroal eye, f o u n d in the family Pagetidae, called

erally outward from the glabella are the cheeks or genae (sin-

a b a t h o c h r o a l (Jell 1 9 7 5 ) . A b a t h o c h r o a l eyes lack the deep inter-

gular, gena). T h e s e areas usually have sutures (Figure 2.5) that

lensar scleral p r o j e c t i o n and the intrascleral m e m b r a n e of schizo-

separate t h e m into free cheeks (Figure 2 . 3 C ) and fixed cheeks

chroal eyes.

(Figure 2 . 3 D ) , called librigenae and fixigenae, respectively. T h e

Holochroal eyes arc found in the majority of trilobites, w h i l e

librigenae usually separate from the cephalic area on m o l t i n g , and

the schizochroal eyes are f o u n d only in the s u b o r d e r Phacopina,

the fixigenae remain p e r m a n e n t l y attached. T h e glabella, together

which arose in the O r d o v i c i a n and disappeared by the end of the

with the fixagenae, is called the c r a n i d i u m (Figure 2 . 3 B ) . M a n y

D e v o n i a n . P h a c o p i n s are well represented in New York, and this

trilobite species, particularly in the C a m b r i a n , are differentiated

type of eye structure is often observed. T h e n u m b e r of optical

on the basis of details in their cranidia. T h e posterior part of the glabella, the occipital ring, is a raised portion almost always separated from the main body of the

elements in schizochroal eyes is usually less, often far less, than that in h o l o c h r o a l eyes. In a series of elegant e x p e r i m e n t s , Towe

(1973)

demon-

glabella by a groove. S o m e occipital rings have a central p r o m i -

strated that the eyes in at least two trilobites were single crystal

nently raised area, n o d e , or spine that is very characteristic for

calcite oriented to give high-quality imaging. Towe mounted

particular genera or species. Spines are often overlooked because

the eye surface of Eldredgeops rana and an Isotelus species and

of the ease with which they are broken o f f and lost during the

demonstrated

process of removing the trilobite from the rock.

species) and each lens of a schizochroal eye (E. rana) gave an

that

each

facet

of a

holochroal

eye

(Isotelus

FIGURE 2.3. The structure of the trilobite c e p h a l o n

using

Calymene s p e c i e s (S.

Insalaco collection,

w h i t e n e d ) ( c e p h a l o n only). A. C e p h a l o n lacking the right free c h e e k . B. The c r a n i d i u m (arrow). C. Free c h e e k (arrow). D. Fixed c h e e k s (arrows). E. The g l a b e l l a (arrow). F. The glabella, with the glabellar lobes n u m b e r e d (arrows). G. The glabella, with the lateral glabellar furrows n u m b e r e d (arrows). H. The glabellar furrows (outlined, with arrows). I. The c e p h a l i c border (arrows).

9

EXOSKELETON

FIGURE

2.4.

Trilobite

eyes.

holochroal e y e s (arrow). B.

FIGURE 2.5.

A.

C e p h a l i c sutures. A.

c e p h a l i c sutures (arrows),

Monodechenella

macrocephala

(G.

Jennings

collection,

whitened)

with

Viaphacops bombifrons ( G J K c o l l e c t i o n , w h i t e n e d ) with s c h i z o c h r o a l eyes (arrow).

Ceraurus pleurexanthemus (GJK c o l l e c t i o n , w h i t e n e d ) s h o w i n g p r o p a r i a n

both e n d s e m e r g i n g anterior to the g e n a l a n g l e .

B.

Calymene niagarensis (S.

Insalaco collection) with g o n a t o p a r i a n c e p h a l i c sutures (arrows), the posterior e n d e m e r g i n g at the g e n a l angle. O n e free c h e e k has b e e n lost on the right side. C. Isotelus maximus (PRI 4 9 6 5 1 ) with o p i s t h o p a r i a n c e p h a l i c sutures (arrows), w h e r e the posterior e n d e m e r g e s a l o n g the rear of the c e p h a l o n . D. Calyptaulax callicephalus (GJK c o l l e c t i o n , w h i t e n e d ) , a trilobite in w h i c h the facial sutures are f u s e d a n d do not s e p a r a t e u p o n molting. This is c o m m o n in the order P h a c o p i d a .

inverted image when viewed from the rear, just as a simple glass

showed clear evidence of optical fibers extending f r o m the lens

lens does.

into the central c e p h a l o n . O n e asteropyge in their study also had

S t u n n e r and Bergstrom ( 1 9 7 3 ) studied the internal structure

similar fibers e x t e n d i n g f r o m the lens. T h e s e structures were c o n -

of the eyes of Phacops s p e c i m e n s f r o m the H u n s r i i c k slates in

sidered c o m p a r a b l e to similar structures in extant a r t h r o p o d s .

Germany. S o m e of the soft tissue of the trilobites was replaced by

Structures of this kind were reported previously in asteropyges

the mineral pyrite (i.e., it was pyritized), a n d X - r a y p h o t o g r a p h s

but not c o n f i r m e d until this study.

10

THE

BIOLOGY

OF

TRILOBITES

On m a n y trilobites there is a medial, glabellar n o d e on the

Naroidae to 40 or m o r e . Each segment has a central or axial

meraspid (juvenile) that generally disappears by the holaspid

p o r t i o n and a lateral part on each side of the body called the

(adult) phase or early in the holaspid growth. T h i s n o d e is inter-

pleura (plural, pleurae). T h e usually grooved pleurae also may

preted as having a visual or light-sensing capability ( R u e d e m a n n

extend laterally beyond the body into short rounded extensions

1 9 1 6 b , Jell 1 9 7 5 ) . Cryptolithus is a c o m m o n O r d o v i c i a n trilobite

called lappets (Plates 50 to 5 6 ) or even into m o r e extended and

genus in New York that lacked n o r m a l eyes b u t retained this

pointed pleural spines (Figure 2 . 2 C ) . T h e distinction between

median glabellar n o d e into the m a t u r e holaspis (Plates 163 to

lappets and spines is qualitative, and in s o m e cases it is not clear

1 6 7 ) . A review of the evolution of trilobite eyes with references

whether the extensions should be termed long lappets or short

for detailed reading is given by C l a r k s o n ( 1 9 7 5 ) . M o r e will be said

spines (Plates 46 and 4 8 ) . O t h e r structures can increase flexibil-

about eye function later in this chapter when the possible m o d e s

ity and s o m e t i m e s tight enrolling, but these are beyond the scope

of life of trilobites are discussed.

of this b o o k . T h e s e structures are covered in detail in the work

In p o s t - C a m b r i a n and m o s t C a m b r i a n trilobites there is a

by Bergstrom ( 1 9 7 3 ) .

suture r u n n i n g across the upper edge of the eye, separating the

T h e most posterior part of the trilobite is the pygidium

lens surface f r o m the palpebral area. T h i s suture or separation

(Figure 2 . I F ) . T h e pygidium, similar to the thorax, has segments

continues to the edge of the c e p h a l o n in b o t h directions and

with axial and pleural p o r t i o n s . However, the pygidial segments

results in a portion of the cheek area (librigena) that can separate

are totally fused so there is no flexibility a m o n g the parts. T h e

from the c r a n i d i u m . T h i s facial or cephalic suture separates the

n u m b e r of axial segments, the n u m b e r of pleurae, and the general

free cheek (librigena) f r o m the fixed cheek (fixigena).

shape of the pygidium are often diagnostic to species. Pygidia are

In most C a m b r i a n trilobites an additional suture runs below

c o m m o n in the trilobite fossil record, and these features are very

the eye and j o i n s the facial suture, f o r m i n g the c i r c u m o c u l a r

i m p o r t a n t to the identification of trilobites. T h e pygidium can

suture so that the visual surface separates on m o l t i n g and is lost.

have marginal lappets or marginal spines (Figure 2 . 2 D ) as exten-

It is also c o m m o n in articulated calymenids for the visual surface

sions of the pleurae, and s o m e t i m e s has a central posteriorly

to be missing. T h i s a b s e n c e suggests that a suture s u r r o u n d e d the

directed spine called the t e r m i n a l axial spine (Plate 8 8 ) . In addi-

visual surface or that it was weakly mineralized, if at all.

t i o n , there is s o m e t i m e s a narrow featureless area around the

T h e a n t e r i o r margin of the c e p h a l o n is rounded and the pos-

margin of the pygidium simply called the border. In s o m e genera

terior margin is less curved laterally, resulting in the f o r m a t i o n of

of trilobites, the pygidium is almost featureless, and when f o u n d

a c o r n e r at the posterolateral e x t r e m i t y k n o w n as the genal angle.

separate, it looks like n o t h i n g m o r e than a dark t h u m b n a i l on or

I )epending on the species, this structure varies f r o m a blunt well-

in the rock. T h i s finding should not be overlooked as an indica-

rounded angle to a genal spine (Figure 2 . 2 B ) that extends back

tor o f the presence o f particular species.

along the body. O n e end of the facial suture crosses the genal area

On the surface of m a n y trilobites, there are pitted areas that

and emerges o n the anterior m a r g i n o f the c e p h a l o n , and the

often penetrate the exoskeleton. T h e exoskeleton of the large

o t h e r e n d emerges either in front or b e h i n d the genal angle. If

trilobite Dipleura dekayi is literally covered with pits, seen

both ends of the sutures emerge a n t e r i o r to the genal angle, it is

Figure 2.6A as small white specks. Figure 2 . 6 B shows a broken

known as a p r o p a r i a n (Fig 2 . 5 A ) suture; if o n e end emerges on

area of this trilobite, with the pits as complete perforations

the posterior cephalic m a r g i n , the suture is called opisthoparian

through the cuticle. Isotelus gigas is similarly covered with pits

in

(Figure 2 . 5 C ) . As o n e might expect, there are trilobites where the

(Figure 2 . 6 D ) . Pits such as on these two trilobites may have served

suture emerges precisely o n , or very near, the genal angle, and that

a sensory purpose and may have contained sensory hairs. A dif-

condition is called g o n a t o p a r i a n (Figure 2 . 5 B ) . In s o m e trilobites

ferent kind of pit is seen on the cephalic border of Cryptolithus

the cephalic suture (Figure 2 . 5 D ) is fused and does not o p e n on

species (Figure 2 . 6 C ) . T h e s e are also perforations but go c o m -

molting.

pletely through the b o r d e r area. T h e i r role is u n k n o w n , but they

T h e area immediately in front of the glabella varies from

m a y have served to sense water currents or m o v e m e n t .

nearly nonexistent to a broad b o r d e r platform or b r i m . In s o m e

T h e exoskeleton covering the entire dorsal surface of the trilo-

families, particularly the calymenids (Figure 2.31), the shape of

bite s o m e t i m e s curls under at the edges of the cephalon and

this area is i m p o r t a n t to the identification of genera.

pygidium to form the doublure (Figure 2 . 7 H , I ) , a fiat terrace

S o m e t i m e s this anterior b o r d e r has a lateral furrow. T h e area

a r o u n d the ventral edges of the cephalon and pygidium. In addi-

between this preglabellar furrow and the glabellar furrow is the

tion to the d o u b l u r e , there are two important pieces of the

preglabellar field (Plates 139 a n d 1 4 2 ) . T h e area between the

exoskeleton on the ventral side of the cephalon. T h e rostral plate,

preglabellar groove and the a n t e r i o r margin

is the a n t e r i o r

cephalic border.

found on m a n y but not all trilobites, is a c o n t i n u a t i o n of the d o u blure b u t is separated from the rest of the cephalon by sutures; it

T h e t h o r a x is divided into a n u m b e r of segments that f o r m a

is located directly under the front central part of the cephalon

highly flexible part o f the exoskeleton. T h e n u m b e r o f t h o r a c i c

(Plate 65 shows a displaced rostral plate immediately in front of

segments can range from zero in the unusual C a m b r i a n family

the c e p h a l o n ) . Under the a p p r o x i m a t e center of the cephalon is

FIGURE 2.6.

Exoskeletal pits or circular perforations. A. Dipleura dekayi(PR\ 4 9 6 2 9 ) . White s p e c k s over

the b o d y are sediment-filled pits. The arrow points to the area s h o w n in B. B. C l o s e - u p of Dipleura pits, showing

that they e x t e n d

through

the

exoskeleton

(arrow).

C.

Cryptolithus

lorettensis (PRI

49657,

whitened), s h o w i n g pits on the c e p h a l i c border (arrow). These are actually perforations that e x t e n d all the way through the border. D. Isotelus gigas (TEW collection, w h i t e n e d ) . The exoskeleton' is heavily pitted (arrow),

a d i a g n o s t i c character of this s p e c i e s .

E.

Greenops grabaui (F.

Barber collection,

whitened), s h o w i n g rows of circular perforations characteristic of the New York a s t r o p y g i d s . F. Greenops? species (GJK collection, w h i t e n e d ) . U n n a m e d , new?, s p e c i e s of Greenops in w h i c h the circular perforations are d e g e n e r a t e .

12

THE

BIOLOGY

OF

TRILOBITES

FIGURE 2.7. Ventral a n a t o m y of the exoskeleton. A-D.

Ceraurus pleurexanthemus

(PRI

49658,

whitened), p r e p a r e d to show the ventral exoskeleton. B. The h y p o s t o m e (arrow). C. Two of the a p o d e m e s (arrows). The a p o d e m e s are a r r a n g e d along the ventral surface u n d e r the axial furrow. There is a pair of a p o d e m e s for e a c h pair of c e p h a l i c a p p e n d a g e s , two for e a c h pair of thoracic a p p e n d a g e s ( w h i c h also c o r r e s p o n d to the n u m b e r of thoracic s e g m e n t s ) , a n d a p o d e m e s a s s o c i a t e d with the p y g i d i a l a p p e n d a g e s . The often large n u m b e r s of pygidial a p p e n d a g e s are not as well reflected in prominent a p o d e m e s . D. The arrows point out the entrance into the hollow exoskeletal genal spines, pleural s p i n e s , a n d pygidial spines. E-l. Isotelus s p e c i e s (Kevin Brett collection), ventral exoskeletal anatomy. A s p e c i m e n from C a n a d a . F. The h y p o s t o m e (arrow), the anterior m a r g i n a n d " w i n g s " of w h i c h are under the d o u b l u r e . G. The a p o d e m e s (arrows) of Isotelus, w h i c h are far less prominent than t h o s e of Ceraurus. Given that these represent m u s c l e a t t a c h m e n t , the shape must represent their use a n d consequently the life-mode of the trilobite. H. The cephalic d o u b l u r e (arrow). I. The p y g i d i a l doublure (arrow), w h i c h is i n c o m p l e t e in this specimen.

a

rounded plate called the h y p o s t o m e

(plural, h y p o s t o m a )

(Figure 2 . 7 B , F ) . T h e m o u t h was a t the rear o f the h y p o s t o m e . T h e h y p o s t o m e is a m o r e i m p o r t a n t feature. F o r s o m e species

T h e a t t a c h m e n t of the h y p o s t o m e is proposed to have significance for the h i g h - o r d e r classification of trilobites (Fortey [1990a]

using observations

m a d e by Fortey and C h a t t e r t o n

it is very robust, distinctive, and a not u n c o m m o n part of the

[ 1 9 8 8 ] ) . Natent h y p o s t o m a are those separated from the cephalic

fossil record. (In at least o n e rare O r d o v i c i a n trilobite, Hypodi-

d o u b l u r e , or rostral plate when present, by a gap and are dis-

cranotus, the presence of its h y p o s t o m e is a very g o o d indicator,

placed or absent in m o s t trilobite specimens. C o n t e r m i n a n t

and o n e o f the only indicators, o f its stratigraphic range.) T h e

h y p o s t o m a are closely j o i n e d to the cephalic d o u b l u r e or rostral

significance of the h y p o s t o m e will be pointed o u t for the indi-

plate and consequently are m o r e likely to be present on speci-

vidual species. T h e h y p o s t o m e is directly under the glabella, and

m e n s (Figure 2 . 7 B , F ) . In both of the above cases, the anterior

together they f o r m an envelope covering and protecting the

margin of the glabella is directly above the anterior margin of the

s t o m a c h . T h e m o u t h of the trilobite was at the posterior central

h y p o s t o m e . T h e third type of h y p o s t o m e , i m p e n d e n t , is when

n o t c h of the h y p o s t o m e (Plates 3 7 , 4 7 , 77, 117, 153, and 1 5 7 ) .

the anterior margin of the h y p o s t o m e is not close to the anterior

13

ONTOGENY margin of the glabella and the anterior margin of the glabella

O n e needs very sharp eyes to spot t h e m a m o n g the n o r m a l fossil

coincides with the cephalic margin. Examples of trilobites with

debris, or to spend hours with a s t e r e o m i c r o s c o p e scanning likely

the different types of h y p o s t o m e a t t a c h m e n t are as follows:

surfaces. M o s t protaspides that have been studied are those in

n a t e n t — s o m e proetids; c o n t e r m i n a n t — / . gigas (Plates 153 and

which their exoskeletons have been replaced by silica, since silici-

155)

fied fossils survive acidic dissolution of a limestone or shaly

£.

and

Cerauruspleurexanthemus

(Plate

77);

and

impendent—

rana.

m a t r i x . O n e then uses the m i c r o s c o p e to pick out the important

Under the lateral sides of the ventral axial region of the t h o -

material f r o m the insoluble residue, including protaspides. T h e

racic segments, glabella, and pygidium are thickened areas called

advantage of this procedure is that in silicified material, very fine

apodemes (Figure 2 . 7 C , G ) o r s o m e t i m e s a p p e n d i f e r s . T h e a p o -

details, including spines and in s o m e cases h y p o s t o m a , are often

demes are believed to have been points of muscle a t t a c h m e n t and

preserved.

may provide evidence for the lifestyle of the trilobite. On s o m e trilobites,

such

as

Ceraurus

pleurexanthemus

(Plate

77),

T h e shape and o t h e r physical features of the protaspis are

the

u n i q u e for specific fossil families and genera, and for this reason

apodemes extend down from the ventral surfaces of the segments

the protaspides are used for t a x o n o m i c assignments and confir-

to form p r o m i n e n t ridges or posts, yet in others, as illaenids, the

m a t i o n ( C h a t t e r t o n and Speyer 1 9 9 7 ) . Protaspides are assigned

apodemal area is fairly s m o o t h . T h e long a p o d e m e s suggest g o o d

to specific trilobites a n d growth series through association with

leverage for the attached muscles and a high level of l i m b m o b i l -

pieces of the m o r e m a t u r e fossil in the same debris and through

ity, perhaps for s w i m m i n g , rapid crawling, or digging.

the prior knowledge of protaspis-adult relationships. Using the presence of m a t u r e trilobites, however, is not always a secure way to assign protaspis-adult relationships.

Ontogeny

It is p r o b a b l e that the pre-protaspid and protaspid phases of

O n t o g e n y is the biological life cycle of an animal; for the trilo-

the trilobite growth cycle served to disperse the trilobites in their

bite this would be from the presumed egg to the smallest larvae

e n v i r o n m e n t , similar to the situation with m a n y m o d e r n m a r i n e

and the various intermediate stages, to the end of its life cycle.

Crustacea. S o m e protaspides were benthic ( b o t t o m dwelling) and

Considerably m o r e is k n o w n about the adult phase of the trilo-

others planktic (in the p l a n k t o n ) , drifting in the Paleozoic seas.

bite life cycle because the vast p r e p o n d e r a n c e of the fossil record

Because o f their differing l i f e - m o d e and preservation, s o m e p r o -

is c o m p o s e d of the pieces of the exoskeleton representing late

taspides m a y never be f o u n d or never be associated with their

growth stages. Careful workers have f o u n d , however, a significant

later growth and adult phases.

a m o u n t of i n f o r m a t i o n related to trilobites' earlier growth stages.

Parts B and C in Figure 2.8 show two protaspides of trilo-

Chatterton and Speyer ( 1 9 9 7 ) provide an extensive and current

bites f r o m the Lower D e v o n i a n of New York. T h e o n e in B is a

review of the present state of knowledge of trilobite ontogeny.

lichid (family Lichidae) and the o n e in C is a phacopid (family

Trilobites most likely began life as an egg, which was either laid

P h a c o p i d a e ) . T h e y are magnified to the s a m e scale and each is

outside the body or hatched within the a n i m a l , although there is

a b o u t a m i l l i m e t e r in actual length. At this phase of growth,

no unequivocal evidence of trilobite eggs. C. D. Walcott ( 1 8 7 7 c ) ,

morphological

in a study of remarkably well-preserved trilobites in New York,

in the adult, are given the profo-prefix. T h u s , the protaspis has a

features, which

represent

a

future body part

found spherical objects within the cross sections of s o m e trilo-

protocephalon,

bites, which he identified as eggs. T h i s and earlier reports a b o u t

adults, and a p r o t o p y g i d i u m . Trilobites also had growth stages

described

similarly

to

the

cephalon

of the

trilobite eggs by Barrande in 1852 apparently have not been inves-

within the protaspid phase. T h i s is observed by increases in the

tigated completely.

n u m b e r of lateral lobes on the glabellar axis and the general size

T h e well-defined phases of trilobite growth are labeled the

(Figure 2 . 8 A ) . T h e p r o t o c e p h a l o n and p r o t o p y g i d i u m , however,

protaspid, meraspid, and holaspid phases. Fortey and M o r r i s

are fused and r e m a i n together in the molted protaspid exoskele-

Lower

ton, although the free cheeks and the h y p o s t o m e may be deta-

Ordovician as a pre-protaspid phase of trilobite called phaselus.

c h e d . Each successive molt is called an instar (Figure 2 . 8 A ) .

Chatterton and Speyer ( 1 9 9 7 ) also found phaseluses in beds with

W h e t h e r or not there is a direct correlation between the n u m b e r

silicified trilobite remains. It is still not clear whether these are

of instars and the n u m b e r of m o r p h o l o g i c a l l y defined phases is

from trilobites or a n o t h e r fossil a r t h r o p o d .

not clear.

(1978)

described

some

small

exoskeletons

from

the

T h e first well-defined phases in growth of the trilobite, after

W h e n the trilobite larvae clearly begin to display the separa-

the presumed egg and the phaselus, is the protaspid phase. ( T h e

tion of the p r o t o c e p h a l o n f r o m the p r o t o p y g i d i u m , they are

name protaspis (plural, protaspides)

was given to the individual

referred to as being in the meraspid phase (Figure 2 . 8 E ) . T h e

silicified exoskeletons found in or on rocks by C. Beecher ( 1 8 9 3 a ,

segments develop from the anterior of this transitory pygid-

1893b).) Protaspides are difficult to find because of their small

i u m . ( O n c e the s e g m e n t a t i o n is definite, the protopygidium is

size. T h e larger ones are about the size of the " o " in the printed

no longer " p r o t o " but is still not the final pygidium, as the t h o -

word "protaspis," and m o s t are between that a n d h a l f that size.

racic segments are being f o r m e d anterior to this new pygidial

FIGURE 2.8.

O n t o g e n y of the trilobite. A. Flexicalymene senaria p r o t a s p i d e s from the O r d o v i c i a n of New York. These silicified s p e c -

imens w e r e p r e p a r e d a n d reported on by Chatterton et al. (1990). R e p r o d u c e d with p e r m i s s i o n . B. Possibly a lichid protaspid from the w o r k of B e e c h e r (1893a) a n d r e p r o d u c e d by Whittington (1957). C. A p h a c o p i d p r o t a s p i d from the s a m e source as B. D. The p r o t a s p i d of Isotelus gigas reported on by Chatterton a n d Speyer (1990). R e p r o d u c e d with permission. The s h a p e p r e c l u d e s this p r o t a s p i d from b e i n g a b o t t o m dweller. It p r o b a b l y w a s planktic, living a n d drifting near the surface of the sea. E. Triarthrus m e r a s p i d instars of d e g r e e 1, 2, a n d 4 from Whittington (1957). This is part of a nearly c o m p l e t e g r o w t h series c o l l e c t e d a n d reported on by Walcott (1918). The m e r a s p i d e s are r e p r o d u c e d at a b o u t eight times their life size. F. A growth series of Isotelus gigas holaspides from R a y m o n d (1914). The h o l a s p i d s are natural size. Young Isotelus h o l a s p i d e s have prominent genal s p i n e s , w h i c h are lost, in New York s p e c i m e n s , w h e n they r e a c h a b o u t 5 0 m m l o n g . G. A molting s e q u e n c e for c a l y m e n i d trilobites p r o p o s e d by Mikulic a n d Kluessendorf (2001). The trilobite on the right first p u s h e s its p y g i d i u m into the surface as an anchor, the c e p h a l i c sutures o p e n , and the animal c r a w l s f o r w a r d a n d out. The c e p h a l i c parts held in position by the ventral integument fall b a c k together, leaving a molt with the c e p h a l o n a n d p y g i d i u m c u r v e d d o w n w a r d a n d the thorax in a c o n c a v e curve d u e to the p u s h i n g up of the c r a n i d i u m during the p r o c e s s .

15

ONTOGENY s t r u c t u r e — h e n c e , the n a m e transitory pygidium.) In trilobites the

125 mm

early meraspides show a line of separation f r o m the cephalon on

Trenton age rocks of New York.

(5

inches)

are c o m m o n

in

the

Middle Ordovician

the anterior margin of the transitory pygidium but no t h o r a c i c

As in all a r t h r o p o d s , growth in trilobites required that the

segments. This is referred to as a "degree 0 meraspis." D u r i n g suc-

exoskeleton be shed or molted at regular intervals. In modern

cessive molts, as the segments detach from the transitory pygid-

a r t h r o p o d s , m o l t i n g (ecdysis) begins by the f o r m a t i o n of a new

ium and can be considered separate, the meraspis grows in size

cuticle or shell beneath the current o n e , separation of these shells

and degree number. Each detached t h o r a c i c segment is c o u n t e d ,

by a space filled with m o l t i n g fluid, and resorption of much of

and this n u m b e r is the degree assigned to the meraspis. T h e fact

the old cuticle to provide the base chemicals to finish the new

that segments are added from the anterior side of the transitory

o n e . W h e n this process is c o m p l e t e , the old shell splits and

pygidium is ascertained by the growth of trilobites with pleural

the animal emerges with a soft cuticle in place. By swelling this

or axial spines on specific t h o r a c i c s e g m e n t s . T h e spine first

soft cuticle through the intake of liquids, the new body rapidly

appears on a segment adjacent to the transitory pygidium, and

b e c o m e s larger. T h e new exoskeleton then hardens and the

each succeeding segment is added behind it

animal has grown o n e m o r e i n c r e m e n t . Because o f the resorption

until the adult

n u m b e r of segments is reached. There are usually p r o f o u n d changes in the shape of the

of s o m e of the old cuticle, the molted shell is significantly thinner and m o r e fragile than it was on the a n i m a l . T h i s process also

cephalon during the meraspid phase. W h e n the meraspid trilo-

lowers the energy r e q u i r e m e n t s of growth because the resorbed

bite molted, the cephalon and transitory pygidium separated, and

chemicals are available for the new exoskeleton.

thus they are found as distinct e l e m e n t s , unlike the o n e - p a r t p r o -

Trilobite molts, on the o t h e r h a n d , are robust and at least as

taspis molts. T h e meraspis can grow until it gains the n u m b e r of

thick as m o l t s attributed to living a n i m a l s that died and were pre-

free thoracic segments f o u n d in the adult, at which t i m e it is

served. T h i s i n f o r m a t i o n indicates that trilobites did not resorb a

called a

significant a m o u n t o f the minerals o f the old exoskeleton and

holaspis.

Figure 2.8E illustrates a limited growth series of Triarthrus

must have e m e r g e d from the m o l t i n g process with a rather thin

eatoni, part of the only nearly c o m p l e t e series k n o w n from a New

cuticle that was little m o r e than a soft template within which the

York trilobite. T h e meraspides appear to be missing their free

new mineralization t o o k place. Very thin a n d compressed or

cheeks and are probably molts. Meraspids are also k n o w n for

wrinkled trilobite fossils are k n o w n and usually are attributed

Elliptoccphala asaphoides from

the Lower C a m b r i a n of New York

to the exoskeletal remains or impressions of recently molted or

(Ford 1877, 1 8 7 8 ) , but articulated holaspids are rare. Parts D and

" s o f t - s h e l l e d " individuals. T h e r e is at least o n e e x a m p l e of a trilo-

F of Figure 2.8 illustrate the m o r p h o l o g i c a l changes in Isotelus

bite preserved in the Burgess Shale beds that is completely

gigas from the protaspid (Figure 2 . 8 D ) through the early holaspid

unmineralized and believed to be a very recently molted individ-

(Figure 2 . 8 F ) . It is surprising, given the n u m b e r of adult trilobite

ual ( W h i t t i n g t o n 1 9 8 5 ) . T h i s finding suggests that trilobites were

remains found in New York, that so few examples of growth series

vulnerable to predators and external t r a u m a for an extended time

have been recorded. Either the exoskeleton on the juvenile f o r m s

and that building the new exoskeleton required significant energy

of most trilobites is too fragile and not easily preserved in the

from the a n i m a l . It also suggests that as trilobites gained size, they

fossil record, or the juveniles did not o c c u p y areas where their

b e c a m e increasingly vulnerable d u r i n g m o l t i n g and that the

remains could be readily preserved or f o u n d .

n u m b e r of trilobites that might grow to an exceptional size for

T h e trilobite exoskeleton did not necessarily b e c o m e fixed in

the species was severely limited. Early trilobite predators such as

its physical structure at the early holaspid phase. T h e achieve-

Anomalocaris species have been identified in the Middle C a m -

ment of the holaspid phase generally only m e a n s that no m o r e

brian, and the n u m b e r of potential predators such as cephalopods

thoracic segments were added during c o n t i n u e d growth. T h e r e

and fish increased t h r o u g h o u t the Paleozoic.

are, however, variations in the n u m b e r of t h o r a c i c segments in

T h e r e are m a n y possible strategies for trilobite molting, and

the holaspis of a very few species; in Aulacopleura koninki, from

the cephalic sutures play a part in m o s t of t h e m . H e n n i n g s m o e n

the Silurian of B o h e m i a , t h o r a c i c segments were added after the

( 1 9 7 5 ) , M c N a m a r a and Rudkin ( 1 9 8 4 ) , Speyer ( 1 9 8 5 , 1990b,

holaspid phase was reached ( H u g h e s and C h a p m a n 1 9 9 5 ) . F o r

1 9 9 0 c ) , and W h i t t i n g t o n ( 1 9 9 2 , 1 9 9 7 ) discussed specific molting

all other trilobites the segment n u m b e r was stable. Trilobites did

strategies in detail.

not reach maturity, or at least their final body p r o p o r t i o n s , until

fossils in m a n y New York rocks. S i n c e m o s t of these parts are

they grew substantially from the first holaspis. In s o m e trilobites

attributable to molts, significant i n f o r m a t i o n is gained from their

such as Eldredgeops species, the growing holaspis changed very

e x a m i n a t i o n . For e x a m p l e , in Eldredgeops rana, the very c o m m o n

little and the small ones looked essentially like the adults. Isotelus

trilobite of the Middle Devonian of New York, c o m p l e t e cephala

gigas, on the other hand, possessed long genal spines in meraspids

and pygidia are the parts most often f o u n d . T h i s evidence shows

and early holaspides (Figure 2 . 8 F ) and did not lose the spines

that the facial sutures were fused and that the c o n n e c t i o n s

until it reached about o n e - t h i r d the size of a full m a t u r e speci-

between the cephalon and thorax and between the thorax and

men. Isotelus tergites or molt remains from specimens longer than

pygidium were o p e n e d or weakened during the molting process.

Disarticulated exoskeletons are c o m m o n

THE

16 T h e a n i m a l generally emerged through the split between the cephalon and t h o r a x .

BIOLOGY

OF

TRILOBITES

spine is on the lower lamella. An articulated specimen of Cryptolithus without the genal spines can be reasonably assumed to be

O n e often-illustrated set of molt remains is the upright t h o r a x

a molt (Plates 163 and 1 6 5 ) . In s o m e extant arthropods like the

and pygidium, with the inverted c e p h a l o n just in front of it. In

h o r s e s h o e c r a b , however, which uses this same molting technique,

this case the molting animal must have pushed forward after the

the suture can reseal after m o l t i n g and the molted exoskeleton

cephalon and t h o r a x parted, with the forward margin of the

remains whole. T h u s , when o n e finds a whole, articulated Cryp-

cephalon pushed down in the s e d i m e n t . T h i s action would pivot

tolithus s p e c i m e n with

the cephalon molt over upside d o w n , and the a n i m a l could then

absolute certainty it is not a molt.

its genal spines, o n e c a n n o t say with

emerge with the thorax and pygidium almost intact and right

M o s t authors agree on the generalities of trilobite molting, but

side up. That the pygidium is usually f o u n d separate suggests that

s o m e unanswered questions are rarely discussed. T h e roles of the

the c o n n e c t i o n is weakened d u r i n g the m o l t i n g process a n d

ventral, unscleritized i n t e g u m e n t and the scleritized appendages

s o m e t i m e s separates f r o m the t h o r a x d u r i n g or shortly after

have been largely ignored ( b u t see W h i t t i n g t o n 1 9 9 2 ) . It is not

ecdysis. T h e r e are other a r r a n g e m e n t s , besides the o n e just dis-

surprising that there is little preserved evidence for the ventral

cussed, of the m o l t remains of E. rana f o u n d in western New

m e m b r a n e ; there is so little soft tissue evidence from the fossil

York. S. E. Speyer ( 1 9 9 0 c ) , w h o has studied these m o l t r e m a i n s ,

record, and only o n e of the k n o w n soft tissue preservation sites

s u m m e d it up well: "Trilobites, like m o d e r n a r t h r o p o d s , displayed

contains any significant ventral anatomical information beyond

a variety of m o u l t behaviors which vary according to ecological

the appendages (Walcott 1 8 8 1 , 1 9 1 8 ) . In the trilobites in which

considerations (e.g., substrate consistency) and individual c o n v e -

the loss of the free cheeks is an i m p o r t a n t first step in ecdysis, the

nience."

inversion of these parts helps d e m o n s t r a t e the actual process

M o s t other trilobites, however, lose their free cheeks during

( M c N a m a r a and Rudkin 1 9 8 4 ) . B r i e f m e n t i o n is m a d e of the pos-

the m o l t i n g process. T h e most c o m m o n fossil remains of /. gigas,

sibility that the free cheeks m a y still have been attached to the

for e x a m p l e , are cranidia, free cheeks, h y p o s t o m a , and pygidia.

ventral m e m b r a n e and would have been inverted as they c a m e

Separated

specimens

away f r o m the a n i m a l . M c N a m a r a and Rudkin as do others,

without their free cheeks are very rarely f o u n d in the fossil record.

explain the inversion of the cephalon in molt remains as evidence

/. gigas evidently molted by the facial sutures o p e n i n g and the

that the trilobite pushed its cephalon down in front while arch-

whole

cephala

of Isotelus, or articulated

free cheeks separating, with the suture between the c r a n i d i u m

ing its t h o r a x to break away the cephalon at the c e p h a l o t h o r a x

and the d o u b l u r e o p e n i n g , possibly along with a break in the c o n -

suture. As the trilobite c o n t i n u e d to m o v e forward, the cephalon

nection between the t h o r a x and the c e p h a l o n . T h e s e breaks per-

inverted. M a n y trilobites are f o u n d with the inverted cephalon

mitted ecdysis by the trilobite m o v i n g straightforward. T h i s

under the t h o r a x . M a n y of these also have long genal spines.

molting strategy is i m p o r t a n t because /. gigas in the early phase

S o m e trilobite genal spines are totally enclosed except for the

had quite long genal spines, and it had to be able to free t h e m

area at the genal angle. For this m e c h a n i s m to take place, the soft

to molt properly. T h e m o s t efficient way to do this was to

spines must be dragged from their exoskeleton prior to total

emerge in a forward direction through the o p e n e d sutures in the

inversion of the free cheeks. Such a m e c h a n i s m is illustrated by

cephalon.

W h i t t i n g t o n ( 1 9 9 2 , Figure 9 ) . Not illustrated is the final struggle

Spines on the trilobites were hollow, and the tissue inside had to be withdrawn during m o l t i n g (Figure 2 . 7 D ) . Any m o l t i n g

of the a n i m a l during the ecdysis process, which drags the dorsal cuticle forward over the now-inverted free cheeks.

strategy of an individual trilobite must a c c o m m o d a t e the phy-

Based on the observation that calymenid trilobites from the

sical shape of the a n i m a l . Since the newly m o l t e d a n i m a l was

Silurian of W i s c o n s i n and Illinois are often found with the

unmineralized and soft, there must have been s o m e strategy to

cephalon and pygidium curled somewhat down, with a distinct

provide s o m e protection while the new exoskeleton b e c a m e suit-

concave sway to the t h o r a x , Mikulic and Kluessendorf ( 2 0 0 1 )

ably mineralized and hardened.

p r o p o s e that the trilobite molted by pushing its pygidium into

It is not always possible to distinguish the m o l t e d parts from the disarticulated

remains

of a

dead

trilobite.

A

complete

the substrate to a n c h o r it, by the sutures between the free cheeks and c r a n i d i u m as well as the anterior cephalic suture o p e n i n g ,

exoskeleton, with free cheeks, is almost always the fossil of the

and by the animal crawling forward, leaving the old exoskeleton

carcass of a trilobite. As in any rule, however, there are exceptions.

b e h i n d . T h e y further propose that since the upper and lower p o r -

Trinucleids and harpids do not have dorsal facial sutures. T h e

tions of the cephalon are held in place by the ventral integument,

dorsal cheeks and preglabellar areas are separated from the

after the m o l t i n g process the parts fall back into place, leaving a

ventral d o u b l u r e by a suture that runs parallel to the horizontal

molt that may be indistinguishable from a carcass (Figure 2 . 8 G ) .

plane. In o t h e r words, there is a suture separating the dorsal

T h e same process is seen in extant horseshoe crabs, which leave

surface from the ventral surface, and the suture line is a r o u n d the

behind an intact m o l t e d exoskeleton.

edge o f the c e p h a l o n . M o l t i n g o c c u r s b y the o p e n i n g o f this

G r o w t h was rapid during the early holaspid phase and could

suture and the trilobite emerging forward. In trinucleids the genal

be expected to slow as the animal reached maturity. In a few rare

SOFT

BODY

PARTS

17

cases, long periods between molts of larger individual species have been inferred. Tetreault ( 1 9 9 2 ) , Kloc ( 1 9 9 3 ,

only five localities worldwide, including the really remarkable

1 9 9 7 ) , and

new C a m b r i a n sites in C h i n a ( S h u et al. 1 9 9 5 ) . Two of these five

Brandt ( 1 9 9 6 ) observed epizoans (encrusting a n i m a l s ) on whole,

sites are in New York and o n e of t h e m , the Walcott-Rust Quarry,

articulated exoskeletons of several species of trilobites.

Such

was not included in Briggs and Allison's list. I n f o r m a t i o n on soft

encrusters must have been on the living a n i m a l , as articulated

or weakly skeletonized b o d y parts is very rare, and because of this

trilobites would not remain whole unless buried a very short t i m e

these data are generalized to a wide range of trilobites. T h e rarity

after death and epizoans would have little o p p o r t u n i t y to b e c o m e

of this s o f t - b o d i e d i n f o r m a t i o n is exemplified by the remarkably

attached to the buried carcass. T h e s e observations indicate either

preserved biota of the Burgess Shale in British C o l u m b i a . Most

a terminal molt, after which there is little growth in the animal

of what is k n o w n of s o f t - b o d i e d a n i m a l s in the C a m b r i a n initially

with no further molting, or long intervals between molts of the

c a m e f r o m these beds, yet of the 22 species of trilobites k n o w n

mature species. Tetreault further observed that b r a c h i o p o d s on

from the Burgess Shale beds, apparently only 4, so far, have

the exoskeleton of Arctinurus boltoni were in

four distinct size

yielded appendage i n f o r m a t i o n and in o n e of these it is from a

classes.

F r o m this he d e d u c e d , a s s u m i n g these b r a c h i o p o d s

single s p e c i m e n . W h e n you are reading through the following

spawned o n c e a year, that the largest b r a c h i o p o d s were 4 years

descriptions, r e m e m b e r that all the soft tissue data c o m e from a

old and that in m a t u r e Arctinurus animals m o l t i n g was terminal

very few sites and only a bare handful of trilobite species.

or occurred at as m u c h as 4-year intervals.

An indirect relationship of trilobites to the annelid w o r m s was

Many collectors find populations of trilobites that are signi-

introduced earlier. T h i s evolutionary trail is s u p p o r t e d by the

ficantly larger than the n o r m . Excellent s p e c i m e n s of E. rana 5

m u l t i s e g m e n t e d b o d y o f the trilobite a n d the observation that

to 6 . 4 c m (2 to 2.5 inches) long and /. gigas 13 to 1 5 c m (5 to

each recognizable s e g m e n t bears a pair of appendages. This

6 inches) long are not u n c o m m o n . S p e c i m e n s of E. rana of 10 to

observation includes the c e p h a l o n and pygidium, in which the

13 cm (4 to 5 inches) and 7. gigas of 3 0 . 5 cm ( 1 2 inches) and larger

segments are fused. Careful studies, by C. D. Walcott ( 1 8 7 6 , 1 8 8 1 ,

are found, but rarely. T h e largest reported articulated trilobite is

1918, 1 9 2 1 ) , of the s p e c i m e n s he had available established that

an Ordovician asaphid from the Arctic. It is 72 cm ( 2 8 inches)

the appendages are b i r a m o u s (Figure 2 . 1 0 A ) . In o t h e r words,

long.

growth

each individual appendage is divided into two parts, o n e part for

throughout life, as do extant lobsters, and could achieve an excep-

walking, the e n d o p o d (Figure 2 . 1 0 D ) , and o n e part, the e x o p o d

This

indicates

that

some

trilobites

continued

tional size in favorable e n v i r o n m e n t s . R a y m o n d ( 1 9 3 1 ) , describ-

(Figure 2.1 OB), possibly an apparatus similar to the gill of fishes,

ing an unusually large h y p o s t o m e of an Isotelus species from the

for breathing.

Ordovician Chazy limestones, estimated the length of the trilo-

T h e o n l y trilobite appendages that are not b i r a m o u s are the

bite at 61 to 6 4 c m ( 2 4 to 26 i n c h e s ) . Estimates of sizes of o t h e r

most anterior, which are modified into a n t e n n a e (Figure 2 . 1 1 A ,

New York trilobites, from molt remains or partial s p e c i m e n s ,

B , C ) . C . E . B e e c h e r ( 1 8 9 3 c , 1 8 9 4 a , 1 8 9 4 b , 1 8 9 6 ) , after years o f

listed by R a y m o n d are as follows:

study on meticulously prepared Triarthrus eatoni from Beecher's Trilobite Bed, published the m o s t f a m o u s , and m o s t often re-

Basilicas Isotelus Isotelus Isotelus Terataspis Trimerus Coronura

whittingtoni "giganteus" gigas maximus grandis major myrmecophorus

- 1 2 inches

(30 cm)

- 2 4 - 2 6 inches

(61-64 cm)

2 . 1 1 A ) . Beecher, possibly following Walcott's lead, gave T. eatoni

- 1 7 inches

(43 c m )

an extra set of appendages u n d e r the c e p h a l o n , but this does not take away from his r e m a r k a b l e a c h i e v e m e n t .

p r o d u c e d , illustration of the trilobite ventral a n a t o m y (Figure

- 1 8 - 1 9 inches

(46-48 cm)

- 2 0 - 2 4 inches

(51-61 cm)

- 1 5 - 1 6 inches

(38-41 cm)

and

- 1 5 inches

(38 c m )

Raymond

T h e works o f Walcott a n d o f Beecher have been modified augmented

by a

(1920a),

number

Stormer

of later workers,

(1939,

1951),

particularly

Sturmer

(1970),

B e r g s t r o m ( 1 9 6 9 , 1 9 7 2 , 1 9 9 0 ) , B e r g s t r o m and Brassel ( 1 9 8 4 ) ,

Soft Body Parts

Cisne ( 1 9 7 5 , 1 9 8 1 ) , W h i t t i n g t o n ( 1 9 8 0 , 1 9 9 2 ) , and W h i t t i n g t o n and A l m o n d ( 1 9 8 7 ) .

T h e unmineralized or soft parts of the trilobite b o d y are very

B i r a m o u s appendages are also the rule in extant crustaceans.

rarely preserved in the fossil record. Allison and Briggs ( 1 9 9 3 )

In the trilobites all the appendages, with the exception of the

made a listing of sites of exceptional fossil preservation, called by

a n t e n n a e , are very similar, differing primarily in size. All but o n e

the G e r m a n n a m e Konservat-Lagerstatten. T h e y recognized 19

of the trilobites recently studied have three pairs of b i r a m o u s

marine sites worldwide in the Paleozoic, where soft b o d y fossils

appendages in the c e p h a l o n , a pair for each thoracic segment,

are preserved. Nine of these sites are in the United States, and six

and multiple pairs in the pygidial section. Four pairs of b i r a m -

of them yield trilobites. O n l y o n e site in the United States in their

ous cephalic appendages reportedly were f o u n d in o n e trilobite

listing has significant trilobite appendage and o t h e r soft body

( B e r g s t r o m and Brassel

information: Beecher's Trilobite Bed in New York. In fact, most

finding is q u e s t i o n a b l e . In the pygidium the segmentation has to

of what we know about the soft parts of trilobites c o m e s f r o m

be inferred. For e x a m p l e , the n u m b e r of appendage pairs under

1 9 8 4 ) , b u t s o m e workers think this

FIGURE 2.9. Trilobite exoskeletons with a t t a c h e d f a u n a or injury. A. Arctinurus boltoni (USNM 449453). This trilobite has b r a c h i o p o d s of different sizes (arrows) a t t a c h e d , indicating the length of time b e t w e e n molts of mature s p e c i m e n s . Arctinurus s p e c i m e n s with a t t a c h e d b r a c h i o p o d s are not rare in the Rochester Shale b e d s , where these c a m e from. It is unlikely that they settled on the exoskeleton after death b e c a u s e the exoskeleton w o u l d have to have b e e n b u r i e d to remain a r t i c u l a t e d . B. The s a m e s p e c i e s of trilobite as in A with healed injuries to the exoskeleton. Three areas (arrows) have b e e n d a m a g e d a n d b e e n t h r o u g h at least one molt (PRI 42095). C. Dalmanites limulurus (F. Barber collection, w h i t e n e d ) . This trilobite has a t t a c h e d b r a c h i o p o d s (arrows). This b r a c h i o p o d a t t a c h m e n t is very unlikely to have o c c u r r e d p o s t m o r t e m for the s a m e reasons. D. The s a m e trilobite as in C, with the eye area e n l a r g e d to better s h o w the b r a c h i o p o d s (arrow). E. The s a m e trilobite, with the thoracic area e n l a r g e d to s h o w the b r a c h i o p o d s (arrows).

FIGURE 2.10.

Trilobite a p p e n d a g e reconstruction a n d n o m e n c l a t u r e . A - l . Triarthrus eatoni b i r a m o u s

a p p e n d a g e after Starmer (1939). B. The exite or brachial a p p e n d a g e (arrow) with the c o m b l i k e structures. C. The basis (arrow), also c a l l e d the coxite in early literature. D. The w a l k i n g leg or t e l e p o d i t e (arrow). This leg has seven s e g m e n t s , i n c l u d i n g the foot, in all trilobites w h e r e the a p p e n d a g e s have b e e n s t u d i e d . E. A p o d o m e r e or individual s e g m e n t (arrow) of the w a l k i n g leg. F. Endites (arrows), small triangular i n w a r d i n g - f a c i n g projections on the p o d o m e r e . T h e s e w e r e possibly u s e d to help transport f o o d a l o n g to the mouth at the rear of the h y p o s t o m e . G. Setae (arrow), hairlike projections on the exites. H. G n a t h o b a s e s (arrow) are s h a r p projections on the basis that may have b e e n used to masticate, to r e d u c e the size of f o o d particles. I. The foot (arrow) with its setae. J. A r e c o n struction of the filaments of the e x o p o d of Ceraurus pleurexanthemus by Starmer (1939). K. A partial axial view, looking toward the rear, of Triarthrus as r e c o n s t r u c t e d by Whittington a n d A l m o n d (1987, p. 42, Fig. 43). R e p r o d u c e d with p e r m i s s i o n .

20

THE

BIOLOGY

OF

TRILOBITES

FIGURE 2 . 1 1 . Ventral anatomy a n d a p p e n d a g e s . A.

Triarthrus eatoni, ventral

anatomy. The first essentially correct reconstruction of a trilobite's ventral s u r f a c e a n d a p p e n d a g e s . After B e e c h e r (1896). B. Ceraurus

pleurexanthemus,

ventral

anatomy.

This reconstruction from R a y m o n d (1920a) w a s from cross sections m a d e by Walcott in the late 1900s. C. Ceraurus pleurexanthemus,

ventral

anatomy.

This

reconstruction by Stormer (1951) w a s from s p e c i m e n s c o l l e c t e d b y Walcott a n d uniquely p r e p a r e d . D.

Triarthrus eatoni, a p p e n d a g e

structure d e v e l o p e d by Cisne (1975, p. 4 9 , Fig. 3) from high-resolution r a d i o g r a p h s of pyritized s p e c i m e n s . R e p r o d u c e d from Fossils a n d Strata, www.tandf.no/fossils, by J. L. Cisne, 1975, vol. 4, 4 5 - 6 3 , by permission of Taylor a n d Francis AS. E. Triarthrus eatoni,

a p p e n d a g e structure

d e v e l o p e d b y Whittington a n d A l m o n d (1987, p. 3 1 , Fig. 41), from direct o b s e r v a t i o n of very carefully p r e p a r e d s p e c i m e n s . R e p r o d u c e d with p e r m i s s i o n . F. Ceraurus pleurexanthemus,

appendage

structure

d r a w n by B e r g s t r o m (1972) from information d e v e l o p e d by Stormer (1939, 1951). R e p r o d u c e d with p e r m i s s i o n . G.

Cryptolithus

bellulus, a p p e n d a g e structure d e v e l o p e d by Bergstrom (1972, 1973) from pyritized s p e c i m e n s p r e p a r e d by Beecher. R e p r o d u c e d with p e r m i s s i o n . H. Phacops cf. P. ferdinandi, a p p e n d a g e structure d e v e l o p e d by B e r g s t r o m (1969) u s i n g the radiographs of pyritized s p e c i m e n s from the Hunsruck Shale in Germany. It is a s s u m e d that the p h a c o p i d trilobites of New York will have similar structures. R e p r o d u c e d w i t h permission.

the pygidium in T. eatoni is significantly m o r e than the n u m b e r

e n d o p o d . Until the work of Cisne ( 1 9 7 5 , 1 9 8 1 ) , all reconstruc-

of axial furrows on the dorsal surface of the pygidium, showing

tions of the appendages included a precoxa from which the

a weak relationship between s e g m e n t s a n d axial furrows.

e x o p o d extended ( S t o r m e r 1 9 3 9 , Figure 1, p. 155). This view is

A m o r e detailed look at an individual trilobite appendage

incorrect, based on all the material recently examined; both the

illustrates that it is a c o m p l e x structure. T h e a t t a c h m e n t to the

e x o p o d and the walking leg are attached to the s a m e apparatus,

ventral surface of the trilobite body is through a part called the

the basis. T h e e x o p o d has a series of thin, flattened filaments

basis (Figure 2 . I O C ) . ( F o r a current view on appendage n o m e n -

extending f r o m it, giving it a feather- or c o m b - l i k e appearance,

clature, see the article by RamskoTd and E d g e c o m b e ( 1 9 % ) . ) T h e

and it is carried up under the pleurae. O n l y in 7' eatoni are the

e x o p o d or outer b r a n c h is attached to the basis, which in turn is

exopods k n o w n to be long enough to extend well out from the

attached to the ventral m e m b r a n e of the trilobite. Beneath the

lateral edge of the dorsal exoskeleton. T h e large surface area of

e x o p o d , and also attached to the basis, is the walking leg, or

the small filaments led most a u t h o r s to believe that they have

LIFE-MODE

21

served for breathing, as an external gill. Bergstrom ( 1 9 6 9 ) argued

hepatopancreatic

that the filaments are t o o small to support an effective circulatory

equivalent of a liver, under the genal areas.

organs

(Figure

2.12A,

label

h),

probably

the

system, and instead they may have served as a filter of f o o d , as a

T h e gut (Figure 2 . 1 2 A , B, C, label g) passes from the stomach

means to circulate water over gill m e m b r a n e s on the ventral

through the axial region of the t h o r a x and terminates at the

surface, or possibly as a s w i m m i n g f u n c t i o n . In all the studies the

anus just under the posterior area of the pygidium (Plate 7 8 ) . T h e

exopods are drawn with the filaments lateral and posterolateral.

position of the gut is k n o w n f r o m several s p e c i m e n s of trilo-

S t o r m e r ( 1 9 3 9 ) actually f o u n d the filaments of Ceraurus pleurex-

bites because the ingested sediment often survives in place (Figure

anthemus pointed forward, but he rotated t h e m in his r e c o n -

2 . 1 2 D , label g) and has a different texture or c o l o r than the sur-

struction. Bergstrom ( 1 9 6 9 )

believed that they were pointed

r o u n d i n g stone ( R a y m o n d 1920a; Cisne 1 9 7 5 ; W h i t t i n g t o n 1993;

forward in life (Figure 2.1 I F ) . S t o r m e r ( 1 9 3 9 ) reconstructed the

Whiteley et al. 1 9 9 3 ; Brett et al. 1 9 9 9 ) . It is assumed that s o m e

filaments of the

f o r m of circulatory and nervous systems also o c c u p i e d the axial

exopod

of C.

pleurexanthemus

(Figure

2.10J),

illustrating the high surface area that supports their use as a brachial organ.

interior region. Small rodlike structures seen in radiographs (Cisne 1981) and

The endopod is multiply jointed with distinct sections called

in unusually well-preserved s p e c i m e n s ( W h i t t i n g t o n 1993) are

podomeres (Figure 2 . 1 0 E ) . T h e r e is general a g r e e m e n t that there

believed to represent muscles, and r e c o n s t r u c t i o n of the m u s c u -

are seven podomeres on all trilobites e x a m i n e d . On s o m e of the

lature related to the appendages has been proposed (Figure 2 . 1 2 A ,

podomeres, starting with the ones closest to the basis, are p r o -

B, C, label m ) . S o m e s p e c i m e n s of E. rana show s y m m e t r i c a l dark

jections, endites (Figure 2.1 OF), with hairlike setae (Figure 2 . 1 0 G )

spots on the exoskeleton ( B a b c o c k 1 9 8 2 ) . T h e s e are interpreted

near or on their tip. On

as m u s c l e a t t a c h m e n t areas.

Triarthrus, and probably most o t h e r

genera, the last p o d o m e r e is a footlike tip to the walking leg (Figure 2.101).

Two

soft-bodied

arthropods,

Naraoia

compacta

and

N.

spinifer, originally discovered from the Burgess Shale, are now

T h e most thoroughly e x a m i n e d trilobite appendages are those

regarded as trilobites and assigned to the family Naraoiidae. T h e

of T. eatoni and C. pleurexanthemus, b o t h from the Ordovician

Naraoiidae now includes five genera (Fortey and T h e r o n 1 9 9 5 ) .

of New York. T h e r e are m o r e s p e c i m e n s available of these trilo-

Two of these are O r d o v i c i a n and o n e survived to Late O r d o v i -

bites with preserved appendages than there are of any others.

cian. If, as s o m e a u t h o r s believe, the heavier exoskeleton of

Figure 2.11A is the Beecher reconstruction of T. eatoni and parts

p o s t - C a m b r i a n trilobites is an evolutionary response to m o r e

B and C of Figure 2.11 are reconstructions of C. pleurexanthemus

advanced predators, then it is unlikely that s o f t - b o d i e d trilobites

by R a y m o n d ( 1 9 2 0 a ) and S t o r m e r ( 1 9 5 1 ) . S t o r m e r ' s figure is

survived past the O r d o v i c i a n . N o n e of these genera are known

modified to show the dorsal a n a t o m y on the right and the ventral

f r o m New York, but given the special c o n d i t i o n s necessary for

on the left. Parts D and E of Figure 2.11 are r e c o n s t r u c t i o n s of

their preservation, this does not prove that they were not present.

the legs of T. eatoni by Cisne ( 1 9 8 1 ) and by W h i t t i n g t o n and A l m o n d ( 1 9 8 7 ) , respectively. Parts F, G, and H are drawings of the legs of Ceraurus,

Cryptolithus hellulus, and

Phacops cf.

P. fer-

dinandi, all as reconstructed by Bergstrom ( 1 9 6 9 ) .

Life-Mode T h e following discussion of l i f e - m o d e is based almost exclu-

Figure 2 . 1 0 K shows T. eatoni as reconstructed by W h i t t i n g t o n

sively on circumstantial evidence. As s u c h , it is highly interpre-

and A l m o n d ( 1 9 8 7 ) . T h e view is from about the midline of the

tive. Fortey ( 1 9 8 5 ) p o i n t e d out that using the s a m e body of

trilobite looking to the rear and illustrates the orientation of the

knowledge, trilobites in the family Agnostidae have been hypoth-

walking legs and their parts. T h e bases are shown with toothlike

esized to be pelagic, b e n t h i c , parasitic, a n d epifaunal, possibly

adaxial projections or gnathobases (Figure 2 . 1 0 H ) . F o o d was

attached to algal strands. T h e fossil record does not often permit

probably collected, masticated, or pulled apart, and passed along

clear, u n a m b i g u o u s c o n c l u s i o n s . However, o n e might assume

forward to the m o u t h at the posterior of the h y p o s t o m e by use

that " f o r m follows f u n c t i o n " and that a trilobite's m o r p h o l o g y is

of the e n d o p o d s and bases. Trilobites so equipped would be effec-

often a g o o d indicator of its life habits.

tive b o t t o m feeders, both as predators and as scavengers. Since

M o s t paleontologists c o n t e n d , by analogy with crustaceans,

this kind of i n f o r m a t i o n on appendages is k n o w n for so few trilo-

that for m a n y trilobites the protaspid phase was planktic. That is

bites, it is difficult to extrapolate too far as to the l i f e - m o d e of the

to say that the larvae floated and drifted in the sea, ensuring a

others.

wide dispersal of the species.

Pyritized trilobites from New York and G e r m a n y that were

Trilobites that were primarily b e n t h i c as adults probably

studied by high-definition X-ray p h o t o g r a p h y provide m u c h of

settled to the sea b o t t o m s o m e t i m e during the meraspid phase.

what we know about

1939;

Pelagic, or f r e e - s w i m m i n g trilobites, may never have left the open

Sturmer and Bergstrom 1 9 7 3 ; Cisne 1 9 7 5 , 1 9 8 1 ) . T h e i r s t o m a c h

the internal a n a t o m y ( S t o r m e r

seas during their t r a n s f o r m a t i o n to adults. All through these

(Figure 2.12A, label c ) , crop, or foregut is located in the glabella.

changes, the i m m a t u r e trilobite was very vulnerable to predators

Along with

and e n v i r o n m e n t a l stress, as the m o l t i n g process left the animal

the stomach

in

the cephalon are organs called

THE

22

FIGURE 2.12.

BIOLOGY

OF

TRILOBITES

Internal a n a t o m y of the trilobite. A. Internal o r g a n s of the c e p h a l o n of Triarthrus d e t e r m i n e d by

Cisne (1975, p. 55, Fig. 9): m, m u s c l e s ; c, c r o p or s t o m a c h ; g, gut; h, h e p a t i c o p a n c r e a t i c o r g a n . R e p r o d u c e d from Fossils a n d Strata, www.tandf.no/fossils, by J. L. Cisne, 1975, vol. 4, 4 5 - 6 3 , by permission of Taylor a n d Francis AS. B. Cross section of the thorax with the internal o r g a n s (Cisne 1975, p. 53, Fig. 7): d, dorsal vessel or "heart"; m, m u s c l e s ; g, gut. R e p r o d u c e d from Fossil a n d Strata, www.tandf.no/fossils, by J. L. Cisne, 1975, vol. 4, 4 5 - 6 3 , by p e r m i s s i o n of Taylor a n d Francis AS. C. Reconstruction of s o m e internal anatomy of Ceraurus pleurexanthemus by R a y m o n d (1920a): d, dorsal vessel or heart; g, gut; m, muscles. D. S p e c i m e n of C. pleurexanthemus that c l e a v e d to s h o w the gut (g) as a dark ferruginous stain ( M C Z 111716).

with little in the way of defense for a period of t i m e and the

(Figure 2 . 8 F ) is well d o c u m e n t e d . B o t h forms are well suited to

energy b u r d e n of continually building new exoskeletons was c o n -

their respective m o d e s of life. T h e change to a b o t t o m - d w e l l i n g

siderable. I n extant a r t h r o p o d s Clarkson ( 1 9 7 9 ) n o t e d that 8 0 %

( b e n t h i c ) f o r m c o m e s at the m e t a m o r p h o s i s f r o m protaspis to the

t o 9 0 % o f m o r t a l i t y c o m e s during the m o l t i n g process. T h e m o r e

meraspis, which is shaped like the adult but with long genal

c o m m o n trilobites had to p r o d u c e large n u m b e r s of larvae in

spines. As m e n t i o n e d earlier, the long genal spines last well into

order for significant n u m b e r s to reach maturity.

the early juvenile holaspis.

asaphid trilobite, Isotelus,

S o m e trilobite species are widely dispersed throughout the

f r o m the planktic protaspid (Figure 2 . 8 D ) to the b e n t h i c adult

world, suggesting that they were planktic or pelagic as adults and

T h e m e t a m o r p h i c c h a n g e in an

23

LIFE-MODE

FIGURE 2.13. Trilobite s h a p e s a n d functions. A. Isotelus gigas ( M C Z 311). This trilobite has a s m o o t h s h a p e suitable for shallow p l o w i n g of the surface m u d s for f e e d i n g . B. Hypodicranotus striatulus ( M C Z 100986). The streamlined s h a p e a n d the 1 8 0 - d e g r e e visual c a p a b i l i t y s u g g e s t a trilobite that m i g h t have b e e n a g o o d swimmer a n d w a s p e r h a p s pelagic. C. Achatella achates (PRI 4 9 6 5 9 ) . This trilobite has a fairly flat b o d y with eyes raised well a b o v e the rest of the c e p h a l o n . In a n a l o g y with b o t t o m dwellers with raised eyes, one might e x p e c t this trilobite to rest on the b o t t o m , with the b o d y just u n d e r the s u r f a c e of the substrate a n d the eyes a b o v e it. This position is a d e f e n s e against p r e d a t o r s a n d possibly a m e a n s of lying in wait for prey. D.

Cryptolithus bellulus (PRI 4 9 6 5 4 ) . This trilobite has a prominent, robust

c e p h a l o n c o m p a r e d to the light exoskeletal material on the thorax a n d p y g i d i u m . This feature a n d other e v i d e n c e ( C a m p b e l l 1975) s u g g e s t a sedentary lifestyle a n d filter f e e d i n g habit. E. Triarthrus eatoni (TEW collection). The a p p e n d a g e , i n c l u d i n g the exite or brachial b r a n c h , e x t e n d s well b e y o n d the e d g e of the thoracic shield. This configuration aids the trilobite to survive in the d y s o x i c , d e e p - w a t e r c o n d i t i o n s s u g g e s t e d by the dark shales in w h i c h they are f o u n d .

moved freely t h r o u g h o u t the seas. Planktic larval f o r m s would

and it is reasonable to suggest that they t o o buried themselves

also serve to disperse species but in a m o r e limited m a n n e r . D i s -

under a thin layer of sediment.

persal into new areas by the n o r m a l l y b e n t h i c trilobites is e x -

B o d y shape suggests the l i f e - m o d e of m a n y trilobites. Fortey

pected to be followed by speciation, so o n e would not expect the

( 1 9 8 5 ) defined three m o r p h o l o g i e s o f pelagic species: ( 1 ) large-

species identity to be m a i n t a i n e d if dispersal was into areas not

eyed, epipelagic, s l o w - s w i m m i n g trilobites; ( 2 ) pelagic, stream-

previously occupied by the species.

lined, faster s w i m m e r s ; and

There are wide variations in the size of trilobite eyes, the

(3)

possible s w i m m i n g Irvingella

types, remopleuridids, and progenetic types. T h e f a s t - s w i m m i n g

n u m b e r of lenses, and the angle of vision. T h e s e variations are

trilobites have r o u n d e d streamlined shapes, which p r o m o t e d

certainly s o m e indication of the l i f e - m o d e , but m o d e r n analogy

b u o y a n c y and low drag while s w i m m i n g . T h e s e shapes are not

is often necessary to c o m e up with suggestions. Animals that b u r y

often found a m o n g New York trilobites, but the Middle O r d o v i -

themselves shallowly in the b o t t o m sediment have eyes that are

cian

raised above the plane of the head, enabling t h e m to see when

and is considered pelagic (Figure 3 . 1 3 B , Plate 1 6 0 ) .

they are slightly buried. S o m e trilobites have such raised eyes (e.g., Achatella

achates

(Figure

2.13C)

and

Dalmanites

species),

remopleurid

Hypodicranotus

striatulus

has

the

right

shape

Vaulted, s m o o t h exoskeletons such as that on /. gigas (Figure 2 . 1 3 A , Plate

1 5 0 ) , Dipleura dekayi (Plate 9 7 ) , and

Trimerus del-

24

THE

BIOLOGY

OF

TRILOBITES

phinocephalus (Plate 9 9 ) were well designed to plow through the

fossils such as tracks, burrows, and distinctive pits preserved in

upper sediment layers in search of f o o d . T. eatoni, with its thin

the fossil record are attributed to trilobites, as supported by the

exoskeleton and outer b r a n c h e s that extend b e y o n d the pleurae,

rare find of a trilobite at the end of a trackway or in o n e of the

was unsuited for shallow, t u r b u l e n t water and for plowing in sed-

burrows (Figure 2 . 1 4 A ) . Two c o m m o n t r a c e s — C r u z i a n a and

i m e n t and was better designed for surface scavenging in deeper,

Rusophycus—are generally preserved as molds

less oxygenated e n v i r o n m e n t s (Figure 2 . 1 3 E , Plate 1 7 2 ) .

basal c o n t a c t of sandstones or c a r b o n a t e beds in shales. O n e type

It has been proposed that to m a x i m i z e visual effectiveness,

(fillings)

on the

of deep, inscribed, horizontal track or furrow, Cruziana, shows

the plane of the upper and lower edges of the eyes should be

" V - l i k e " scratch patterns m a d e by the dactyls (claws) of the trilo-

parallel to the substrate (Plates 5 a n d 6 ) . In m a n y outstretched

bite and a central groove corresponding to an axial ridge of debris

trilobites it is apparent that the eyes are parallel to the s u b -

pushed up by the trilobite (Figure 2 . 1 4 B ) . T h e bilobed burrows,

strate. However, m a n y species of illaenids, when outstretched,

or resting pits also showing V-shaped scratches, are called Ruso-

have eyes that are angled upward and posteriorly. Westrop

phycus, and the trackways consisting of small " f o o t p r i n t s " on the

( 1 9 8 3 ) and B e r g s t r o m ( 1 9 7 3 ) , a m o n g others, argued that these

substrate

trilobites were i n f a u n a l , b u r y i n g themselves backward into a

1 9 9 0 , p. 1 6 1 ) , although O s g o o d ( 1 9 7 0 ) did not hold this t e r m in

soft b o t t o m with their cephalon on the surface at an angle to the

high regard.

thoracopygidium.

are

sometimes

known

as

Diplichnites

(see

Bromley

Trace fossils attributed to various burrowing animals (worms?)

In this attitude the eye base is parallel to the surface and gives

have been f o u n d ending in Rusophycus, suggesting the trilobite

the m a x i m u m all-around vision. T h e s e infaunal trilobites fed and

had attacked a n o t h e r burrower. T h e s e fossils indicate that m a n y

breathed by the exchange of water on the buried ventral anatomy.

trilobites walked a r o u n d on the b o t t o m and dug into the sediment

T h i s exchange o f water was the result o f the m o v e m e n t o f the

for b o t h food and resting places (Hall 1852, Plate 9, Figure 1).

appendages a n d a n upstream o r i e n t a t i o n o f the burrow. T h e r e

In the case of Cruziana the direction of travel for the trilobite

are other trilobites with this l i f e - m o d e , which Westrop termed

is toward the o p e n end of the V-shaped appendage traces. M o s t

" i l l a e n i m o r p h s . " W h i t t i n g t o n ( 1 9 9 7 b ) rebutted this view on the

Rusophycus traces f o r m a V, with the gape end or anterior being

basis of the high flexibility of the t h o r a x in illaenids and that they

wider than the posterior, suggesting that the trilobite rested (or

are m o r e suited to crawling a r o u n d the b o t t o m and over irregu-

h u n t e d ) with the cephalon toward the " g a p e " end. T h e r e is little

lar objects than living or resting primarily in burrows.

a r g u m e n t that Rusophycus traces are most readily explained as

Westrop also p o i n t e d out that on s o m e of the illaenimorphs

trilobite h u n t i n g or resting pits, but the same is not true for

there is a median tubercle on the glabella, midway between the

Cruziana. W h i t t i n g t o n ( 1 9 8 0 ) , based on his in-depth studies of

palpebral lobes on the sagittal line. T h i s tubercle is also a thin

Olenoides

spot and is characterized as having possible light-sensing p r o p -

readily allow for the type of traces represented by Cruziana and

erties. It is the highest point when the b o d y is in a n o r m a l life

that s o m e o t h e r a n i m a l , perhaps not even an a r t h r o p o d , may be

serratus,

believed

that

trilobite

appendages

do

not

position, thus covering any blind spots of the c o n v e n t i o n a l eyes.

responsible. However, m a n y Cruziana traces end in Rusophycus,

R u e d e m a n n ( 1 9 1 6 b ) f o u n d a significant n u m b e r trilobites with

and since the latter are u n a m b i g u o u s l y trilobite, this reference is

such median tubercles, even n o m i n a l l y blind trilobites such as in

questionable.

the genus Cryptolitluis.

It is reasonable to c o n j e c t u r e that the

In New York, traces attributed to trilobites are c o m m o n in the

tubercles had a light-sensing utility and played a role in the trilo-

Silurian C l i n t o n G r o u p , particularly on the base of sandstone

bite's life-mode. Such light sensing tubercles probably could sense

layers near the village of C l i n t o n , Oneida County. O s g o o d and

m o v e m e n t but not resolve o b j e c t s . In m o d e r n a r t h r o p o d s larger eyes are f o u n d on n o c t u r n a l

D r e n n e n ( 1 9 7 5 ) provided a g o o d description of these traces and their literature. In o t h e r strata they are far less well k n o w n , either

species or those adapted to low daylight levels. A n i m a l s with a

because c o n d i t i o n s were n o t right for their preservation

wide visual angle need it to watch for predators. Very large eyes

because little effort has been m a d e to find and identify t h e m in

and a wide visual angle are seen on s o m e pelagic trilobites (Figure

appropriate strata.

2 . 1 3 B ) . Fortey ( 1 9 8 5 ) considered the large-eyed trilobites as epipelagic and slow s w i m m e r s . C o m p o u n d eyes permit insects to be highly aware of m o v e -

or

Fortey and O w e n ( 1 9 9 9 ) proposed that trilobite feeding habits can be related to the position and a t t a c h m e n t of the h y p o s t o m e and other physical characteristics. Trilobites that are considered

m e n t but do not necessarily provide high visual acuity. R e d u c -

predatory (i.e., they fed o f f m a c r o f a u n a such as w o r m s ) had

tion in eye size has been noted for trilobite genera that m o v e d to

a c o n t e r m i n e n t h y p o s t o m e fixed or strongly supported at the

deeper water through t i m e . Blind trilobites, such as in the genus

anteroventral c e p h a l o n . T h e h y p o s t o m e provided a strong base

Cryptolithus (Figure 2 . 1 3 D ) , may have b u r r o w e d into sediment

for the appendages so the trilobite could manipulate and masti-

where sight would have been less i m p o r t a n t than o t h e r sensory

cate the prey. F o o d was passed forward along the ventral median

capabilities.

by the bases to the m o u t h at the posterior of the hypostome.

M o s t trilobites were b e n t h i c . T h e y passed m o s t of their life

Examples of this type of h y p o s t o m e a t t a c h m e n t in an Isotelus

on or in the u p p e r m o s t part of the sediment layer. S o m e t r a c e

species may be seen in Figure 2 . 7 E and Plates 153, 155, and 157.

25

LIFE-MODE

FIGURE 2 . 1 4 .

Trilobite traces. A. Rusophycus pudicum ( U C M 3 7 5 7 4 ) . S a n d s t o n e d e p o s i t s over trilo-

bite-rich b o t t o m m u d s often have c o n v e x , slightly V - s h a p e d traces on their lower s u r f a c e . These t r a c e s are known as Rusophycus a n d have b e e n long r e g a r d e d as trilobite "resting t r a c e s . " O s g o o d ( 1 9 7 0 ) reported on a remarkable Rusophycus that h a d the trilobite responsible for it still in p l a c e . B. Flexicalymene meeki. This trilobite w a s f o u n d on the Rusophycus in A. The trilobite is a b o u t 46 mm long a n d is from the U p p e r O r d o v i c i a n of Ohio. C. Trachomatichnus numerosum ( U C M 3 7 6 9 5 ) . A trilobite w a l k i n g trace attributed to Cryptolithus ( O s g o o d 1 9 7 0 ) . The illustration is life size. All figures r e p r o d u c e d with permission.

Impendent hypostoma that are also attached to the d o u b l u r e also

(weak)

suggest a predatory habit. Bellacartwrightia species (Plate 4 7 ) and

c e p h a l o n , as well as trace fossils clearly attributable to Cryp-

Calyptaulax callicephalus

tolithus resting ( a n d feeding) sites.

(Plate

117)

show this

mode

of h y p o -

stome a t t a c h m e n t .

thorax

and

thoracic

appendages

compared

to

the

Trilobites are f o u n d in a variety of e n v i r o n m e n t s , from fairly

Trilobites whose h y p o s t o m a were not strongly attached to the

shallow waters near s h o r e , to reefs, c o n t i n e n t a l shelves and slopes,

cephalon (i.e., natent) are considered to be particle feeders. T h e y

and m o d e r a t e l y deep basins. T h e observation has been m a d e

relied on m u c h smaller food particles swept up f r o m the b o t t o m ,

that trilobites from the shallower areas with m o r e wave turbul-

and the rigid h y p o s t o m e was unnecessary. T h e s e trilobites tend

ence have thicker exoskeletons (Fortey and W i l m o t 1 9 9 1 ) . T h e s e

to be smaller than the predatory ones because their food sources

thicker exoskeletons are possibly an evolutionary response to the

were not as rich and c o n c e n t r a t e d . T h e genera Harpidella (Plate

greater e n v i r o n m e n t a l energy. As m e n t i o n e d earlier, exoskeletons

128) and Triarthrus (Plates 170 to 174) represent this group of

are generally thicker in p o s t - C a m b r i a n trilobites, which may also

trilobites. The

last

signal the rise of better-developed predation, a n o t h e r form of feeding m o d e to

consider here

is filter-chamber

e n v i r o n m e n t a l stress.

feeding. This type of feeding is typical of trilobites with reduced

M a n y trilobites were gregarious, at least at s o m e point during

mobility and relatively large cephala. T h e s e trilobites settled in a

their life cycles. T h e large n u m b e r s of death and molt assem-

position and stirred up the sediment immediately under t h e m ,

blages, well illustrated by E. rana in New York, are no statistical

and then filtered out the m i n u t e food particles c o n t a i n e d in the

accidents. It is not u n c o m m o n , within a n u m b e r of different

top layer of sediment. M o v e m e n t o c c u r r e d only after the food

trilobite species, for a large n u m b e r of individuals to be found in

supply was exhausted. T h e genus Cryptolithus (Plates 163 to 167)

local " p o c k e t s " on the s a m e bedding plane or horizon, indicating

is the example used, and the evidence is the relatively small

s o m e f o r m o f group behavior (Plates 5 9 , 8 9 , 102, 128, 146, 147,

26

THE

BIOLOGY

OF

TRILOBITES

and 1 5 2 ) . All this suggests that it was c o m m o n for m a n y trilo-

d a m a g e . T h e s e m a l f o r m a t i o n s can c o m e about in several ways,

bites to congregate for breeding or m o l t i n g , or just because it was

but d a m a g e due to p r o b l e m s in molting and damage caused by

their n o r m a l l i f e - m o d e to be together in " s c h o o l s " (Speyer and

actual attack by a predator were probably the most c o m m o n . T h e

Brett 1985, Speyer 1 9 9 0 a ) .

m e c h a n i s m of a defect is not always clear, but healed punctures

Trilobites such as phacopids and calymenids were capable

and crescent-shaped m a l f o r m a t i o n s are readily attributed to pre-

of very tight e n r o l l m e n t , literally into a ball. T h i s position was

dation. Figure 2 . 1 5 illustrates four examples of exoskeletons with

undoubtedly a defense m e c h a n i s m resorted to in times of stress.

clear indication of predation. Panels A and B show " b i t e " marks

If the stress was an undersea s e d i m e n t flow t o o large to get out

out of trilobites from the Rochester Shale that have been through

of, the trilobite would be e n t o m b e d in the tightly enrolled posi-

at least o n e m o l t , as shown by the broken edges of the thoracic

tion. Most of the p o s t - C a m b r i a n trilobites in New York could

s e g m e n t s being r o u n d e d to a new termination. Panel C shows the

enroll, and the frequency of this position versus the o p e n posi-

unusual situation of Dalmanites limulurus with the pygidial spine

tion is perhaps an indication that it was a c o m m o n reaction to

missing ( c o m p a r e to Figure 2 . 1 5 A ) and the damage healed over.

stress for the species.

Panels D through F show a calymenid from the Rochester Shale

S o m e b e n t h i c trilobites u n d o u b t e d l y could swim. M o d e r n

with evidence of b o r i n g on its exoskeleton. This finding is par-

horseshoe c r a b s , a n o r m a l l y b e n t h i c species, are g o o d s w i m m e r s .

ticularly interesting because crinoids from the Rochester Shale

T h e y also swim upside d o w n , and it has been shown that the

have been described with similar boring marks (Brett

hydrodynamics of their s w i m m i n g works best in this attitude

1 9 8 5 ) . S i g n o r and Brett ( 1 9 8 4 ) and Pratt ( 1 9 9 8 ) s u m m a r i z e d the

(Fisher 1 9 7 5 ) . It is reasonable to a s s u m e that s o m e n o r m a l l y

possible

benthic trilobites could swim also and possibly quite well. S o m e

d o c u m e n t e d predator o f the C a m b r i a n , and many o f the circular

predators

in

the

Paleozoic.

Anomalocaris

is

a

1978, well-

likely swam upside d o w n . ( H . B u r m e i s t e r first proposed this

scars on trilobites are attributed to the circular m o u t h of Anom-

in 1843.) T h i s m o d e of s w i m m i n g may not have been involved in

alocaris. C e p h a l o p o d s b e c a m e a predation factor in the O r d o v i -

their

cian, and fishes b e c a m e p r o m i n e n t in the Devonian.

food

gathering,

but

they

could

move

from

place

to

place and evade danger by s w i m m i n g . In o n e trilobite bed, the

Babcock

(1993)

has collected

information

related to the

result of a burial event, at least 9 8 % of the trilobites with a wide

c o n c e p t of behavioral a s y m m e t r y . T h i s means that when a trilo-

variety of sizes are f o u n d buried upside down ( W h i t e l e y et al.

bite was attacked by a predator, its response was not r a n d o m ,

1993; Brett et al. 1 9 9 9 ) . T h i s observation applies to b o t h the lower

b u t there was a preference to m o v e in a m a n n e r that resulted in

surface and internal to the l i m e s t o n e . For m o r e on this, see

m o s t d a m a g e to the right side of the animal. Conversely, pre-

Chapter 3.

ferred d a m a g e to the right side of the trilobite could suggest the

Spininess in trilobites has invoked a n u m b e r of explanations,

attack strategy of the predator.

most o f t h e m probably correct for o n e species o r another. T h e r e

G e n e t i c or embryological abnormalities cannot be easily diag-

seems to be little need to invoke j u s t a single e x p l a n a t i o n , any

nosed in fossils. Pathological abnormalities are due to disease and

m o r e than there is o n e explanation for spininess in m o d e r n

parasites. Disease is impossible to d o c u m e n t in fossils, but para-

species of a r t h r o p o d s . Spines can be a defense m e c h a n i s m against

sitic attack is seen by the presence of w o r m - s h a p e d borings and

predators, provide support on a soft substrate, assist the a n i m a l

gall-like swellings. It is m o r e difficult to determine if borings were

in burying itself when

The

m a d e on the living animal (versus on the exuviae or p o s t m o r t e m )

Lower Devonian s t r a t u m in New York ( a n d the Devonian strata

than to recognize a healed injury. Swellings are known from a

necessary, and sensory devices.

of O k l a h o m a and M o r o c c o ) has trilobites with elaborate spines,

n u m b e r of different trilobite families, and s o m e can be diagnosed

s o m e curling up and over their t h o r a x . T h e s e spines of the genus

as the result of parasites based on the direct presence of w o r m -

Dicranurus c o m m o n l y carried algae and o t h e r encrusting org-

like structures.

anisms on t h e m , possibly as a defense m e c h a n i s m ( K l o c 1 9 9 3 ,

M c N a m a r a and Rudkin ( 1 9 8 4 ) d o c u m e n t e d the death of a

1 9 9 7 ) . T h e spines provided g o o d a t t a c h m e n t s and presumably

partially molted Pseudogygites latimarginatus.

helped break up the visual b o d y lines to provide c a m o u f l a g e .

the a n i m a l was o v e r c o m e and buried while molting.

S o m e m o d e r n a r t h r o p o d s do exactly this.

It seems likely that

Often trilobites are f o u n d in association with other fossils in

O n e can a s s u m e , based on m o d e r n analogy, that trilobites

rapid-burial deposits. If there is little indication of their being

were subject to injury, parasitism, and predation, as reflected in

t r a n s p o r t e d any distance, then this can be taken as evidence of

their preserved parts. O w e n ( 1 9 8 5 ) extensively reviewed trilobite

their ecology. An example is the o d o n t o p l e u r i d Meadowtownella

abnormalities.

He listed three general types of trilobite a b -

trentonensis from the Trenton G r o u p . T h i s small, spiny trilobite

n o r m a l i t i e s : injury, genetic or embryological m a l f u n c t i o n , a n d

is often f o u n d whole on fossil hash layers, particularly with

pathological a b n o r m a l i t i e s .

b r a n c h e d bryozoans, and also in burial event deposits with the

Not u n c o m m o n l y , trilobites are f o u n d with m a l f o r m a t i o n s

cystoid

Cheirocrinus

and

fenestrate

bryozoans.

M.

trentonensis

that are ascribed to healed injuries (Figure 2 . 9 B ) . M o s t of these

was probably a scavenger on b o t t o m s with animal debris accu-

injuries are seen on the pleura either by a s y m m e t r y or by healed

m u l a t i o n s and also in bryozoan thickets with their attached

FIGURE 2.15.

Trilobite injuries. A. Dalmanites limulurus with a semicircular portion of the

thorax missing. The d a m a g e has " h e a l e d " in that the e d g e s of the d a m a g e are r o u n d e d , indicating the trilobite has molted at least o n c e s i n c e the injury (K. Smith collection). B. Dicranopeltis nereus with an injury to the thorax. The trilobite has m o l t e d at least o n c e since the injury (K.

Smith collection).

C.

Dalmanites limulurus with the p y g i d i a l spine

missing. The e n d of the p y g i d i u m is r o u n d e d , indicating one molt s i n c e the loss of the spine. (K. Smith collection). D-F. Calymene s p e c i e s , s h o w i n g circular " b o r i n g s " (arrows) similar to those of Tremichnus on several different s p e c i e s of c r i n o i d s from the Rochester Shale reported by Brett (1985) (NYSM 16796).

THE

28

FIGURE 2.16.

BIOLOGY

OF

TRILOBITES

Cryptolithus, the

m o s t - s t u d i e d trilobite g e n u s f o u n d in New York. A. Cryptolithus tessellatus (TEW

collection,

whitened). This trilobite, in N e w York, is f o u n d only in the M i d d l e Ordovician Sugar River Formation. It is r e c o g n i z e d by the three rows of pits anterior to the c h e e k area (arrow).

B.

Cryptolithus

lorettensis

(PRI 49657, w h i t e n e d ) . In New York this trilobite is f o u n d only in the upper Sugar River Formation. It differs from C. tessellatus in that there are four rows of pits anterior to the c h e e k (arrow). The first approximately nine radial abaxial pit rows are well a l i g n e d . C. Cryptolithus

bellulus (PRI

49654,

latex pull, w h i t e n e d ) from the U p p e r O r d o v i c i a n Lorraine G r o u p in New York. This trilobite differs from C. lorettensis primarily in the poor radial alignment of the first four abaxial pit rows. D. A d r a w i n g of a silicified s p e c i m e n of C.

tessellatus by C a m p b e l l

(1975). R e p r o d u c e d with permission. E. A d r a w i n g of the same s p e c i m e n by B e r g s t r o m (1972) with the a p p e n d a g e s drawn in. The a p p e n d a g e information is from B e e c h e r s p e c i m e n s of C. bellulus. R e p r o d u c e d with p e r m i s s i o n . F. Raymond's (1920a) reconstruction of the ventral anatomy of C. bellulus using

specimens

p r e p a r e d by Beecher. G. Bergstrom's (1972) reconstruction of the s a m e s p e c i m e n s . R e p r o d u c e d with permission.

cystoids. A further possibility is that this trilobite fed o f f living

preserved in a wide variety of e n v i r o n m e n t s and the possibility

bryozoa.

of new i n f o r m a t i o n on the lifestyle and biology is enhanced.

Trilobites of the genus Cryptolithus are a m o n g the best u n d e r -

Cryptolithus

specimens

with

appendages

are

preserved

in

stood of the New York trilobite genera (Figure 2 . 1 6 ) . T h e r e are

Beecher's Trilobite B e d , which enables detailed observations of

several reasons for this. T h e genus is widely distributed g e o -

the ventral a n a t o m y ( B e e c h e r 1895a, R a y m o n d 1920a (Figure

graphically and geologically. W i d e distribution m e a n s that it is

2.16F), Bergstrom

1972 (Figure 2 . 1 6 G ) ) . At least o n e whole,

29

LIFE-MODE three-dimensional s p e c i m e n , preserved in silica, is k n o w n . Figure

covered by W h i t t i n g t o n ( 1 9 5 9 ) . P h o t o g r a p h s of this specimen

2 . 1 6 D is a drawing of the specimen by C a m p b e l l ( 1 9 7 5 ) , and

reproduced by C a m p b e l l ( 1 9 7 5 ) reveal that the ventral plane of

Figure 2 . 1 6 E is a drawing of the same s p e c i m e n by B e r g s t r o m

the t h o r a c o p y g i d i u m was well above the apparent plane of the

with the legs included. Walking and digging trace fossils unequiv-

ventral surface of the c e p h a l o n . In o r d e r to m o v e about on the

ocally assigned to Cryptolithus are k n o w n f r o m Kentucky. T h e

b o t t o m and to burrow, the trilobite must have had long, strong,

Cryptolithus protaspid is s o m e t i m e s found silicified and is easily

ventral walking legs or have developed o t h e r m o d e s of m o v e -

characterized. T h e unique c e p h a l o n with its heavily pitted b r i m

m e n t . C a m p b e l l ( 1 9 7 5 ) explored this in detail, but in s u m m a r y

is readily recognized in stratigraphic samples, and it is impossi-

Cryptolithus species could n o t have been

ble to mistake it for other genera. A n u m b e r of authors have

or deep burrowers (see Figure 2 . 1 6 G ) . O s g o o d ( 1 9 7 0 , Plate 5 8 ,

very active crawlers

studied the distribution of Cryptolithus so there is a large data-

Figure 1 and 2) figured the resting trace fossil Rusophycus cryptolithi, which because of size and the impressions of genal spines

base of i n f o r m a t i o n . In New York there are three distinct species or " m o r p h s " of

could only have been m a d e by Cryptolithus a n i m a l s . T h e s e traces

Cryptolithus ( W h i t t i n g t o n 1 9 6 8 , Shaw and Lesperance 1 9 9 4 ) : C.

indicate that the trilobite sat in a shallow depression, facing into

tessellatus (Figure 2 . 1 6 A ) , C. lorettensis (Figure 2 . 1 6 B ) , b o t h from

the c u r r e n t , and swept particles of detritus f r o m the b o t t o m into

the Middle Ordovician Sugar River F o r m a t i o n , and C. bellulus

its m o u t h .

(Figure 2 . 1 6 C ) from the Upper Ordovician Lorraine G r o u p , all in

T h e m o u t h of Cryptolithus species is at the rear of the small

New York. T h e y are distinguished primarily by the rows of pits

h y p o s t o m e in the ventral part of the c e p h a l o n . T h e s t o m a c h

or the pit a r r a n g e m e n t , or b o t h , so that it is justified to assume

occupies the glabella, a n d digestive capability extends out into the

that any biological i n f o r m a t i o n from o n e species is essentially the

genal area. T h e a l i m e n t a r y track lay along the axis of the t h o r a -

same for all of t h e m .

c o p y g i d i u m and o c c u p i e d a b o u t 2 0 % o f the width o f the axial

Trinucleids arose as a family in Europe and migrated to North America during the Middle O r d o v i c i a n

(Whittington

rings. T h e anus is at the posterior p o i n t of the pygidium. Fortey and O w e n s

(1999)

described

Cryptolithus species as

1 9 6 8 ) . T h e pelagic protaspis ( C h a t t e r t o n et al. 1994) ensured that

filter-chamber feeders, m e a n i n g that the resting trilobites stirred

o n c e in the North A m e r i c a n epicontinental sea, the trilobite

the sediment directly u n d e r t h e m , using the cavity between the

spread rapidly wherever currents t o o k the protaspis. Molts f r o m

cephalon and the substrate, and filtered o u t the food particles

protaspides and cephala of what is probably the meraspid phase

from the rest of the suspended s e d i m e n t . Fortey and O w e n s also

are c o m m o n l y found in the deep-water Frankfort Shales includ-

suggested that the cephalic perforations provided c h a n n e l s for

ing the Beecher's Trilobite Beds. T h e holaspid is blind except

water to flow out of this cavity while it was swept forward by the

for the possible eye spot or visual receptor centered on the

appendages. T h i s flow b r o u g h t the food particles forward to the

median line of the glabella. T h e r e is a wide b r i m on all but the

m o u t h and kept oxygenated water flowing over the exopods.

posterior of the cephalon. T h i s b r i m is bilaminar, separating into

As

in

all

specimens

of trilobites

with

preserved ventral

an upper and lower lamella through a plane parallel to the ventral

appendages, the b i r a m o u s limbs of Cryptolithus included walking

plane of the trilobite. T h e b r i m is perforated with holes, c o m -

legs, e n d o p o d s , and o u t e r b r a n c h e s , e x o p o d s , which may have

monly referred to as pits, that pass through b o t h lamellae. T h e

served as a breathing organ as well as provided s o m e ability to

pits are in circumradially arranged rows for the first three or four

sweep the surface under the trilobite. T h e exopods do not extend

circumferal rows. T h e r e are a n u m b e r of speculations as to the

b e y o n d the b o r d e r of the t h o r a c i c s e g m e n t s . T h e r e are three pairs

function of the pits. T h e m o s t current thinking is that they

of appendages under the c e p h a l o n and o n e pair under each

were sensory devices, perhaps to d e t e r m i n e c u r r e n t direction

t h o r a c i c segment. U n d e r the pygidium there are a large n u m b e r

(Campbell 1 9 7 5 ) .

o f m u c h - r e d u c e d appendages, reflecting the n u m b e r o f fused

T h e long genal spines are on the lower lamella. Cephala are

segments in the pygidium.

found with and without genal spines, as are n e a r - w h o l e a r t i c u -

A s s u m i n g the relationship of the appendages to the exoskele-

lated specimens. T h e trilobite molted by m o v i n g forward through

ton is correct, it is hard to see m e m b e r s of the genus Cryptolithus

a gap between the lamella, and this gap possibly closed after

as active surface crawlers.

molting (a m e c h a n i s m observed in extant h o r s e s h o e c r a b s ) .

On the w h o l e , o n e can a s s u m e that trilobites initially occupied

Alternatively, the lower lamella b e c a m e detached during the

m a n y of the e n v i r o n m e n t a l niches that are o c c u p i e d today by

molting process. Consequently, it is difficult to k n o w if a c o m -

m o d e r n m a r i n e a r t h r o p o d s . T h e ecological niche for the indi-

pletely whole articulated specimen with the genal spines intact is

vidual species enabled trilobites to b e c o m e part of a p a l e o c o m -

a molt or an animal killed and buried. T h e absence of genal spines

munity. W i t h i n this c o m m u n i t y the trilobites shared the local

and lower lamella, however, ensures it is a m o l t .

e n v i r o n m e n t with a variety of o t h e r a n i m a l s and plant life. W h e r -

T h e thorax and pygidium are m u c h reduced c o m p a r e d to the

ever o n e finds the necessary associations within the rocks, o n e can

cephalon. T h e r e are six t h o r a c i c segments and a small triangular

expect

pygidium. A nearly whole silicified Cryptolithus species was dis-

is no different than what is seen in extant, and undisturbed,

t o f i n d the o t h e r

m e m b e r s o f the c o m m u n i t y . T h i s

30

THE

BIOLOGY

OF

TRILOBITES

c o m m u n i t i e s today. S o m e trilobites, such as the illaenids, are

tion must offer a competitive advantage to the species. N o n c o m -

f o u n d in a fairly n a r r o w range of e n v i r o n m e n t a l c o n d i t i o n s ,

petitive genetic changes will s o o n disappear, as the animal is

and s o m e like in the genus Isotelus are f o u n d in a wide variety

unable to c o m p e t e for the o p p o r t u n i t y to pass the changes along

of c o m m u n i t i e s from shallow nearshore areas to deep r a m p -

to its offspring. Next, the new trait should o c c u r in an isolated

basin transition areas. Fortey ( 1 9 7 5 ) defined c o m m u n i t i e s in the

small p o p u l a t i o n so that it will not be " l o s t " in a m u c h , m u c h

northern

c o m m u n i t i e s , the

larger gene pool. Since m u t a t i o n occurs relatively frequently, a

cheirurid-illaenid and the olenid, fit m u c h of the New York

beneficial m u t a t i o n will happen at s o m e w h a t regular intervals,

Middle Ordovician very well.

statistically. In a stable e n v i r o n m e n t , however, with many others

Europe

Ordovician.

Two

o f his

T h e geographic restrictions of specific trilobite families and

of the same species, this change may not b e c o m e fixed. A better

genera also are used to identify p a l e o b i o g e o g r a p h i c provinces.

o p p o r t u n i t y for a new m u t a t i o n to be passed along is when a

W h i t t i n g t o n ( 1 9 6 1 b ) , W h i t t i n g t o n and Hughes ( 1 9 7 2 ) , and Ross

group, for s o m e reason, is o c c u p y i n g an e n v i r o n m e n t where there

( 1 9 7 5 ) , for e x a m p l e , used this a p p r o a c h to define the early posi-

is little o u t b r e e d i n g c o m p e t i t i o n or there are new environmental niches to occupy. Essentially populations are stable until a change

tions o f the p a l e o c o n t i n e n t s . T h e early evolutionary success of trilobites was probably due

takes place in an isolated e n v i r o n m e n t , and after this c h a n g e (or

to their development of a mineralized exoskeleton and their wide

c h a n g e s ) , the new species b e c o m e s competitive with the f o r m e r

geographic dispersal. T h e n u m b e r o f trilobite genera increased

stable species and displaces it or in s o m e cases occupies a differ-

from their first a p p e a r a n c e until the Late C a m b r i a n and then

ent available niche. T h u s , evolution is not a process of continual

decreased c o n t i n u o u s l y through the Paleozoic. T h i s is graphically

small changes b u t o n e of relative stability followed by abrupt step

shown in Ludvigsen ( 1 9 7 9 b , Figure 9 ) . A n u m b e r of explanations

changes. Eldredge and G o u l d ( 1 9 7 2 ) used the term punctuated

for this have been proposed. T h e n u m b e r of potential predators

equilibria to reflect their observation that evolution is not a

continually increased d u r i n g these s a m e times. It is likely that

s m o o t h transition f r o m o n e species to the other b u t rather is

the increased predation, increased n u m b e r o f c o m p e t i t o r s for

c o m p o s e d of periods of relative stability punctuated by periods

environmental niches, and the b u r d e n of m o l t i n g to a completely

o f rapid c h a n g e .

defenseless individual all played a part in the reduced success of

T h e observation

that s o m e

fossil

c o m m u n i t i e s s h o w re-

trilobites through t i m e . Trilobites disappeared completely at the

m a r k a b l e stability, s o m e t i m e s over millions of years, has led

end o f the P e r m i a n .

to s o m e i n - d e p t h investigations. In New York s o m e Middle Devonian fossil c o m m u n i t i e s , particularly in dysaerobic envir o n m e n t s , show this stability. As a result of these and o t h e r

Evolution and Cladistics

studies, Brett and Baird ( 1 9 9 2 , 1 9 9 5 ) coined the term coordinated

Fortey and O w e n s ( 1 9 9 7 ) reviewed the evolutionary history of

stasis for this f o r m of evolutionary stability (see also K a m m e r

trilobites. T h i s review should be considered the latest in what will

et al. 1 9 8 6 , M o r r i s et al. 1 9 9 5 , Brett et al. 1 9 9 6 ) . Similarly in

be an o n g o i n g series of a r g u m e n t s .

the C a m b r i a n , for e x a m p l e , there is evidence that populations

T h e phylogeny or evolution of trilobites is k n o w n f r o m the

of trilobites in the shallower water environments underwent a

first calcified r e m a i n s in the Lower C a m b r i a n rocks to the last

n u m b e r of e x t i n c t i o n s , and the area where they o n c e were was

trilobites in the Late P e r m i a n . It is generally believed that trilo-

repopulated with trilobites f r o m deeper water. T h e s e episodic

bites as a class are m o n o p h y l e t i c ; that is they are f r o m a c o m m o n

e x t i n c t i o n s and repopulations, called biomeres ( P a l m e r 1 9 6 5 ,

ancestor ( R a m s k o l d and E d g e c o m b e 1 9 9 1 ) . T h e earliest k n o w n

1 9 8 4 ) , are recorded from the C a m b r i a n of North A m e r i c a (see

trilobites are from the s u b o r d e r Olenellina f o u n d exclusively in

also E d g e c o m b 1 9 9 2 ) .

the Lower C a m b r i a n . T h e s e trilobites lack facial sutures, which is

Relationships of trilobites at all t a x o n o m i c levels are currently

considered a primitive characteristic (Fortey and W h i t t i n g t o n

being revised using cladistic methodology. Cladistics as used in

m e m b e r of

paleontology is the grouping of taxa by their shared physical c h a r -

this early group. Facial sutures first appear in the s u b o r d e r

acteristics. Close relationships are based on synapomorphies or

Redlichiina, also in the Lower C a m b r i a n . It is p r o b a b l e that there

"shared derived" characteristics. Traits may be divided into p r i m -

1989).

In

New York

Elliptocephala

asaphoides

is

a

are ancestral trilobites that did not have mineralized exoskeletons,

itive ( p l e s i o m o r p h i c ) or derived ( a p o m o r p h i c ) . For trilobites the

perhaps back into the late P r e c a m b r i a n . T h e r e is no c o m p e l l i n g

b i r a m o u s appendages are plesiomorphic or "shared primitive"

reason to believe that all trilobites sprang from olenellin a n c e s -

characteristics, m e a n i n g they are primitive to the group (i.e., they

tral stock.

represent a c o m m o n ancestral trait of a r t h r o p o d s not exclusive

F r o m these ancestors evolved the large n u m b e r of trilobite

to trilobites) and may be used only to c o m p a r e trilobites with

orders, families, and genera that are recognized today. Evolution,

o t h e r a r t h r o p o d s . Schizochroal eyes are only f o u n d in the subor-

however, is not s o m e t h i n g that proceeds s m o o t h l y with a calen-

der P h a c o p i n a , and thus this characteristic forms a derived char-

dar-like precision. For evolutionary c h a n g e to occur, at least two

acteristic or a p o m o r p h y . A n o t h e r example involves the trilobite

m a j o r factors must be in place. First, any genetic c h a n g e or m u t a -

h y p o s t o m e . Fortey ( 1 9 9 0 a ) developed the a r g u m e n t that hypos-

EVOLUTION

AND

CLADISTICS

31

t o m e a t t a c h m e n t , natent versus c o n t e r m i n a n t versus i m p e n d -

trilobites by the t i m i n g of the a p p e a r a n c e of the selected derived

ent, is an

characteristics. W i t h a large n u m b e r of characteristics, the g r o u p -

indicator of trilobite phylogeny.

other relationships, Fortey ( 1 9 9 0 a , Figure phylogeny/hypostome

attachment

chart

for

Using these a n d 19)

constructed a

trilobites,

ings are best d o n e with c o m p u t e r p r o g r a m s designed for cladis-

which

tics that search for the closest or most p a r s i m o n i o u s fit. Cladistics

By selecting a significant n u m b e r of derived characteristics

depth review, see the works by Fortey ( 1 9 9 0 b , 2 0 0 1 ) and Novacek

summarizes the current state of knowledge. and evaluating their presence or absence, o n e can group related

is clarifying m a n y relationships a m o n g trilobites. For a m o r e inand W h e e l e r ( 1 9 9 2 ) .

3

Taphonomy

Taphonomy is t h e study of processes that influence the preser-

a c c r e t i o n , the fossil is evidence of the death of an individual. C o n -

vation of potential fossils. T h i s field e n c o m p a s s e s the disciplines

versely, with trilobites, the presence of body parts is not a simple

of

indicator o f population density.

biostratinomy,

the

study

of

processes

affecting

organism

remains or traces prior to their final burial, and fossil diagenesis, the investigation of p h e n o m e n a affecting potential fossils after burial. Recently, t a p h o n o m y has developed b o t h as a m e a n s of assessing bias in the fossil record and m o r e positively, as a critical tool for p a l e o e n v i r o n m e n t a l analysis. T a p h o n o m i c analyses

Death, Decay, and Disarticulation Death

and fossil g e o c h e m i s t r y provide valuable i n f o r m a t i o n on the

T h e t a p h o n o m i c history o f most organisms generally begins

physical and chemical p a r a m e t e r s o f e n v i r o n m e n t s . T h e a s s u m p -

with their death, although in a r t h r o p o d s , including trilobites,

tions of u n i f o r m i t a r i a n i s m are applicable at this level because the

molted exuviae also b e c o m e a part of the preserved record. Death

physical and c h e m i c a l properties o f the skeletons o f o r g a n i s m s

of o r g a n i s m s m a y involve gradual n o r m a l mortality. However,

have probably been invariant t h r o u g h geologic t i m e , despite the

m a n y of the spectacular Lagerstatten occurrences involve mass

n o n u n i f o r m i t y i m p a r t e d b y evolution. T h e t a p h o n o m i c features

m o r t a l i t y of m a n y individuals and species due to environmental

of trilobites (e.g., articulation of delicate skeletal e l e m e n t s ) m a y

crises (Brett and Seilacher 1 9 9 1 ) . T h e s e crises may include s t o r m

provide u n a m b i g u o u s evidence for episodic s e d i m e n t a t i o n ; c o n -

and seismic s h o c k events, volcanic eruptions such as those at

versely, highly c o r r o d e d fossil material provides a distinctive sig-

Pompeii, overturn of the water c o l u m n , and anoxia. However,

nature o f l o n g - t e r m c o n d e n s a t i o n .

only the m o r t a l i t y events associated with episodes of burial will

Articulated s p e c i m e n s o f trilobites, while generally u n c o m m o n , may be a b u n d a n t in s o m e beds. Moreover, the totally m i n -

be recorded as such. M o s t bodies decay rapidly after death, with a resultant loss of soft parts.

eralized body parts of trilobites c o m m o n l y have been preserved

Scavengers of all sorts are also part of the normal fauna, and

nearly u n c h a n g e d for at least 5 2 0 million years. However, preser-

a dead animal can be expected to b e c o m e a food source for a wide

vational features of fossil s p e c i m e n s can be used to decipher the

variety of o t h e r animals, which in Paleozoic seas included other

t a p h o n o m i c history of these s p e c i m e n s and provide useful clues

trilobites. T h e result of this is that a dead trilobite exposed on the

as to original e n v i r o n m e n t .

seafloor can be expected to b e c o m e disarticulated and the body

T h e structural c o m p l e x i t y of the trilobite exoskeleton and the

parts scattered within a relatively short period of time. C o n s e -

process of m o l t i n g of the exoskeleton d u r i n g growth increase the

quently, very shortly after death the animal must be buried at least

n u m b e r of fossil parts that can be generated by a single individ-

deeply e n o u g h

ual. Trilobite skeletal parts can be f o u n d in a m a j o r i t y of fossilif-

oxygen inhibits scavenging and also favors the preservation of

erous localities in New York, and well-preserved cephala and

intact skeletons.

pygidia are generally identifiable to species. W i t h most o r g a n i s m s , like bivalves or gastropods in which the skeletal growth is by

32

to physically inhibit disarticulation.

Lowered

DEATH,

DECAY,

AND

Soft Tissue Decay

m o n t h s . As such, skeletons m a y be completely disarticulated

T h e most destructive process to affect the bodies of o r g a n i s m s is the decay of soft parts. T h e most volatile parts are tissues, such as internal organs and muscle, and as a result such tissues are very rarely encountered as fossils. W h e r e they are preserved, it is usually (but not always: Butterfield 1 9 9 0 ) the result of early diagenetic mineralization (Allison 1 9 8 8 b ) . Anoxia historically has been viewed as a prerequisite for the preservation of such tissues (e.g., W h i t t i n g t o n 1 9 7 1 b ) . However, the removal of e n v i r o n m e n t a l oxygen does not prevent microbial activity ( B e r n e r 1 9 8 1 b ; Allison 1988a; Allison and Briggs 1 9 9 1 a ) . Microbes simply utilize a variety of alternative oxidants for carbon degradation. In fact, it has been suggested that anoxia may retard the decay process by only a factor of two or three (Canfield and Raiswell 1 9 9 1 a ) . M o r e importantly, anoxia prevents scavenging and favors early mineralization. T h e microbial reactions that are involved in anaerobic decay also generate a series of reactive e l e m e n t s , which in s o m e c i r c u m s t a n c e s can go on to produce early diagenetic minerals. T h e s e minerals, in turn, may preserve the decaying tissues themselves. T h e minerals most frequently associated with soft-part preservation are pyrite (Allison

33

DISARTICULATION

1 9 8 8 a ) , phosphate (Allison

1 9 8 8 b ; Briggs and Kear

1 9 9 3 ) , and carbonates. T h e activity of anaerobic bacteria is a necessity for the f o r m a t i o n of all three. F o r m a t i o n of organic-clay complexes or clay coatings may also be i m p o r t a n t in soft-part preservation (Butterfield 1 9 9 0 ) . Most well-preserved b e n t h i c fossils are preserved approximately at their life sites, so b o t t o m - w a t e r anoxia can be ruled out as a preservational factor. Allison's ( 1 9 9 0 ) calculations demonstrate that most o r g a n i s m bodies b e c o m e anoxic m i c r o e n v i r o n m e n t s internally during early phases of decay. I n h i b i t i o n of scavenging in these e n v i r o n m e n t s may p r o l o n g the association of skeletal elements. 1 lowever, even under conditions of a n a e r o b i o sis or anoxia, bacterial decay of ligaments is rapid and the slightest currents will serve to disarray pieces (Allison 1988a, 1 9 9 0 ) . Not surprisingly, most cases of soft-part preservation a m o n g trilobites are associated with dysoxic m u d r o c k facies, typically dark, slightly organic-rich shales. T h e Burgess Shale ( M i d d l e C a m b r i a n , British C o l u m b i a ) , Frankfort Shale (Beecher's Trilobite Bed, Upper O r d o v i c i a n , New Y o r k ) , and the Hunsriick Shale (Lower Devonian, G e r m a n y ) are a few of the m o s t notable e x a m ples (Allison and Briggs 1991a, 1 9 9 1 b , 1 9 9 3 ; see b e l o w ) .

within a period of a few m o n t h s or less ( P l o t n i c k 1986, Allison 1988a). A variety of articulated trilobite remains are f o u n d . Speyer and Brett ( 1 9 8 6 ) recognized three basic categories: ( 1 ) partially articulated exoskeletons, ( 2 ) m o l t remains or exuviae, and (3) c o m pletely articulated skeletons representing carcasses (Figure 3 . 1 ) . Partially

articulated

remains,

such

as

groups

of

thoracic

segments, are of i n d e t e r m i n a t e origin and may represent either partially decayed remains of carcasses or molt parts. Exuviae in m a n y trilobites are recognizable by the absence of specific structures. For m o s t trilobites m o l t i n g involves the shedding of free cheeks. T h e r e f o r e , articulated exoskeletons with cranidia lacking free cheeks are almost certainly exuviae. P h a copids had fused facial sutures and shed the entire cephalic shield in m o l t i n g . T h u s , articulated thoracopygidia ("headless trilob i t e s " ) suggest m o l t parts. Molt e n s e m b l e s are groups of closely associated m o l t parts, such as free cheeks lying in close p r o x i m ity to articulated r e m a i n s with cranidia, or cephalic shields closely associated with thoracopygidia in p h a c o p i d s . Carcasses are represented by completely articulated exoskelet o n s , with the cephala intact a n d articulated (i.e., free cheeks are i n t a c t ) . T h i s category m a y be subdivided f u r t h e r into o u t stretched or p r o n e s p e c i m e n s and in s o m e trilobite species, partially enrolled and fully enrolled individuals. O r g a n i s m s with m u l t i e l e m e n t skeletons, including trilobites, are particularly sensitive indicators of rapid

and p e r m a n e n t

burial. Well-preserved, articulated trilobites typically o c c u r on certain bedding planes within

m u d r o c k s that would not be

recognizable as event-beds by other sedimentological m e a n s . Because such skeletons c a n n o t b e reworked, the o c c u r r e n c e o f even a single intact s p e c i m e n of a trilobite is an excellent indicator that the enclosing sediment a c c u m u l a t e d rapidly and was not subsequently disturbed. T h e o c c u r r e n c e o f large n u m b e r s o f completely

articulated

trilobites

provides

dramatic

evidence

for a p o p u l a t i o n of o r g a n i s m s that was abruptly wiped out. Conversely, the o c c u r r e n c e of well-preserved molt ensembles need not imply any m o r t a l i t y but rather indicates burial under relatively low-energy c o n d i t i o n s

that

prevented

scattering of

parts. Certain widely traceable levels in the Middle Devonian H a m i l t o n G r o u p are characterized by a b u n d a n t articulated molt ensembles but few, if any, c o m p l e t e trilobites (that would represent carcasses). Such findings may reflect rapid a c c u m u l a t i o n of thin layers of s e d i m e n t that did not kill or s m o t h e r living trilo-

Articulated Remains

bites but were sufficient to preserve molts (Speyer 1 9 8 7 ) . M a n y assemblages of well-preserved trilobites are also d e m o n -

Skeletons of organisms in which the skeleton is c o m p o s e d of

strably in situ ( b u r i e d in their living sites). A particularly sensi-

multiple elements weakly b o u n d together by ligaments or m u s -

tive indicator is the o c c u r r e n c e of trilobite molt ensembles, that

culature, such as trilobites, are o n l y rarely preserved intact.

is, associated, disarticulated m o l t parts. It is virtually impossible

M o d e r n experimental studies indicate that the degradation of

for different disarticulated p o r t i o n s of the skeleton to be trans-

soft tissues in arthropods occurs within a period of a few hours

ported any distance and still remain associated. T h e hydrody-

after death, while destruction of ligaments ensues in weeks to

n a m i c properties of whole exuviae versus free cheeks would

FIGURE 3 . 1 . Fossil a s s e m b l a g e s reflecting various c o n d i t i o n s a n d timing of burial. A. Low rates of s e d i mentation a n d slow burial a l o n g with reworking of the prefossilized hard parts. Sclerites are broken a n d scatt e r e d . B. Slow burial with disarticulation a n d m i x i n g . C. O b r u t i o n : burial, under a thin blanket of sediment, with s o m e disarticulation a n d infaunal s c a v e n g i n g . D. O b r u t i o n : s u d d e n burial under a thick blanket of s e d iment, resulting in g o o d preservation of articulated fossils a n d r e d u c e d infaunal s c a v e n g i n g . A - D from Brett a n d Baird (1993). E. Trilobites that exhibit s o m e d e g r e e of disarticulation b e c a u s e they were not b u r i e d d e e p l y e n o u g h or soon e n o u g h after mortality, PRI 4 9 6 6 1 . F. A g r o u p of w e l l - p r e s e r v e d trilobites as a result of r a p i d , relatively d e e p burial, PRI 4 9 6 6 2 . G. A trilobite that is tightly c o i l e d a n d well p r e s e r v e d , PRI 4 9 6 6 3 . Trilobites c o i l e d under stress, p r o b a b l y a s s o c i a t e d with the burial event.

TRANSPORT

AND

35

REORIENTATION

be so different that it is extremely unlikely they could be trans-

downward

ported and yet end up together. Molt ensembles thus constitute

that m a y be interpreted as indicators of storm-generated scour

p r o o f of life activity (i.e., m o l t i n g ) by trilobites in the precise site

and fill.

o f burial. O t h e r dramatic examples of in situ trilobites are the very rare

or lateral-oblique

positions

along

linear

features

M a n y skeletal e l e m e n t s , including articulated trilobites, as well as their cranidia and pygidia, have approximately concavo-

specimens of articulated skeletons directly associated with their

convex dish-shapes. R a n d o m o r preferred c o n v e x - u p o r convex-

trace fossils, such as famous s p e c i m e n s of Flexicalymene attached

down

to Rusophycus (see Figure 2 . 1 4 B ) . T h e o c c u r r e n c e of beds of en-

assemblages,

rolled trilobites also suggests a behavioral response to stressed

c o n d i t i o n s . Instances o f r a n d o m o r nearly o n e - t o - o n e ratios o f

orientations and

may each

be has

observed distinct

in

different

implications

trilobite

for

burial

conditions in which trilobites may have b u r r o w e d into the sedi-

c o n v e x - u p and - d o w n o r i e n t a t i o n s o c c u r primarily in heavily

m e n t and enrolled themselves, only to be buried in place and

b i o t u r b a t e d sediments, w h e r e , in addition, skeletal elements may

apparently unable to escape from m u d blanketing.

display lateral or edgewise o r i e n t a t i o n s . T h e m i x i n g of skeletal

Speyer and Brett ( 1 9 8 5 ) also recognized species-segregated

c o m p o n e n t s into sediment m a y a c c o u n t for the randomizing

clusters of fully articulated skeletons ( " b o d y clusters"; Plates 5 9 ,

of o r i e n t a t i o n . However, such o r i e n t a t i o n s are unstable under

102, 147, and 152) and m o l t e n s e m b l e s ( " m o l t clusters") involv-

hydrodynamic currents and h e n c e , are probably o n e of the better

ing at least three species of trilobites on single bedding planes in

indicators o f b i o t u r b a t i o n o r s o m e type o f protective c o n c e n t r a -

the Devonian Hamilton G r o u p . T h e s e trilobite clusters appear

tion trap on the substrate.

to represent preserved behavioral patterns. Using the a r g u m e n t

C o n c a v o - c o n v e x trilobite skeletal e l e m e n t s and whole bodies,

that the molt ensembles could not have been t r a n s p o r t e d any dis-

like

tance, Speyer and Brett inferred that these represented species-

c o n v e x - d o w n o r i e n t a t i o n s . For e x a m p l e , cephala and pygidial

segregated aggregations of trilobites that molted en mass. Speyer

shields in a preferred c o n v e x - u p position are p r o b a b l y most

and Brett further pointed out that synchronized m o l t i n g typically

typical

serves as a prelude to m a t i n g in m o d e r n peracarid crustaceans

Hesselbo 1987, Lask 1 9 9 3 ) showed that even gentle currents will

(e.g., marine isopods) and that several species also m a y t i m e their

affect trilobite r e m a i n s resting on the seafloor in such a way that

m a n y shells, c o m m o n l y display preferred c o n v e x - u p or

of c o n c e n t r a t e d

trilobite

beds.

Flume

studies

(e.g.,

reproductive cycles to a c o m m o n external stimuli, such as lunar

they flip to a hydrodynamically stable o r i e n t a t i o n , at which point

cycles. This analog suggests that trilobite clusters may represent

currents will glide over their s t r e a m l i n e d , c o n v e x - u p surfaces.

preserved mating "orgies."

T h e effect is particularly evident in areas of m u d d y substrate because o f the i m p e d a n c e (i.e., frictional d r a g ) .

Transport and Reorientation Trilobite skeletons can be sensitive indicators of hydrody-

Hence,

the

occurrence

of

abundant

convex-up

trilobite

cephala or pygidia on bedding planes m a y provide evidence for reworking of skeletal material under slightly current-agitated

namic conditions in the depositional e n v i r o n m e n t . U n d e r low-

conditions.

energy e n v i r o n m e n t s , typical of m u d r o c k s , o r g a n i s m remains

was processed by o n e or m o r e s t o r m - g e n e r a t e d current events.

may be buried in situ. O n e might use the a r g u m e n t that well-

Excellent examples are f o u n d in large assemblages of Flexicaly-

Beds of this sort represent skeletal material that

articulated fossils such as trilobites must not have been trans-

mene and Isotelus pygidial

and cephalic

ported and that their o c c u r r e n c e therefore indicates quiet water

o f h u m m o c k y laminated

calcisiltite beds, and

environments, but this inference must be m a d e cautiously. Aside

Pseudogygites

from obvious cases where this is not so (e.g., in which these skele-

in prep.).

from

the

Ordovician

shields on

the bases

pavements o f

Collingwood

Shale

(Brett,

tons are found at the bases of turbidites or even within skeletal

Beds of preferentially c o n c a v e - u p w a r d trilobite t a g m a are not

grainstone deposits), there is experimental evidence that if o r g a n -

as c o m m o n . In settings where the m o l t parts are suspended

isms are transported within the first few hours following death,

briefly and allowed to resettle from suspension, they will almost

their remains may stay articulated. Allison ( 1 9 8 6 ) d e m o n s t r a t e d

invariably settle c o n c a v e - u p w a r d (Lask 1 9 9 3 ) . Such reorienta-

in tumbling barrel e x p e r i m e n t s that a r t h r o p o d s such as s h r i m p ,

tion would o c c u r in areas very close to s t o r m wave-base in which

which provide possible analogs to trilobites, m a y be potentially

the

moved even tens of kilometers without disarticulating, provided

materials t e m p o r a r i l y o f f the b o t t o m and allow t h e m to free-fall

that this happens within the first few hours following their

b a c k to the substrate. Rapid burial following this stirring would

demise.

i n c o r p o r a t e such shells as a basal pavement of a possibly graded

Trilobite fossils also may provide evidence for reworking or

rather

gentle

storm-generated

waves

would

lift skeletal

m u d s t o n e layer. Excellent e x a m p l e s of this m o d e of burial are

transport of skeletons that would otherwise remain unsuspected.

seen

in

pavements of Triarthrus cranidia

in

Ordovician dark

It is not unusual in m a r i n e m u d r o c k s to observe c o n c e n t r a t i o n s

shales. C o u n t s of m a n y bedding planes from the Ordovician

of shells in localized pockets, typically associated with evidence

C o l l i n g w o o d Shale of O n t a r i o show a p r e d o m i n a n c e of concave-

for current scour. Such a c c u m u l a t i o n s c o m m o n l y display c o n v e x -

upward o r i e n t a t i o n s of the cranidia and of tiny ostracode valves,

36

TAPHONOMY

even on bedding planes in which larger skeletons are r a n d o m

slightly, by currents after death. As noted already, however, c u r -

o r c o n v e x - u p w a r d ( C . Brett, unpublished o b s e r v a t i o n , 1 9 9 8 ) . W e

rents usually have the effect of flipping concavo-convex elements

suggest that under certain c o n d i t i o n s only the smallest, light-

to a preferred convex-upward position. If trilobite remains were

weight skeletons were suspended and then resettled—typically

lifted into a current slightly and then resettled, they might still

concave-upward.

assume this position. Also, the generation of decay gasses within

Stacks of nested or shingled fossils apparently o c c u r where

the b o d y cavities of trilobites might give t h e m slight buoyancy

densely packed skeletal r e m a i n s were affected by oscillatory,

and make t h e m m o r e subject to the lifting and settling required

s t o r m - g e n e r a t e d waves or currents, and provide an indication

to invert the carcasses. All such inferences seem to point to a b r i e f

of deposition well within s t o r m wave-base. A similar m o d e of

interlude between m o r t a l i t y and final burial.

involves c o n c a v o - c o n v e x

A few o c c u r r e n c e s of p r e d o m i n a n t l y convex-upward out-

shells bundled together in nested groupings, either c o n v e x -

preservation

in

shell

accumulations

stretched trilobites are also k n o w n ; for example, groupings of

upward or -downward and often b o t h in the s a m e layers. T h e s e ,

Eldredgeops milleri f r o m the Silica Shale typically show this o r i -

too, seem to reflect the effects of settling and c o n c e n t r a t i o n of

e n t a t i o n . T h e s e are c o m m o n l y associated with perfectly enrolled

skeletal remains during t u r b u l e n c e events, and they are c o m -

trilobites and they m a y represent examples of m o r e nearly instan-

m o n l y associated with m i n o r s e d i m e n t grading. An intriguing

t a n e o u s burial with little disturbance.

example consists of masses of nested cephalic and pygidial shields

Speyer ( 1 9 8 7 ) and B r a n d t ( 1 9 8 5 ) also considered the possi-

of bumastid trilobites from Silurian b i o h e r m s , such as those in

bility of preferential orientation of enrolled trilobites but c a m e

the Silurian I r o n d e q u o i t L i m e s t o n e . T h e s e m a y represent molt

to different c o n c l u s i o n s .

parts that were c o n c e n t r a t e d in sheltered " p o c k e t s " or scours on

o r i e n t a t i o n s in s o m e mass occurrences of enrolled Flexicalymene

b i o h e r m surfaces.

meeki f r o m Upper Ordovician shales of the C i n c i n n a t i , O h i o ,

Brandt

reported essentially r a n d o m

A particularly intriguing a n d still e n i g m a t i c aspect of o r i e n t a -

region. In contrast, Speyer recognized preferred and species-

tion in trilobites is the p r e d o m i n a n t l y c o n c a v e - u p w a r d (dorsal

specific o r i e n t a t i o n s in Devonian enrolled trilobites from New

shield d o w n )

York.

o r i e n t a t i o n o f articulated trilobites. M a n y o c c -

Greenops

s p e c i m e n s were

commonly found

a

cluding

the

showed cephalon-lateral or -downward positions. Speyer sug-

Ordovician Trenton L i m e s t o n e of New York (Brett et al. 1 9 9 9 ) ,

gested that these findings recorded different modes of pre-enroll-

beds

m e n t behavior by the trilobites.

occurrences

of Dalmanites

(Taylor and

Brett

limulurus

of Ceraurus pleurexanthemus in

the

Silurian

from

Rochester

Shale

Eldredgeops rana

in

cephalon-up

mass

position, while

most

urrences of clusters of trilobites display this p h e n o m e n o n , in-

more commonly

1 9 9 6 ) , and aggregations of Eldredgeops rana

T h e preferred azimuthal ( c o m p a s s bearing) orientation o f

from the f a m o u s trilobite beds of the Lake Erie region (Speyer

elongate skeletons has been the subject of n u m e r o u s studies,

and Brett 1 9 8 5 ) . Several explanations for such o r i e n t a t i o n s have

including

been put forth. R a y m o n d ( 1 9 2 0 a ) believed that these represented

Kidwell a n d B o s e n c e 1 9 9 1 , for s u m m a r y ) . From such studies, it

both

observational

and

experimental

studies

(see

examples of trilobites buried in a life position, postulating that

has b e c o m e c o m m o n knowledge that elongate particles typically

these animals swam upside down, like horseshoe crabs, and per-

o r i e n t themselves selectively within a current. Elongate objects

ished in this position. However, m o s t later a u t h o r s have c o n s i d -

that do not roll, such as the trilobite carcasses m e n t i o n e d earlier,

ered this unlikely and argued for a p o s t m o r t e m reorientation of

c o m m o n l y will be aligned parallel to the direction of the current.

carcasses. O n c e again, if the c o n c a v o - c o n v e x carcasses of trilo-

Such may be the case with consistently aligned specimens of C.

bites were suspended and resettled freely, they would very likely

pleurexanthemus reported by Brett et al. ( 1 9 9 9 ) . T h e o c c u r r e n c e

assume this position. Several features associated with the dorsal-

of s o m e aligned trilobites in elongated "windrows," such as in the

downward trilobites m a y bear on this issue. F o r e x a m p l e , Speyer

Silurian Rochester Shale, may represent accumulation in very

and Brett ( 1 9 8 5 ) n o t e d that s o m e o f the " i n v e r t e d " trilobites were

m i n o r scours o r gutters (Whiteley and Smith 2 0 0 1 ) .

headless and thus, likely molted thoracopygidia. Such s p e c i m e n s obviously were not " s w i m m i n g , " and yet they are f o u n d alongside c o m p l e t e specimens that are also p r e d o m i n a n t l y c o n v e x - d o w n -

Fragmentation and Biased Preservation

ward. Even a m o n g these latter s p e c i m e n s there m a y be signs of

Trilobite skeletal elements are variably affected by biotic and

incipient disarticulation (e.g., c e p h a l o n or pygidium is rotated

abiotic destructive agents p o s t m o r t e m . T h e degree to which the

slightly away f r o m thorax; t h o r a c i c s e g m e n t s are very slightly

skeletons are affected is a function not only of the delicacy of their

pulled a p a r t ) . Such observations suggest that the trilobites repre-

original c o n s t r u c t i o n but also of residence t i m e on the seafloor.

sent carcasses that had u n d e r g o n e a very slight a m o u n t of decay

O n c e e l e m e n t s are disarticulated, they may be acted on by

prior to burial. In all of the a b o v e - m e n t i o n e d cases, there is also

various hydrodynamic processes that serve to sort, fragment,

a vaguely to strongly preferred long-axis o r i e n t a t i o n (e.g., see

abrade, or c o r r o d e t h e m . H y d r o d y n a m i c size sorting is u n c o m -

Brett et al. 1 9 9 9 ) . T h i s would also seem to imply that the trilo-

m o n in m o s t m u d r o c k s , for which generally low-background

bites reflect carcasses or m o l t s that were t r a n s p o r t e d , if only

e n v i r o n m e n t a l energies are characteristic. However, size sorting

FOSSIL

37

DIAGENESIS

may o c c u r on the scale of a single graded bed as a result of tur-

exposure t i m e , as well. Conversely, s o m e shells in condensed

bulent events that briefly suspend skeletal particles and sediment

deposits show few, if any, epibionts. M i c r o b o r i n g s of forms such

and allow them to resettle.

as endolithic algae may be recognized and may provide particu-

Biased ratios of skeletal parts, for which original p r o p o r t i o n s

larly useful indicators of exposure a n d , in s o m e cases, of relative

are known to have been o n e - t o - o n e , m a y provide evidence of

depth ( G o l u b i c et al. 1 9 7 5 ; Vogel et al. 1 9 8 7 ) . Endolithic algae of

sorting or, m o r e frequently in the case of m u d r o c k s , of preferen-

various sorts, for e x a m p l e , are c o n f i n e d to various p o r t i o n s of the

tial destruction. For e x a m p l e , it is a c o m m o n observation that

e u p h o t i c to upper dysphotic zone. Algal m i c r o b o r i n g s in Dicra-

certain portions of trilobite skeletons are preferentially preserved,

nurus s p e c i m e n s have been used to suggest that these trilobites

whereas the others tend to be f r a g m e n t e d . T h i s results in a selec-

lived in the e u p h o t i c zone. Kloc ( 1 9 9 7 ) suggested that abundant

tive bias that is not related to size but rather to relative robust-

encrusters on the cephalic spines of these trilobites may have

ness of the skeletal parts. For e x a m p l e , the rather robust pygidia

settled during the life of the trilobite and served as camouflage

of dalmanitids and asaphids are m o r e c o m m o n l y preserved intact

against visual predators.

than are cephala. Pygidia-cephala ratios up to t e n - t o - o n e were found in s o m e spectacular bedding plane pavements of Pseudogygites latimarginatus from the C o l l i n g w o o d Shale in O n t a r i o ( C . Brett, unpublished d a t a ) . Conversely, for the small trilobite Tri-

Fossil Diagenesis: Geochemical Processing of Potential Fossils

arthrus eatoni, from the same beds the small, fragile pygidia are

Early diagenetic p h e n o m e n a c o m p r i s e the physicochemical

very rare, and s o m e bedding planes show n o t h i n g but cranidia

processes that act on o r g a n i s m r e m a i n s primarily after burial.

("head shales"). Beds with approximately o n e - t o - o n e ratios of

Diagenetic features of fossils m a y provide i n f o r m a t i o n regarding

cephala and pygidia may indicate rather rapid and intact burial,

the g e o c h e m i s t r y o f b o t t o m waters and the upper " t a p h o n o m i -

whereas those that show a strongly biased ratio probably repre-

cally active z o n e " ( T A Z ) of the sediment c o l u m n . Diagenetic fea-

sent time-averaged a c c u m u l a t i o n s in which rather long exposure

tures of note include evidence for early dissolution, c o m p a c t i o n ,

times on the sea b o t t o m prevailed. D u r i n g these intervals, m i n o r

and mineralization of fossils.

physical disturbances, such as multiple s t o r m s or even biotic disturbances, fragmented the less rigid skeletal parts preferentially.

T h e relative t i m i n g of dissolution is c o m m o n l y recorded in skeletons. Trilobite exoskeletons were i m p r e g n a t e d with calcite and thus are relatively resistant to dissolution and are preservable;

Abrasion, Corrosion, and Encrustation

however, they still

may show evidence of early dissolution.

Trilobite skeletons that are dissolved prior to c o m p a c t i o n may

It is often difficult to distinguish between trilobite skeletons

leave no record but, in m a n y cases, m a y be preserved as plasti-

that have been physically abraded and those that have been

cally d e f o r m e d molds (Seilacher et al. 1 9 8 5 ) . Such preservation

corroded by biogeochemical processes. As a generalization most

would indicate u n d e r s a t u r a t i o n with respect to calcite in the

trilobite remains are too fragile to withstand p r o l o n g e d abrasion,

upper s e d i m e n t s and possibly low pH c o n d i t i o n s . Conversely,

and this fragility may a c c o u n t for the rarity of trilobite skeletons

many f o s s i l skeletons and their molds display mosaic fracture

in s o m e nearshore, sandy e n v i r o n m e n t s in which trace fossils indi-

patterns on their surfaces; these are particularly p r o m i n e n t on

cate that trilobites were c o m m o n . It is well k n o w n that clay-sized

large shields such as the cephala and pygidia of Isotelus species.

sediment is ineffective as an abrasive agent. H e n c e , truly abraded

Such skeletons r e m a i n e d hard in early phases of c o m p a c t i o n ,

fossils are rare in m u d r o c k s and, if f o u n d , might indicate a m u c h

which caused brittle fracture. (In rare instances, both plastically

m o r e c o m p l e x history to the deposit in which shells were trans-

d e f o r m e d " g h o s t e d " s p e c i m e n s and brittly fractured (or unfrac-

ported into a quieter water e n v i r o n m e n t by a turbulent event.

tured)

well-calcified

specimens

occur

on

the s a m e bedding

C o r r o d e d trilobite remains tend to o c c u r in offshore, low-

planes. Such associations have been used to suggest the presence

energy e n v i r o n m e n t s , and b i o e r o s i o n , likewise, tends to p r e d o m -

o f " s o f t - s h e l l e d " ( i m m e d i a t e l y p o s t m o l t ) and intermolt individ-

inate over physical abrasion in these offshore settings (Kidwell

uals (Speyer 1 9 8 7 ) . )

and Bosence 1 9 9 1 ; Parsons and Brett 1 9 9 1 ) . M a n y apparently

Early diagenetic minerals such as siderite, calcite, and pyrite

abraded shells in m u d r o c k s probably have been chemically etched

generally f o r m as a result of the action of anaerobic bacteria

or acted on by m i c r o b o r i n g o r g a n i s m s .

and are partly c o m p o s e d of their respiratory b y - p r o d u c t s (Allison

Even in life, trilobite exoskeletons may b e c o m e encrusted with epibiontic organisms, such as b r y o z o a n s and even b r a c h i o p o d s

1 9 8 8 a ) . T h e y m a y provide valuable i n f o r m a t i o n o n sediment g e o c h e m i s t r y and rates of burial.

(Tetreault 1992; Kloc 1993; Taylor and Brett 1 9 9 6 ) . P o s t m o r t e m

O n e o f the best u n d e r s t o o d o f the early diagenetic minerals

trilobite remains may be encrusted both externally and internally.

is pyrite, iron disulfide ( B e r n e r 1981a; Canfield and Raiswell

Internal encrustation provides an excellent indication that skele-

1 9 9 1 a , 1 9 9 1 b ) . Pyrite is c o m m o n in m a n y m a r i n e m u d r o c k s and

tons have lain disarticulated for a period of t i m e on the sea

is c o m m o n l y associated with fossil trilobite remains. T h e ferrous

b o t t o m . T h e extent o f encrustation may provide a n indicator o f

iron required in pyrite f o r m a t i o n is available in terrigenous

38

TAPHONOMY

sediments, and dissolved sulfate is a b u n d a n t in m a r i n e water (but

as a

not in fresh water). Under aerobic decay of organic matter, the

the m o s t c o m m o n trilobite in these beds, and s o m e specimens

m a j o r respiratory b y - p r o d u c t s o f o r g a n i s m s are water ( H 0 ) and

are partially pyritized and have a solid pyritic core and s o m e

c a r b o n dioxide ( C O , ) .

However, under a n a e r o b i c c o n d i t i o n s

coiled s p e c i m e n s form the nucleus of a pyrite nodule. These beds

particular types of bacteria, referred to as sulfate-reducing bacte-

appear to represent the rapid burial of organism bodies in an o t h -

ria, use sulfate ( S 0 ~ ~ ) as an oxygen d o n o r for metabolizing

erwise l o w - o r g a n i c sediment. T h e high c o n c e n t r a t i o n of pyritic

:

4

nucleus for over-pyrite precipitation.

Greenops grabaui is

organic matter, and p r o d u c e hydrogen sulfide ( H , S ) and bicar-

material a r o u n d burrows and fossils indicates nucleation around

b o n a t e ( H C 0 " ) as b y - p r o d u c t s . Iron r e d u c t i o n , mediated by a

local centers of a n a e r o b i c decay associated with buried organic

second group of a n a e r o b i c bacteria, can generate ferrous ions,

matter.

3

which in turn m a y react with the H , S generated by sulfate reduc-

A n a e r o b i c decay processes, including sulfate reduction, also

tion, to produce the precursors of pyrite (Canfield and Raiswell

generate H C O , " ( b i c a r b o n a t e ) , which may initiate the precipita-

1991 b ) . T h e presence of pyrite shows that the s e d i m e n t was anoxic

tion of calcite or siderite c o n c r e t i o n s around decaying organic

but does not necessarily d e m o n s t r a t e that the overlying water

matter. W h e r e trilobites or other fossils are enclosed within car-

c o l u m n was anoxic. Pyrite can f o r m either very early or relatively

b o n a t e c o n c r e t i o n s , they are nearly always t h r e e - d i m e n s i o n a l .

late in the burial history of a sediment ( H u d s o n 1 9 8 2 ; Brett and

T h i s proves that the c o n c r e t i o n s f o r m e d early and before organ-

Baird 1 9 8 6 ; Allison 1 9 8 8 a , 1 9 8 8 b ; Canfield a n d Raiswell 1 9 9 1 a ) .

ism remains could be c o m p a c t e d by overburden pressure.

Under c o n d i t i o n s o f high o r g a n i c - m a t t e r p r o d u c t i o n , anoxic

It is less c o m m o n for phosphatic nodules to form because

c o n d i t i o n s may e x t e n d into the water c o l u m n ; in such euxinic set-

p h o s p h o r u s is only present in very small quantities in seawater.

tings H , S is in excess, and any iron that is i n t r o d u c e d into the

However, the a n a e r o b i c decay of organic matter does liberate

system is pyritized as it is deposited. T h u s , pyrite tends to be

phosphate-bearing

distributed evenly in the s e d i m e n t as disseminated tiny crystal

can b e c o m e a d s o r b e d to ferrous hydroxides in the sediment.

aggregates called framboids; it is n o t c o n c e n t r a t e d a r o u n d any

As these ferrous hydroxides are buried and pass through the

o r g a n i s m remains that m a y settle into these settings. U n d e r oxic

anoxic-oxic

b o t t o m - w a t e r c o n d i t i o n s , however, o r g a n i c material is not dis-

liberates phosphates to pore-water. Dissolved phosphate m a y

tributed so u n i f o r m l y because m u c h of it is degraded aerobically

be released b a c k to the water c o l u m n if anoxia persists to the

at or near the s e d i m e n t - w a t e r interface, a n d the sediment b e -

s e d i m e n t - w a t e r interface. However, if a micro-oxidized zone

c o m e s anoxic b u t nonsulfidic, in Berner's ( 1 9 8 1 a ) terminology.

exists in the upper s e d i m e n t , then the phosphates may be repre-

T h u s , pyritization tends t o o c c u r m o r e locally within the n o n -

cipitated, especially a r o u n d phosphatic skeletal nuclei, such as

sulfidic s e d i m e n t , particularly in the vicinity of anaerobically

the

decaying organic matter. As a result of local sulfate r e d u c t i o n ,

(Swirydczuk et al. 1 9 8 1 ; B e r n e r 1981a; Allison 1 9 8 8 b ) . Trilobites

sulfide is liberated a r o u n d this d e c o m p o s i n g organic material.

are not u n c o m m o n l y phosphatized. Phosphatization of trilobites

Dissolved iron will react at the site of sulfate r e d u c t i o n so that

occurs primarily under c o n d i t i o n s of slow sedimentation. T h u s ,

pyrite is restricted to a n o x i c o r g a n i c - r i c h m i c r o e n v i r o n m e n t s

for e x a m p l e , in the M i d d l e Devonian Hamilton G r o u p , p h o s -

within a broadly dysoxic, l o w - o r g a n i c setting. Well-preserved

phatized internal m o l d s of enrolled trilobites may o c c u r at m i n o r

pyritized fossils, including trilobites tend to o c c u r in b i o t u r b a t e d

disconformities.

compounds

boundary,

chitinophosphatic

they

are

material

to

solution.

reduced.

forming

Also,

This

phosphate

process

arthropod

also

skeletons

gray m u d s t o n e s and thus are indicators of b o t t o m - w a t e r oxy-

If the s e d i m e n t a t i o n rate is high, then the time spent by any

genation (Brett and Baird 1 9 8 6 ; Allison and Brett 1 9 9 5 ) . T h e ear-

particular s e d i m e n t layer at this micro-oxidized interface will be

liest phases of pyrite tend to be fine-grained fillings of cavities,

low, and the p h o s p h o r u s c o n c e n t r a t i o n in pore-water will be

such as the interiors of enrolled trilobites. Later generations of

increased only slightly. Conversely if the sedimentation rate is

larger crystalline " o v e r p y r i t e " may nucleate on existing pyritic

low, then the t i m e spent at the interface will be high. T h u s , a large

cores. In this way, pyritic nodules m a y f o r m (Figure 3 . 2 ) . T h e r e are a n u m b e r of M i d d l e D e v o n i a n fossil beds in New

p r o p o r t i o n o f the a d s o r b e d p h o s p h o r u s c o m p o u n d s will b e c o n centrated at o n e layer in the sediment. Such c o n c e n t r a t i o n can

York wherein large a m o u n t s of pyrite are f o u n d associated with

increase pore-water levels of p h o s p h o r u s so that phosphate m i n -

the fossils ( D i c k and Brett 1 9 8 6 ) . T h e best k n o w n of these is the

erals can precipitate. T h e s e minerals may replace organic remains

Alden Pyrite Beds in the Ledyard Shale. T h e Ledyard Shale is

o r f o r m c o n c r e t i o n s . T h u s , the o c c u r r e n c e o f phosphatic fossil

a dark-gray, generally poorly fossiliferous shale. However, a

molds or c o n c r e t i o n s is nearly always an indicator of low rates of

h o r i z o n in the lower Ledyard in western New York is rich in pyrite

sedimentation.

nodules and pyritized m o l d s o f fossils o f all sorts. M o s t c o m m o n

O t h e r f o r m s o f diagenetic modification o f trilobite material

are the fossils that had calcific or aragonititic shells in life, such

are u n c o m m o n to absent in New York. T h e r e are a few references

as pelecypods, b r a c h i o p o d s , nautiloids, a m m o n o i d s , and trilo-

to silica replacement of exoskeletal material in trilobite protaspids

bites. T h e pyrite nodules have fossils at their core, which indicates

b u t n o observations o f phosphate replacement o r carbonized

that the original pyrite, f o r m e d f r o m the organic decay, acted

specimens.

FIGURE 3.2. Conditions for the formation of pyritized, w e l l - p r e s e r v e d fossils. A. Fauna on a b o t t o m with poor oxygenation. There is low diversity, a n d the b o t t o m is anoxic a short d i s t a n c e b e n e a t h the s u r f a c e . The plus s i g n s (+) indicate anoxic conditions. B. R a p i d burial by s e d i m e n t a n d the r e d u c e d o x y g e n levels of the water raise the anoxic level to the newly b u r i e d o r g a n i s m s . A n o x i c bacteria in m e t a b o l i z i n g o r g a n i c matter of the trilobites also r e d u c e the sulfate in the pore water, resulting in sulfide ions that then react with r e d u c e d ( F e ) iron in the sediment. In a s e d i 2+

ment rich in terrigenous material, the iron level is high e n o u g h to c a u s e iron sulfide precipitation at or c l o s e to the d e c a y i n g organic material. C. Pyrite a c c u m u l a t e s at the source of the o r g a n i c decay, a n d the fossil is c o v e r e d with pyrite at this nucleation site. A - C from Speyer a n d Brett (1991). R e p r o d u c e d with p e r m i s s i o n . D, A trilobite b u r i e d in a rapid burial event but in an o x y g e n a t e d s e d i m e n t so that only a minor a m o u n t of pyrite f o r m e d . E. A coiled trilobite buried under anoxic, low-organic ( e x c e p t at the site of trilobite d e c a y ) , a n d iron-rich c o n d i t i o n s , resulting in a total c o v e r i n g of pyrite, PRI 4 9 6 6 4 .

40

TAPHONOMY M o r e c o m p l e t e i n f o r m a t i o n on the processes of fossil preser-

plete typically outstretched, inverted individuals may occur, even

vation can be f o u n d in collective volumes edited by Briggs and

in clusters. U n d e r lower sedimentation the event signature c o m -

C r o w t h e r ( 1 9 9 0 ) ; Allison and Briggs ( 1 9 9 1 a , 1 9 9 1 b ) ; D o n o v a n

prises primarily intact molt e n s e m b l e s , with few if any fully artic-

( 1 9 9 1 ) ; Einsele, Ricken, and Seilacher ( 1 9 9 1 ) ; a n d M a r t i n ( 1 9 9 9 ) .

ulated carcasses. Finally, under low-energy, dysoxic (background) c o n d i t i o n s , intact molt parts and tagma are the rule; the event signature of this setting is distinctive in showing an abundance

Trilobite Taphofacies

o f enrolled, c o m m o n l y pyritized, s p e c i m e n s o f trilobites.

Various aspects of fossil preservation can be c o m b i n e d into

Each taphofacies records different types of i n f o r m a t i o n . T h e

the recognition and description of t a p h o n o m i c facies or t a p h o -

distinctive m o d e s of preservation provide i n f o r m a t i o n on sedi-

facies (Speyer and Brett 1 9 8 6 , 1 9 9 1 ) . Together with lithofacies,

m e n t a r y e n v i r o n m e n t s that c a n n o t be determined otherwise.

biofacies, and ichnofacies, taphofacies tend to vary predictably

F o r e x a m p l e , the e n r o l l m e n t of trilobites may reflect a response

with sedimentary e n v i r o n m e n t s , as shown by studies in m o d e r n

to toxic stimuli triggered by a stirring up of anoxic, sulfide-rich

marine settings (Parsons and Brett 1 9 9 1 ) . T h e m o d e s o f preser-

m u d s . Similarly, pyritization suggests burial in anoxic, low-

vation of fossils can provide i m p o r t a n t insights into a n u m b e r of

organic m u d s .

features o f m u d r o c k deposition, including ( 1 ) the s e d i m e n t a r y

In this way, the study of trilobite preservation has helped to

e n v i r o n m e n t (depth, t e m p e r a t u r e , salinity, oxygen level, substrate

provide a new tool in paleoenvironmental analysis. Development

consistency);

of predictive models relating preservation to depositional envi-

(2)

the

dynamics

of

sediment

accumulation,

average rates, as well as evidence for episodicity of s e d i m e n t a t i o n

r o n m e n t s and positions in sedimentary sequences, in turn, may

and erosion;

aid

(3)

the temporal scope o f individual m u d r o c k

units; and ( 4 ) the s e d i m e n t g e o c h e m i s t r y and early diagenetic

paleontologists

in

prospecting

for

new fossil

bonanzas,

including spectacular trilobite beds.

environments. T h e overall c o n d i t i o n of trilobite skeletons can be assessed qualitatively or quantitatively but certainly should be n o t e d in the

Trilobite Lagerstatten

field. Semiquantitative indices can be f o r m u l a t e d by d e t e r m i n i n g

Lagerstatten (derived from the G e r m a n mining term trans-

the p r o p o r t i o n of skeletal parts in different, arbitrarily defined

lated loosely as " m o t h e r lodes") are extraordinary fossil assem-

preservational states. In such cases, it is c o m m o n l y useful to

blages. Trilobite Lagerstatten include o b r u t i o n deposits, reflecting

determine a set of standards with which particular shells can be

a rapid s m o t h e r i n g of benthic faunas by sediment, yielding fully

c o m p a r e d and assigned to a category, in m u c h the s a m e way that

articulated remains and Konservat-Lagerstatten, in which even

grain shapes and roundness indices have long been assessed on

soft parts are preserved by a c o m b i n a t i o n of rapid burial, anaer-

the basis of standardized profiles by sedimentologists. Skeletal

o b i c decay, and early diagenetic mineralization (Seilacher et al.

condition is particularly valuable for recognizing qualitatively

1 9 8 5 ) . In this section we describe examples of trilobite Lager-

the differing relative extents of s e d i m e n t a r y time-averaging and

statten f r o m New York State to illustrate the general t a p h o n o m i c

therefore, may be related to burial rates.

concepts.

In their original f o r m u l a t i o n of the n o t i o n of taphofacies,

A f a m o u s trilobite site is Beecher's Trilobite Bed in the Upper

Speyer and Brett ( 1 9 8 6 ) used M i d d l e Devonian trilobites and

Ordovician Frankfort F o r m a t i o n just north of R o m e , New York.

their modes of preservation to exemplify the general m o d e l . T h e y

A 5 - m m - t h i c k , light-gray layer within a dark-gray m u d s t o n e

also subsequently emphasized the fact that fossils in a particular

contains an unusual collection of fossil material (Cisne 1 9 7 3 ) .

taphofacies may show b o t h b a c k g r o u n d and event t a p h o n o m i c

The

signatures. That is, there may be distinct aspects of preservation

appendages and s o m e internal organs replaced by pyrite. B e e c h e r

Triarthrus

eatoni

specimens

within

this

layer

have

their

of fossils under day-to-day c o n d i t i o n s or under episodic cata-

( 1 8 9 3 , 1 8 9 4 , 1 8 9 5 ) reported the discovery by Valiant and the

strophic burial c o n d i t i o n s in a given e n v i r o n m e n t (Speyer and

preparation o f specimens. Cisne ( 1 9 7 5 , 1981) prepared very-

Brett 1 9 8 8 ) . T h e well-known D e v o n i a n trilobite species E. rana

high-resolution radiographs of Beecher's specimens and was able

and Greenops species o c c u r in m a n y distinct associations repre-

to report on internal structures never seen before. W h i t t i n g t o n

senting different e n v i r o n m e n t s . Yet, these trilobites show very dis-

and A l m o n d ( 1 9 8 7 ) also e x a m i n e d specimens from the beds and

tinctive m o d e s o f c o m m o n

suggested that certain structural elements of the appendages were

preservation that are u n i q u e t o

particular o n s h o r e - o f f s h o r e positions and s e d i m e n t a t i o n c o n d i -

utilized in food t r a n s p o r t , a m o n g other things. Replacement of

tions. For example, in high-energy shallow water, m o s t trilobite

organic tissue in such high resolution by pyrite is very unusual.

remains are disarticulated, abraded f r a g m e n t s , although articu-

Briggs, Bottrell, and Raiswell ( 1 9 9 1 ) e x a m i n e d these trilobites and

lated, typically outstretched individuals may o c c u r occasionally,

concluded that this type of soft tissue replacement was due to

owing to pulses of burial. In low-energy, fully oxic settings,

bacterial decay in anoxic c o n d i t i o n s resulting in sulfide f o r m a -

mainly u n b r o k e n , t h o u g h typically disarticulated trilobite m a t e -

tion. T h e rocks represent deep-water turbidites, and anything

rial is preserved; under episodes of higher s e d i m e n t a t i o n , c o m -

buried probably would have been subject to anoxic conditions.

TRILOBITE

LAGERSTATTEN

41

T h e concentration of organic matter in the sediment was rela-

b i o t u r b a t e d . A possible explanation is that the subsequent thicker

tively low, and the c o n c e n t r a t i o n of iron in the pore-water rela-

beds were deposited a short t i m e after this o n e , essentially sealing

tively high. In this situation the sulfide produced at local decay

it and m a k i n g any decay anaerobic. T h e low level of iron in the

sites was precipitated as an iron m o n o s u l f i d e (a precursor to

sediment precluded significant pyrite f o r m a t i o n .

pyrite) at the site where it was f o r m e d , resulting in the nearly perfect

replacement

Edgecombe

of

soft

tissue

by

pyrite

(Briggs

T h i s f o r m of appendage preservation

is unique and was

and

only f o u n d when Walcott m a d e sections of the trilobites and

1 9 9 3 ) . Beecher's Trilobite Bed remains the most

observed t h e m by t r a n s m i t t e d light. T h e very fine calcite in-filling

productive source of preserved trilobite soft tissue k n o w n .

in a c a r b o n a t e m a t r i x is very difficult to see and evaluate by

Trilobites found on limestone bedding planes typically are

reflected light. T h i s difficulty raises the question as to whether

compressed for the same reasons that trilobites are c o m p r e s s e d

this m o d e of preservation is actually m o r e c o m m o n but gener-

on shale partings. T h e i r history is similar in that they were buried

ally unobserved.

by a calcareous m u d f l o w with little t r a n s p o r t . S o m e of the best

T h e Lower Silurian R o c h e s t e r Shale c o n t a i n s several horizons

trilobites, however, from the physical preservation standpoint, are

yielding n u m e r o u s trilobites. S p e c i m e n s of the large lichid genus

found within limestones. In s o m e instances, these trilobites were

Arctinurus, when articulated, are usually f o u n d right side up but

apparently caught up in a calcareous sediment flow, killed, p r o b -

flattened.

ably transported s o m e distance, and e n t o m b e d in the settled

always inverted and often o c c u r s in narrow, elongate " w i n d r o w s "

sediment. In such limestones the trilobites typically are r a n d o m l y

that may show s o m e evidence of a preferred o r i e n t a t i o n . T h e

oriented, with the bodies flexed in unusual postures, and retain

living Arctinurus a n i m a l s probably were buried in place by a

much

of

their

original

three-dimensional

character.

Dalmanites

limulurus,

from

several

layers,

is

almost

Large

heavy blanket of s e d i m e n t , which resulted in their death. T h e D.

numbers of Isotelus gigas have been taken from the limestones of

limulurus, however, were t r a n s p o r t e d s o m e w h a t before the burial

the Middle Ordovician Trenton G r o u p in central New York. T h e

process, aggregated, and c u r r e n t aligned in windrows. T h e fact

specimens from bedding planes are flattened and c o m m o n l y

that most are upside d o w n is less easily explained. Convex surface

upside down, while those from within the limestone retain their

down may be a preferred o r i e n t a t i o n d u r i n g transport in a

three-dimensional character.

c u r r e n t , or the living a n i m a l m a y have been t u m b l e d by the

In the Walcott-Rust Q u a r r y within the Trenton G r o u p , several

current and the u p s i d e - d o w n trilobites m a y not have been able

layers of the thinly bedded limestone have yielded excellent trilo-

to right themselves. Again, alignment probably indicates slight

bites (Brett et al. 1 9 9 7 , 1 9 9 9 ) . O n e thin micritic limestone yielded

transport of dead individuals by a c u r r e n t . Alternatively, it is pos-

large

sible that these trilobites swam upside down to escape the sedi-

numbers

of articulated

C.

pleurexanthemus,

Flexicalymene More

m e n t and were buried in this p o s i t i o n . A possible model for this

than 9 8 % of the trilobites on the base and those within the layer

latter behavior c o m e s from the living h o r s e s h o e c r a b , Limulus,

were upside down while 6 0 % o f those o n the upper surface,

which n o r m a l l y crawls a r o u n d the b o t t o m but m o r e rarely swims

including many that were still partially within the l i m e s t o n e , were

upside d o w n .

senaria, and

Meadowtownclla

trentonensis

(but

no

I.

gigas).

right side up. T h e t h i n n e r bed probably records a large popula-

T h e siltstones,

m u d s t o n e s , shales, and

limestones

Hamilton

yielded

of the

tion of trilobites caught in a current and transported far e n o u g h

Middle

to be mixed within the small a m o u n t of sediment involved. M o s t

n u m b e r s o f articulated s p e c i m e n s o f trilobites. O n e well-studied

of the trilobites were killed in the process. T h e larger m o r e robust

bed, the B r o w n s C r e e k B e d , a lime m u d s t o n e in the lower C e n -

ones may have managed to struggle to the surface and die there

terfield

or were covered and killed by a subsequent event. T h e observa-

Monodcchenella

tion that no /. gigas were involved suggests that they were large

b e d can be traced f r o m Centerfield, O n t a r i o C o u n t y , to East

Devonian

Limestone,

yields

macrocephala,

Group

superbly and

have

preserved

Pseudodechenella

enormous

Eldredgeops

rana,

rowi.

This

and strong enough to escape. Two other, thicker beds had no

Bethany, G e n e s e e C o u n t y , a distance of over 4 9 k m (31 miles).

trilobites on the base or top but well-preserved s p e c i m e n s inter-

T h e trilobites are f o u n d in r a n d o m o r i e n t a t i o n , indicating they

nal to the limestone. T h e s e internal trilobites, which included /.

were swept up, t u m b l e d , and t r a n s p o r t e d s o m e distance from

gigas, were randomly oriented.

their original position in the sudden event f o r m i n g this bed.

Within the thin bed, coiled and semicoiled C. pleurexanthemus and F. senaria were discovered by C. D. Walcott ( w h o also discovered

the

Burgess

was

Wanakah

and

the

Windom

rana. Especially notable are the " G r a b a u Trilobite B e d s " (lower

This unique m o d e of preservation is believed to result from

Creek and the S m o k e C r e e k Beds in the f o r m e r P e n n - D i x i e

anoxic

the

Q u a r r y at H a m b u r g , Erie C o u n t y . T h e s e trilobite beds yield

appendage, followed by calcite in-filling as the appendage m a t e -

t h r e e - d i m e n s i o n a l clusters of E. rana, which Speyer and Brett

precipitation

evidence

lower

W a n a k a h Shale) along the Lake Erie shore near Eighteenmile

calcite

there

the

of

induced

and

within

appendages preserved as calcite infillings (Walcott 1876, 1 8 7 7 b ) . bacterially

Shale),

Horizons

m e m b e r s of the H a m i l t o n G r o u p are especially productive of E.

within

rial decayed (Brett et al. 1997, 1 9 9 9 ) . T h e Ceraurus bed is a thin,

( 1 9 8 5 ) divided into molt and b o d y clusters. T h e clusters are

15 to 5 0 - m m bed that normally would be expected to be heavily

nearly intact, which suggests little t r a n s p o r t . T h e s e beds are the

42

TAPHONOMY

result of very rapid burial and death, with very little turbulence

of 5 to 20 individuals are k n o w n . T h e general preservation is

d u r i n g the burial event.

similar to that of the M u r d e r Creek Beds.

T h e E. rana s p e c i m e n s from the lower W a n a k a h M u r d e r Creek

In s u m m a r y , t a p h o n o m i c analysis is a m a j o r factor in under-

Beds are f o u n d tightly coiled, fully o u t s t r e t c h e d , and in various

standing trilobite deposits, as well as fossil deposits in general.

semicoiled configurations in between these two e x t r e m e s . Typi-

T h e understanding that c o m e s from such analyses not only is

cally, in the semicoiled s p e c i m e n s , the pygidium appears to be

intellectually rewarding but also provides a foundation for inter-

missing. On close e x a m i n a t i o n , however, the pygidium can always

preting the geological history of fossil sites. T h e r e is also a

be f o u n d inside the body cavity of the trilobite. It is suggested

predictive factor that c a n n o t be ignored. For example, storm

that the pygidium was displaced when the tightly coiled trilobite,

deposits over stable sea b o t t o m s , below storm wave-base, often

u p o n decay, partially o p e n e d and viscous m u d filled the n o w -

b u r y a living fauna, resulting in well-preserved articulated fossils

e m p t y cavity.

such as trilobites and crinoids. Fossil preservation provides

T h e trilobites in the f o r m e r P e n n - D i x i e Q u a r r y are mostly in

the interpretation of fossil deposits and

the S m o k e Creek Beds o f the W i n d o m M e m b e r n a m e d for their

a n c i e n t e n v i r o n m e n t s . T a p h o n o m y and its concepts are power-

outcrop on S m o k e Creek, Erie C o u n t y . Well-preserved individ-

ful tools for general fossil collectors as well as professional

ual trilobites are c o m m o n in these beds, and occasional clusters

paleontologists.

1

1

i m p o r t a n t clues in

The Penn-Dixie Quarry is a public fossil site operated by the Hamburg

Natural History Society (P.O. Box 7 7 2 , Hamburg, NY 1 4 0 7 5 ; 7 1 6 - 6 2 7 - 4 5 6 0 ) .

4

The Paleozoic Geology of New York

T h e Paleozoic strata of New York State are a classic repository of

they c a n n o t be u n d e r s t o o d in isolation from the region as a

fossils, including, at m a n y levels, trilobites and a host of o t h e r

whole. D u r i n g this interval, present-day New York lay generally

invertebrate and even vertebrate and plant fossils. For details on

in southern subtropical to w a r m t e m p e r a t e latitudes, with the

the paleoecology and fossils, we r e c o m m e n d the publications

equator

by Linsley ( 1 9 9 4 ) , Isachsen et al. ( 1 9 9 1 ) , Landing ( 1 9 8 8 ) , Shaw

C l i m a t e s ranged from hot and arid to warm and h u m i d during

( 1 9 6 8 ) , and the references therein.

this t i m e .

running

approximately

centrally

through

Laurentia.

T h e purposes of this chapter are twofold: first, to give the reader both s o m e general b a c k g r o u n d regarding the tectonic, climatic, and paleoenvironmental history of life on earth (Archean through Pleistocene, Figure 4 . 1 A ) , and m o r e specifically of New York State and adjacent ancestral North A m e r i c a during the early

Prelude to the Paleozoic: Late Proterozoic Collisions and the Grenville Orogeny T h e oldest rocks in New York, exposed in the Adirondack

to middle Paleozoic Era ( C a m b r i a n through D e v o n i a n , Figure

M o u n t a i n s and the

4 . I B ) , the time during which trilobites lived and were deposited

than 1 billion years old. T h e s e are crystalline rocks that were

Hudson

Highlands, are s o m e w h a t m o r e

in New York's sedimentary rocks; and second, to provide s o m e

m e t a m o r p h o s e d or altered from older rocks by e n o r m o u s heat

details on the stratigraphy, sedimentology, and paleoecology of

and pressure (Figure 4 . 2 ) . S o m e were originally igneous rocks,

the intervals from Early C a m b r i a n to Middle Devonian that have

f o r m e d from the c o o l i n g and crystallization o f m a g m a s , and

yielded abundant trilobite remains. To these ends, the discussion

others are s e d i m e n t a r y deposits, such as q u a r t z sandstones,

of each Paleozoic t i m e interval is subdivided into two p o r t i o n s :

limestones,

first, an overview of global and New York geological history, and

phosed) by recrystallization and under intense heat and pressure;

and

shales.

T h e s e were

transformed

(metamor-

second, details of the stratigraphy and sedimentary e n v i r o n m e n t s

for example, sandstones were altered to tough metaquart/ites,

of the trilobite-bearing intervals, listed chronologically. Such

limestones to m a r b l e s , and shales to m i c a - r i c h schists. By looking

general discussion of geology might seem out of place in a b o o k

at the types of minerals f o r m e d within these rocks by m e t a m o r -

devoted to trilobites; however, we believe that students of New

p h i s m , geologists can be certain that the rocks now exposed in

York's trilobites should be well aware of these b r o a d e r contexts

the Adirondacks were o n c e buried up to 25 km within Earth

in order to understand the e n v i r o n m e n t s and ecology ot these

during a great o r o g e n i c or m o u n t a i n - b u i l d i n g e p i s o d e — a b o u t a

remarkable ancient o r g a n i s m s .

billion years ago. T h i s event, the Grenville Orogeny, apparently resulted when the (present) eastern edge of ancestral North

Overview T h e Paleozoic deposits of New York record a p o r t i o n of the

America

was overridden

by a n o t h e r c o n t i n e n t , perhaps the

northwestern side ot" present-day South America. This e n o r m o u s collision helped to weld together a supercontinent known as

history of ancestral North America or Laurentia during s o m e

P r o t o p a n g e a or Rodinia (Figures 4.3 and 4 . 4 ) . For nearly half a

2 0 0 million years of geologic t i m e (Figure 4 . I B ) , and as such,

billion years, this s u p e r c o n t i n e n t held together, and the massive •13

A

FIGURE 4 . 1 . A. Time scale for Earth history a n d for life on Earth. The New York Paleozoic is from the early C a m b r i a n to the e n d of the D e v o n i a n . A d a p t e d from S. M. Stanley, Exploring Earth and Life through Time. New York: W. H. Freeman, 1989. B. G e n e r a l i z e d g e o l o g y a n d detailed scale for the Paleozoic rocks in New York. The vertical scale is linear a n d proportional to time; note that the d a t e s of b e g i n n i n g s a n d e n d s of periods are given in millions of years before present. The right c o l u m n s list the n a m e s of major unconformities a n d the n a m e s of Sloss s u p e r s e q u e n c e s . Most of the information is from a n u m b e r of s o u r c e s . The d a t e s for the C a m b r i a n are from D a v i d e k et al. (2000) a n d L a n d i n g et al. (1998a,b). The T in the C a m b r i a n time p e r i o d indicates where trilobites first a p p e a r in the fossil r e c o r d , 5 1 9 million years before present. The d a t e s in the E p o c h s are the most current. The d a t e s in the Stages h a v e yet to be r e c o n c i l e d in the literature.

45

OVERVIEW

B

Grenville m o u n t a i n belt, fully f o r m e d by a billion years ago, was

present eastern seaboard region (eastern Massachusetts, eastern

exposed in a life-less continental interior to the forces of weath-

Nova Scotia, eastern N e w f o u n d l a n d ) , Florida, California, and

ering and erosion. We know that by about 5 5 0 million years ago,

o t h e r marginal areas that were added later. Laurentia was isolated

an entire thickness of continental crust had b e e n removed and

as a separate c o n t i n e n t during rifting and o p e n i n g of new ocean

erosion had exposed the roots of the ancient Grenville M o u n t a i n s .

basins that began approximately 7 0 0 to 6 0 0 million years ago

Laurentia is the term geologists apply to the ancestral Paleo-

during the interval of t i m e referred to as late P r o t e r o z o i c (or N e o -

zoic core of N o r t h A m e r i c a , lacking certain areas such as the

p r o t e r o z o i c ) . Notably, on the present east side of Laurentia,

THE

46

PALEOZOIC

GEOLOGY

OF

NEW

YORK

FIGURE 4 . 2 . P r e c a m b r i a n Grenville ( 1 . 0 BP) m e t a m o r p h i c / i g n e o u s rocks. Note the granitic pegmatite (a) and smaller folded dikes (b) cutting g n e i s s . Rte. 12, near Alexandria Bay, J e f f e r s o n County.

rifting or fracturing of the crust began over 6 0 0 million years

Initially, a large v o l u m e of sediment that eroded from the

a g o — s o m e 4 0 0 million years after the Grenville Orogeny. T h e

ancient Grenville terrane was shed o f f the old weathered craton

fractures and faults ultimately tore the s u p e r c o n t i n e n t of Rodinia

and into the n a r r o w Iapetus basin. However, as the sea level c o n -

apart. Evidently, ancestral S o u t h A m e r i c a , which had collided

tinued to rise during the latest Proterozoic and Early C a m b r i a n ,

with p r o t o - L a u r e n t i a to f o r m the Grenville M o u n t a i n s , n o w

the old land was finally flooded and the source of sediments cut

pulled back away. A new o c e a n , the Iapetus, or P r o t o - a t l a n t i c ,

o f f (Figure 4 . 5 A ) . T h e entire eastern b o r d e r of Laurentia had

began to open along a line that would pass through present-day

b e c o m e a passive continental edge; a sea with a very broad c o n -

central

tinental shelf ultimately extended from the area of central New

New

Carolinas, a

England bit

east

and of the

southward Blue

Ridge

to

the

east-central

Mountains

in

the

Appalachian chain (these m o u n t a i n s f o r m e d later).

England and the m i d Atlantic states region westward to the present Mississippi Valley during the C a m b r i a n to Early O r d o v i -

At the b e g i n n i n g of the Paleozoic Era, a b o u t 5 4 5 million years

cian (Figure 4 . 5 A , B ) . As spreading ensued in the Iapetus m i d o -

ago, a narrow, but widening Iapetus O c e a n lay slightly to the east

cean rift, the ocean basin grew wider, at least up to the Early

of present-day New York State (Figure 4 . 5 A ) . East of the present

Ordovician t i m e , about 4 8 0 million years ago, before the process

Berkshire ( M a s s a c h u s e t t s ) and Green ( V e r m o n t ) M o u n t a i n s lay

began to reverse and the Iapetus basin began to shrink and

the edge of Laurentia, w h i c h , m u c h like the present eastern edge

ultimately close.

of modern North A m e r i c a , f o r m e d a continental shelf bordered eastward (southward at that t i m e ) by a relatively steep d r o p - o f f along a continental slope into the deep water of the Iapetus Ocean.

Cambrian Period T h e C a m b r i a n Period, as it is now dated, spans approximately

Seawater was displaced upward o u t of the Iapetus O c e a n ,

54 million years from about 5 4 3 to 4 8 9 million years before

partly because of the e x p a n d i n g m i d o c e a n ridge ( o r spreading

present. Yet this was o n e of the most significant times in the

center, an area of hot upwelling m a g m a ) . T h i s seawater spread

history of life, for it was during this time that nearly all phyla or

out o n t o the c r a t o n of Laurentia and caused a m a j o r rise of the

m a j o r groups of a n i m a l s appeared in the rock record.

shoreline (transgression) up o n t o the old weathered r e m n a n t s of the Grenville rocks.

T h e onset of the C a m b r i a n was marked by a time of lowdiversity fossil assemblages typified by "small shelly" skeletons

FIGURE 4.3. M a p s h o w i n g the extent of the Grenville belt in eastern North A m e r i c a . Rocks in this area were d e f o r m e d a n d m e t a m o r p h o s e d about 1 billion years a g o . The d o t t e d pattern s h o w s regions w h e r e Grenville rocks are buried b e n e a t h y o u n g e r strata; the slanted lines indicate areas w h e r e Grenville rocks are e x p o s e d ; a n d cross-hatching shows areas where the Grenville rocks are d e f o r m e d by later o r o g e n i e s . M o d e r n A d i r o n d a c k Mountains lie just to the east of the Frontenac A r c h ( l a b e l e d ) . From Isachson et al. (1991). Printed with permission of the New York State M u s e u m , Albany, N.Y.

•18

THE

PALEOZOIC

GEOLOGY

OF

NEW

YORK

FIGURE 4 . 4 . P a l e o m a g n e t i c reconstruction of the supercontinent Rodinia as it existed in the late Proterozoic, a b o u t 7 0 0 million years a g o . Note the position of Laurentia, near the center. The dark belt shows the position of the Grenville O r o g e n i c belt. After Dalziel (1997), r e p r o d u c e d with permission.

including a variety of calcareous p h o s p h a t i c tubes, rods, and

divided

plates. O n l y in later Early C a m b r i a n t i m e ( - 5 1 9 millon years ago)

a u t o c h t h o n o u s ( n o n t r a n s p o r t e d ) rocks, which are in the site

into two great packages of strata

(Figure 4 . 7 ) . T h e

did trilobites first appear as body fossils, although fossil track-

of original deposition, a shallow-shelf e n v i r o n m e n t , and the

ways (traces of walking on the b o t t o m ) and resting pits (Ruso-

Taconic

phycus) suggest that unpreserved s o f t - b o d i e d trilobites, or similar

shales (now often slates) that were originally deposited to the east

a r t h r o p o d s , o c c u r r e d earlier.

of New York in o c e a n i c e n v i r o n m e n t s . T h e Taconic rocks were

T h e C a m b r i a n rocks of New York State are generally s u b -

allochthonous

transported

westward

(displaced)

80km

rocks,

during

the

mostly deep-water

Middle

Ordovician

CAMBRIAN

PERIOD

49

FIGURE 4 . 5 . Position of the Laurentian plate and neighboring Baltica and Avalonia terranes from the Cambrian to the Devonian. Areas of e x p o s e d land are dark, a r e a s c o v e r e d by water a r e white, a n d New York is highlighted in black. A. Middle Cambrian as most of what is the United S t a t e s w a s beginning to be flooded by shallow s e a s resulting in c a r b o n a t e depositions in the Late C a m brian (note Taconic island a r c s ) . B. Middle Ordovician with almost c o m p l e t e flooding of Laurentia and the beginning of the Taconic Orogeny with collision in the s o u t h e a s t . C. Silurian, with Baltica colliding with Laurentia from the e a s t . Also note the smaller "islands of Avalonia." D. Middle Devonian, with the A c a d i a n O r o g e n y fully d e v e l o p e d d u e to collision of the Avalon t e r r a n e s ; note heavy sedimentation from the e a s t e r n mountains. Modified from Witzke ( 1 9 9 0 ) . R e p r o d u c e d with permission.

Taconic Orogeny (a m a j o r m o u n t a i n - b u i l d i n g event) along m a j o r

continental shelf. Following the interval of rifting that produced

thrust faults. T h i s d e f o r m a t i o n apparently was related to the

the Protoatlantic or Iapetus O c e a n , the continental shelf, which

convergence of an island arc c o m p l e x with eastern Laurentia ( o r

is represented by the region f r o m New England westward into

ancestral North A m e r i c a ) .

central New York, u n d e r w e n t rapid subsidence due to cooling. L i m e m u d and silt probably were produced by o r g a n i s m s such as

Cambrian Autochthon T h e a u t o c h t h o n o u s rocks o f the central Appalachians, which

algae, the growth of which was evidently able to keep up with the rate of subsidence so that these shelf e n v i r o n m e n t s remained in very shallow water, above the n o r m a l wave-base. C a m b r i a n to

include basal sandstone and limestone or d o l o s t o n e , represent

Early

extensive shallow, subtropical platform seas, s o m e t i m e s referred

carbonates—the

Ordovician

rocks

to as the Great American Tidal Flat (Figures 4 . 5 , 4 . 7 ) . In s o u t h -

by major unconformities.

Sauk

form

a

package

Sequence—bounded

of sandstones above

and

and below

eastern New York and southern Pennsylvania these beds may be

D u r i n g C a m b r i a n and Early O r d o v i c i a n t i m e , eastern North

up to 5 km thick and were mainly deposited in very shallow, tide-

A m e r i c a lay in a subtropical position, perhaps 25° south of

influenced e n v i r o n m e n t s . T h e i m m e n s e thickness is a c c o u n t e d

the p a l e o e q u a t o r (Figure 4 . 5 ) . Today this zone is known as the

for by active subsidence, or downward sinking, of the C a m b r i a n

"subtropical desert b e l t " because it is here that s o m e of the driest

FIGURE 4.6. C a m b r i a n rocks in New York. A. U p p e r C a m b r i a n P o t s d a m S a n d s t o n e at Ausable

Chasm

near

Plattsburg,

Clinton

County.

B.

Tilted

Precambrian-Cambrian

(Lippalian) nonconformity. A p p r o x i m a t e l y 500 million years of n o n d e p o s i t i o n a n d erosion s e p a r a t e dark a m p h i b o l i t e s (a) ( m e t a m o r p h i c rocks) from the light gray, U p p e r C a m b r i a n Little Falls Formation (b). Cut a l o n g U.S. Rte. 5S near Fonda, M o n t g o m e r y County.

CAMBRIAN

51

PERIOD

conditions on Earth develop. T h e r e is s o m e evidence that ances-

stone of the M o h a w k Valley, the Hoyt L i m e s t o n e of the Saratoga

tral North America in the C a m b r i a n was relatively arid in the

area, the Whitehall F o r m a t i o n of Lake G e o r g e , and the Theresa

(present) eastern regions. T h e r e is also evidence for the buildup

D o l o s t o n e of the Saint Lawrence region are carbonates: lime-

of slight hypersalinity in the C a m b r i a n waters. C a m b r i a n d o l o -

stones, and d o l o s t o n e s , f o r m e d very late in the C a m b r i a n or in

stones contain vugs and s o m e t i m e s m o l d s of evaporite crystals

earliest O r d o v i c i a n t i m e (Figures 4.7 and 4 . 9 ) . T h e y display an

such as gypsum, anhydrite, and halite. T h e o c c u r r e n c e of o o i d s

a b u n d a n c e o f stromatolites. S o m e o f the most f a m o u s stromato-

(small spherical, concentrically ringed c a l c i u m c a r b o n a t e grains)

lites in the n o r t h e a s t e r n part of North A m e r i c a o c c u r in the

and stromatolites ( m o u n d l i k e structures f o r m e d o f sediment

Petrified G a r d e n s within the Hoyt Limestones near Saratoga

trapped by cyanobacteria or blue-green algae) also is typical of

Springs, New York (Figure 4 . 9 ) .

hypersaline (elevated-salinity) waters in the subtropics today.

T h e Little Falls F o r m a t i o n stromatolitic dolostones (up to

Whatever the case, m u c h of the C a m b r i a n seafloor in the New

30 m thick) are only very sparsely fossiliferous. O n l y a single free

York area was relatively low in shelly o r g a n i s m s .

c h e e k of the trilobite Elvinia has been f o u n d from the C a m b r i a n

T h e broad continental shelf of the C a m b r i a n sea was bordered

Little Falls F o r m a t i o n , but this is sufficient to bracket its age

to the east, in what are today central V e r m o n t , western Massa-

within the s e c o n d to last or F r a n c o n i a n Stage of the C a m b r i a n .

chusetts, and C o n n e c t i c u t , by an abrupt slope into deeper water.

( T h e Little Falls is noted for its characteristic vugs or cavities that

In the region flanking the continental shelf of N o r t h A m e r i c a ,

contain beautiful, doubly t e r m i n a t e d q u a r t z crystals referred to

sediments accumulated very gradually (Figures 4.7 and 4 . 9 ) .

as H e r k i m e r D i a m o n d s ; such crystals f o r m e d m u c h later during deep burial of the Little Falls sediments.) Just why most Upper C a m b r i a n c a r b o n a t e s are so p o o r in b o d y fossils, including trilo-

Cambrian Trilobite-Bearing Autochthonous Rocks T h e lowest and shallowest-water deposit of the C a m b r i a n

bites, but rich in stromatolites is as yet unclear. It may be that

a u t o c h t h o n o u s rocks belong to the Potsdam S a n d s t o n e or equiv-

the seas were s o m e w h a t hypersaline. However, the Hoyt L i m e -

alent sandy Little Falls F o r m a t i o n (Figures 4.6 and 4 . 8 ) . T h e

stone c o n t a i n s not only the f a m o u s stromatolites but also beds of

Potsdam Formation consists of up to 140 m of clean quartz a r e n -

oolitic l i m e s t o n e and s o m e fossiliferous limestone

ites or quartzose sandstones that display c r o s s - s t r a t i f i c a t i o n ,

sclerites (skeletal pieces) of trilobites b e l o n g i n g to a n u m b e r

ripple marks, and other features indicative of deposition in

of Late C a m b r i a n species are f o u n d ; Ludvigsen and Westrop

shallow-wave

and

sometimes

tide-dominated

environments

(Figure 4 . 8 ) . T h e Potsdam sediments represent sand eroded from deeply weathered areas of the N o r t h A m e r i c a n c r a t o n . The

presence

of

herringbone

cross-stratification

in which

( 1 9 8 3 ) recently described these species f r o m the Hoyt and Galway limestones. T h e s e trilobites are associated with o t h e r fossils, including

(inclined

b r a c h i o p o d s , m o l l u s c a n f r a g m e n t s , and even plates of the world's

bedding formed by alternate migration of ripples in opposite

oldest c h i t o n s . T h i s diverse assemblage indicates relatively favor-

directions) is an indication of the oscillatory currents associated

able, n o r m a l - s a l i n i t y c o n d i t i o n s in the area of Saratoga Springs

with tidal action. S o m e p o r t i o n s display large-scale trough cross-

during this p e r i o d . However, relative high energy due to wave

bedding and may represent w i n d - f o r m e d sand dunes in coastal

action and slow deposition prevented the easily disarticulated

areas.

trilobites f r o m being preserved whole. T h e trilobites o f the

The Potsdam is generally sparse in body fossils, although trace

Galway and Hoyt are:

fossils (burrows, tracks, and trails) of a variety of forms are present, including the bizarre and huge (by C a m b r i a n standards)

GALWAY

Climactichnites. T h i s elongate trail up to 3 0 c m ( o r m o r e than a

Calocephalites

foot) wide closely resembles m a r k s m a d e by a tractor tire in soft

Dellea

sand. This trace is found in flat-bedded sands that may represent

Drabia cf.

FORMATION

cf.

C.

minimus

saratogensis D.

menusa

Cameraspis Drabia

cf.

Elvinia

convexa D.

curtoccipita

granulata

the upper foreshore or beach. Just what large o r g a n i s m in the C a m b r i a n was able to c o m e out into very shallow water is quite

HOYT

unclear. Traces may have been preserved by the sun drying ini-

Delicti?

tially wet sands of coastal areas. Yochelson and F e d o n k i n ( 1 9 9 3 )

Keithiella

argued that it might have been a large gastropod-like mollusk. In

Pie tho pelt is sara togensis

Prosaukia

hartti

slightly m o r e offshore Potsdam f a d e s , trace fossils such as verti-

Prosaukici

Saratogia

(Saratogia)

cal

shafts

(Skolithos)

and

U - s h a p e d burrows

(Diplocraterion)

LIMESTONE

landingi depressa tribulis

Hoytaspis Pletlwpeltis

speciosa granulosa calcifera

are

quite abundant. Lingulid b r a c h i o p o d s and small fragments of trilobites also have been o b t a i n e d in a few levels, but in general body fossils are rare.

Cambrian of the Taconic Allochthon Initially, a substantial a m o u n t of silt, sands, and muds was

T h e higher beds of the Upper C a m b r i a n and those straddling

swept from the Grenville b a s e m e n t of Laurentia, which had been

the Ordovician b o u n d a r y are c a r b o n a t e s . T h e Little Falls D o l o -

exposed to weathering and erosion for over 4 0 0 million years.

FIGURE 4.7. N e w York in the C a m b r i a n . A. New York in the U p p e r C a m b r i a n , s h o w i n g the c a r b o n a t e bank over m u c h of the state. B. Cross section of the plate m o v e m e n t d u r i n g the U p p e r C a m b r i a n . C. Stratigraphic chart of the C a m b r i a n e x p o sures in N e w York. From Isachsen et al. (1991). Printed with p e r m i s s i o n of the New York State M u s e u m , Albany, N.Y.

CAMBRIAN

53

PERIOD

FIGURE 4 . 8 . C l o s e - u p of Upper Cambrian P o t s d a m S a n d s t o n e showing s e t s of c r o s s - b e d d e d quartz-rich s a n d s t o n e . Cut along Street, Whitehall, Washington County.

T h e coarser sands derived from this erosion a c c u m u l a t e d in

ing redox (oxidation states) c o n d i t i o n s on the seafloor. At certain

nearshore areas to form the Potsdam S a n d s t o n e facies (Figures

intervals, the b o t t o m water seems to have been better oxygenated,

4.8 to 4 . 1 0 ) .

However, substantially larger a m o u n t s of fine-

grained sediment (clay minerals) were either carried in dilute sus-

leading to the d e v e l o p m e n t of reddish or green slates with little o r n o a c c u m u l a t e d organic m a t t e r (Figure 4 . 1 0 ) .

pensions to offshore areas, where they settled o u t as h e m i p e l a g i c " r a i n " of m u d , or perhaps were blown offshore d u r i n g dust storms, eventually to settle out and a c c u m u l a t e as deep-water deposits.

Cambrian Trilobite-Bearing Allochthonous Rocks T h e green and purple Early C a m b r i a n shales or slates of the T a c o n i c M o u n t a i n s (up to 6 0 0 m t h i c k ) are c o m m o n l y quarried

T h e rocks that were deposited in the continental slope and rise

as roofing slates in eastern New York and V e r m o n t , but these

belt are no longer found in their area of original a c c u m u l a t i o n .

quarries are not m a j o r fossil localities. In general, it appears that

Rather, they are found as a series of thrust sheets that lie east of

relatively few o r g a n i s m s

the Hudson River Valley in present eastern New York, referred to

C a m b r i a n t i m e , and m o s t slates are b a r r e n , even as life was just

inhabited

the deep sea

during the

as the Taconic M o u n t a i n s (see under O r d o v i c i a n ) . T h e earliest,

bursting forth in shallow-shelf settings. Very few fossils have been

pretrilobite, portion of the C a m b r i a n is poorly recorded in New

f o u n d within these beds, although an unusual b r a n c h i n g trace

York. However, s o m e of the thick, m u d d y sandstones and silt-

fossil, Oldhamia, is a b u n d a n t in s o m e of the purple shales low in

stones of the high Taconic M o u n t a i n s may represent this t i m e

the T a c o n i c succession. T h e s e very small trace fossils may repre-

interval.

sent s o m e of the earliest deep-water grazing animals. A few local-

T h e low or western p o r t i o n s of the Taconics display well-

ities

have

yielded

trilobites.

The

Lower

Cambrian

Middle

preserved successions of C a m b r i a n - E a r l y Ordovician strata that

Granville or Nassau F o r m a t i o n , in the vicinity of Troy, Rensselaer.

comprise a series of alternating green to purple or black slaty

County,

shales (Truthville, Browns Pond, Middle Granville). T h e alterna-

asaphoides as well as a fairly c o m p l e t e growth series of this trilo-

tion between purple, green, and black m u d r o c k s indicates differ-

bite. T h e Lower C a m b r i a n trilobites found are:

has

yielded

articulated

remains

of

Elliptocephala

FIGURE 4 . 9 . U p p e r C a m b r i a n limestones. A. U p p e r C a m b r i a n limestone, Whitehall Formation. Note the darker gray oolitic limestone (a) in s h a r p c o n t a c t with fine-grained " r i b b o n limestone" (b). Also note the small stromatolite (c) a t t a c h e d to the U p p e r c o n t a c t of the oolitic limestone. Warner Hill Cuarry, Whitehall, W a s h i n g t o n County. B. D o m a l stromatolites ( " c r y p t o z o a n " ) in u p p e r C a m b r i a n Hoyt Formation. C r y p t o z o a n l e d g e , Petrified G a r d e n s R o a d , Lester Park, S a r a t o g a County.

CAMBRIAN

PERIOD

55 nant or when productivity in the surface waters was increased, allowing the a c c u m u l a t i o n of organic matter. T h e s e intervals also contain beds of l i m e s t o n e breccia or angular c o n g l o m e r a t e s that represent debris flows broken f r o m the edge of the continental shelf that avalanched d o w n into deeper water. Actually, a rather diverse fauna o f trilobites has b e e n o b t a i n e d f r o m s o m e o f the l i m e s t o n e breccias o r c o n g l o m e r a t e s . T h e dark facies include the Lower C a m b r i a n Browns Pond F o r m a t i o n and the Lower to Upper C a m b r i a n Hatch Hill Form a t i o n (a 1 5 0 - m interval of dark slaty shales) (Figures 4 . 6 C and 4 . 1 1 ) . B o t h units c o n t a i n n u m e r o u s interbeds of several types, including ripple cross-stratified sandstones that probably record turbidites. T u r b i d i t y c u r r e n t s (masses o f suspended sediment that flow d o w n s l o p e u n d e r the influence of gravity) swept finegrained siliciclastic silt and sand o f f of shelf regions into the deeper water. A n o t h e r c o m m o n type o f b e d consists o f lightgray weathering b a n d s of very fine-grained l i m e s t o n e . Careful e x a m i n a t i o n of s o m e of these beds reveals that they contain very fine l a m i n a t i o n s or even c r o s s - l a m i n a t i o n s and display sharp bases. T h e r e f o r e , they have been inferred to have been deposited as relatively dilute turbidites of suspended c a r b o n a t e silt and m u d that were e x p o r t e d into the deeper water f r o m the carb o n a t e b a n k near the top of the slope. Such deposits rarely contain fossils, t h o u g h trilobite fragments are k n o w n from s o m e turbidites. A n o t h e r type o f a c c u m u l a t i o n within the Taconic dark

shale

Perhaps

consists

the

"Schodack

best

of brecciated

known

Limestone"

of these

found

near

(fragmented) is

the

limestones.

Lower

Castleton

Cambrian

Cutoff

in

the

Hudson Valley. Relatively few o r g a n i s m s could actually live in the low-oxygen deeper waters.

But the remains of shallow-water

o r g a n i s m s were abruptly t r a n s p o r t e d into s o m e o f these envir o n m e n t s as debris flows from the shallow-shelf regions above where these a n i m a l s lived. T h e fossiliferous breccia beds are a key to the stratigraphy of the lower part of the T a c o n i c rocks. T h e s e thin limestone-clast c o n g l o m e r a t e s contain a sandy m a t r i x that yields a b u n d a n t fossils of a variety of trilobites, including agnostids, b r a c h i o p o d s , and s o m e of the world's oldest bivalves. T h e s e fossils, particularly the trilobites, are invaluable for dating the succession. A few Lower C a m b r i a n a l l o c h t h o n o u s rocks are rich with fragFIGURE 4 . 1 0 . Simplified stratigraphy of the C a m b r i a n -

mentary, small trilobites, particularly agnostids and eodiscids.

Ordovician rocks in the Taconic allochthon. A d a p t e d from

Rasetti ( 1 9 4 6 , 1 9 5 2 , 1 9 6 6 a , b , 1967) with T h e o k r i t o f f ( 1 9 6 7 )

Landing ( 1 9 8 8 ) , with permission.

reported the following: LOWER

MIDDLE

GRANVILLE

Calodiscus lobotus

Elliptocephala

Fordaspis nana

Kootcnia

Serrodiscus

CAMBRIAN

Acidiscus

FORMATION

asaphoides

fordi

speciosus

birdi

Acimctopus Analox

Acidiscus

bilobatus obtusa

Bathydiscus

Analox Atops

dolichometopus

Bolboparia

hexacanthus bipunctata trilineatus elongata

Bolboparia

superba

Calodiscus

T h e dark shaly intervals with m o r e n u m e r o u s interbeds rep-

Calodiscus

fissifrons

Calodiscus

lobatus

agnostoides

resent a period of time either when the b o t t o m was m o r e stag-

Calodiscus

meeki

Calodiscus

occipitalis

THE

56

PALEOZOIC

GEOLOGY

OF

NEW

YORK

FIGURE 4 . 1 1 . Lower C a m b r i a n allochthonous b e d s of the low Taconic Mountains. Thin-striped white b e d s in the lower view are lime turbidites. A thin b e d of b r o k e n or b r e c c i a t e d limestone (a) o c c u r s (to the left of the h a m m e r ) . U p p e r b e d s are b l a c k shaly H a t c h Hill Formation ( b ) . Rte. 9 south of H u d s o n , C o l u m b i a County.

Calodiscus

reticulatus

Calodiscus

schucherti

Olenoidcs

Calodiscus

theokritofft

Calodiscus

walcotti

Pagetia

Chelediscus

chathamensis

Elliptoccphala

Eoagnostus

acrorhachis

Fordaspis

Hyolithellus

micans

"Kochiella"

Kootenia Oodiscus Pagetia

longispinus binodosus

bigra nulosa

Pagetides

amplifrons

fitchi

Seopagetina

punctulatus taconica

Oodiscus Pagetia

connexa

Pagetides

elegans

leiopygus

Pagetides

minutus

Pagetides

rupestris

Peronopsis

evansi

Rimouskia

cf.

P.

primigenea

Serrodiscus

speciosus

Serrodiscus

subclovatus

Stigmadiscus

Prozacanthoides Serrodiscus

typica

stenometopus

clytioides

Ptychagnostus

gibbus

Plethomctopus

knopfi

punctuosus

UPPER

Prosaukia

CAMBRIAN

briarcliffcnsis

subgranulatus

Pagetides Peronopsis

Ptychagnostus

Pagetia

nana

Leptochilodiscus

fordi

Litometopus

asaphoides

stockportensis erratica

Serrodiscus

Ordovician Period Unlike the C a m b r i a n , the Ordovician Period was a relatively long interval, s p a n n i n g about from 4 8 9 to 4 3 8 million years eatoni

griswoldi

ago. D u r i n g this long span, North America c o n t i n u e d to straddle the paleoequator, and New York lay in the southern subtropics

spinulosis

(Figure 4 . 5 ) . Early Ordovician saw a c o n t i n u a t i o n of the passive

Stigmadiscus

gibbosus

Great A m e r i c a n Tidal Flat e n v i r o n m e n t . But during the Middle

Weymouthia

nobilis

O r d o v i c i a n t i m e the eastern edge of Laurentia began to enc o u n t e r an offshore volcanic island arc ( c h a i n ) (Figure 4 . 1 2 ) .

MIDDLE

Ultimately this collision pushed (thrust) a great mass of deep-sea

CAMBRIAN

Baltagnostus

angustilobus

Baltagnostus

Bathyuriscus

eboracensis

Bolaspidella

Corynexochides?

expansus

Hypagnostus

stockportensis fisheri parvifrons

sediments up o n t o the present eastern edge of Laurentia, creating the Taconic M o u n t a i n s and causing the continental edge to collapse into a f o r e l a n d basin.

ORDOVICIAN

57

PERIOD

FIGURE 4.12. Stratigraphic chart of the O r d o v i c i a n e x p o s u r e s in N e w York.

M o d i f i e d from I s a c h s o n et al. (1991).

Printed with

permission of the New York State M u s e u m , Albany, N.Y

Early Ordovician

the C a n a d i a n Series. S o u t h of the Adirondacks, in the central M o h a w k River Valley, the Lower O r d o v i c i a n rocks are relatively

T h e Lower Ordovician interval in eastern N o r t h A m e r i c a is locally referred to as the Canadian Series (Figures 4 . 1 2 and 4 . 1 3 ) .

thin ( a b o u t 35 to 5 0 m ) a n d are assigned to a single f o r m a t i o n , the Tribes Hill (Figure 4 . 1 2 ) .

This interval, s o m e 20 million years in d u r a t i o n , is set o f f f r o m

T h e Lower O r d o v i c i a n ( C a n a d i a n ) Series rocks c r o p out in a

the higher Ordovician rocks in New York State and in most parts

roughly c o n c e n t r i c belt a r o u n d the A d i r o n d a c k region. To a large

of North America by the m a j o r K n o x U n c o n f o r m i t y , a 2 5 - to 30

extent, this o u t c r o p belt is controlled by the rather recent (late

million-year gap in the geological record. Moreover, the type of

C e n o z o i c ) uplift of the Adirondacks. However, it should be noted

sediments and the style of stratigraphy c h a n g e markedly between

that C a n a d i a n or Lower O r d o v i c i a n rocks are thin to absent in a

the Lower Ordovician and the late M i d d l e O r d o v i c i a n rocks that

belt r u n n i n g n o r t h w a r d f r o m Utica, New York, to an area north

overlie the unconformity. Lower O r d o v i c i a n rocks contain a

of Watertown.

sparse and rather poorly d o c u m e n t e d fossil fauna, d o m i n a t e d by

A m e r i c a was covered by shallow seas d u r i n g the Early O r d o v i -

certain small mollusks, such as various gastropods and nautiloid

cian, a low peninsular area of land extended eastward o f f the

cephalopods and rare trilobites. T h i s restricted Early O r d o v i c i a n

C a n a d i a n Shield roughly in the area of the T h o u s a n d Islands and

fauna suggests that somewhat unusual, perhaps slightly hyper-

Adirondacks of the present day. T h i s peninsula probably has

saline, conditions c o n t i n u e d in the N o r t h A m e r i c a n interior seas

n o t h i n g to do with the present expression of the Adirondacks. It

This

suggests

that

although

most

o f North

during this interval ot geologic time.

represents an a n c i e n t arch that was present in the c o n t i n e n t and

T h e Lower Ordovician strata

in New York generally are

probably developed during the t i m e of rifting of North America

assigned to the upper part of the B e e k m a n t o w n G r o u p that takes

f r o m a n o t h e r c o n t i n e n t in the late Proterozoic (late P r e c a m -

its name from an area near Lake C h a m p l a i n . In the o u t c r o p belt

brian). This

the Lower Ordovician rocks are best exposed and most c o m p l e t e

Ordovician c a r b o n a t e s thickened regularly to the south away

in areas around Lake C h a m p l a i n and southward to a b o u t Lake

f r o m this area. I s o p a c h m a p s ( m a p s showing variations in thick-

region

is referred to as the Frontenac Arch. T h e

formations,

ness of a particular rock unit) for the Lower Ordovician reveal a

each b o u n d e d by a m i n o r u n c o n f o r m i t y , are represented in

pattern c o m p a r a b l e to that seen in the C a m b r i a n in which the

George.

In

this

vicinity

at

least

four

distinct

FIGURE 4.13. New York d u r i n g the Early a n d early M i d d l e O r d o v i c i a n . A. Early O r d o v i c i a n , 495 million years before present. B. Early O r d o v i c i a n , 475 million years before present C. Cross section of plate m o v e m e n t d u r i n g the Early Ordovician s h o w i n g the Taconic Orogeny. D. C h a z y a n time. E. Black River times. F. Cross section of the plates d u r i n g the Middle O r d o v i c i a n . From I s a c h s o n et al. (1991). Printed with p e r m i s s i o n of the N e w York State M u s e u m , Albany, NY

FIGURE 4.13.

Continued.

THE

60

PALEOZOIC

GEOLOGY

OF

NEW

YORK

rocks thicken dramatically southward from the a p p r o x i m a t e zero

Ordovician were exposed to the a t m o s p h e r e for s o m e 25 to 30

line ( p i n c h - o u t of the Lower O r d o v i c i a n strata) that coincides

million years and b e c a m e deeply eroded. Because they had a

approximately with

relatively low siliciclastic c o n t e n t when exposed to rainwater, they

the

present

position

of the s o u t h

Lake

O n t a r i o shoreline. O r d o v i c i a n or C a n a d i a n age strata attain a

mainly underwent solution, although s o m e thin residues of sili-

thickness of nearly 1500 m in the subsurface near the New York

ciclastic m u d may have been developed on the karstic or solution

State-Pennsylvania b o r d e r and thicken still m o r e into central

surface. M a j o r solution features, such as sink holes and collapse

Pennsylvania, where they may exceed 3 0 0 0 m in thickness. T h e

b r e c c i a s , developed at this t i m e owing to karstification or disso-

rocks also thicken eastward from the area of the eastern A d i r o n -

lution and cave f o r m a t i o n and collapse of the older Ordovician

dacks into New England where they are represented as m e t a -

and C a m b r i a n c a r b o n a t e s . In places, the u n c o n f o r m a b l e surface

morphosed

has a relief of up to tens of meters.

carbonates

M a r b l e , about

1000m

(marble), thick.

including

North

the

o f the

Stockbridge

F r o n t e n a c Arch,

relatively thin sandy d o l o s t o n e s of the u p p e r m o s t Theresa and

Lower O r d o v i c i a n Strata and Trilobites

Ogdensburg f o r m a t i o n s represent the Lower O r d o v i c i a n c a r b o n -

T h e oldest o f the Lower Ordovician Canadian Series o f rocks

ates. T h e high sand c o n t e n t in these c a r b o n a t e s and in s o m e thin

are represented by the Whitehall F o r m a t i o n (Figures 4 . 1 2 and

intervals within the Lower O r d o v i c i a n of the M o h a w k Valley sug-

4 . 1 3 ) that is well exposed in the region n o r t h of Lake George near

gests that s o m e t e r r i g e n o u s sediment c o n t i n u e d to be swept f r o m

the town of Whitehall. T h i s f o r m a t i o n technically spans the

the now deeply weathered and eroding highlands of the F r o n -

C a m b r i a n - O r d o v i c i a n b o u n d a r y , but an upper unit within the

tenac Arch into adjacent shallow seas.

Whitehall appears to be set o f f by a m i n o r u n c o n f o r m i t y that

T h e upper units of the Lower O r d o v i c i a n , particularly the Fort

o c c u r s close to that b o u n d a r y . An erosion surface and overlying

Cassin F o r m a t i o n (Figures 4 . 1 2 a n d 4 . 1 3 ) , are restricted to areas

sandstone

east of the Adirondack M o u n t a i n s and the C h a m p l a i n Valley. No

appears to be a signature of a drop and initial rise in sea level.

and

siltstone

unit,

the

Winchell

Creek

Member,

trace of these units is f o u n d in the M o h a w k Valley farther west.

T h i s may represent a widespread regression that occurred near

T h i s suggests that toward the e n d of the Early O r d o v i c i a n ,

the end of the C a m b r i a n but still within the overall Sauk Super-

the area of deposition was restricted to a relatively narrow,

s e q u e n c e . T h e W i n c h e l l Creek Siltstone is overlain by somewhat

n o r t h - s o u t h trending basin lying close to the present eastern

fossiliferous limestone that has yielded occasional fragments of

New York State line and into New E n g l a n d . T h i s m a j o r change

trilobites as well as o t h e r m a r i n e fauna, suggesting partially

from widespread

normal marine conditions.

shallow seas over m u c h

of eastern

North

America to a n a r r o w eastern basin is n o t fully u n d e r s t o o d . In

T h e next higher and s o m e w h a t better-known interval, the

part, it may reflect m a j o r regression (shallowing or lowering of

Tribes Hill F o r m a t i o n (0 to 3 0 m ) , in the M o h a w k Valley, again

sea level) associated with the end of the Sauk S u p e r s e q u e n c e

c o m m e n c e s with a sandy or silty c a r b o n a t e in New York State, the

(Figure 4 . 1 3 B ) . A n o t h e r factor m a y b e tectonic d i s t u r b a n c e o f

Palatine Bridge M e m b e r . Again, this silt and sandstone unit over-

the eastern m a r g i n of N o r t h A m e r i c a . Such a d i s t u r b a n c e m a y

lies an u n c o n f o r m i t y that may represent an interval of m i n o r sea-

have produced a s u b s i d i n g ( d e e p e n i n g due to crust d e f o r m a t i o n )

level drop. T h e Palatine Bridge is overlain by b u r r o w - m o t t l e d and

trough in the region east of New York and New E n g l a n d , while at

s o m e w h a t fossiliferous W o l f Hollow M e m b e r that represents

the same t i m e the f o r m e r shelf area to the west was uplifted in a

shallow m a r i n e shelf deposition. T h e most fossiliferous unit

broadly upwarped archlike feature. It is notable that the Fort

within the Tribes Hill is the Fonda M e m b e r . T h e Fonda is a fossil-

Cassin F o r m a t i o n bears a n u m b e r of faults that are truncated by

rich limestone. S o m e beds display reddish to greenish c o l o r due

the overlying u n c o n f o r m i t y . T h e s e faults m u s t have o c c u r r e d

to the presence of iron mineralization, especially the clay mineral

following the deposition

glauconite. This latter mineral is believed to form in open marine

of the Fort

Cassin

Formation

but

before the deposition of the overlying M i d d l e O r d o v i c i a n strata.

e n v i r o n m e n t s during times of relative sediment starvation that

Evidently, the eastern edge of the c o n t i n e n t was u n d e r g o i n g s o m e

enables

stresses, perhaps associated with an initial e n c o u n t e r of eastern

decaying organic matter, especially fecal pellets. T h e glauconite

North A m e r i c a with a trench and the d e v e l o p m e n t of an offshore

granules of the Fonda M e m b e r are also associated with hashy,

volcanic island arc c o m p l e x . S o m e geologists have argued that

finely broken d o w n , skeletal remains of many types of organisms.

mineral

precipitate to b e c o m e concentrated

around

m i n o r volcanic ash input was already c o m i n g into the basin

Particularly prevalent are several species of small gastropods,

during the t i m e of the late C a n a d i a n E p o c h .

c e p h a l o p o d s , and a bivalve-like organism referred to as a ribeiroid

Early

Ordovician

deposition

was

terminated

throughout

rostroconch.

The

rostroconchs

represent

a

nonhinged

bivalve

eastern North A m e r i c a by a m a j o r fall in sea level, and an e r o -

mollusk that possibly was ancestral to the bivalves. T h e Fonda

sional u n c o n f o r m i t y , c o m m o n l y referred to as the Knox Uncon-

M e m b e r also contains rare, disarticulated fragments of trilobites.

formity,

middle

Finally the upper p o r t i o n of the Tribes Hill is represented

p o r t i o n of the O r d o v i c i a n , in places such as M o h a w k Valley, the

was

initiated

(Figure

again by stromatolitic dolostones assigned to the C h u c t u n u n d a

older c a r b o n a t e s that

C r e e k M e m b e r . T h i s unit c o n t a i n s large, but very poorly pre-

had

4.13A-D).

been

During

deposited

the

d u r i n g the

Early

ORDOVICIAN

PERIOD

61

served stromatolites referred to as " h i p p o b a c k s " where they c r o p

assigned to the Poulteney or D e e p Kill F o r m a t i o n (Figure 4 . 1 0 ) .

out, especially along C a n a j o h a r i e Creek, M o n t g o m e r y County.

Although p r e d o m i n a n t l y green, s o m e thin dark shale partings

T h e two higher packages of p r e d o m i n a n t l y d o l o m i t i c but

o c c u r within these strata, particularly in the vicinity of Deep Kill,

mollusk-containing carbonates, the Rochdale and the Fort Cassin

a small creek near Melrose, Rensselaer County. T h e s e Deep Kill

F o r m a t i o n , make up the remainder of the B e e k m a n t o w n G r o u p

black beds have yielded a highly diverse and well-preserved

of Lower Ordovician in New York (Figure 4 . 1 2 ) . T h e Fort Cassin

assemblage of graptoloid graptolites, typically preserved as silvery

shows a repeat of the same pattern observed in the lower units,

c a r b o n i z e d r e m n a n t s on the dark slaty bedding planes. T h e s e

particularly the Tribes Hill; that is, it c o m m e n c e s with a wide-

graptolites have been used to correlate the D e e p Kill rocks with

spread silt and sandstone unit, the Ward Siltstone M e m b e r , and

p o r t i o n s of the Lower O r d o v i c i a n in o t h e r parts of the world.

this in turn is overlain by a fossiliferous c o n d e n s e d limestone that

However, the bulk of the p r e d o m i n a n t l y green Poulteney or Deep

may record m a x i m u m m a r i n e flooding o f the c r a t o n o n a n o t h e r

Kill F o r m a t i o n is sparsely fossiliferous. In the Taconic allochthon

higher cycle. T h e upper part of the Fort Cassin, the B r i d p o r t

succession as on the c r a t o n , the Sauk U n c o n f o r m i t y or the Knox

Member, consists mostly of t h i n - b e d d e d to massive stromatolitic

U n c o n f o r m i t y appears to be present as a gap or break in sedi-

dolostones and records the final regression in the late part of the

m e n t a t i o n . Just why this should be so in deeper water is unclear.

Canadian Series. Brett and Westrop ( 1 9 9 6 ) recently reviewed

In fact, o n e might anticipate the o c c u r r e n c e of an increase in the

the trilobites from the Fort Cassin F o r m a t i o n .

influx of s e d i m e n t s , at least if shales were uplifted and exposed

Trilobites reported, in total, from the Lower O r d o v i c i a n are

to erosion d u r i n g the long span of the K n o x U n c o n f o r m i t y . However, the c o n t i n e n t a l slope and rise area of New England

as follows:

appear to have been relatively sediment starved during this interAcidiphorus

whittingtoni

Bathyurus

Bathyurus?

perkinsi

Bathyurellus

Bellefontia

gyracanthus

Bellefontia

Benthamaspis

striata

Clelandia

caudatus

Hystricurus Hystricurus

cf.

platypus

able volcanic ash beds that were being implaced within the

seelyi

world's oldest r a d i o l a r i a n - b a s e d , deep-sea silica o o z e deposits.

Iapetus O c e a n . Also, s o m e cherty beds represent s o m e of the

sp.

Hystricurus

H.

Hystricurus

T h e Poulteney is overlain, probably with an u n c o n f o r m i t y , by the

cassinensis

Grinnellaspis

conicus

val of t i m e . Siliceous layers within the Poulteney represent p r o b -

(?)

Bolbocephalus Eoharpes

parabola

Strigigenalis

levis

cf.

G.

marginiata

crotalifrons ellipticus

the east edge of Laurentia began u n d e r t h r u s t i n g the rest of

Isotcloidcs

canalis

Isoteloides

Isoteloidcs

whitfieldi

Paraplethopeltis

cf.

Shumardia

In the Early to M i d d l e O r d o v i c i a n , the Iapetus O c e a n no longer c o n t i n u e d to widen, and a p o r t i o n of seafloor attached to

oculilunatus

Robergiella

Indian River red slates. Trilobites are not present in these deposits.

R.

brevilingua

pusilla

Symphysurina

sp.

Symphysurus

convexus

peri

the seafloor (Figures 4 . 5 B and 4 . 1 3 C ) . T h i s a c t i o n produced a sp.

deep trench on the Iapetus O c e a n floor and a so-called sub-

Scotoharpes

cassinensis

duction zone, wherein the western plate or slab was forced d o w n -

Strigigenalis

cassinensis

ward beneath the eastern or overriding slab. T h i s interaction

Symphysurina

cf.

S.

woosteri

p r o d u c e d a n offshore island a r c — t h e Taconic o r A m m o n o o s u c Arc, a chain of volcanoes that f o r m e d on the overriding plate of p r o t o - A t l a n t i c seafloor. T h e m a g m a s (melted rock) were gener-

Allochthonous Rocks of Early Ordovician Age Lower Ordovician a l l o c h t h o n o u s rocks exposed in the western

ated by frictional heating and partial melting of the d o w n g o i n g slab and b r o k e through to the surface, f o r m i n g the volcanic chain.

part of the Taconic M o u n t a i n s closely resemble those of the

As s u b d u c t i o n of the p r o t o - A t l a n t i c seafloor c o n t i n u e d , the

Upper C a m b r i a n . Lowest Ordovician strata are represented by

eastern edge of Laurentia itself eventually was b r o u g h t close to

beds of the upper Hatch Hill F o r m a t i o n , as indicated by the pres-

the s u b d u c t i o n zone. Ultimately, the s e d i m e n t s that bordered

ence of distinctive index fossils including c o n o d o n t s . Graptolites

Laurentia along the c o n t i n e n t a l slope and deep o c e a n floor were

first b e c o m e c o m m o n in the strata of the Taconic M o u n t a i n s in

scraped o f f f r o m the d o w n g o i n g slab, f o r m i n g a s o m e w h a t c h a o t -

the earliest Ordovician, where they are represented by dendroid

ically d e f o r m e d series of slabs of s t r a t a — a n accretionary wedge.

graptolites such as the genus Dictyonema. Hatch Hill Shales, n o w

T h i s mass would b e c o m e the rocks of the T a c o n i c Allochthon (a

m e t a m o r p h o s e d in places to slates, c o n t i n u e upward from the

mass of rock ultimately displaced s o m e 80 km west of its site

Cambrian to the Ordovician. T h i n c a r b o n a t e s , sandstones, and

o f origin into the area o f present-day eastern New York). T h e

carbonate breccias, o c c u r r i n g at or near this level as well, repre-

Taconic a l l o c h t h o n was thrust or pushed up o n t o the c o n t i n e n -

sent sediments that were washed o f f the shallow p l a t f o r m of

tal shelf of Laurentia, or o n e m i g h t say that the east edge of the

North America at the end of the C a m b r i a n and earliest O r d o v i -

continental shelf was subducted beneath this mass of deformed

cian. T h e Hatch Hill dark shales give way upward in the strati-

sediments. T h e latter area also was being compressed and thrust

graphic succession to olive-greenish, slaty shales with s o m e thin

westward by collision of the A m m o n o o s u c Arc with the accre-

limestones but no debris flow breccias. T h e s e strata have been

tionary wedge and Laurentia.

THE

62

Middle Ordovician

PALEOZOIC

GEOLOGY

OF

T h e K n o x U n c o n f o r m i t y is manifested as the sharp upper units. T h e Knox U n c o n f o r m i t y , with a relief of up to several meters, due to karstification, is o n e of N o r t h America's m a j o r stratal breaks and f o r m s the subdivision

between two huge

packages of strata, referred to as Sloss supersequences: the Sauk Supersequence below and the base of the Creek phase of the T i p p e c a n o e Supersequence above (Sloss 1 9 6 3 ; Figure 4 . 1 ) .

o f trilobites: Acanthoparypha? Apianurus Bumastoides

(Basiliella)

gardenensis

Calyptaulax

annulata triacantheis granulosa

the Knox U n c o n f o r m i t y in New York are the sandstones and car-

Eobronteus Gabriceraurus

(Figure 4 . 1 3 D ) . T h e s e strata are o f middle M i d d l e Ordovician

Glaphurus

or Chazyan age (the Llandeilo Series of the British t e r m i n o l o g y )

Hemiarges

(Figures 4 . 1 3 D , 4 . 1 4 , 4 . 1 5 ) . T h e Chazy G r o u p strata evidently

Hibbertia Illaenus

Carrikia

globosus setoni

Ceraurinella

latipyga (Nieszkowskia)

Cyrtometopinid

dintoncnsis

bonates of the Lake C h a m p l a i n area, assigned to the Chazy G r o u p

comes

Bumastoides

Chcirurus

prima

Dinieropyge

accumulated in a relatively narrow, restricted trough or foreland

Bumastoides

aplatus

Bumastoides

Cybeloides

T h e oldest Middle O r d o v i c i a n strata to a c c u m u l a t e above

minganensis

Basilicas

whittingtoni

Ccratocephala

Middle O r d o v i c i a n C h a z y G r o u p

Amphilichas

sp. narrawayi

Ceraurus

hudsoni pustulosus turneri

amiculus

valcourensis crassicauda

antiquatus

Glaphurina

lamottensis

Heliotneroides Hibbertia Hyboaspis

depressa

Isotelus

angusticaudum

Isotelus Isotelus

and V e r m o n t . Laterally equivalent s e d i m e n t s of the Y o u n g m a n

Kawina?

and C a r m e n f o r m a t i o n s o f western V e r m o n t consist o f thin-

Kawina

bedded,

shales

Lonchodomas

halli

Nanillaenus?

that represent m o r e basinal a c c u m u l a t i o n s (Figure 4 . 1 3 D ) . T h e

Nanillaenus?

raymondi

Nieszko wskia

localized nature of the Chazy basin probably reflects additional

Nieszkowskia?

salyrus

Nileoides

subsidence o f the o u t e r p o r t i o n o f the continental margin o f

Otarion

Laurentia, w h i c h , d u r i n g the Middle O r d o v i c i a n , was b e g i n n i n g

Physemataspis

to e n c o u n t e r the trench or s u b d u c t i o n zone associated with the

Platillacnus

collision of a volcanic island arc.

Proetus

and

interbedded

dark

beta giganteus chazyensis vulcanus

spinicaudatum insularis limbatus

referred

to

as

the

Day

including lingulid b r a Point

Formation.

These

canalis

Isotelus

harrisi

Kawina?

sp.

Lonchodomas

chaziensis punctatus billi) lgs i perkinsi

Paraceraurus

ruedemanni

Platillacnus

erastusi

Pliomerops

canadensis

approximus Remopleurides

Pseudosphaerexochus

canadensis

vulcanus

siliciclastic sands apparently were recycled from older sandstones

Sphaercxochus

that had been e r o d e d d u r i n g the long span of the K n o x U n -

Thaleops

conformity. T h e y were deposited in shallow subtidal to inter-

Uromystrum

tidal e n v i r o n m e n t s . T h e overlying beds of the C r o w n

Vogdesia

Point

Isotelus

Pseudosphaerexochus?

clelandi

Chazy strata typically c o m m e n c e with c r o s s - b e d d e d sandstones c o n t a i n i n g sparse fossils, b u t

akacephala

sp.

o n c e extended farther to the n o r t h and east into central Q u e b e c

limestones

sp.

Eoharpes

sp.

mars

sp.

Dolichoharpes

basin that existed in present-day n o r t h e a s t e r n New York State and

chiopods,

YORK

trilobite fauna of the Chazy (Shaw 1968) includes over 60 species

contact o f the B e e k m a n t o w n G r o u p o r the underlying C a m b r i a n

ribbon-like

NEW

parvus

arctura brevispinum bearsi

Sphaerocoryphe Thaleops Uromystrum Vogdesia?

goodnovi

longispina minor obtusus

and Valcour in the Chazy G r o u p are c a r b o n a t e s that display generally deepening upward trends. C o a r s e - g r a i n e d limestones representing c r o s s - b e d d e d shoals of crinoidal and o t h e r skeletal

Middle Ordovician Allochthonous Rocks

debris occur low in the C r o w n Point F o r m a t i o n but are inter-

As previously m e n t i o n e d , the A m m o n o o s u c island arc, lay

bedded with and succeeded by n o d u l a r to wavy-bedded fine-

o u t b o a r d of N o r t h A m e r i c a in the proto-Atlantic in the region

grained limestones c o n t a i n i n g a b u n d a n t fossil fragments. Locally,

that today would be o c c u p i e d by central New England. T h e old

within

were

c r a t o n i c edge of Laurentia m a y have been uplifted to the east of

developed o n skeletal shoals (Figure 4 . 1 4 ) . T h e s e were c o m -

the Chazy trough. T h i s relatively narrow trough area lay to the

posed of sponges and b r y o z o a n s , with s o m e primitive rugose and

east, between the old continental margin (present-day central

tabulate corals. A small patch reef or b i o h e r m in a cow pasture

V e r m o n t and Massachusetts) and an accretionary prism, consist-

the

Crown

Point,

small

bioherms

or

reeflets

on Isle L a m o t t e , V e r m o n t , is often said to be the world's oldest

ing of the s e d i m e n t a r y rocks and s o m e o c e a n - f l o o r volcanics,

coral reef, although most of these b i o h e r m s were not c o m p o s e d

which were being o b d u c t e d o f f of the d o w n g o i n g o c e a n i c - f l o o r

o f corals.

plates (Figure 4 . 1 3 B , part E, F ) . T h e u p p e r m o s t or youngest sed-

Trilobites as disarticulated e l e m e n t s are rather c o m m o n and

iments of the Taconic a l l o c h t h o n succession accumulated in this

highly diverse in s o m e of the Chazy n o d u l a r limestone beds. T h e

trench during the Middle Ordovician and are approximately the

ORDOVICIAN

PERIOD

63

FIGURE 4 . 1 4 . Details of the stratigraphy of the Chazy Group in northeastern New York. From Shaw (1968), reproduced with permission.

same age as the Chazy carbonates of New York State. T h e s e strata

developed d u r i n g the l o n g - t e r m exposure of the craton during

belong to the Normanskill C r o u p and have been subdivided into

development of the K n o x U n c o n f o r m i t y . However, it also reflects

three m a j o r f o r m a t i o n s (Figure 4 . 1 0 ) . T h e lowest is a very dis-

a high degree of oxygenation of the b o t t o m waters during this

tinctive brick-red shale or slate referred to as the Indian River For-

t i m e . T h i s might be associated with the elevation of the seafloor

mation. This slate is exposed in m a n y places in the low Taconics

due to buckling and arching as the c o n t i n e n t edge of Laurentia

and has been quarried extensively tor roofing slates in the region

was driven into a t r e n c h .

of the New Y o r k - V e r m o n t border. T h e s e red slates lack b o d y

Overlying s e d i m e n t s o f the M o u n t M e r i n o F o r m a t i o n are

fossils but contain small trace fossils apparently m a d e by deep-

mostly dark gray or greenish gray siliceous shale. T h e y are also

sea burrowing organisms. T h e red coloration of the Indian River

noted for thin, r i b b o n - l i k e beds of distinctive light green cherts.

Slate is unusual and makes it particularly attractive as building

T h e s e cherts perhaps represent a c c u m u l a t i o n s o f radiolarian

stones. It reflects oxidized iron c o n c e n t r a t i o n within the m u d d y

(silicaceous microfossil)

sediments. However, the source of these iron e n r i c h m e n t s is still

seafloor. B o d y fossils are, again, extremely rare within the M o u n t

poorly understood. It might reflect highly weathered soil that

M e r i n o F o r m a t i o n . No trilobites are known.

skeletal

oozes on

the proto-Atlantic

THE

64

PALEOZOIC

GEOLOGY

OF

NEW

YORK

T h e highest and thickest p o r t i o n of the Normanskill G r o u p is

water intervals of the Black River deposition. T h e r e are no really

c o m p o s e d of the Austin Glen F o r m a t i o n ( c o m m o n l y referred to

g o o d m o d e r n analogs of such vast tidal flats with which to

as graywacke or m u d - r i c h s a n d s t o n e ) . In places, the Austin Glen

c o m p a r e the Black River depositional e n v i r o n m e n t s . Probably the

is enriched in small fragments of m e t a m o r p h i c rocks, including

closest would be s o m e of the extensive platform of the Bahama

slates

metamorphosed

Banks of today. Presumably, the Black River sediments a c c u m u -

c h u n k s o f the original proto-Atlantic seafloor s e d i m e n t s . T h e

lated in subtropical e n v i r o n m e n t s , approximately 25° south of

Austin Glen is noted for its thick sandstone deposits that are

the e q u a t o r (Figure 4 . 7 ) . However, s o m e workers have argued that

interpreted as t u r b i d i t e s , the product of deposition f r o m basin-

the overlying Trenton sediments may actually have developed

ward-flowing masses of suspended

under c o o l e r t e m p e r a t e rather than warm subtropical conditions.

that

probably

represent

uplifted

and

sediment and water that

moved due to gravity (Figure 4 . 1 5 ) . It is evident f r o m distinctive

Perhaps a climatic fluctuation did characterize the transition

flute and groove-casts on the undersides of m a n y of these thick

from the Black River to the Trenton.

turbidite beds that the sediment source now was f r o m the east,

T h e b r o a d , flat-shelf c o n d i t i o n s of the Black River deposition

probably o f f the erosion of the rising a c c r e t i o n a r y prism and vol-

indicate tectonic quiescence. However, the presence of thick b e n -

canic island arc. T h e s e rocks c o m p r i s e the highest p o r t i o n of the

t o n i t e s (volcanic ash beds) within the Black River strata indicates

Taconic strata, and they were thrust westward s o m e 80 km to their

that volcanism was o c c u r r i n g , perhaps in the A m m o n o o s u c Arc

present resting position, which approximates the position of the

at this t i m e .

modern Hudson River Valley. T h e Austin Glen does c o n t a i n o c c a -

T h e main b o d y of the Black River G r o u p consists of the

s i o n a l f o s s i l s i n places, including s o m e m a r i n e benthic fauna o f

Lowville F o r m a t i o n , also called Gull River F o r m a t i o n in O n t a r i o .

b r a c h i o p o d s , bryozoan scraps, and very rare trilobites.

T h i s is distinct, very pale gray weathering, massive micritic limestone. In past times it was c o m m o n l y referred to as the "bird's eye

Black River G r o u p

l i m e s t o n e " because of dark calcite spar-filled vugs. T h i s term

T h e rocks of the Chazy G r o u p in the C h a m p l a i n region are

originally referred to burrows of vertically excavating w o r m s ,

c o n f o r m a b l y overlain by a n o t h e r series of typically pale gray,

Phytopsis (Figure 4 . 1 6 ) . However, the term "bird's eye structure"

rather pure limestones referred to as a part of the Black River

has c o m e to refer to smaller vug- or pit-filling areas of dark calcite

G r o u p (Figures 4 . 1 3 E , 4 . 1 6 , a n d 4 . 1 7 A ) . T h e Black River G r o u p ,

also c o m m o n in the Lowville or Gull River F o r m a t i o n of the

n a m e d for exposures in the Black River Valley near W a t e r t o w n ,

Black River G r o u p . T h e s e are thought to represent originally

Jefferson C o u n t y , is a very widespread and distinctive package of

gas b u b b l e holes that developed from desiccation of c a r b o n a t e

shallow m a r i n e limestones that ranges up to 70 m thick (Figures

sediments in a tidal flat or perhaps from the decay of algal or

4 . 1 3 E , 4 . 1 6 , and 4 . 1 7 ) . Unlike the restricted Chazy, however, the

bacterial filaments within the sediments. Black River limestones

Black River limestones e x t e n d over most of central and western

contain

New York State and into the m i d c o n t i n e n t . In places, the Black

example, desiccation crack polygons are beautifully displayed on

evidence of extremely shallow-water deposition.

For

River c a r b o n a t e s rest directly on the K n o x U n c o n f o r m i t y and

m a n y bedding planes (Figure 4 . 1 6 A ) . Stromatolites also may be

c o m p r i s e the basal p o r t i o n of the Creek phase of the T i p p e c a n o e

c o m m o n locally, as are flat pebble conglomerates. T h e unit tends

Supersequence. In o t h e r areas to the northwest, the Black River

to be rather sparsely fossiliferous, although in places it contains

G r o u p rests directly on C a m b r i a n or even the Grenville (billion

spectacular, large nautiloid and e n d o c e r i d cephalopods. Scattered

year old)

unit,

trilobite fragments have been found within these rocks, but they

referred

basement to

as

rocks.

Pamelia

In these

Formation

in

regions, the basal

Shadow Lake

are not particularly c o m m o n or well preserved. Nonetheless,

F o r m a t i o n in O n t a r i o , consists of greenish gray to reddish m u d -

New York

or

the laterally equivalent Gull River Formation in O n t a r i o has

stones and sandstones, typically as p o o r l y sorted thin layers.

yielded beautifully articulated remains of the trilobite genus

W h e r e it rests on P r e c a m b r i a n b a s e m e n t , the S h a d o w Lake

Bathyurus

may incorporate cobbles o f quartzite o r other m e t a m o r p h i c

evidently ranged into relatively shallow water, as their remains

rocks. T h i s unit is n o r m a l l y unfossiliferous and is interpreted as

are associated with "bird's e y e " structures and other features

and

the

large

asaphid

Isotelus

sp.

These

trilobites

extremely shallow m a r i n e or n o n m a r i n e fluvial s e d i m e n t . H o w -

c o m m o n l y taken to indicate the upper subtidal to intertidal

ever, a few very scrappy r e m a i n s of fossils, including trilobites,

zone (Figure 4 . 1 6 B ) . Perhaps these represent carcasses that were

have been discovered from c a r b o n a t e beds in the S h a d o w Lake

stranded within the inner lagoon or tidal m u d flat e n v i r o n m e n t

F o r m a t i o n in O n t a r i o .

and buried intact.

T h e carbonates of the Black River G r o u p were deposited at a

Slightly darker gray limestones within the Black River G r o u p ,

t i m e when shallow, rather m o n o t o n o u s c o n d i t i o n s existed over

particularly near the top in what has been referred to as the House

very broad tracts of seafloor. Judging from the persistence of fea-

Creek and

tures, such as beds of m u d c r a c k s over h u n d r e d s of square miles

of the distinctive coral Tetradium, so called because of the four-

(Figure 4 . 1 6 A ) , it appears that vast areas were exposed and wetted

fold s y m m e t r y of its corallites and septa. T h e s e strata reflect

periodically by particularly high tides, at least d u r i n g shallow-

shallow-shell" lagoonal e n v i r o n m e n t s .

Watertown formations,

may contain

abundant

thickets

ORDOVICIAN

PERIOD

65

FIGURE 4.15. Flute casts on Austin Glen g r a y w a c k e ("dinosaur leather"). Basal surface of a vertically d i p p i n g b e d of M i d d l e O r d o v i c i a n sandstone turbidites shows sole marks i n c l u d i n g groove casts (a), ripple-like s c o u r s , a n d smaller flute casts (b). These features clearly indicate deposition from a turbidity current. A l l o c h t h o n o u s b e d s of low Taconics Austin Glen Formation. Cut in Rte. 9W near C o x a c k i e , G r e e n e County.

In a few locations, trilobites are f o u n d in the Lowville but

Basilicus ulrichi

Basilicus?

mostly in the upper or Watertown F o r m a t i o n (Young 1943a,

Basiliella barrandei

Bathyurus

1943b; D e M o t t 1 9 8 7 ) . T h e trilobites reported from the Black

Bathyurus johnsoni (Lowville)

Bumastoides

River are as follows':

vetustus extans

*Bumastoides milleri (Lowville)

Ceraurinella

Eoharpes pustulosus

b'ailleana

Illaenus latiaxiatiis

Isotelus

Isotelus simplex

Pterygometopus

tinguished by early authors. The trilobites with an asterisk may be early

Raymondites longispinus

*Raymonditcs

Trenton.

Thaleops ovata

The base of the Trenton and the top of the black River were not well dis-

(Lowville)

billingsi scofieldi indeterminata homalonotoides schmidti spiniger

FIGURE 4.16. Black River limestones. A. D e s i c c a t i o n c r a c k p o l y g o n s on the u p p e r surface of a b e d of fine-grained limestone. Lowville Formation, Black River G r o u p , East C a n a d a Creek near I n g h a m Mills in Fulton County. B. Beds of laminated limestone (intertidal environment) with vertical burrows (a) (Phytopsis). Note the s h a r p contact (b) with the dark gray limestone ( d e e p e r subtidal). East C a n a d a Creek at I n g h a m Mills in Fulton County.

FIGURE 4.17. M i d d l e O r d o v i c i a n Black River G r o u p . A. Overview of Black River G r o u p ( M i d d l e Ordovician) at East C a n a d a Creek, near I n g h a m Mills in Fulton County. Note the c h a n n e l in the u p p e r left a n d the sharp contact (arrow) of light gray vertically b u r r o w e d limestone over dark gray fossiliferous limestone. B. Sharp c o n t a c t (arrow) between the M i d d l e O r d o v i c i a n Watertown Limestone (Black River G r o u p ) a n d t h i n - b e d d e d N a p a n e e Limestone (Trenton G r o u p ) , Sugar River, Lewis County (north of Booneville, O n e i d a County).

G8

T H E

G E O L O G Y

O F

N E W

Y O R K

River erosion surface in m a n y localities, as the Napanee or A m s -

Trenton Group (General) A m o n g the most fossiliferous c a r b o n a t e rocks within the New York O r d o v i c i a n section are those o f the 3 0 - t o

P A L E O Z O I C

terdam F o r m a t i o n (Figure 4 . 1 2 ) .

130-m-thick

Trenton G r o u p (Figures 4 . 1 2 and 4 . 1 8 t o 4 . 2 3 ) . T h e Trenton rocks

Lower T r e n t o n G r o u p S h e l f Facies and Trilobites

record a m a j o r change f r o m shallow c a r b o n a t e shelf into a deep

T h e N a p a n e e F o r m a t i o n (Figure 4 . 1 8 ) ( 0 t o 1 0 m ) consists

foreland basin due to the thrusting of the T a c o n i c a l l o c t h o n .

o f t h i n - b e d d e d , b r o w n i s h c a r b o n a t e m u d s t o n e s o r calcisiltites

T h i s interval, which is classically exposed at Trenton Falls on West

interbedded with dark brownish gray shales that reflect a sig-

Canada Creek (Figures 4.21 to 4 . 2 3 ) , is a very widespread, highly

nificant increase in the a m o u n t of siliciclastic m u d input into

fossiliferous and c o m p l e x c a r b o n a t e succession.

the depositional system relative to the underlying clean car-

T h e lower portion of the Trenton rests sharply on the u n d e r -

b o n a t e s o f the Black River G r o u p . T h e Napanee carbonates

lying Black River G r o u p with an erosion surface that represents

are highly fossiliferous and are characterized particularly by

a regional u n c o n f o r m i t y . H e n c e , the base of the Trenton repre-

the b r a c h i o p o d Triplesia, but also a high diversity of other b r a -

sents a lesser s e q u e n c e b o u n d a r y within the T i p p e c a n o e Creek

c h i o p o d , b r y o z o a n , mollusk, and trilobite fossils. T h e s e beds

Supersequence (Figure 4 . 1 ) . Presumably, at the t e r m i n a t i o n of

are

Black River G r o u p deposition, seas were briefly withdrawn from

Flexicalymene

m u c h of eastern N o r t h A m e r i c a . However, the overlying Trenton

Napanee has been a source of debate. S o m e have argued that

strata appear to represent relatively deeper-water facies. All of the

the

Trenton G r o u p beds are highly fossiliferous.

lagoon system inboard of and protected by a c a r b o n a t e shoal.

some

of the

muddy

lowest

trilobites.

that

The

carbonates

contain

depositional

record

the

abundant

remains

environment

deposition

of a

of

of the shallow

Apparently, the t r a n s g r e s s i o n or deepening that began the

However, the widespread nature of these beds and the resem-

Trenton s e d i m e n t a t i o n was a strong or rapid o n e , of perhaps a

b l a n c e of their lithology and fauna to those of s o m e of the indis-

few tens of t h o u s a n d s of years, such that offshore l i m e m u d s and

putably deeper-water upper Trenton beds suggest a very different

silts were the first deposits that a c c u m u l a t e d above the top Black

interpretation.

FIGURE 4.18. C l o s e - u p of s h a r p Black River/Trenton ( W a t e r t o w n - N a p a n e e ) c o n t a c t . Note the massive limestone of the Watert o w n (a) a n d the thinly b e d d e d b r o w n limestone a n d shale of the N a p a n e e (b). East C a n a d a Creek near I n g h a m Mills in Fulton

ORDOVICIAN

PERIOD

69

T h e Napanee Limestone is abruptly overlain by a very thin interval

(0.5 m)

of beds

that

display a

shallow-water

River-like lithology with the return of Phytopsis and

Black

Tetradium

finds

Erratencrinurus

vigilans

and

Hemiargespaulianus,

two

trilo-

bites rarely f o u n d , if at all, in the higher units of the Trenton. Calyptaulax

callicephalus

occasionally

found

in

the

higher

rugose corals. These beds give way upward to the distinctive Kings

Trenton is c o m m o n in the Kings Falls. T h e trilobites notably

Falls Limestone, which contains a m i x t u r e of skeletal g r a i n s t o n e s

a b u n d a n t are s p e c i m e n s of Flexicalymene senaria and in the Sugar

that represent high-energy shoal e n v i r o n m e n t s and are c o m p o s e d

River

primarily

and

Cryptolithus lorettensis; the latter two fossils are considered to be

crinoids (Figure 4 . 1 8 ) . T h e grainstones are interbedded with

an index of the Sugar River ( S h o r e h a m i a n age). T h e y disappear

thinner-bedded limestones and dark gray shales that may repre-

f r o m the stratigraphic sections above the Sugar River in New

sent shallow, subtidal deposits that a c c u m u l a t e d o u t b o a r d from

York, but a related species reappears considerably higher, in the

the shoals. In turn, the Kings Falls c a r b o n a t e beds pass grada-

Lorraine G r o u p .

of

the

fragmentary

remains

of brachiopods

specimens

of the

trinucleids

Cryptolithus

tessellatus

and

tionally upward into the thicker Sugar River F o r m a t i o n ( 1 5 to

In the west, the upper Sugar River F o r m a t i o n includes a

25 m ) , which comprises, for the most part, wavy-bedded, rather

b u n d l e o f t h i n - b e d d e d micrites o r lutites ( f i n e - g r a i n e d , light

massive, slightly shaly wackestones and p a c k s t o n e s .

gray weathering l i m e s t o n e s ) , or R a t h b u n M e m b e r , that alternate

T h e Sugar River and Kings Falls units thin eastward to the

with dark gray shales capped by m o r e skeletal grainstones. T h e s e

vicinity of C a n a j o h a r i e , M o n t g o m e r y C o u n t y , where they are

seem to represent distal s t o r m deposits or lime m u d turbidites

locally pinched out near the crest of an apparent arch feature

that were a c c u m u l a t e d from shallower-shelf regions from the

on the Ordovician seafloor referred to as the Canajoharie Arch

n o r t h and west. T h e R a t h b u n appears to pass eastward into dark

(Figures 4.12 and 4 . 2 0 ) . A sharp discontinuity in this area sepa-

brownish gray shales in the vicinity of Little Falls, H e r k i m e r

rates the Sugar River, or Glen Falls L i m e s t o n e , the eastern New

C o u n t y . T h e y are typically rich in small, r a m o s e b r y o z o a n s and

York equivalent of the Sugar River, from the overlying dark gray

also m a y c a r r y a b u n d a n t trilobites of a n u m b e r of species, but

calcareous shales. T h e s e beds are particularly noted for their diverse assemblages of bryozoans, b r a c h i o p o d s , and trilobites. In the Kings Falls, o n e

particularly

dominated

by

Flexicalymene

sp.

Cryptolithus

lorettensis.

FIGURE 4 . 1 9 . C l o s e - u p of storm b e d s in the Middle Ordovician Kings Falls Limestone (Trenton Group). Note the c h a n n e l e d b a s e of b e d (arrow) midway up the h a m m e r handle. East C a n a d a C r e e k near Ingham Mills in Fulton County.

tes-

sellatus is mostly replaced in the R a t h b u n by a variant called C.

FIGURE 4 . 2 0 . M a p s of New York d u r i n g late M i d d l e O r d o v i c i a n times. A. Kirkfieldian d u r i n g deposition of the lower Trenton. B. S h e r m a n i a n d u r i n g the d e p o s i t i o n of the m i d d l e Trenton. From Isachson et al. (1991). Printed with permission of the N e w York State M u s e u m , Albany, N.Y

ORDOVICIAN

71

PERIOD

Trilobites of the lower T r e n t o n , up through the Sugar River are as follows:

C o m m o n l y the beds display a basal surface that may be overlain by a thin (millimeters thick) layer of shell and trilobite hash. U p p e r parts of the beds m a y be laminated but typically show disruptions due to b u r r o w i n g . C o n t a c t s with the overlying c h o c o -

Amphilichas

trentonensis

Bathyuropsis

schucherti

Bumastoides

porrectus

Bumastoides

trentonensis

late-brown shales may also display well-preserved fossils, such as

callicephalas

Calyptaulax

eboraceous

articulated

pleurexanthemus

Cryptolithus

lorettensis

ticularly c o m m o n in beds of the Poland near Trenton Falls. Large

C.

s p e c i m e n s of Isotelus gigas are also locally a b u n d a n t , and a bed

Calyptaulax Ceraurus Cryptolithus

tesscllaius

Cyphoproetus

cf.

Encrinuroides

cybeleformis

Encrinuroides

Eomonorachus

convexus

Erratencrinurus

Flexicalymene

senaria

Gabriceraurus

Gravicalymene

Hemiarges

wilsonae

/.

Isotelus

gigas

Isotelus

latus

near the top of the Poland at Trenton Falls apparently yielded the

vigilans

m a j o r i t y of the well-preserved, black, articulated I. gigas specim e n s that are f o u n d in m u s e u m s a r o u n d the world. T h i s is a

dentatus

relatively coarse bed of skeletal debris, a p p r o x i m a t e l y 30 cm thick,

paulianus

Illaenus Isotelus

served, mostly inverted, on the base of this b e d . T h e s e evidently

latidorsatus

represent o r g a n i s m s that were caught up and buried in a graded

jacobus

Plaiylichas ingalli

Triarthrus

is par-

which fine upward into c a r b o n a t e silt and trilobites were pre-

conradi

Raymondites

T h e trilobite Flexicalymene senaria

trentonensis

magnotuberculata Illaenus cf.

trilobites.

debris bed deposited by s t o r m waves.

inconsuetus

Sceptaspis

bebryx

Various features of the Poland beds strongly suggest that they

beckii

represent s t o r m - d e p o s i t e d c a r b o n a t e s t r a n s p o r t e d to offshore, n o r m a l l y quiet water e n v i r o n m e n t s . A relatively diverse fauna

M i d d l e and Upper T r e n t o n G r o u p

o c c u r s in these beds. In addition to trilobites, varied b r a c h i -

T h e middle p o r t i o n of the Trenton has been referred to as the Denley or Denmark Formation ( 1 9 3 7 , 1943,

(Figures 4 . 2 1

and 4 . 2 2 ) .

Kay

o p o d s and b r y o z o a n s , especially small s p e c i m e n s of Prasopora, are a b u n d a n t within s o m e layers in the Poland. F o r a listing of

1968) subdivided the middle Trenton into two

the trilobites of the Denley F o r m a t i o n , see the publications by

m e m b e r s : the Poland and the Russia, b o t h defined in the T r e n t o n

Titus ( 1 9 8 2 , 1 9 8 6 ) and D e l o ( 1 9 3 4 ) for discussions o f the trilo-

Falls area. M o r e recently, the middle Trenton units of the Poland

bites and their c o m m u n i t i e s .

and Russia M e m b e r s were grouped into the D e n l e y L i m e s t o n e . T h e s e units

Toward the top of the Poland interval occurs a series of thin

represent a transition f r o m d e e p - s h e l f to m o r e

b e n t o n i t e beds. W e a t h e r i n g o f these beds typically f o r m s n o t c h e s

shallow-shelf encrinal limestones. T h e y pass eastward in dark

in o u t c r o p s , such as those seen near the top of the classic

gray and black shales, the Flat C r e e k F o r m a t i o n , that signify c o l -

S h e r m a n Falls section at Trenton Falls, H e r k i m e r C o u n t y (Figure

lapse of the eastern Laurentia shelf area into a foreland basin as

4 . 2 2 ) . T h e top of the Poland is b o u n d e d by a distinctive wide-

the Taconic O r o g e n y set in.

spread interval including two key b e n t o n i t e s . T h e s e two beds,

In the area around Middleville, H e r k i m e r C o u n t y (in par-

separated by 0 . 5 - to 1-m n o d u l a r l i m e s t o n e , f o r m the base of the

ticular, outcrops on City B r o o k ) , the thin beds of the R a t h b u n

Russia M e m b e r (Figure 4 . 2 3 ) . T h e Russia, overall a b o u t 2 3 m

Member

fossiliferous

thick, is divisible into a series of small-scale coarsening upward

limestone about 1 m thick that marks the base of the Denley

cycles. Each cycle c o m m e n c e s with dark shale and thin tabular,

F o r m a t i o n . T h i s interval, the " C i t y B r o o k b e d " o f the Poland

very-fine-grained micritic limestones similar to those seen in

M e m b e r , is exceptionally rich in fossil nautiloid and e n d o c e r i d -

parts o f the Poland. T h e tops o f these cycles are c o m p o s e d o f

cephalopods. T h e City B r o o k bed carries the distinctive coiled

m o r e thickly bedded, nodular, fossil-rich l i m e s t o n e . A particu-

nautiloid

are

capped

Trocholites

by

nodular,

larly distinctive package of fine, evenly b e d d e d , light gray weath-

particularly

ering limestones o c c u r s near the top of the Russia in areas around

c o m m o n . T h i s interval is also rich in the remains of Flexicalymene,

Trenton Falls (Figure 4 . 2 3 ) . Like the Poland, the Russia M e m b e r

mostly disarticulated, but s o m e of which are preserved as enrolled

yields a b u n d a n t and c o m m o n l y well-preserved fossils. Certain

individuals. T h i s c e p h a l o p o d - and trilobite-rich bed is considered

bedding planes again display completely articulated trilobites

to represent a condensed h o r i z o n , that is, a b e d that records a

and crinoids, indicating very rapid pulses of burial. As with the

considerable a m o u n t of t i m e in a relatively thin interval. Such

P o l a n d , it is t h o u g h t that m a n y of these thin limestones repre-

cephalopod beds are typical of times of relatively rapid deepen-

sent distal w a s h o f f of c a r b o n a t e silt sands and m u d s following

ing when siliciclastic sediments appear to b e c o m e trapped in

times when s t o r m s disrupted the shallow shelf. S t o r m s resus-

nearshore areas and carbonates are not produced at a high rate.

pended finer c a r b o n a t e silts and m u d s and incorporated them

although

was

distinctive

the

Trocholites bed,

and

a

the

previously latter

fossil

referred is

not

to

as

T h e remainder o f the Poland M e m b e r consists o f thin- t o

into basin-flowing g r a d i e n t c u r r e n t s . T h e s e currents carried the

m e d i u m - b e d d e d , fine-grained limestones with c h o c o l a t e - b r o w n

sediments d o w n a gently sloping shelf or r a m p to the southeast.

shale partings (Figure 4 . 2 2 ) . M a n y of the limestones are rather

Nodular beds within the Russia represent s o m e w h a t shallower

fossiliferous and c o m p o s e d mainly of c a r b o n a t e silt (calcisiltite).

water e n v i r o n m e n t s that were disturbed b o t h by w i n n o w i n g

FIGURE 4 . 2 1 . M i d d l e Trenton at Trenton Falls. A. C o n t a c t of the Poland (a) a n d Russia (b) M e m b e r s of the Denley Formation ( M i d d l e O r d o v i c i a n Trenton G r o u p ) , m a r k e d by a d e e p re-entrant (arrow at b a s e of s h a d o w ) of Kayahoora bentonite b e d s . West C a n a d a Creek a b o v e S h e r m a n Falls, Trenton Falls, O n e i d a County. B. Overview of the M i d d l e O r d o v i c i a n Trenton G r o u p , s h o w i n g the Russia M e m b e r (a) of the Denley Formation a n d the Rust Formation (b). U p p e r H i g h Falls, Trenton Falls on West C a n a d a Creek, O n e i d a County.

ORDOVICIAN

73

PERIOD

FIGURE 4.22. M i d d l e O r d o v i c i a n Trenton G r o u p limestone (mainly Poland M e m b e r of the Denley Formation) at S h e r m a n Falls, West C a n a d a Creek, Trenton Falls, O n e i d a County. Note the d e e p l y r e c e s s e d n o t c h e s (arrow) m a r k i n g the positions of bentonites (volcanic ash b e d s ) near the t o p of the falls.

currents and by b u r r o w i n g o r g a n i s m s that flourished in the

Ash

somewhat better-oxygenated shelf e n v i r o n m e n t s . T h e sediment

the base of a thin shaly interval at the b o t t o m of the Rust

(Figure

4.23A).

This

critical

marker

bed

occurs

at

shutoff associated with the t o p s of t h e cycles allowed develop-

Formation.

m e n t of s o m e thin skeletal hash limestone deposits that capped

Approximately 17 m above the base of the Rust is an interval

the cycles. Abrupt deepening above these caps is recorded by

up to 3 m thick in which the beds are heavily c o n t o r t e d and

a

d e f o r m e d (Figure 4 . 2 3 B ) . In places, individual beds appear to

shift

back

to

dark

shales

and

then

to

very-fine-grained

limestones.

have b e e n o v e r t u r n e d u p o n o n e a n o t h e r and doubled along

Overlying the Denley F o r m a t i o n , near Trenton Falls, is the Rust

F o r m a t i o n , approximately 30 m of rather nodular, fos-

r e c u m b e n t folds. In o t h e r areas such as near the spillway of the power d a m

within Trenton G o r g e , these d e f o r m e d

intervals

siliferous, poorly bedded, t h i n - b e d d e d limestone (Figure 4 . 2 3 ) .

appear to be confined to lenticular channel-like features. T h e s e

T h e Rust

begins abruptly with a very distinctive b e n t o n i t e

beds record an interval of s l u m p i n g of sediment on the Trenton

bed exposed in the upper High Falls of the Trenton G o r g e on West

seafloor that may have b e e n the result of tectonic steepening

Canada Creek in H e r k i m e r C o u n t y , referred to as the High Falls

o f the c a r b o n a t e r a m p . T h i s d e f o r m a t i o n together with the

FIGURE 4.23. Trenton at Trenton Falls. A. View of U p p e r H i g h Falls s h o w i n g c o n t a c t of the t h i n - b e d d e d , light gray w e a t h e r i n g Russia Member, Denley Formation (a), overlain by the darker Rust Formation (b). C o n t a c t is m a r k e d by a re-entrant (arrow) at the position of the H i g h Falls bentonite. Trenton Falls on West C a n a d a Creek, O n e i d a County. B. C o n t o r t e d b e d s (a) in the m i d d l e portion of the Rust Formation. Thin b e d s near the b a s e (b) are the Walcott-Rust Quarry b e d s . Spillway at the p o w e r d a m within the Trenton Falls G o r g e , Herkimer County.

ORDOVICIAN

PERIOD

7b

abundant thin bentonite (or volcanic ash) layers in the D e n l e y -

fine structure of appendages was well preserved by very early

Rust interval signals the onset of m a j o r tectonic activity in the

calcite infilling. T h e s e fossils were the first trilobites for which

Taconic belt east of the present Hudson River Valley. T h e s e

appendage structure was carefully analyzed and d o c u m e n t e d

channel-like

features are still

poorly u n d e r s t o o d

but

might

(Walcott 1 8 7 5 a , b , c , d ) . T h i s s a m e bed yielded abundant speci-

represent m i n o r bypass channels eroded into the underlying c a r -

m e n s of C. pleurexanthemus, m o s t (at least 9 5 % ) in an inverted

bonate muds and then infilled with n o d u l a r shaly limestones,

position, along the lower surface and in c o n t a c t with the brown-

which in turn were slumped during a t i m e of tectonic distur-

ish gray interbedded shale. T h i s parting also has produced nearly

bance.

c o m p l e t e crinoids

There

is

no

doubt

that

this

slumping

deformation

( w i t h o u t the holdfasts)

and several other

occurred in relatively soft, wet sediments on the seafloor. T h e

species of whole trilobites. T h e q u a r r y limestone beds appear to

upturned edges of the folded beds in the middle part of the

represent distal deposits of s e d i m e n t s that were resuspended,

Rust are truncated by an erosion surface and overlapped by a bed

probably during s t o r m s in shallower water areas, and imported

of crinoidal grainstones that c o n t a i n s a breccia of pebbles derived

onto

from the underlying d e f o r m e d beds. T h e highest beds of the

Typical c o n d i t i o n s in this area were low-energy, soft, muddy

a

southeastward-sloping c a r b o n a t e

ramp

environment.

Rust Formation are t h i n - b e d d e d , coarser-grained crinoidal lime-

substrate settings that s e e m e d to favor a variety of delicate

stones that appear to b e c o m e s o m e w h a t thicker and coarser

b r y o z o a n s , c r i n o i d s , cystoids, and at least 21 reported species of

upward, perhaps in transition to the overlying massive crinoidal

trilobites, including the following:

grainstones of the Steuben F o r m a t i o n . T h e Rust limestones c o n t a i n very a b u n d a n t trilobite and

Achatella

achates

Amphilichas

crinoid debris, bryozoans, b r a c h i o p o d s , and particularly n a u -

Amphilichas

tiloid cephalopods. T h e beds tend to be rather poorly defined

Bumastoides

and c o m m o n l y s o m e w h a t a m a l g a m a t e d (bundled together) in

Bumastoides

porrectus

Calyptaulax

the lower portion of the Rust.

Calyptaulax

eboraceous

Ceraurus

A package of t h i n - b e d d e d

limestones referred to as

cornutus

conifrons

Amphilichas

decemsegmentus

inaequalis

Bumastoides

holei callicephalus pleurexanthemus

the

Diacanthaspis

parvula

Flexicalymene

VValcott-Rust Q u a r r y beds, o c c u r r i n g a b o u t 12 m above the base

Gabriceraurus

dentatus

Gerasaphus

of the Rust F o r m a t i o n s , has yielded exquisitely preserved fossils

Hypodicranotus

(Figure 4 . 2 3 B ) . T h i s t h i n - b e d d e d and rather fine-grained inter-

Isotelus

val in the Rust F o r m a t i o n sharply overlies burrowed fossiliferous

Nanillaenus

limestone that caps a shallowing cycle within the lower Rust.

Sphaerocoryphe

striatulus

Isotelus

walcotti

senaria ulrichiana

gigas

Meadowtownella

americanus

trentonensis

Proetid sp.

robusta

T h e presence of m o r e distal, deeper-water facies suggests that this interval represents a time of m i n o r deepening within the basin

T h e strata above the q u a r r y beds interval including the upper dis-

due to either tectonics or sea-level rise. T h e W a l c o t t - R u s t Q u a r r y

turbed zone c o m p r i s e t h i n - b e d d e d , very nodular, shaly fossili-

beds interval exposed near the f o r m e r Rust farm estate was dis-

m e n i d ferous wackestones and packstones that are particularly

covered and initially excavated by Charles Walcott. Collections

rich

from this site were sold to the M u s e u m of C o m p a r a t i v e Z o o l o g y

Platystrophia. Nautiloids are also c o m m o n , but trilobites are less

at Harvard in the 1870s and were listed in a paper by Delo ( 1 9 3 4 ) .

a b u n d a n t than below and are typically fragmentary. T h e s e beds

in

strophomenid

brachiopods

such

as

Rafinesquina

and

T h e Walcott-Rust Q u a r r y beds consist of sharply based a n d , in

record heavily b u r r o w e d sediments deposited in shallow, s t o r m -

s o m e cases, graded layers of fossil debris and c a r b o n a t e silt or

wave influenced e n v i r o n m e n t s .

m u d . Fossils o c c u r both on bedding planes and within s o m e of

T h e Rust grades up into the Steuben L i m e s t o n e , a heavy

the very-fine-grained beds. Remains of these o r g a n i s m s were

bedded

caught up within the turbid flows that carried the c a r b o n a t e

w i n n o w e d c r i n o i d remains and indicates a p e r i o d of shallow

m u d . Carcasses or living o r g a n i s m s may have been transported

water above wave-base. Although trilobites have been reported

crinoidal

grainstone.

The

Steuben

is

composed

of

a short distance locally before being deposited and very rapidly

from the c o m p r e s s e d shale between the beds of the S t e u b e n , they

covered by the settling c a r b o n a t e m u d s .

are u n c o m m o n .

However, in s o m e

instances, organism remains were buried exactly in situ as evidenced by upright cystoids and b r y o z o a n s encased within a l i m e -

In

the

Poland,

H e r k i m e r C o u n t y , area the entire

upper

Trenton also appears to u n d e r g o a rapid t h i n n i n g and passage

stone bed. Most of the carbonates represent individual c a r b o n a t e

into gray shales and calcilutites to the southeast. T h e Rust beds

event beds, either gradient current deposits or turbidites that fol-

and the underlying Russia are b o t h very c o n d e n s e d and thin

lowed turbulent scouring and resuspension in upslope areas. T h e

in the vicinity of Middleville,

original quarry site was re-excavated and the layers e x a m i n e d for

entire Rust M e m b e r , over 27 m at Trenton Falls, is thinned to just

trilobites in s o m e recent work (Brett et al. 1 9 9 9 ) . In particular, a

under 2 m.

bed at the base of the quarried interval yielded a series of partially enrolled F.

senaria and C. pleurexanthemus, in which

the

H e r k i m e r C o u n t y , where the

North and west of the M o h a w k Valley, the Hillier Limestone overlies the Steuben L i m e s t o n e in a generally deepening upward

76

THE

PALEOZOIC

GEOLOGY

OF

NEW

YORK

progression. T h e Hillier consists of shaly, nodular limestone with

upward with a series of thin ash beds into the overlying Dolgeville

abundant

Formation.

cephalopods

and

a

few

Flexicalymene specimens.

Lag

deposits between the Hillier and the overlying black shales ( D e e r

To the east, in the Hudson Valley area, the black Flat Creek or

River F o r m a t i o n ) with bored p h o s p h a t e pebbles c o n t a i n the trilo-

C a n a j o h a r i e shales grade into a thick succession (over 5 0 0 m ) of

bites

dark gray shales and turbidite sandstones referred to as the Snake

Ceraurus

sp.,

Flexicalymene

sp.,

and

Pseudogygites

latimar-

ginatus. T h e latter, a c o m m o n trilobite from the equivalent beds

Hill

in O n t a r i o , is only k n o w n f r o m the Hillier and the base of the

rapidly in a trough that lay just west ( m o d e r n directions) of the

Deer River in New York.

Formation

(Figure

4.20B).

These

sediments

accumulated

rising Taconic thrust mass. T h i s is evident not only because the

Trilobites are c o m m o n and diverse in the upper Trenton strata

thrust sheets lie o n , or in, the Snake Hill Shale, but also because

from Middleville northwest into O n t a r i o . W i t h i n the Trenton

the Snake Hill includes pebbles and even huge blocks of rocks

above the Sugar River are f o u n d the following:

derived from the old shelf edge to the east. T h e s e include limestone blocks that c o n t a i n disarticulated trilobite parts, evidently

Achatella

achates

Amphilichas

cornutus

Bumastoidcs

decemsegmcntus

Bumastoides Calyptaulax Ceraurus

inaequalis

lapsed as debris flows into the Snake Hill Shales.

Bumastoidcs

eboraceous

Ceraurinus

vigilans dentatus

Gravicalymene

magnotuberculata

gigas

Kawina

" b u l l d o z e d " by the i n c o m i n g Taconic thrust sheets and then col-

Amphilichas Calyptaulax

Erratenerinurus

Isotelus

conifrons

porrectus pleurcxanthemus

Gabriceraurus

Amphilichas

T h e eastern equivalent of the highest Trenton beds is a very

callicephalus marginal us

Little

Falls

exit,

called

the

Dolgeville

F o r m a t i o n . Dolgeville consists o f thin ( 5 t o 2 0 m m ) platy beds o f very-fine-grained limestone alternating with black shale (Figure

ulrichiana

4 . 2 4 A ) . T h e black and light bed striping are a very striking m o t i f

Gerasaphus Hypodicranotus

striatulus

walcotti

Lonchodomas

Proetid sp.

Pseudogygites Triarthrus

in weathered o u t c r o p s . T h e thin limestones are believed to be turbidites of l i m e m u d washed o f f the shallow platform (Rust to Steuben depositional area) to the west. T h e shaly intervals of the Dolgeville

americanus

contain

Triarthrus

beckii.

T h e top of the Dolgeville beds shows deformation presumably due to s l u m p i n g on the seatloor prior to deposition of the over-

latimarginatus Triarthrus

the

senaria

Nanillaenus

robusta

near

parvula

Meadowtownella trentonensis

Sphaerocoryphe

Thruway,

Flexicalymene

hastatus

Irenlonensis

distinctive rock unit, well exposed along the New York State

Diacanthaspis

Isotelus (Pseudosphaerexochus)

holei

bcckii

lying black shale. All of this suggests strong tectonic influence of the T a c o n i c O r o g e n y in the foreland basin at this time (Figures 4 . 2 0 B and 4 . 2 5 ) . T h e Dolgeville F o r m a t i o n and Steuben Lime-

catoni

stone are abruptly overlain by black shales of the Indian Castle Eastern T r e n t o n Equivalents a n d Utica Shale T h e eastward fate o f the upper p o r t i o n s o f the Trenton G r o u p remains s o m e w h a t u n c e r t a i n , pending correlation o f b e n t o n i t e

( U t i c a ) F o r m a t i o n (Figure 4 . 2 4 B ) . T h i s implies abrupt deepening over m u c h of New York State due to an episode of tectonic Subsidence.

beds within the section. T h e Poland and Russia M e m b e r s appear

On the basis of the m e t a b e n t o n i t e s and graptolites, it can be

to undergo a transition into p r e d o m i n a n t l y dark gray to black

shown that the Indian Castle Shale is a westwardly thinning

platy shales in the vicinity of Caroga Creek, Fulton C o u n t y , and

wedge of rock with progressively higher units onlapping the

St. Johnsville, M o n t g o m e r y C o u n t y . However, p o r t i o n s of the

Trenton U n c o n f o r m i t y in a westwardly direction. T h e s e black

Rust appear to e x t e n d eastward as a calcareous z o n e , " t h e W i n -

shale beds appear c o n f o r m a b l e with the underlying Dolgeville

tergreen Flats b e d s " that c a r r y Prasopora and c a l y m e n i d trilobite

in eastern M o h a w k Valley. Finally, near Middleville, H e r k i m e r

material at least as far east as Flat C r e e k near Sprakers, M o n t -

Count}', black shales of the u p p e r Utica b e d s rest with sharp dis-

g o m e r y County. D a r k Flat C r e e k ( C a n a j o h a r i e ) Shales, p a r t i c u -

c o n f o r m a b l e c o n t a c t on a c o r r o s i o n surface in the upper Steuben

larly those overlying the W i n t e r g r e e n Flats Prasopora b e d , contain

Limestone.

an a b u n d a n c e of the trilobite

Triarthrus beckii. T h e shales also

T h e dark Flat Creek and Snake Hill shales that are laterally

b e c o m e quite rich in graptolite fossils that are dated as near the

equivalent to the upper Trenton are sparsely fossiliferous and rep-

top of the Corynoides americanus graptolite zone. A dark gray or

resent deeper-water e n v i r o n m e n t s with high rates of sediment

black shale bed overlies the W i n t e r g r e e n beds in the vicinity of

accumulation.

C a n a j o h a r i e and appears to represent a m a j o r deepening within

sparingly.

Graptolites and

Triarthrus specimens are found

the section. T h i s interval may c o i n c i d e with the W a l c o t t - R u s t

In the H u d s o n Valley the Snake Hill Shale also contains debris

Q u a r r y beds in the Trenton Falls area. It is the zone that carries

flows and b l o c k s of exotic material that were thrust in from the

the m o s t a b u n d a n t Triarthrus beckii in the central and eastern

eastern area. O n e such mass is the Rysedorph C o n g l o m e r a t e .

M o h a w k Valley region. T h i s dark gray shale, newly t e r m e d the

Two miles southeast of Rensselaer, New York, Rysedorph Hill

"Valley B r o o k S h a l e " (Brett and Baird, in press), appears to pass

is underlain by an unusual c o n g l o m e r a t e , the Rysedorph C o n -

FIGURE 4 . 2 4 . Middle Ordovician Dolgeville and Utica rocks. A. Middle Ordovician Dolgeville Formation sharply overlain by Indian Castle (Utica Group) black shale (upper white arrow at the contact). Note the thin "ribbon limestones" and black shale, and the small folds (lower white arrow) in the Dolgeville beds. New York State Thruway, 1.6km (1 mile) west of the Little Falls exit, Herkimer County. B. Black Indian Castle (Utica Group) shale, with light weathering limestone beds. East Canada Creek, Dolgeville, Herkimer County.

78

THE

PALEOZOIC

GEOLOGY

OF

NEW

YORK

g l o m e r a t e . Various pebbles within this unit c o n t a i n fossils f r o m

center of the Utica trough, which extended eastward toward New

C a m b r i a n t o U p p e r O r d o v i c i a n . S o m e o f the M i d d l e Ordovician

England.

trilobites o b t a i n e d by R u e d e m a n n ( 1 9 0 1 ) are n o t f o u n d elsewhere in New York, but s o m e are k n o w n in Virginia. M o s t of

Lorraine Group

these remains are fragmentary, and the actual species assign-

Strata of the late p o r t i o n of the Ordovician Period in New

m e n t s may not be correct in all cases. T h e trilobites include the

York State reflect the filling and overfilling of the Taconic fore-

following:

land basin. In eastern and east-central New York State these strata above the Schenectady F o r m a t i o n have been removed by a s u b -

Achatella

achates

Calyptaalax

callicephalus

Ceraurus Cybele

Calyptaulax Ceraurus

pleurexanthemus

Isotelus

ulrichiana

Lonchodomas Otarion? Thaleops

Tretaspis

ovata

Tretaspis

the F r a n k f o r t ) , and Pulaski

americanus

m e m b e r s , and the Oswego and

Q u e e n s t o n f o r m a t i o n s (Figures 4 . 1 2 and 4 . 2 5 ) . T h e Frankfort-

linguatus

Sphaerocoryphe

tumidus

G r o u p with its Frankfort, W h e t s t o n e G u l f (western equivalent of

maximus

Remopleurides

matutinum

Remopleurides

filling phases of the Taconic Basin are recorded in the Lorraine

senaria

Nanillaenus

hastatus

M o h a w k Valley region and northwestern New York State, the

lunatus

Flexicalymene

Gerasaphus

Silurian and Early Devonian deposits. However, in the western

sp.

Eobronteus

sp.

sequent period of uplift and erosion prior to onlapping of

eboraceous

Pulaski succession c o m m e n c e s with dark gray shales and shows

major

a general c o a r s e n i n g - u p w a r d trend through siltstones and sand-

reticulata

stones. Parallel with this is a change from anoxic to fully oxy-

diademata

genated seafloor c o n d i t i o n s reflected in increasingly diverse fossil assemblages. Overall, the seafloor was shallower due to fill-in or

Late Ordovician

p r o g r a d a t i o n of the sediments from the east.

Utica S h a l e - S c h e n e c t a d y F o r m a t i o n

L o r r a i n e G r o u p E n v i r o n m e n t s a n d Trilobites

D u r i n g later Middle O r d o v i c i a n , c a r b o n a t e deposition ceased

T h e Frankfort F o r m a t i o n , o f the Lorraine G r o u p , consists o f

and was abruptly followed by deposition of widespread, black

a series of dark gray to black shales with interbedded, thin, silty

Utica Shale facies (Figure 4 . 2 5 ) . T h e eastern p o r t i o n o f the

turbidites and o n e significant package (Hasenclever) of fine-

basin was b e g i n n i n g to receive increased a m o u n t s of coarse

grained, m u d d y sandstones. T h i s package appears to represent a

siliciclastic sediments, primarily siltstone and sandstone turbidite

m i n o r sea-level lowstand or a drop in the relative sea level that

beds,

caused progradation or westward migration of the coarser silici-

Schenectady

eroding

Taconic

Formation,

Mountains

which

during

occur

the

closer

same

time

to

the

interval

(Figure 4 . 2 5 B ) .

clastic silt and sand facies over m u c h of central New York. This b u n d l e , however, is overlain by a return to dark gray shales,

T h r o u g h o u t m u c h o f the M o h a w k Valley, alternating c a r b o n -

referred to as Moyer Creek M e m b e r in the Utica region, and Deer

ates and shales of the Dolgeville F o r m a t i o n ( p r o b a b l e equivalents

River dark shales to the northwest. T h e s e upper Frankfort shales

of the u p p e r m o s t Rust or Steuben limestones) are abruptly over-

are notable in the area in R o m e , New York, for yielding extraor-

lain by a black, rusty weathering l a m i n a t e d shale, Utica (Indian

dinarily preserved fossils. T h e s e are displayed in thin beds of silty

Castle), with a b u n d a n t thin (1 to 2 cm thick) clay layers that r e p -

shale referred to as Beecher's Trilobite Bed that is exposed along

resent m e t a b e n t o n i t e s .

S i x M i l e Creek n o r t h of R o m e . T h e s e beds have yielded spectac-

These black shales are referred to herein as the Indian Castle Formation of the Utica Shale G r o u p .

T h e trilobite

Triarthrus

ularly

pyritized

Triarthrus

eatoni

specimens

with

preserved

appendages, in significant n u m b e r s in o n e thin band. T h e s e trilo-

of

bites were buried very rapidly by a thin, silty turbidite, probably

O n t a r i o , is found in the upper Indian Castle Shale i m m e d i a t e l y

c o m i n g out of the then-developed deltaic regions to the east. Very

spinosus, above

normally the

seen

Steuben

in

the

Limestone

Collingwood near

Holland

Formation Patent,

Oneida

early infilling of the appendages by fine-grained pyrite preserved these fossils exceptionally well. T h e y have been the subject of

County. Throughout

the

Mohawk

Valley

region,

black

shales

of

n u m e r o u s a n a t o m i c a l and t a p h o n o m i c studies. T h e similarly

varying age ranging up to 3 0 0 m thick constitute a relatively

pyritized

m o n o t o n o u s facies c o m p o s e d largely of black laminated g r a p -

beecheri are present but relatively rare.

tolite-rich shales. O n l y certain beds of the Indian Castle c o n tain o t h e r fossils, such as highly flattened o r t h o c o n i c nautiloids and pear

the trilobite to

have

Triarthrus eatoni.

been

particularly

Again, these trilobites a p adapted

to

the

trilobites

Exceptionally

Cryptolithus

well-pyritized

bellulus

cephalopod

arthrus s p e c i m e n s are also k n o w n

and

Cornuproetus?

remains

and

from the Frankfort

Tri-

(Deer

River) shales in the vicinity of Constableville, Lewis County, and

low-energy,

W h e t s t o n e Gulf, Lewis C o u n t y , in northwestern New York State.

low-oxygen e n v i r o n m e n t s represented by the Utica Shale deposi-

T h e s e beds show increasingly thick, silty and sandy beds that rep-

tion. Waters were probably relatively deep and stagnant in the

resent distal or m o r e proximal turbidites or storm deposits; these

FIGURE 4 . 2 5 . New York maps during the late Middle Ordovician and the Upper Ordovician. A. Late Middle Ordovician. B. Late Ordovician. C. Cross section of the plate movement during Late Ordovician. From Isachson et al. (1991). Printed with permission of the New York State Museum, Albany, N.Y.

80

THE

PALEOZOIC

GEOLOGY

OF

NEW

YORK

beds are interbedded with m e d i u m to b r o w n i s h gray shales that

(Figure 4 . 2 8 ) . Locally, bundles o f f i n e - g r a i n e d sandstone, s o m e o f

may represent b a c k g r o u n d c o n d i t i o n s . T h e s t o r m beds typically

t h e m c o n t a i n i n g a n i m a l burrows, are also present within the

display a hash or lag of shelly material that includes b r a c h i o p o d s ,

Q u e e n s t o n , for e x a m p l e , at Rochester. However, the presence of

bivalves, and c r i n o i d stems on their bases. T h e s e coarser skeletal

small, limey nodules, referred to as calcretes, in certain horizons

debris layers grade upward into fine grainstones and siltstones

suggests the development of s o i l - f o r m i n g features within the

that c o m m o n l y display h u m m o c k y c r o s s - l a m i n a t i o n ; these low-

Q u e e n s t o n F o r m a t i o n . T h e presence o f calcretes implies long

m o u n d e d l a m i n a t i o n s , typically c o n v e x - u p w a r d , are thought to

periods of aerial exposure during the deposition of these muds.

be f o r m e d by the interference of s t o r m waves and currents in rel-

We visualize the Q u e e n s t o n as representing a broad alluvial flood-

atively shallow waters. Tops of s a n d s t o n e beds also display fea-

plain of possibly m e a n d e r i n g streams that originated in the

tures such as interference and w a v e - f o r m e d ripple marks that

Taconic Highlands and spread sheetlike masses of sediment over

further indicate a relatively shallow-water origin for these beds.

a wide tract of the Appalachian Basin. Red coloration, together

T h e Pulaski beds are d o m i n a t e d by b r a c h i o p o d s , c l a m s , and a few

with the calcretes, indicates subaerial exposure for m u c h of the

species of crinoids. However, trilobites are k n o w n at certain levels

unit in New York State, at least. However, to the west, the Q u e e n -

and

ston interfingers with the gray calcareous m u d s t o n e and even

include

Cryptolithus

bellulus,

as

well

as

some

Flexicalymene

species and Isotelus species, which m a y o c c u r in thin, skeletal hash

brachiopod-

beds. T h e s e beds represent s o m e o f the highest o c c u r r e n c e s o f

H a m i l t o n , O n t a r i o . Still farther west, the Q u e e n s t o n appears to

and

bryozoan-rich

limestones

northwest

of

these trilobites. In New York the overlying beds of the Oswego

b e equivalent t o the R i c h m o n d G r o u p o f the C i n c i n n a t i , O h i o ,

and Q u e e n s t o n f o r m a t i o n s represent n e a r s h o r e o r n o n m a r i n e

area, part of the section n o t e d for exceptionally well-preserved

fades inappropriate for the preservation of trilobites, although

fossils, including a b u n d a n t trilobites of the genera Flexicalymene,

these genera persisted, with a b u n d a n t Flexicalymene and Isotelus

Isotelus, and others. H e n c e , these organisms lived on in the later

remains c o m m o n in the R i c h m o n d G r o u p in southwestern O h i o .

part of the O r d o v i c i a n in the m i d c o n t i n e n t , while New York State

Cryptolithus and

developed into a delta plain and tidal fiat c o m p l e x .

Isotelus and the entire trinucleid

and

asaphid

trilobite groups to which they b e l o n g appear to have b e c o m e extinct in the Late O r d o v i c i a n crisis, which affected m o r e than 2 0 % o f m a r i n e families.

T h e latest

p o r t i o n o f the Ordovician

Period

(Gamachian

Stage) is not recorded in New York, or in most of the m i d c o n t i nent of North A m e r i c a . T h e Q u e e n s t o n is terminated by a m a j o r

T h e reported trilobites of the U p p e r O r d o v i c i a n are as follows:

erosional

u n c o n f o r m i t y (referred

to as

the Cherokee

Unconfor-

mity; Figures 4 . 1 and 4 . 2 6 ) . T h i s erosion surface increases in magCalyincnc?

conradi

Ceraurinus

marginatus

Calyptaulax Ceraurus

cf.

beecheri

Cryptolithus

Flexicalymene

granulosa

Flexicalymene

stegops

Odontopleura Proetus

ceralepta

spurlocki

Triarthrus

eatoni

Triarthrus

spinosus

Isotelus

nitude to the east along the Q u e e n s t o n clastic wedge. Ultimately, it cuts down through the entire thickness of the Q u e e n s t o n (over 4 0 0 m) and through the underlying Pulaski, Frankfort, and upper

bellulus

parts of the Utica or Schenectady f o r m a t i o n s (Figures 4 . 1 2 and

meeki

pulaskiensis

4 . 2 6 ) . T h i s suggests that several things were happening in the Late

hudsonica

O r d o v i c i a n . First, there was a period of uplift in the eastern

Otarion? Pseudogygites Triarthrus

callicephalus

sp.

Cornuproetus? Homotelus

C.

p o r t i o n s of the old Q u e e n s t o n delta. T h i s might reflect renewed

latimarginatus

o r o g e n i c or m o u n t a i n - b u i l d i n g activity at the very end of the

glaber

O r d o v i c i a n or Early Silurian, or possibly isostatic forces (buoya n c y forces) that caused the eastern areas, formerly part of the m o u n t a i n belt, to b o b upward in m u c h the same way that land

Upper O r d o v i c i a n O s w e g o a n d Q u e e n s t o n F o r m a t i o n s T h e record of benthic life in the highest part of the O r d o v i c i a n

r e b o u n d s after removal of the weight of a glacier (Figure 4 . 2 5 B ) .

deposits in New York is sparse. T h e Pulaski gives way upward to

T h i s " p o p - u p " p h e n o m e n o n or isostatic r e b o u n d would be the

coarser g r a y - a n d - m a r o o n - m o t t l e d sandstones o f the Oswego For-

result of erosional redistribution of sediments from the old thrust

m a t i o n . Here, a b u n d a n t wave m a r k s , desiccation cracks, and other

belt of the Taconic M o u n t a i n s and out into a wider tract of the

features toward the top indicate shallowing of the O r d o v i c i a n

interior of North A m e r i c a . A second event that may have c o n -

seafloor effectively to sea level. T h i s shallowing was p r o d u c e d by

tributed to the development of a m a j o r widespread u n c o n f o r m i t y

the rapid in-filling of clastic s e d i m e n t s that were being shed out of

or erosion surface at the end of the Ordovician was the develop-

the n o w eroding Taconic Highlands to the east. T h e effect of this

m e n t of extensive continental glaciers in the region that today

was the o u t w a r d - b u i l d i n g or progradation of the so-called Q u e e n -

is

ston delta c o m p l e x into the Appalachian foreland basin.

have locked up a considerable a m o u n t of water as glacial ice and

Saharan Africa.

These

Late Ordovician

ice sheets would

along

thereby caused a d r o p in sea level from the Late Ordovician on

the s o u t h shore o f Lake O n t a r i o f r o m O s w e g o C o u n t y westward

the o r d e r of perhaps 100 m. T h i s is reflected in successions of rock

t o the Niagara G o r g e , consists o f m a r o o n - r e d blocky m u d s t o n e

worldwide as a m a j o r erosion surface associated with regression

with occasional streaks of greenish gray siltstone and sandstone

of seas. T h i s t i m e also corresponds to o n e of the great mass

T h e overlying Q u e e n s t o n

F o r m a t i o n , well

exposed

SILURIAN

81

PERIOD

FIGURE 4 . 2 6 . Ordovician/Silurian unconformities. A. Ordovician/Silurian unconformity. Upper Ordovician, black Frankfort S h a l e (a) is sharply overlain by Lower Silurian, light gray O n e i d a c o n g l o m e r a t e and s a n d s t o n e (b), which g r a d e s upward into gray Sauquoit S h a l e . Cut along Rte. 1 7 1 , Frankfort G o r g e of Moyer Creek, Frankfort, Herkimer County. B. Angular C h e r o k e e unconformity (arrow) b e t w e e n Ordovician Austin Glen Formation ( b ) (nearly vertical b e d s on right side) and gently dipping u p p e r m o s t Silurian Rondout Formation (a). Note that the unconformity, p r o d u c e d by erosion of the folded Taconic terrane, w a s later rotated to 45 d e g r e e s during the Devonian A c a d i a n Orogeny. Exit from Rte. 23 to 2 3 B , Catskill, G r e e n e County.

extinctions in Earth's history and o n e that decimated m a n y trilo-

recovery from m a j o r Late O r d o v i c i a n extinction and ended with

bites, such as the genux Isotelus.

m i n o r extinction before the D e v o n i a n . T h e r e is really not a m a j o r S i l u r i a n - D e v o n i a n break in m o s t areas. T h e Silurian marks a

Silurian Period

return to g r e e n h o u s e c o n d i t i o n s following the Late Ordovician glaciation, but there appears to have been s o m e lingering glacia-

T h e Silurian Period was a relatively short span ( 4 3 8 to 4 0 8

tion in the paleo-Andes M o u n t a i n s of S o u t h A m e r i c a through the

million years ago) (Figures 4.1 and 4 . 2 7 ) that c o m m e n c e d with

Early Silurian. Middle and Late Silurian climates appear to have

THE

82

PALEOZOIC

GEOLOGY

OF

NEW

YORK

FIGURE 4.27. Stratigraphic chart of the Silurian rocks in New York. The n u m b e r s are millions of years before present. M o d i f i e d from Brett et al. (1985).

been quite equable worldwide, with lots of shallow c a r b o n a t e

(Figures 4.5 and 4 . 2 6 ) . E t t e n s o h n and Brett ( 1 9 9 8 ) recognized

deposition and s o m e return to stagnation and black shale devel-

a third and final tectophase of Taconic O r o g e n y in the Early

o p m e n t in deeper basins.

Silurian; this m o u n t a i n - b u i l d i n g activity produced a new clastic

T h e eastern side of Laurentia, n o w a b o u t 25 to 30° south latitude, experienced the f i n a l r u m b l e s o f the Taconic O r o g e n y

wedge, the T u s c a r o r a - M e d i n a f o r m a t i o n s , and pulse of westward subsidence.

SILURIAN

83

PERIOD

Baltica (Ancestral Europe) had m o v e d northward through the

( M i d d l e t o n et al. 1 9 8 7 ) . T h e s e s e d i m e n t s appear to represent

Ordovician and now collided with n o r t h e r n Laurentia to f o r m

a reworking of older O r d o v i c i a n siliciclastics, as the Whirlpool

the widespread Caledonian

created

locally contains very m i n o r thin seams of greenish gray shale that

Euramerica ( o r " O l d Red C o n t i n e n t " ) straddling the p a l e o e q u a -

not o n l y c o n t a i n early Silurian a c r i t a r c h s , small microfossils

tor (Figure 4 . 5 ) . At the same t i m e the m i c r o c o n t i n e n t of Avalo-

representing p r o b a b l e algal resting cysts, but also acritarchs

nia was converging on (present-day) eastern N o r t h A m e r i c a ,

reworked f r o m the O r d o v i c i a n .

making initial

New

Trilobites evidently were present in s o m e of these environm e n t s , but their b o d y fossils are rare. T h e upper p o r t i o n of the

appears to have been s o m e orogenesis during the M i d d l e Silurian

W h i r l p o o l S a n d s t o n e is distinctly m a r i n e and locally shows h u m -

in

m o c k y c r o s s - l a m i n a t e d s a n d s t o n e beds with m i n o r fossil debris.

North

in

the

America

northern

Europe and

England region in the Late Silurian or Fail}' Devonian. T h e r e eastern

contact

O r o g e n y in

(Laurentia),

M a r i t i m e and

termed

the

Salinic

Orogeny, as evidenced by a renewed pulse of subsidence and west-

R e m n a n t s of starfish and c r i n o i d s have been f o u n d in the upper

ward migration of the foreland basin.

layer of the W h i r l p o o l in O n t a r i o , and farther west the Whirlpool

Sea level rose in the Early Silurian, following the lowest sea

grades laterally into or is overlain by the M a n i t o u l i n D o l o s t o n e ,

level at the end of a regression that p r o d u c e d the C h e r o k e e

a rather massive

Unconformity

locally c o n t a i n s a b u n d a n t b r a c h i o p o d s and m i n o r disarticulated

in

the

latest

Ordovician.

The

Silurian-Early

Devonian bundle of strata forms the Tutelo ( s e c o n d )

Phase

fine-grained

d o l o m i t i c c a r b o n a t e . T h i s unit

trilobite material. T h e probably equivalent massive Tuscarora

of Sloss's T i p p e c a n o e S u p e r s e q u e n c e . Sea level was quite high

Sandstone of Pennsylvania is generally devoid of body fossils but

throughout the mid Silurian but was beginning to fall in the later

contains

Silurian. Smaller-scale (third and fourth order) sequences were

resting traces o f trilobites.

developed owing to s h o r t e r - d u r a t i o n rises and falls of sea level during the Silurian in eastern N o r t h A m e r i c a .

abundant

traces

including

Rusophycus,

the

probable

In Niagara C o u n t y and westward into O n t a r i o the W h i r l p o o l S a n d s t o n e is overlain by dark gray to m e d i u m greenish gray

Although the Silurian is a relatively shorter interval of time

shales and with s o m e thin q u a r t z - r i c h sandstones. In western

than the Ordovician or the D e v o n i a n , Silurian rocks in New York

New York this Power Glen Shale tends to be sparsely fossiliferous.

State are highly varied, indicating a b r o a d range of depositional

O n l y m i n o r trace fossils, including Rmophycus, are f o u n d on the

environments. T h e Silurian can be subdivided into five m a j o r

base of sandstones at L o c k p o r t . At Niagara the unit is s o m e w h a t

divisions that are generally construed as groups (Figure 4 . 2 7 ) . In

m o r e fossiliferous, yielding a small fauna including snails, small

ascending order these are the (1) M e d i n a G r o u p : predominately

twiglike b r y o z o a n s , nautiloid c e p h a l o p o d s , and a single species

shales and sandstones of early Silurian age; ( 2 ) C l i n t o n G r o u p : a

of small c r i n o i d . Westward in O n t a r i o the unit b e c o m e s even

heterogeneous group c o m p o s e d o f shales, m i n o r sandstones, and

m o r e fossiliferous, and

shell-rich carbonates with m i n o r h e m a t i t e beds; ( 3 ) L o c k p o r t

a b u n d a n t remains o f several species o f b r y o z o a n s , b r a c h i o p o d s ,

G r o u p : predominantly d o l o m i t i c c a r b o n a t e s in western New

c r i n o i d s , and starfish. Trilobites tend to be u n c o m m o n in these

York, grading eastward into dark gray or greenish shales and thin

beds, but a few r e m a i n s of c a l y m e n i d s and dalmanitids have been

stromatolitic limestones; (4) Salina G r o u p : Upper Silurian shales,

collected.

near H a m i l t o n , O n t a r i o , it contains

carbonates, and evaporites; and ( 5 ) Bertie and R o n d o u t G r o u p s :

T h e Power Glen Shale and laterally equivalent C a b o t Head

dolomitic limestones and dolostones with s o m e shales and m i n o r

Shales appear to have a c c u m u l a t e d in shallow offshore shelf or

evaporites.

pro-deltaic settings of early M e d i n a . D a r k gray and greenish colo r a t i o n , as well as an a b u n d a n c e of pyrite at s o m e levels, suggests a c c u m u l a t i o n under low-oxygen, quiet water c o n d i t i o n s . Perhaps

Early Silurian

the i n n e r - s h e l f m u d s were deposited in a sheltered, muddy

Medina G r o u p

lagoon. However, s o m e w h a t m o r e o f f s h o r e sediments in the

T h e Early Silurian Medina S a n d s t o n e of New York and its equivalents, the Tuscarora sandstones and c o n g l o m e r a t e s of the

vicinity o f H a m i l t o n , O n t a r i o , d o show a b u n d a n t storm deposits, indicating deposition by s t o r m waves and currents.

central Appalachian region, represent a renewed influx of silici-

T h e higher beds of the M e d i n a G r o u p in western New York,

clastic sediments following the m a j o r e n d - O r d o v i c i a n u n c o n f o r -

assigned to the G r i m s b y F o r m a t i o n , are primarily reddish and

mity or period of erosion. T h e M e d i n a G r o u p is c o n f i n e d to

white-mottled, quartz-rich,

western and west-central New York, pinching out eastward in the

stones interbedded with green and red m u d s t o n e s . Generally,

vicinity o f O n e i d a , O n e i d a C o u n t y (Figure 4 . 2 8 ) . T h e M e d i n a i s

these sediments are sparsely fossiliferous, particularly east of

fine-grained

sandstones and silt-

characterized by quartz-rich sandstones and shales, m a n y of

L o c k p o r t , New York. But in the west they may contain abundant

which are red.

shells of lingulid b r a c h i o p o d s , a

In western New York and O n t a r i o the basal unit is a quartzose

few species of clams, and

even b r y o z o a n s at Niagara G o r g e . T h e presence of abundant

sandstone with trough c r o s s - b e d d i n g , the W h i r l p o o l S a n d s t o n e ,

b u r r o w i n g with m a n y p r i m a r y sedimentary structures, such as

which

wave and current ripple m a r k s , m i n o r trough and h u m m o c k y

may

represent,

in

part,

nonmarine

stream

deposits

84

THE

PALEOZOIC

GEOLOGY

OF

NEW

YORK

FIGURE 4.28. A. Ordovician-Silurian (Cherokee) unconformity (arrow). U p p e r O r d o v i c i a n , dark m a r o o n Q u e e n s t o n Shale (a) is sharply overlain by light gray Whirlpool S a n d s t o n e (Lower Silurian) (b). In turn, the Whirlpool g r a d e s a b r u p t l y u p w a r d into gray Power Glen Shale ( M e d i n a Group) (c). Cut on West J a c k s o n Street, Lockport, Niagara County. B. O r d o v i c i a n Lower Silurian s u c c e s s i o n . U n c o n f o r m i t y (arrow) at the t o p of the U p p e r O r d o v i c i a n Queenston Shale (a) is overlain by Lower Silurian Medina G r o u p (b). The white b a n d at the top of the M e d i n a is the K o d a k Sandstone (c). This unit is overlain, in turn, by green M a p l e w o o d Shale (d) of the Clinton G r o u p . G e n e s e e River G o r g e . Rochester, Monroe County.

cross-stratification, rare desiccation c r a c k s , evidence o f c h a n n e l -

upward to h u m m o c k y cross-laminated sandstone beds that may

ing and soft sediment d e f o r m a t i o n in the f o r m of load casts

be capped by thin lag beds of bryozoans and / inguhi brachiopod

and b a l l - a n d - p i l l o w - s t r u c t u r e s all point to deposition in very

shell hash representing m i n o r deepening events. In Rochester,

shallow waters associated with outer- to inner-tidal flats. W i t h i n

New York, s o m e w h a t different, fining upward cycles seem to have

the M e d i n a , o n e m a y recognize small-scale, c o a r s e n i n g , upward

s h a r p - b a s e d , channel-fill sandstones at the b o t t o m s , which are

cycles in western New York that range from m a r o o n m u d s t o n e s

often extensively burrowed by large wormlike organisms that pro-

SILURIAN duced

8b

PERIOD Daedalus, apparently as

ironstones are c o m m o n l y associated with phosphatic nodules and

feeding burrows in muddy sands. T h e upper reddish m u d s t o n e s

structures called Arthrophycus or

flooding surfaces (surfaces with very low sedimentation rates

in higher parts of the cycles apparently reflect upper tidal-flat

during deepening episodes).

conditions, where low-energy c o n d i t i o n s prevailed, allowing fine-

T h e lowest part of the C l i n t o n G r o u p c o m p r i s e s greenish gray

grained muds to drop out of suspension. All of these sediments

shales, the Neahga or M a p l e w o o d of western New York, overlain

apparently accumulated from c o n t i n u e d erosion and deposition

In- thin limestones. T h e Neahga is a highly fissile, very soft, chippy

o f f m o u n t a i n o u s highlands to the s o u t h - s o u t h e a s t . At present, it

shale that like the Power Glen seems to represent nearshore but

appears that a late phase of the Taconic O r o g e n y o c c u r r i n g within

dysaerobic m u d d y b o t t o m c o n d i t i o n s . T h e M a p l e w o o d contains

the early part of the Silurian m a y have uplifted or re-uplifted

very a b u n d a n t microfossils of acritarchs, algal resting cysts, and

these source terrains.

s o m e early plant spores but is almost devoid of macrofossils. A

Trilobites are extremely rare b o d y fossils in the upper sand-

very meager fauna, including o n e species o f calymenid, o n e

stones of the Medina G r o u p . Two persistent, often light gray or

odontopleurid

pinkish sandstones, the T h o r o l d and the Kodak, contain a b u n -

o b t a i n e d f r o m a basal p h o s p h a t e - r i c h layer that immediately

dant trace fossils but very few body fossils. Near Rochester the

overlies the u n c o n f o r m i t y at the b o t t o m of the M a p l e w o o d .

Kodak bears remains of beautifully preserved traces of trilobite

However, in general, the c o n d i t i o n s appear to have been unfa-

trilobite,

and

a

few

brachiopods,

has

been

activity, although as yet no b o d y fossils have been f o u n d . T h e s e

vorable for benthic or b o t t o m - d w e l l i n g life during deposition of

include the coffee b e a n - s h a p e d Rusophycus as well as delicately

the M a p l e w o o d m u d s .

detailed scratch marks produced by trilobites walking on the tips

T h e M a p l e w o o d grades eastward into a sandy, hematite-rich

of their claws. T h e fact that slabs of sandstone from Glen Edith

c o n g l o m e r a t e that is generally lacking in fossils. However, it

near Irondequoit Bay, M o n r o e County, display trilobite trackways

grades upward and laterally to the west into t h i n - b e d d e d lime-

superimposed on m u d cracks suggests that these trilobites m a y

stones and fossil-rich h e m a t i t e beds. T h e s e limestones, the Rey-

have lived in a very shallow water area that was subject to peri-

nales F o r m a t i o n , are rich in b r a c h i o p o d s , particularly the large

odic exposure and desiccation.

robust Pentamerus, which appears to have f o r m e d shell banks

Toward the end of Medina deposition, uplift of a b r o a d arch-

in shallow shoal areas on the seafloor. To the west, these b r a -

like feature, the Algonquin axis or Findley Arch, to the west of

c h i o p o d - r i c h shoals and crinoidal grainstones pass laterally into

New York State elevated parts of the M e d i n a seafloor above sea

m o r e nodular, shaly, and probably m o r e offshore limestones.

level and caused erosion to bevel down through the highest beds

T h e s e facies c o n t a i n smaller b r a c h i o p o d s , a b u n d a n t and diverse

of the Medina, producing a widespread u n c o n f o r m i t y that sepa-

b r y o z o a n s , c r i n o i d s , and a few trilobites. Particularly notable in

rates this unit from the overlying Clinton G r o u p (Figure 4 . 2 8 B ) .

these beds are a b u n d a n t cephala and pygidia of the trilobite

T h e T u s c a r o r a - S h a w a n g u n k - M e d i n a clastic wedge consists of quartz-rich sandstones overlying the angular T a c o n i c U n c o n f o r mity in the Appalachians, which seem to record renewed uplift

Encrinurus. Reported f r o m

the Reynales are the following species of

trilobites:

and sedimentation. In the Niagara region, these show a transgressive succession from n o n m a r i n e and nearshore sandstones, to

Bumastus sp.

deeper marine gray shales, followed by a shallowing (regression)

Encrinurus cf. E.

into tidal flat and n o n m a r i n e red beds.

Scutellum

Calymene rayhesli

sp.

Eophacops trisulcatus

niagarensis

Green and purplish shales of the overlying S o d u s F o r m a t i o n

Middle Silurian

in west-central New York represent a return to shallow water Lower C l i n t o n G r o u p

m u d d y c o n d i t i o n s similar to but s o m e w h a t different from those

Middle Silurian (late Llandovery series) m i x e d shales, c a r -

of the M a p l e w o o d . T h e s e m u d d y seafloors supported a modest

bonates, and ironstones of the lower C l i n t o n G r o u p record the

diversity of b r a c h i o p o d s d o m i n a t e d by the small atrypid Eocoelia,

wearing down of Taconic m o u n t a i n o u s source terranes to the east

small bryozoans, a few c r i n o i d ossicles, the conical fossil Tenta-

and a shift back to o p e n m a r i n e sediments. O n e distinctive

culites, and scattered s p e c i m e n s of small tabulate corals. A few

feature is the widespread " C l i n t o n iron o r e s " ; these f a m o u s fossil-

trilobites make up the r e m a i n d e r of the fauna. Both Diacalymene

rich and oolitic hematites have been m i n e d extensively f r o m

rostrata and Eophacops trisulcatus have been extracted from these

near B i r m i n g h a m , Alabama, to central New York for m a k i n g steel

beds. Here c o n d i t i o n s alternated between dysoxic and s o m e -

and red paint oxides. T h e s e beds probably were associated

what better oxygenated, as indicated by the green and purple

with enrichment of iron in sediments due to deep weathering of

b a n d i n g typical

laconic uplifts. Hematite coatings on grains precipitated under

temporarily hospitable to b e n t h i c assemblages of a very shallow-

conditions

in

water restricted type. T h e s e m u d s apparently represent accu-

muddy sediments, during times of sediment starvation. Hence,

m u l a t i o n s in a b r o a d shallow-water lagoonal setting inboard of

of

fluctuating

oxidizing-reducing

conditions

of the

unit, and

the seafloor was at least

THE

86

PALEOZOIC

GEOLOGY

OF

NEW

YORK

offshore, b r a c h i o p o d - r i c h shoals, which at that t i m e were as far

underlying middle and to the west of the lower Clinton units. It

west as O h i o .

is again a particularly oolitic-rich ironstone that contains a b u n -

T h e Wolcott F o r m a t i o n represents a return to Reynales-like

dant, small (1 to 2 m m ) spheroidal bodies of hematite that appear

c o n d i t i o n s in which a b u n d a n t p e n t a m e r i d b r a c h i o p o d s o n c e

to have f o r m e d by accretion of i r o n - r i c h coatings on grains that

again flourished and f o r m e d shell banks in west-central New

were at least intermittently rolled on the sea b o t t o m . This unit

York. However, an u n c o n f o r m i t y has removed western p o r t i o n s

probably represents a deposit accumulated during sea-level deep-

of the Wolcott so it is not possible to trace these facies westward

ening in which the fine-grained portion was winnowed away,

past Wayne C o u n t y into offshore n o d u l a r sediments c o m p a r a b l e

associated with an episode of a very widespread rise in sea level that o c c u r r e d globally during mid Silurian times. It is well dated

to those seen in the western Reynales. T h i n hematite bands, usually only a few c e n t i m e t e r s thick but traceable over distances of tens of kilometers, are f o u n d at several

by ostracods and sawblade-like graptolites that o c c u r in the interbedded shales.

levels within the lower part of the C l i n t o n G r o u p . As n o t e d , these

Beds of black-green shale of the mid Silurian Williamson

appear to represent periods of m a r i n e s e d i m e n t starvation in a

F o r m a t i o n and its eastern equivalent Willowvale Shale carry an

shoal margin e n v i r o n m e n t in which ferrous iron b e c a m e c o n -

a b u n d a n t fossil assemblage. Fossils typically are poorly preserved

centrated in pore-waters and precipitated out as coatings and

in the shales but they may include over a hundred species of

ooidlike grains on the seafloor. Reworking of these grains into

b r a c h i o p o d s , b r y o z o a n s , the small " b u t t o n " coral Palacocyclus,

windrows or piles c o n c e n t r a t e d

the iron oxide c o m p o n e n t s ,

crinoids, and

trilobites.

Both

Dalmanites and

Calymene species

making them lean iron ores. T h e s e ores are mostly "fossil ores,"

are relatively a b u n d a n t in the Willowvale of central New York.

meaning that they contain a b u n d a n t f r a g m e n t a r y fossils, espe-

To the west, the m e d i u m gray shales give way laterally to green

cially c r i n o i d ossicles, bits of b r y o z o a n s , and shell fragments.

satiny-smooth

Again trilobites, especially c a l y m e n i d s , are present but only as

s o m e t i m e s sandy shales that yield a great a b u n d a n c e locally of the

highly c o m m i n u t e d debris.

sawblade

T h e middle part of the C l i n t o n is represented by the Sauquoit Shales

and

their

eastern

reddish

sandstone

equivalent

the

clay

shales,

monograptid

alternating graptolite

with

black-laminated,

Monograptus

clintonensis,

which enables correlation of the Willowvale and Williamson Shales with o t h e r deposits globally that

represent this mid

Otsquago F o r m a t i o n in the Utica area and eastward. T h e s e units

Silurian highstand or sea-level rise event. T h e Williamson Shales

may be in excess of 30 m thick, and e x p a n d dramatically to the

in

southwest into a succession, up to 140 m thick, of purplish green

f o s s i l s , although s o m e beds carry small b r a c h i o p o d s and rare

the

Rochester

area

generally contain

few o t h e r

benthic

shales referred to as Rose Hill in Pennsylvania and M a r y l a n d . T h e

s p e c i m e n s of the trilobite Calymene have been f o u n d . Overall the

Sauquoit Shale from the middle part of the C l i n t o n G r o u p rep-

W i l l i a m s o n - W i l l o w v a l e Shales probably record the deepest-water

resents c o n d i t i o n s quite similar to those of the Sodus and M a p l e -

interval during deposition of the Silurian in New York State.

wood m u d s , and like t h e m it tends to c a r r y a restricted fauna,

B o t t o m c o n d i t i o n s range from anoxic or having very low oxygen,

although the trilobite Calymene is relatively c o m m o n and the

near the basin center, to fully oxygenated conditions favorable to

genus Dalmanites has also been reported f r o m these shales.

life in central New York Willowvale sections.

Upper C l i n t o n G r o u p

Sandstone represent s o m e w h a t shallower water c o n d i t i o n s in

T h e overlying

Rockway D o l o s t o n e and equivalent

Dawes

A very widespread u n c o n f o r m i t y separates the middle C l i n t o n

which r h y t h m i c limestones or calcareous sandstones a c c u m u -

and lower C l i n t o n shales from the overlying upper part of the

lated, alternating with shales. Again, fossils tend to be sparse

Clinton G r o u p . D u r i n g this medial part of Silurian t i m e , m o r e

because of p o o r preservation in these beds. But a few species of

dramatic arching of the sea b o t t o m in the vicinity of the Algo-

brachiopods,

nquin Arch (near H a m i l t o n , O n t a r i o ) and farther east exposed

graptolites, mostly dendroids (or brushy graptolites), and rare

m a j o r parts of the older C l i n t o n sediments to erosion and pro-

trilobites, such as Dalmanites, have been f o u n d in these beds.

duced a widespread beveling-surface u n c o n f o r m i t y that eroded

In

western

including

the

New York

the

large

form

Rockway

Costistricklandia,

consists

of pale

and

to

o f f the western edges of the middle and lower C l i n t o n units.

m e d i u m gray, argillaceous dolostones with interbedded greenish

H e n c e , a good deal of Middle Silurian t i m e may be missing at this

gray shales. Overall, the Rockway appears to represent an off-

important unconformity.

shore m u d d y c a r b o n a t e unit deposited well below wave-base

T h e upper part of the C l i n t o n G r o u p is a varied succession of

and under s o m e w h a t restricted c o n d i t i o n s . It grades eastward

shales a n d c a r b o n a t e s that are readily g r o u p e d into two u n c o n -

and southeastward into the Dawes S a n d s t o n e of central New

f o r m i t y - b o u n d sequences o r packages. T h e lower consists o f

York, an interbedded, h u m m o c k y c r o s s - l a m i n a t e d , fine-grained

the W e s t m o r e l a n d

sandstone and shale unit with the beautiful trilobite trace fossil,

Hematite

(locally), W i l l i a m s o n - W i l l o w v a l e

shales, and the R o c k w a y F o r m a t i o n and its lateral eastern equivalent, the Dawes S a n d s t o n e . T h e basal hematite b e d , or Westm o r e l a n d , rests u n c o n f o r m a b l y on

the beveled edges of the

Rusophycus. T h e Rockway and its equivalents are sharply overlain by a thin, widespread blanket deposit of crinoidal limestone. T h i s unit,

FIGURE 4.29. M a p s of New York. A. Early W e n l o c k times d u r i n g the d e p o s i t i o n of the Irondequoit Limestone. B. Mid Wenlock d u r i n g the deposition of the Rochester Shale. C. Cross section s h o w i n g the a p p r o a c h of Avalon with proto North A m e r i c a . C is from Isachson et al. (1991). Printed with p e r m i s s i o n of the N e w York State M u s e u m , Albany, N.Y

THE

88

FIGURE 4.30.

PALEOZOIC

GEOLOGY

OF

NEW

YORK

Irondequoit-Rochester b i o h e r m at the

upper part of the M i d d l e Silurian Clinton G r o u p . The sharp contact at the knee level of William G o o d m a n is the u n c o n f o r m a b l e c o n t a c t of R o c k w a y Dolostone (a) a n d massive Irondequoit Limestone (b). The lens-shaped b o d y at the top of the Irondequoit is a small b i o h e r m ("reefs") (arrow) of b r y o z o a n s a n d algae. It o c c u r s at the c o n t a c t of the dark gray Rochester Shale (c). N i a g a r a G o r g e , Lewiston, Niagara County.

4.29),

resent very small buildups or "reeflets" that developed on the

consists almost entirely o f the disarticulated and c o m m o n l y

seafloor during a t i m e of deepening. T h e s e m o u n d s , however,

abraded skeletal remains of crinoids and cystoids. However, there

have yielded s o m e intriguing fossil deposits that are not found

are s o m e thin, interbedded shaly units, and in the R o c h e s t e r area,

elsewhere within the Irondequoit L i m e s t o n e or the overlying

referred

to

as

the

Irondequoit

Limestone

(Figure

the Irondequoit is s o m e w h a t finer-grained and carries a lower

R o c h e s t e r Shale. For e x a m p l e , pockets of greenish shale within

diversity of fauna typified by a few species of b r a c h i o p o d s , of

the c r e a m - c o l o r e d , f i n e - g r a i n e d limestone o f the m o u n d s i n

which Whitfieldella is a c o m m o n e l e m e n t . Also in this area, as

Niagara C o u n t y yield extremely a b u n d a n t remains of the trilo-

well as in Niagara County, small (up to 5m across and 2m h i g h ) ,

bite genera Bumastus and Illaenoides. T h e s e relatively large fossils,

irregular, lenticular m o u n d s , or b i o h e r m s , o c c u r within the I r o n -

up to 3 cm across, appear to represent the remains of reef- or

dequoit (Figure 4 . 3 0 ) . In Niagara C o u n t y these o c c u r mainly at

b i o h e r m - d w e l l i n g trilobites that accumulated or collected in the

the upper c o n t a c t of the crinoidal limestone and extend upward,

small pockets and cavities within the b i o h e r m framework. Also

s o m e t i m e s as m u c h as 1 to 2 m (4 to 5 feet), into the overlying

found

R o c h e s t e r Shale. T h e s e are rather a m o r p h o u s masses of very-

rochesterense, and a new species of Diacalymene that is also rather

fine-grained ( m i c r i t i c ) l i m e s t o n e with s o m e leaflike b r y o z o a n s

large and represented by nearly c o m p l e t e articulated remains

that apparently helped s u p p o r t the m o u n d s . T h e b i o h e r m s rep-

from the Niagara G o r g e .

in

these

associations

are

a

Cheirurus

sp.,

Scutellum

SILURIAN

89

PERIOD

T h e Irondequoit and its b i o h e r m s represent a shallow, highly

of the Rochester, like the middle p o r t i o n of the Lewiston Member,

agitated shelf e n v i r o n m e n t . Water depths were close to n o r m a l

is characterized by dark gray, nearly barren shales in m u c h of

wave-base, ranging from perhaps 10 to 20 m in western New York

western New York. Nonetheless, s o m e bedding planes contain

and no m o r e than 20 to 30 m in the slightly deeper waters a r o u n d

a b u n d a n t remains, mostly disarticulated, as well as articulated

Rochester. T h e skeletal remains of crinoids and cystoids were

s p e c i m e n s of the trilobite genera Dalmanites and Trimerus. These

reworked and accumulated to thicknesses of up 3 or 4 m. C o n -

dark, sparsely fossiliferous shale facies, representing deeper por-

sidering that it takes about 1 5 , 0 0 0 average-sized crinoids to make

tions of the R o c h e s t e r sea, were deposited during relative rises in

1 m o f limestone, the total n u m b e r o f e c h i n o d e r m s represented

the sea level. H e r e , high rates of s e d i m e n t a t i o n c o m b i n e d with

in these beds is stunningly high ( 1 0 ' ° or even 1 0

low-oxygen c o n d i t i o n s near the substrate m a d e the b o t t o m c o n -

3

12

individuals).

These organisms flourished in shallow, relatively clean waters

ditions inhospitable for m o s t invertebrate species. Nonetheless,

associated with a m a j o r lowering of relative sea level in New York

s o m e trilobites, as scavengers, appear to have thrived in these

State. To the southeast, the Irondequoit skeletal limestone grades

e n v i r o n m e n t s . Shallower p o r t i o n s of the Rochester are repre-

first into hematitic limestone (the Kirkland F o r m a t i o n ) a n d

sented by banks of b r y o z o a n s and e c h i n o d e r m s (crinoids and the

beyond into quartzose, cross-bedded sandstones of the upper

cystoid Caryocrinites). Trilobites were less d o m i n a n t here but are

Herkimer F o r m a t i o n . A few trilobites are reported from the

represented by a greater diversity of species.

Irondequoit, including the following:

H e r k i m e r S a n d s t o n e , the eastern equivalent of the Rochester Shale, represents sandy shallow shelf to n e a r s h o r e e n v i r o n m e n t s .

Bumastus sp.

Diacalymene

Calymene sp.

Cheirurus

Liocalymene clintoni

Scutellum

sp.

It

sp.

yields

Trimerus

and

Dalmanites

specimens

and

excellently

preserved trilobite trace fossils, especially the large resting trace

rochesterense

Rusophycus. T h e paleogeographic distribution

of the trilobites

in

the

Irondequoit and its lateral equivalents, the Kirkland and Keefer

Lewiston M e m b e r is of interest. T h e trilobites east of Rochester

formations, are overlain sharply, but apparently c o n f o r m a b l y , by

are different f r o m those west of this area. Differences are at the

gray m u d s t o n e s of the Rochester F o r m a t i o n . Perhaps no Silurian

species as well as genus level. C e r t a i n genera such as Arctinurus,

unit in North America is m o r e noted for its exquisite fossils than

Decoroproetus,

the Rochester. Although m u c h of the unit is relatively sparsely

have been f o u n d o n l y in the west, while Cheirurus, Maurotarion,

fossiliferous, a total fauna of over 2 0 0 species of invertebrate

and

fossils is k n o w n from the Rochester Shale, including over 20

Dalmanites and Calymene o c c u r b o t h east and west of Rochester,

species o f trilobites. T h i n lenses o f b r a c h i o p o d - and b r y o z o a n -

but

rich m u d s t o n e s and argillaceous limestone yield prolific faunas,

Trimerus are

with over 80 species of bryozoans alone k n o w n from the middle

delphinocephalus is also f o u n d in equivalent age beds in England.

beds of the Rochester. In western New York the unit is divisible into two m e m b e r s : a fossil-rich lower half, b o u n d e d on its top by

Deiphon,

Dicranopeltis,

Staurocephalus have b e e n they

are

represented

found

in

found

Illaenoides, to

the east.

by different

both

the east

and

species.

Radnoria

T h e genera Bumastus and

and the west.

Trimerus

Rochester Shale trilobites reported f r o m western New York are as follows:

a bundle of limestone bryozoa beds and referred to as the Lewiston Member, and an upper sparsely fossiliferous, d o l o m i t i c shale

Acanthopygc

unit, the Burleigh Hill M e m b e r .

Bumastus

T h e Lewiston M e m b e r has yielded most of the diverse trilo-

Calymene

Arctinurus

sp.

boltoni

Calymene

ioxus

Cheirurus

sp.

niagarensis sp.

bite and e c h i n o d e r m faunas for which the Rochester is justifiably

Dalmanites

famous. Fossils are exceptionally well preserved, especially in beds

Decoroproetus

near the transition from a lower, highly shell-rich interval into a

Diacalymene

middle barren portion of the Lewiston and in the upper transi-

Illaenoides

tion from this sparsely fossiliferous interval to the overlying b r y -

Odontopleurid

Proetid

ozoan-rich beds. T h e s e beds c o n t a i n a n u m b e r of trilobites, s o m e

Radnoria

Staurocephalus

of them in an extraordinary state of preservation. T h e well-

Trimerus

Dalmanites

limulurus corycoeus /.

sp. pisum

Dicranopeltis

sp. cf.

Deiphon

trilobita

sp. delphinocephalus

nereus

Maurotarion

Trochurus

sp. sp. halli

known examples of the large lichid Arctinurus boltoni, as well as abundant

and

T h e R o c h e s t e r Shale seems to reflect siliciclastic muds that were

exquisite

derived from erosion of newly developed highlands to the east or

preservation of s o m e of the fossils suggests that they were buried

southeast. Initiation of this new input is represented through

Trimerus

Dalmanites delphinocephalus,

limulurus, occur

in

Calymene these

levels.

niagarensis, The

instantly by sediment plumes or turbidity currents. T h e Burleigh Hill M e m b e r consists of m e d i u m to dark gray

m u c h o f the Appalachian Basin b y the o c c u r r e n c e o f rather thick sands k n o w n as Keefer S a n d s t o n e in Pennsylvania and

shales with thin calcisiltites, especially toward the top, that grade

the H e r k i m e r S a n d s t o n e in central New York State (Figure 4 . 2 9 ) .

upward into the overlying D e C e w F o r m a t i o n . T h i s upper p o r t i o n

O t h e r circumstantial

evidence suggests

that a new pulse of

THE

90

PALEOZOIC

GEOLOGY

OF

NEW

YORK

tectonic activity o c c u r r e d a b o u t the middle part of the Silurian.

the L o c k p o r t G r o u p c o m e s to rest on the underlying crinoidal

T h i s c o m e s in the f o r m of the shifting of the depositional basin

grainstone o f the I r o n d e q u o i t .

itself. In the t i m e period represented by the W i l l i a m s o n Shale

D u r i n g the Late Silurian a vast c a r b o n a t e bank, somewhat like

to the upper part of the Rochester Shale, the area of thickest

that which existed in the C a m b r o - O r d o v i c i a n , developed o n c e

sediment a c c u m u l a t i o n , d o m i n a n t l y of shale, shifted westward

again in Laurentia. Very widespread shoals were developed from

approximately 100 km from the region of O n e i d a Lake to the area

sand- and gravel-sized skeletal pieces ( m a i n l y columnals) of

of Wayne C o u n t y . T h i s m i g r a t o r y pattern together with the

crinoids and cystoids. Under similar, high-energy environments,

increased input of coarser sediments suggests that renewed thrust

tabulate corals and s t r o m a t o p o r o i d s established reefs in the Great

faulting may have taken place in the f o r m e r T a c o n i c landmass.

Lakes area. A barrier reef c o m p l e x developed around a circular,

Possibly this is the result of new o c e a n - f l o o r s u b d u c t i o n u n d e r -

subsiding a r e a — t h e M i c h i g a n B a s i n — a n d patch reefs developed

neath the eastern margin o f N o r t h A m e r i c a (Figure 4 . 2 9 C ) .

on the tops of crinoidal skeletal shoals from Indiana, to O h i o , and

T h e Rochester Shale represents a relatively shallow but m u d d y -

into New York. M a n y such reefs or b i o h e r m s show a good suc-

b o t t o m sea that ranged upward to over a h u n d r e d meters of water

cession of pioneer thicket formers to climax c o m m u n i t i e s d o m -

depth. T h e Rochester Shale facies grades eastward to the sandy

inated by head corals and s t r o m a t o p o r o i d s . Trilobites were a

shoreline facies of the H e r k i m e r S a n d s t o n e in central New York

m i n o r b u t significant c o m p o n e n t of the reefal faunas.

and to the northwest into c a r b o n a t e banks.

T h e basal L o c k p o r t

unit, G a s p o r t

L i m e s t o n e , consists o f

T h r o u g h o u t m u c h of western New York, the R o c h e s t e r Shale

d o l o m i t i c limestones and s o m e argillaceous dolostone. M u c h o f

is overlain by a rather unusual unit in the D e C e w D o l o s t o n e . T h i s

it can be described as an e c h i n o d e r m packstone or grainstone,

unit is a thin (3 to 5 m) and u n i f o r m interval of b u f f - c o l o r e d

like the underlying I r o n d e q u o i t , that consists of disarticulated

c a r b o n a t e silt with h u m m o c k y cross-stratification. T h e result of

and c o m m o n l y abraded fragments of c r i n o i d and cystoid plates

storm deposition, the D e C e w is also highly convoluted and c o n -

and

torted and in s o m e places displays o v e r t u r n e d folds. We suggest

deposits were m o v e d by s u b m a r i n e currents. Consequently the

columnals.

Typically

these

crinoidal

sands

and

gravel

that this represents a period of seismic s h o c k ( e a r t h q u a k e ) activ-

unit shows m e d i u m - to small-scale cross-stratification (Figure

ity on the floor of the foreland basin or interior continental sea.

4 . 3 2 A ) . S o m e p o r t i o n s o f the Gasport also show bimodal cross-

T h i s effect was widespread; we have f o u n d evidence for a similar

stratification, two opposite o r i e n t a t i o n s of cross-bedding that

d e f o r m a t i o n in D e C e w age strata in central Pennsylvania and

might reflect the influence of oscillating tidal currents. T h e

southern O h i o . Because o f the rapid deposition o f the c a r b o n a t e

Gasport sediments evidently accumulated during a time of initial

silts, this is not a highly fossiliferous unit, although occasional

transgression following a m a j o r regression of seas from western

remains of s o m e fossil crinoids and the trilobite Trimerus have

New York that p r o d u c e d the u n c o n f o r m i t y beneath the unit.

been found within the unit. T h e source o f the D e C e w c a r b o n a t e

D u r i n g a t i m e of rising sea level, b u t still in e n v i r o n m e n t s of

silts and fine sands is s o m e w h a t unclear, but it probably was rep-

shallow, agitated waters, perhaps no m o r e than a few meters deep,

resented by c a r b o n a t e shoals in the f o r m of c r i n o i d gardens that

c r i n o i d banks developed extensively over m u c h of western and

existed to the northwest of the m a i n New York depositional area.

west-central New York. In the Rochester area, these banks appar-

T h e s e shoal facies e n c r o a c h e d u p o n New York d u r i n g the d e p o -

ently interfingered with quartz sand bars represented by the

sition of the succeeding L o c k p o r t G r o u p .

Penfield F o r m a t i o n . T h e s e cross-stratified dolomitic sandstone

An eastern shaly facies equivalent to the DeCew, the G l e n m a r k

units seem to reflect the input of quartzose sediment from a

Shale, yields a diverse fauna of small rugose corals, b r a c h i o p o d s ,

n o r t h e r n or northeasterly source terrain. T h e y form an elongate

and trilobite genera, including Daltnanites sp.,

shoal or barlike feature that extended southward from Rochester

Trimerus, Encrin-

urus sp., calymenid, Maurotarion sp., Cheirurus sp., and proetids.

to the subsurface of New York State. To the east of this area, in Wayne C o u n t y , the sands give way to m u d d y dolostones and d o l o m i t i c limestones, m a n y o f t h e m containing remains o f ostra-

Lockport Group T h e L o c k p o r t G r o u p is an interval over 65 m thick of pre-

cods, s o m e stromatolites, and the trilobite genera Trimerus, Caly-

d o m i n a t e l y d o l o m i t i c c a r b o n a t e rocks. However, to the east of the

mene, Encrinurus, and Maurotarion.

Rochester

Still farther to the east, these

limestones

interfinger with dark gray shale of the Ilion F o r m a t i o n . W i t h i n

interfinger with dark gray shales of the Ilion F o r m a t i o n . In the

the upper part of the Gasport F o r m a t i o n , deepening produced

central Appalachians the L o c k p o r t G r o u p is represented by a

a c h a n g e in s e d i m e n t a t i o n patterns, in western New York, to

d o m i n a n t l y dark, shaly interval with thin r i b b o n - l i k e limestones

t h i n n e r - b e d d e d , m o r e argillaceous dolostones. At the same t i m e ,

termed

small patch reefs, which had begun developing on the now-

area,

the

these

Mackenzie

dolostones

Formation.

and

The

dolomitic

Lockport

represents

a

depositional s e q u e n c e . It is b o u n d e d at its base by a m a j o r erosion

stabilized surface of the crinoidal shoals, built upward, f o r m i n g

surface that locally cuts into the D e C e w D o l o s t o n e and removes

the famed G a s p o r t reefs or b i o h e r m s (Figure 4 . 3 2 B ) . T h e s e reefs

it in areas near H a m i l t o n , O n t a r i o , where the u n c o n f o r m i t y c o n -

were built primarily of favositid corals and stromatoporoids. T h e

tinues to cut d o w n w a r d into the Rochester Shale until the base of

G a s p o r t is not particularly n o t e d for trilobites, although s o m e

FIGURE 4 . 3 1 . M i d Silurian s u c c e s s i o n s . A. Lowest light limestone l e d g e , Irondequoit L i m e s t o n e (a) is overlain by about 20 m of dark gray Rochester Shale (b). Thick layers of the L o c k p o r t G r o u p (c) protrude at the t o p of the cliff. Niagara River G o r g e , south of L e w i s t o n - Q u e e n s t o n B r i d g e , N i a g a r a County. B. Lowest rhythmic thin b e d s are Rockway Formation (a). These are sharply overlain by Irondequoit Limestone (b) b e a r i n g small b i o h e r m s ("reefs") (arrow) that protrude slightly into the overlying Rochester Shale (c). G e n e s e e River G o r g e , Rochester, Monroe County.

FIGURE 4.32. Silurian c a r b o n a t e s . A. C r o s s - b e d d e d crinoidal limestone, G a s p o r t Formation, cut along Robert M o s e s Parkway, Lewiston, N i a g a r a County. B. B i o h e r m or reef m o u n d of s t r o m a t o p o r o i d s a n d tabulate corals, Goat Island Formation, overlies t h i n - b e d d e d u p p e r G a s p o r t Formation on the right e n d of the cut. Road cut on Rte. 429, N i a g a r a e s c a r p m e n t , Pekin, N i a g a r a County.

SILURIAN

93

PERIOD

specimens of calymenids are f o u n d . An area of interfingering

dolostones are characterized by small thickets or biostromes of

(shaly)

grainstones

corals, especially c l a d o p o r i d s . T h e y represent thickets of small

occurs in the Sweden-Walker Q u a r r y at B r o c k p o r t , M o n r o e

tabulates and o t h e r corals that grew in shallow waters. S t r o m a t o -

County. This transitional facies has yielded the r e m a i n s of

poroids are also c o m m o n as isolated heads within these beds, typ-

dolostones with

Dalmanites,

Trimerus,

and

typical

another

Gasport

rare

crinoid

homalonotid

trilobite.

ically up to a foot across b u t highly altered by diagenesis. T h e s e

Also, s o m e of the b i o h e r m a l faunas have yielded f r a g m e n t a r y

beds, like the underlying G o a t Island, are typically vuggy and

remains of the calymenid, Diacalymene, and o t h e r trilobites.

c o n t a i n a b u n d a n t mineralized pockets that are well known to

T h e overlying G o a t Island F o r m a t i o n is separated in most

local mineralogists. In O n t a r i o , C a n a d a , however, the basal beds

places from the Gasport by a m i n o r u n c o n f o r m i t y . It represents

of the E r a m o s a that overlie E r a m o s a Shales and appear almost

the second cycle of shallowing, followed by deepening and the

gradational into the latter, are platy argillaceous dolostones that

development of crinoidal shoals and in places such as at B r o c k -

seem to represent s o m e w h a t m o r e offshore c a r b o n a t e a c c u m u l a -

port, the development of small patch reefs of s t r o m a t o p o r o i d s

t i o n . T h e s e basal E r a m o s a c a r b o n a t e s are n o t e d for abundant,

and corals (Figure 4 . 3 1 B ) . T h e s e reefs have m a n y features in

although m a i n l y disarticulated, trilobites. Q u a r r i e s in the vicin-

c o m m o n with the underlying G a s p o r t . However, in m a n y places,

ity o f D u n d a s , O n t a r i o , have yielded t h o u s a n d s o f specimens o f

the G o a t Island has been affected severely by late diagenetic

the otherwise rare trilobite Encrinurus raybesti, along with caly-

dolomitization, which has altered its texture and m a d e it difficult

m e n i d s , and a new d a l m a n i t i d species. T h e E r a m o s a represents

to decipher the original fossil content and o t h e r features.

a return to c o n d i t i o n s s o m e w h a t m o r e like those of the Rochester

An argillaceous d o l o s t o n e bed near the base of the G o a t

Shale, although pulses of rapid burial were rare in the E r a m o s a ;

Island, however, has yielded an e x t r a o r d i n a r y biota of s o f t - b o d i e d

hence, most

trilobites

are disarticulated.

In

New York and

organisms, particularly algae, s o m e w o r m s , and graptolites. T h i s

t h r o u g h o u t at least the eastern Niagara Peninsula of O n t a r i o , the

deposit, which L o D u c a ( 1 9 9 5 ) studied extensively, appears to rep-

upper beds of the E r a m o s a reflect an abrupt shallowing. Layers

resent an a c c u m u l a t i o n of muds in shallow waters between patch

o f stromatolites o r bacterial mat b o u n d s t o n e s were c o m m o n and

reefs in the G o a t Island F o r m a t i o n . Unfortunately, to date, it has

widespread at this t i m e . T h e s e stromatolites f o r m e d d o m a l heads

yielded few, if any, trilobite remains.

up to 2 or 3 m across and a m e t e r tall (Figure 4 . 3 3 ) . T h e s t r o m a -

T h e upper Goat Island in western New York, and particularly

tolites are generally associated with a sparse low diversity of

been

favositid corals, o s t r a c o d s , and a few species of b r a c h i o p o d s . T h e

misidentified as the E r a m o s a F o r m a t i o n . It is presently t e r m e d

i n c o m i n g of these beds appears to reflect the stress of increased

in

O n t a r i o , is

highly argillaceous and

frequently has

the Vinemount Shale Member. V i n e m o u n t Shale beds have yielded

hypersalinity in the Appalachian Basin. To the east, beds of the

several fragmentary fossil r e m a i n s , including trilobites, small

S c o n o n d o a and upper Ilion reflect these s a m e sorts of changes.

rugose corals, and b r a c h i o p o d s , although the extensive d o l o m i t i -

S t r o m a t o l i t i c limestones give way abruptly eastward to dark

zation of these argillaceous c a r b o n a t e s has o b s c u r e d m o s t of the

shales c o n t a i n i n g few n o r m a l m a r i n e o r g a n i s m s but remains o f lingulid b r a c h i o p o d s and eurypterids. T h e s e in turn pass upward

details. Near Ancaster, O n t a r i o , and locally in Niagara C o u n t y , New York, an upper portion of the G o a t Island yields white chert nodules that contain the remains of n u m e r o u s species of fossils

to the red beds of the V e r n o n F o r m a t i o n . Although not generally considered a trilobite-rich interval, the L o c k p o r t G r o u p in total has yielded the following trilobites:

in a rather g o o d state of preservation. Particularly notable are small siliceous sponges that may hint at the source for the silica of the light-colored cherts. Also, a variety of b r a c h i o p o d s and several trilobite species, including calymenids and dalmanitids, have been obtained as fragments f r o m these chert nodules. Evidently, early replacement by silica protected fossils f r o m d o l o m i tization, thereby leaving a reasonable record of these fossils.

Calymene

singularis

Calymene

Dalmanites

sp.

Diacalymene

sp.

Maurotarion

sp.

Encrinurus Proetus Scutellum

raybesti artiaxis wardi

Proetus Trimerus

sp.

tenuisulcatus delphinocephalus

Howell and Sanford ( 1 9 4 7 ) described trilobites from the G o a t Island

Formation

(formerly

misidentified

as

Oak

Orchard

M e m b e r ) in the Rochester area:

Late Silurian Salina G r o u p

Calymene Proetus

singularis artiaxis

Encrinurus

sp.

Scutellum

wardi

D u r i n g the Late Silurian, a m o r e arid climate prevailed over eastern Laurentia, and a landlocking of seas o c c u r r e d in two areas. T h e later part of the Silurian in eastern N o r t h America is

T h e Eramosa F o r m a t i o n is represented over m o s t of central and

represented by the Salina G r o u p . As the n a m e implies, these

western New York by vuggy, massive dolostones that have c o m -

deposits represent a m i x t u r e of s o m e shales and dolostones but

m o n l y been termed Oak Orchard Formation

are primarily n o t e d for evaporites. In the M i c h i g a n Basin, the

in the past. T h e s e

94

THE

PALEOZOIC

GEOLOGY

OF

NEW

YORK

FIGURE 4 . 3 3 . Domal stromatolites (arrow). Guelph Dolostone, Robert M o s e s Power Plant a c c e s s road, Lewiston, Niagara County.

barrier reef c o m p l e x restricted circulation, while in the eastern

ite beds within the Vernon reflects restriction of the Appalachian

Appalachian region, a new pulse of s e d i m e n t s eroded o f f coastal

Basin. T h e Vernon clastic sediments appear to represent a final

m o u n t a i n s . T h e V e r n o n - B l o o m s b u r g d e l t a — w a s derived f r o m

pulse of elastics derived f r o m erosion of the newly uplifted m o u n -

Salinic O r o g e n i c uplifts southeast (present directions) of New

tainous source terrain to the southeast of New York State. In

York State. T h e outward building ( p r o g r a d a t i o n ) o f the V e r n o n -

Pennsylvania, extremely thick red mudstones of the B l o o m s b u r g

B l o o m s b u r g delta

a

Shale take the place of the Vernon and seem to point to a nearby

partial barrier to o c e a n i c circulation in the n o r t h e r n Appalachian

source of m u d s and silts. North America at this time appears to

Basin of New York. T h e s e restrictive barriers prevented o p e n cir-

have lain within the subtropical desert belt, probably in paleolat-

culation to the sea and enabled salinity to build up to the p o i n t

itudes between 20 and 30° south of the equator (Figure 4 . 5 ) .

into

south-central

Pennsylvania

formed

of precipitating evaporites. A cyclic process of seawater influx

U n d e r such c i r c u m s t a n c e s , the development of a large wedge of

then evaporation enabled evaporites, such as anhydrite, g y p s u m ,

deltaic m u d s t o n e s and sandstones in the B l o o m s b u r g / V e r n o n

and halite, to a c c u m u l a t e to considerable thickness. T h e salt layer

F o r m a t i o n produced a restriction in the circulation in the n o r t h -

under Detroit, M i c h i g a n , is over 1 km thick.

ern Appalachian Basin region. T h i s restricted circulation in c o m -

T h e Upper Silurian V e r n o n F o r m a t i o n consists o f probably

b i n a t i o n with the arid climate led to the development of a

n o n m a r i n e or very shallow tidal-flat deposits of a red, rather

hypersaline seaway, probably similar in s o m e ways to the m o d e r n

massive m u d s t o n e . T h e s e beds c o n t a i n few fossils, although an

D e a d Sea. As seawater evaporated away, salt and anhydrite or

occasional interbedded d o l o s t o n e yields remains of fossil jawless,

gypsum deposits began to a c c u m u l a t e in the lower sags of the

a r m o r e d fish. Small clams and b r a c h i o p o d s also m a y be present

basin, while on the margins s o m e , at least seasonal, input of

in these beds. To the west the Vernon gives way from red m u d -

siliciclastic m u d s c o n t i n u e d .

stones to greenish gray d o l o m i t i c shales a n d d o l o s t o n e s , m a n y of

Although salt deposition o c c u r r e d within the western New

which contain evaporite crystal m o l d s . T h e V e r n o n in western

York/Genesee Valley region during deposition of the Vernon

New York is probably m o s t n o t e d as the source of key salt beds

Shales at the base of the Salina G r o u p , the locus of salt deposi-

that have been m i n e d for m a n y decades at the R e t s o f M i n e s in

tion

the area of the Genesee Valley. T h e a p p e a r a n c e of these evapor-

the Salina G r o u p sediments. T h i s eastward shifting also may

shifted progressively eastward during the deposition

of

DEVONIAN

PERIOD

have been associated with the m i n o r uplift of the old Vernon/

95 position (Figure 4 . 3 6 A ) . O n l y a few species of normal marine

B l o o m s b u r g deltaic land above sea level, which p r o d u c e d an e r o -

fossils are f o u n d within parts of the Bertie. T h e y include lingulid

sional beveling of Late to Middle Silurian sediments in areas east

b r a c h i o p o d s , a few o t h e r species of articulate b r a c h i o p o d s , and

of Utica, O n e i d a County. A large salt depositional basin existed

a

in the central region of the Finger Lakes and eventually in the

cephalopods).

classic Syracuse area. T h e s e deposits, the Syracuse F o r m a t i o n ,

e n o u g h that n o r m a l m a r i n e c o m m u n i t i e s still were not estab-

take their n a m e from that city. T h e f o r m a t i o n consists of thin-

lished in the offshore areas.

few

species

of

mollusks

(snails,

clams,

and

orthoconic

Evidently, salinity remained high and variable

bedded dolostones and shales and in places thick a c c u m u l a t i o n s

A new, unusual trilobite, apparently a lichid, was recently

of anhydrite or salt. Although the remains of n o r m a l m a r i n e

collected f r o m the e u r y p t e r i d - b e a r i n g waterlimes in Fort Erie,

organisms are u n c o m m o n within these beds, there are stray

O n t a r i o , near Buffalo. On the whole t h o u g h , these beds reflect

reports o f s o m e b r a c h i o p o d s and even o f o n e o c c u r r e n c e o f a

unusual hypersaline c o n d i t i o n s , and trilobites are very rare.

trilobite, a calymenid, within the Syracuse F o r m a t i o n in the Syra-

However, finally within the latest part of the Silurian, normal

cuse area. O t h e r w i s e , c o n d i t i o n s generally were far t o o harsh,

m a r i n e c o n d i t i o n s returned over New York, Pennsylvania, and

owing to the elevated salinity, to s u p p o r t n o r m a l m a r i n e c o m -

m u c h o f the Appalachian Basin. T h e Keyser F o r m a t i o n o f Penn-

munities, and most o f the beds o f the Salina G r o u p are barren o f

sylvania and the laterally equivalent R o n d o u t G r o u p and Decker

fossils. M o r e diverse m a r i n e fossils, including c a l y m e n i d trilo-

F o r m a t i o n in New York State c o n t a i n a far m o r e diverse assem-

bites, are k n o w n from the laterally equivalent Tonoloway F o r m a -

blage of m a r i n e fossils than do the underlying Bertie and Salina

tion in Pennsylvania, M a r y l a n d , and West Virginia.

beds. At least d u r i n g times of the deposition of the R o n d o u t ,

Salina deposition was terminated by the a c c u m u l a t i o n of the

shallow marine c o n d i t i o n s rather akin to those that developed

Camillus F o r m a t i o n , a relatively thick interval of m o t t l e d gray to

during the L o c k p o r t deposition existed over p o r t i o n s of eastern

slightly reddish barren shales with salt crystal molds and s o m e

and central New York State. At times, units such as the Cobleskill

dolostones, c o m m o n l y with molds of small gypsum or anhydrite

L i m e s t o n e a c c u m u l a t e d with a b u n d a n t c r i n o i d , coral, s t r o m a t o -

lathlike crystals. Not surprisingly, the Camillus is nearly barren of

poroid, and o t h e r remains. Trilobites are scarce but are repre-

fossils. It too has served as a source for e c o n o m i c a l l y i m p o r t a n t

sented

gypsum deposits in western New York.

camerata,

Hedstroemia

Dalmanites

aspinosus.

Bertie D o l o s t o n e and R o n d o u t G r o u p During the very late phases of Silurian deposition in New York

by

a

fair

diversity

of species

pachydermata, In

such

Richtcrarges

Pennsylvania

the

as

the

Calymene

ptyonurus,

laterally

and

equivalent

Keyser F o r m a t i o n c o n t a i n s small reef buildups of corals and strom a t o p o r o i d s and o t h e r shaly beds, rather reminiscent of the

State, the Bertie G r o u p sediments a c c u m u l a t e d . T h e Bertie is an

m u c h older Rochester Shale, that c o n t a i n diverse bryozoan and

unusual rock unit that consists of argillaceous, b u f f - c o l o r e d d o l o -

b r a c h i o p o d faunas and a b u n d a n t , well-preserved cystoids. Again,

stone, referred to in the past as waterlimes because of their p r o p -

s o m e trilobites are reported f r o m these Keyser beds. Preservation

erty as natural cement r o c k s , yielding c e m e n t s , which hardened

within the Keyser ranges f r o m disarticulated to exquisite arti-

underwater. T h e Bertie, as with the underlying Salina G r o u p , c o n -

culated remains. T h u s , the last chapter of Silurian m a r i n e de-

tains m u c h evidence for deposition at or near sea level. W i t h i n

position records a b r e a k d o w n of barriers to n o r m a l marine

the f o r m a t i o n are beds of low d o m a l stromatolites, extensive

circulation, as well as possible climatic changes from the m o r e

layers of fine, m u d - c r a c k e d d o l o s t o n e , gypsum crystal m o l d s ,

arid c o n d i t i o n s that characterized deposition of the Salina and

very shallow water ripples, and o t h e r evidence for deposition in

Bertie

a restricted tidal flat to shallow lagoonal setting. T h e Bertie is

Appalachian Basin, so t o o did n o r m a l m a r i n e representatives,

most noted for its extraordinary eurypterids at certain horizons.

which must have i m m i g r a t e d in f r o m outside the basin.

Groups.

As

normal

marine

seas

returned

to

the

T h e e n v i r o n m e n t of these interesting c h e l i c e r a t e a r t h r o p o d s is still debatable. Although they are often preserved in rocks that contain evidence for hypersalinity, such as salt crystal casts, the

Devonian Period

eurypterids probably did not live under these highly saline c o n -

T h e Devonian Period ( 4 1 5 to 3 6 0 million years ago) was

ditions. Rather, the local heavy a c c u m u l a t i o n s of carcasses of

relatively long, with m a n y i m p o r t a n t events in Earth and life

these animals probably represent dead remains that were washed

history (Figure 4 . 1 ) . M a j o r orogenies took place in Europe (end

out from estuaries that fed into the m o r e saline Bertie sea; c a r -

of C a l e d o n i a n ) , eastern N o r t h A m e r i c a ( A c a d i a n ) , and for the

casses were rapidly buried in briney sediments. T h e a p p e a r a n c e

first t i m e in the P h a n e r o z o i c , western North America (Antler

of small land plants, s o m e of the oldest k n o w n in the world, along

O r o g e n y ) (Figure 4 . 3 4 ) . M u c h o f the Devonian was characterized

with the eurypterids suggests that these sediments a c c u m u l a t e d

by w a r m , " g r e e n h o u s e " - t y p e climates and a strong tendency for

in very close proximity to low-lying lands of the upper tidal flats

stagnation in deeper sea e n v i r o n m e n t s , leading to the f o r m a -

and probably in small estuaries that e m a n a t e d o f f the exposed

tion of very widespread a n o x i c (oxygen-deprived) black shale

land that were, at least periodically, brackish water in their c o m -

deposits (Figure 4 . 3 5 ) . However, toward the end of the period

96

THE

PALEOZOIC

GEOLOGY

OF

NEW

YORK

FIGURE 4.34. C o m p o s i t e stratigraphic chart for the northern a n d central parts of the A p p a l a c h i a n Basin, s h o w i n g the depositional s e q u e n c e s a n d their relationship to t e c t o p h a s e s . From Ettensohn (1987), © 1987 by the University of C h i c a g o . All rights r e s e r v e d . R e p r o d u c e d with p e r m i s s i o n . there is evidence for climatic stress associated with renewed

lying Tristates groups, including the m o r e offshore facies, are c o n -

glaciation in G o n d w a n a (especially S o u t h A m e r i c a ) .

fined to the Hudson River Valley and probably o n c e extended northeastward into New England and Q u e b e c .

Early Devonian T h e Lower D e v o n i a n rocks of New York State are represented primarily by the Helderberg a n d Tristates G r o u p s . T h e final,

Late Early Devonian H e l d e r b e r g Facies and Trilobites

regressive phases of Sloss's T i p p e c a n o e (Tutelo phase) Superse-

T h e lowest unit of the Helderberg G r o u p is the T h a c h e r

quence are recorded in the Helderberg c a r b o n a t e s of eastern New

M e m b e r o f the M a n l i u s F o r m a t i o n (Figure 4 . 3 5 C ) . However, the

York and Pennsylvania (Figure 4 . 3 5 ) . T h e Helderberg G r o u p is

M a n l i u s facies are distinctly d i a c h r o n o u s , being younger in the

a series of limestones and m i n o r shales that c r o p out in central

area near Syracuse, New York, than in the Hudson Valley and

to eastern New York State. O u t s t a n d i n g exposures of these rocks

equivalent in age to the C o e y m a n s or even Kalkberg F o r m a t i o n s

are cuts along Rte. 1-88 in the S c h o h a r i e Valley, and a n u m b e r of

in the H u d s o n Valley. T h e M a n l i u s is considered to be close to the

quarries and road cuts from the area of Albany, at the Helderberg

S i l u r i a n - D e v o n i a n b o u n d a r y (Rickard 1 9 7 5 , 1 9 8 1 ; K l a p p e r 1 9 8 1 ) .

E s c a r p m e n t , southward to the state line at Port Jervis, O r a n g e County.

T h e M a n l i u s F o r m a t i o n bears m a n y resemblances to the O r d o v i c i a n Black River G r o u p . B o t h intervals contain a series of

It should be noted that d u r i n g Helderberg deposition, the axis

peritidal to very shallow subtidal facies. T h e Manlius represents

(deepest part) of the Appalachian Basin was at a position s u b -

the belt of low-energy but very shallow lagoonal to tidal-fiat envi-

stantially farther east than d u r i n g Silurian or later Devonian

r o n m e n t s that were sheltered to shoreward by offshore shoals and

t i m e . T h e basin axis appears to have shifted eastward d u r i n g a

bars. T h i s suite o f e n v i r o n m e n t s has been called the " Z " zone

t i m e of tectonic quiescence b e g i n n i n g in the late part of the

(Irwin 1 9 6 5 ) . T h e s e facies typically are arranged in 1- to 3 - m

Silurian, and to have been in a position east of the H u d s o n Valley

scale, shallowing-upward cycles referred to as punctuated aggra-

extending northeastward into New England at this p o i n t in Early

dational cycles (PACs)

D e v o n i a n t i m e . For this reason, m o s t of the Helderberg and over-

cyclic facies are typical of the older T h a c h e r M e m b e r of the

( G o o d w i n and Anderson

1 9 8 5 ) . Such

I Acadian O r o g e n y - Collision of Avalon and P r o t o North A m e r i c a

<- N Y - t

Auburn

Syracuse

Richfield Springs

L'Qca

Schoharie

Albany

CauJall

Legend DolomuK f»c*» •J Mienoc hoes ^| Bujirroroe [iciei

,

Skfieal pKluwn* piuwone ficies £3 fKaam-caiarwau wale ton Sh»kr *«c*«kdi» tam A

g ? l B«6tm>

—

— i

:

A

'' .

•

- L

~~

**

~"-i

= ^ Roodout

. ^ 1 ^ 5

* ""'

— ~

,

• = ~— -

a

l

r

" - ^ ^ Kalkberg^-'

-

- * » i i p j ^ - ^ - ^ g = = jf

-

^.PonJ-wcn

~ - ^ - ^ ^ " ^ " ^ F ^ Sevi

Scotland-j

.

^^^^^^^^^^^^^^^^^

tr~3

FIGURE 4.35. New York d u r i n g the Early D e v o n i a n . A. M a p of the state d u r i n g this time. B. Cross section of the A c a d i a n Orogeny. C. Stratigraphic chart of the Early D e v o n i a n . B, C from Isachson et al. (1991). Printed with permission from the New York State M u s e u m , Albany, N.Y

THE

98 Manlius in the H u d s o n Valley. T h e typical M a n l i u s cycle begins

PALEOZOIC

GEOLOGY

OF

NEW

YORK

Jerusalem Hill area, H e r k i m e r C o u n t y , just east of Utica, Dal-

with s o m e w h a t nodular, m e d i u m gray, b i o t u r b a t e d l i m e s t o n e ,

manites

c o m m o n l y with

tabu-

material is disarticulated, although rare articulated specimens are

late corals. Fragments of a variety of o t h e r fossils, including gas-

k n o w n . T h e Ravenna M e m b e r represents a high-energy shoal

t r o p o d s , nautiloids, s o m e b r a c h i o p o d s , and ostracodes, may be

e n v i r o n m e n t , c o m p a r a b l e in m a n y ways to the older Silurian

present. Such beds may be transitional into thin platy limestones

Gasport F o r m a t i o n , Irondequoit L i m e s t o n e , or other similar

that often have been referred to as " r i b b o n l i m e s t o n e s " and may

units. In the traditional m o d e l of X, Y, and Z zones (a low-,

contain rather well-preserved fossils on s o m e bedding planes. For

high-, low-energy profile) associated with an offshore shoal, the

example,

C o e y m a n s represents Y-zone (high-energy) facies. As such, it

a b u n d a n t s t r o m a t o p o r o i d s and

famous

outcrops

near

Litchfield,

some

New York,

have

litchfieldensis

and

Odontochile

micrurus

are

found.

Most

yielded bedding planes with a b u n d a n t well-preserved crinoids

is t h o u g h t that the C o e y m a n s shoal-like e n v i r o n m e n t s sheltered

and s o m e cystoids ( G o l d r i n g 1 9 2 3 ) . Trilobites, o t h e r than Odon-

the low-energy belt in which Manlius fine-grained carbonates

tochile micrurus, tend to be very rare in these facies. Shallower

a c c u m u l a t e d in a series of low-energy lagoons and tidal flats.

water p o r t i o n s of the M a n l i u s consist of planar to wavy laminated

T h e C o e y m a n s grainstone grades upward into the Kalkberg

micritic limestones that display a regular, even slightly wavy l a m -

and New Scotland shaly limestones. T h e s e intervals are typically

ination. A regular alternation of thicker coarser and finer t h i n n e r

c o m p o s e d of finer-grained c a r b o n a t e muds and silts, with s o m e

laminae suggests that they have a c c u m u l a t e d under the influence

thin shaly intervals. Fossils are moderately to highly abundant,

of tidal currents. T h e waviness of l a m i n a t i o n within these facies

although typically not m a k i n g up the m a j o r c o m p o n e n t of these

suggests that thin bacterial mats m a y be responsible for s o m e of

rocks, in contrast to the C o e y m a n s skeletal limestone. T h e lower

the trapping of sediment deposited f r o m e b b i n g tidal currents.

Kalkberg ( H a n n a c r o i x ) M e m b e r is typified by a series of black

H e n c e , these l a m i n a t i o n s are s o m e t i m e referred to as " c r y p t a l g a l "

chert beds, each a b o u t 10 cm thick, which have been traced later-

or tidal laminites. T h i s facies is generally sparsely fossiliferous.

ally in the H u d s o n Valley. T h e unit is notable for a fauna of b r a -

However, occasional thin layers or b e d d i n g planes, s o m e repre-

c h i o p o d s , b r y o z o a n s , and p e l m a t o z o a n fragments. T h e upper

senting hard grounds (early c e m e n t e d seafloors), do display small

Kalkberg and p o r t i o n s of the New Scotland are typically s o m e -

fossils such as ostracodes, Tentaculites, m i n o r b r y o z o a n s , small

what darker gray, shaly limestones that display a banded appear-

bivalves, and edrioasteroids. Again trilobites tend to be very rare

ance o f alternating 2 0 - t o 3 0 - c m - t h i c k , b u f f and gray bands. T h e

in these facies.

b u f f b a n d s are s o m e w h a t d o l o m i t i c limestones, typically rich in

Finally, the shallowest facies of the M a n l i u s c o m p r i s e thinly

b r a c h i o p o d shells, whereas the darker gray bands are c o m p o s e d

bedded, s o m e t i m e s shaly d o l o m i t i c limestones, often with m a j o r

of shale, often with a b u n d a n t fossil fragments and s o m e m i n o r

desiccation cracks that may e x t e n d d o w n w a r d into the rock,

phosphatic pebbles. Beds of w i n n o w e d skeletal hash in the Kalk-

f o r m i n g polygonal prismatic c o l u m n s as m u c h as 5 0 c m into the

berg, however, suggest the influence of storm-wave deposition at

section

times.

(Figure

4.36A).

These

mudcracked

facies

represent

supratidal e n v i r o n m e n t s ( a c c u m u l a t i o n above m e a n high-tide level).

T h e New Scotland shaly limestone appears to represent a c u l m i n a t i o n of a deepening cycle. T h e New Scotland may be

T h e M a n l i u s F o r m a t i o n extends the farthest west o f any o f

c o m p a r e d in s o m e ways to the older Rochester Shale facies in

the Helderberg units, being f o u n d in considerable thickness in the

the Silurian. Like the R o c h e s t e r it represents an area close to the

vicinity of Syracuse and extending as a thin feather edge westward

lower effects of s t o r m waves ( c o m m o n l y referred to in the Irwin

to Cayuga Lake. However, p o r t i o n s of the M a n l i u s are probably

M o d e l of facies as the "X z o n e " ) . T h e New Scotland is a calcare-

age equivalent to s o m e of the middle p o r t i o n of the Helderberg

ous m u d s t o n e and argillaceous limestone. It is highly fossilifer-

G r o u p farther east. T h e upper M a n l i u s Olney, Jamesville, and

ous in s o m e beds and m o r e sparsely fossiliferous elsewhere. T h e

Pools B r o o k m e m b e r s in the Syracuse area are the shallow-water

New Scotland is rich in b r a c h i o p o d s , bryozoans, and mollusks

equivalents of the middle Helderberg beds and represent a m a r -

and carries a fairly diversified trilobite fauna. In c o m m o n with

ginal m a r i n e , c a r b o n a t e m u d - f l a t to lagoonal e n v i r o n m e n t that

the Silurian R o c h e s t e r Shale, these deeper-water facies in the D e v o n i a n appear to be d o m i n a t e d by dalmanitid trilobites such

existed on the northwest side of the Appalachian Basin. In the Hudson Valley and S c h o h a r i e regions, the M a n l i u s is

as

Dalmanites

pleuroptyx,

Neoprobilium

nasutus,

and

N.

tridens.

sharply overlain by the C o e y m a n s ( R a v e n n a ) M e m b e r . To the

A m o r e c o m p l e t e listing of the K a l k b e r g - N e w Scotland trilobites

west, C o e y m a n s appears to intertongue and grade into M a n l i u s

is as follows:

facies in the vicinity of Herkimer, H e r k i m e r C o u n t y , or Utica. T h e Ravenna

Member

is

best

developed

in

the

Hudson

Valley

and consists o f rather coarse-grained skeletal limestone c o m -

Acanthopyge

posed m a i n l y o f ossicles o f crinoids and the unusual cystoid

Dalmanites

Lepocrinites.

It

also

contains

pentamerid brachiopods

the

remains

of

(Lobopyge)

Cordania

cyclurus

consanquinea

robust

shelled

Gerastos

(Gypidida), b u t few trilobites.

In the

Kettneraspis

pleuroptyx protuberans sp.

Dicranurus

hamatus

Kettneraspis

tuberculata

Neoprobilium

nasutus

FIGURE 4.36. U p p e r Silurian/Lower Devonian rocks. A. M u d c r a c k p o l y g o n s in the U p p e r Silurian Salina G r o u p (Wills Creek Formation), near C u m b e r l a n d , M a r y l a n d . B. Lower D e v o n i a n , u p p e r H e l d e r b e r g G r o u p . Lowest white b e d s are Becraft crinoidal limestone (a). These are overlain by m e d i u m gray Alsen Formation (b) a n d the latter, by dark to light gray Port Ewen Formation (c). Note the anticline (fold) f o r m e d d u r i n g the A c a d i a n Orogeny. Rte. 199 north of Kingston, Ulster County.

100

THE

Neoprobiliutn tridens

Oinochoe

Oinochoe pustulosus Scutellum

Paciphacops

from

bigsbyi

PALEOZOIC

overlying

Kaskaskia

GEOLOGY

OF

Supersequence.

NEW

YORK

T h e higher Lower

D e v o n i a n strata are assigned to the Tristates G r o u p and c o m -

logani

prise quartzose sandstones, dark gray mudstones and inter-

pompilius

bedded calcareous m u d s t o n e s , and silty argillaceous siltstones T h e top of the New Scotland is m a r k e d by the abrupt return

(Rickard 1 9 6 2 , 1 9 7 5 ) . T h e early phase of sea-level rise resulted in

to shallower-water facies. T h e unit is overlain by pinkish gray

deposition of basal transgressive quartz sandstones (Oriskany)

crinoidal grainstone referred to as the Becraft Limestone. T h i s unit

analogous

bears s o m e resemblance to the older C o e y m a n s F o r m a t i o n , al-

4 . 1 ) — t h e Oriskany sandstones and equivalent limestones, an

though it is a m o r e thoroughly crystalline (well-washed c r i n o i d

o r t h o q u a r t z i t e - c a r b o n a t e s u i t e — b u t these give way to mixed

g r a i n s t o n e ) , pinkish gray l i m e s t o n e , typically with green shale

shales and c a r b o n a t e s .

partings near the base. T h e unit also is c o m p o s e d mainly of crinoidal fragments including the strange, disk-shaped shields,

to

Potsdam

(Sauk

S o m e uncertainties remain

Supersequence;

see

Figure

about the positions o f conti-

nents. G o n d w a n a l a n d was apparently getting close to E u r a m e r -

referred to as Aspidocrinus, which are t h o u g h t to be a type of h o l d -

ica. Laurentia still sat on the paleoequator, though it had rotated

fast or a t t a c h m e n t structure of crinoids. T h e b r a c h i o p o d Gypidula

slightly f r o m its earlier position. T h e present east side was south

occurs in this unit, as it does in the C o e y m a n s , although is repre-

of the equator, the northwest in the d o l d r u m s , while Alaska and

sented by a different species. T h e Becraft represents the return of

Arctic C a n a d a developed reefs and evaporites in the northern

shallow, high-energy shoal c o n d i t i o n s . T h e s e e n v i r o n m e n t s do not

subtropics.

appear to have been highly favorable to the growth or preservation of trilobites; very few have been reported f r o m this unit.

In

Europe

the

Caledonian

Orogeny continued

from

the

Silurian and caused m a j o r folding and thrusting in Scandinavia

T h e Becraft L i m e s t o n e is followed by a succession of rocks

and parts of n o r t h e r n Britain. A m a j o r t h e m e for eastern North

that closely m i m i c s that seen in the C o e y m a n s - K a l k b e r g - N e w

A m e r i c a involved the convergence of the s u b c o n t i n e n t of Avalo-

Scotland succession

Helderberg

nia with Laurentia, to p r o d u c e the Acadian O r o g e n y in a series of

G r o u p . T h u s , the Becraft is directly overlain by a s o m e w h a t

o f the lower p o r t i o n o f the

three or four t e c t o p h a s e s (tectonic episodes); each follows a

cherty, fine-grained, buff- and g r a y - b a n d e d l i m e s t o n e , the Alsen

similar pattern (Figures 4 . 3 3 and 4 . 5 D ) .

F o r m a t i o n that strongly resembles the older Kalkberg. T h i s layer

S o m e of the first activity occurs in the Northeast, even during

is followed, in t u r n , by an analog of the New S c o t l a n d , referred

the Helderberg times. T h i n ash beds have been reported in the

to as Port Ewen F o r m a t i o n . T h e Port Ewen is b r o w n i s h gray

Kalkberg, and o n e in particular ( t h e Bald Hill b e n t o n i t e ) in

weathering with distinctive white, podlike, c o n c r e t i o n a r y l i m e -

C h e r r y Valley, O t s e g o C o u n t y , has been dated at approximately

stone layers. T h e s e layers s o m e w h a t resemble the bands of the

4 1 7 million years b e f o r e present. T h e s e ash beds indicate that vol-

New Scotland but are m o r e distinctly lenticular in f o r m . T h e y

c a n i s m was o n g o i n g during the deposition of the Helderberg

appear to represent b u r r o w e d l i m e s t o n e that has u n d e r g o n e

G r o u p . Indeed, in n o r t h e r n M a i n e and the M a r i t i m e Provinces,

s o m e alteration during c o m p a c t i o n and c e m e n t i n g of the sedi-

Helderberg-age

m e n t . T h e Port Ewen and Alsen units also c o n t a i n m u c h the s a m e

developed. However, the first m a j o r effect in the New Y o r k - P e n n -

fauna

sylvania area is reflected by the development of the Tristates

as

the

Kalkberg-New

Scotland

succession,

including

familiar bryozoans, b r a c h i o p o d s , and the d a l m a n i t i d trilobites.

(Lower

Devonian)

volcanics

are

rather well

Group.

However, the latter are less c o m m o n in the Port Ewen than in the

Avalonia attached to the outer side of Laurentia through a

New Scotland. Overall, the Port Ewen c o n t a i n s a substantial

suture or line of c o n t a c t , in central England (southern England

a m o u n t of sparsely fossiliferous, although

heavily b u r r o w e d ,

muddy limestone and calcareous m u d s t o n e .

is part of Avalonia, Scotland is part of Laurentia), producing the Acadian O r o g e n y (Figure 4 . 5 ) . Eastern Newfoundland (Avalon

T h e highest unit of the Helderberg G r o u p , the Port Jervis F o r -

Peninsula) was welded to western Newfoundland, and the eastern

m a t i o n , is only exposed in a n a r r o w region of southeastern New

Massachusetts area was added to Laurentia. Effects of the Acadian

York near the state line at Port Jervis, and in a small isolated

O r o g e n y are evident t h r o u g h o u t New England and the M a r i t i m e

o u t c r o p belt referred to as the Skunnemunk Outlier. Port Jervis is

Provinces; s u b d u c t i o n of the Avalonian plate westward under the

somewhat argillaceous l i m e s t o n e , similar to the New S c o t l a n d ,

old T a c o n i c land of New England created a new m a g m a t i c arc

but it is noted particularly for an a b u n d a n c e of trilobites. Indeed,

(Figure 4 . 3 5 B ) . M a n y o f the granite and gneiss d o m e s o f New

a landmark in the Port Jervis area is called " T r i l o b i t e M o u n t a i n , "

H a m p s h i r e ( t h e " G r a n i t e S t a t e " ) , as well as those of the Acadia

n a m e d for the a b u n d a n c e of the large d a l m a n i t i d trilobites Pha-

National Park area in M a i n e ( f r o m w h e n c e the t e r m Acadian),

langocephalus dentatus

were f o r m e d in the D e v o n i a n . S e d i m e n t s of basins associated

found

within

this

unit.

with the m a g m a t i c arc in New England were heavily folded, Acadian O r o g e n y

thrusted, and m e t a m o r p h o s e d at high grade.

T h e m a j o r Wallbridge U n c o n f o r m i t y truncates the Helder-

T h e Acadian fold and thrust belt propagated from east to west,

berg strata westward from the Hudson Valley and separates t h e m

owing to the collisional c o m p r e s s i o n , reaching as far west as the

DEVONIAN

101

PERIOD

Hudson Valley region of eastern New York. T h e H u d s o n Valley

glass-making sand because of the purity of its quartz content.

fold and thrust belt is evident along the thruway between Albany

In these areas, the unit frequently exceeds 30 m in thickness and

and Kingston, Ulster County. Farther west, a foreland basin devel-

may hold up ridges in the Valley and Ridge sector of the Appala-

oped and then migrated westward in response to episodes of

chians because of its resistance to erosion. T h e Oriskany itself

thrust loading back to the east.

generally lacks trilobites b u t c o n t a i n s large robust shelled b r a -

As noted, the Acadian O r o g e n y involved a series of pulses or

c h i o p o d s , such as Costispirifer arenosus, the large circular orthid

tectophases; each shows a similar pattern: ( 1 ) quartz sandstone

Hipparionyx, and the terabratulid Rensselaeria. A thin remnant of

and limestone to (2) dark shales to gray m u d s t o n e s and (3) sand-

the O r i s k a n y S a n d s t o n e near Cayuga Lake also has yielded a b u n -

stones including red beds. T h e s a n d s t o n e - l i m e s t o n e succession

dant s p e c i m e n s of favositid corals and s o m e large Naticonema

reflects tectonic quiescence. T h e sudden switch to black shale

gastropods but few, if any, trilobites. To the southeast, in the

(flysch) records an abrupt pulsed subsidence in the foreland

Hudson Valley region, the O r i s k a n y grades into a sandy to silty

basin, and the sandstone and red beds ( m o l a s s e ) represent the

limestone referred

filling of the basin with clastic sediments.

to as the Glenerie Limestone.

In contrast to the Oriskany, the G l e n e r i e was deposited in

Tectophase I of Early Devonian age is seen primarily in

e n v i r o n m e n t s similar perhaps to those of the Kalkberg or Alsen

the n o r t h . T h e Tristates G r o u p shows an upward c h a n g e f r o m

F o r m a t i o n that were extremely favorable to a diversity of species;

orthoquartizes and limestone ( O r i s k a n y - G l e n e r i e ) through black

the unit even displays c h e r t beds similar to those in the latter

shales with K-bentonites (Esopus S h a l e ) , shallowing upward to

units. Evidence for s t o r m waves is a b u n d a n t in the Glenerie in

siltstones and sandstones and then a shift to c a r b o n a t e - s h a l e

the form of a b u n d a n t s t o r m hash layers or c o q u i n a s of shells and

(Upper Esopus S h a l e - S c h o h a r i e F o r m a t i o n ) .

fragments of trilobites. T h e Glenerie is highly fossiliferous, c o n taining an a b u n d a n t , diverse fauna of b r a c h i o p o d s , snails, and trilobites. Again, large d a l m a n i t i d trilobites appear to be a m o n g

Tristates G r o u p T h e Oriskany Sandstone appears to represent nearshore sand

the m o r e c o m m o n e l e m e n t s within this unit.

that was reworked from older sandstones and redeposited during

It s h o u l d be n o t e d that the trilobite fauna, although a n a l o -

a m a j o r rise in sea level that followed a p o s t - H e l d e r b e r g regres-

gous in s o m e ways to that f o u n d in the Kalkberg and Alsen, is

sion of seas. Erosion that preceded the Oriskany beveled the

quite distinct at a generic level from Helderberg faunas. A m a j o r

Helderberg units successively to the west, such that m o v i n g west-

faunal event separates the Helderberg faunas f r o m those of

ward from the vicinity of Catskill, G r e e n e C o u n t y , the Post Ewen,

the overlying Oriskany. T h i s faunal event very likely is associated

Alsen, Becraft, New Scotland, Kalkberg, and finally the C o e y m a n s

with the m a j o r sea-level d r o p that created the m a j o r post-Helder-

and Manlius f o r m a t i o n s underlie the Wallbridge U n c o n f o r m i t y

berg erosion surface or s e q u e n c e b o u n d a r y that underlies the

and are overlain by Oriskany S a n d s t o n e . T h e sands probably

Oriskany and Glenerie F o r m a t i o n s . Glenerie trilobites include the

accumulated in a very shallow, high-energy beach and offshore

following:

sandbar type of e n v i r o n m e n t . This e n v i r o n m e n t was conducive to the growth of abundant large b r a c h i o p o d s and even s o m e

Cordania

corals but does not appear to have been favorable to trilobites.

Homalonotus

During Oriskany t i m e , waves m u s t have broken

Paciphacops

near shore

and produced pile-ups of clean, rather well-rounded quartz sand

Synphoria

that ultimately were c e m e n t e d to f o r m the Oriskany S a n d s t o n e .

Synphoria

T h e " X Y Z " ( l o w - t o - h i g h - t o - l o w - e n e r g y ) pattern typical o f the

becraftensis major clarkei sopita stemmata

Dalmanites

bisigmatus

Odontochile

phacoptyx

Phacopina?

correlator

Synphoria

stemmata

Trimerus

vanuxemi

compacta

stemmata

Helderberg G r o u p appears to have been broken down at this time, such that no low-energy, nearshore tidal-flat deposits are

T h e Glenerie and O r i s k a n y are abruptly overlain by a dark

known. Offshore the sandbars appear to have graded into subti-

shale and m u d s t o n e unit up to 100 m thick in p o r t i o n s of the

dal, below-wave-base a c c u m u l a t i o n s of finer-grained sandy/silty

H u d s o n Valley and in the S k u n n e m u n k Outlier. T h i s unit, the

muds and lime muds that form the Glenerie L i m e s t o n e .

Esopus Shale, represents a m a j o r influx of siliciclastic muds

T h e Oriskany forms the base of the Tristates G r o u p and in

and silts that followed the rather clean sands and limestones of

New York State is a generally thin, clean quartz sandstone, rarely

the Oriskany and G l e n e r i e t i m e s . T h e o c c u r r e n c e o f thin but

exceeding 2 m in thickness. In m a n y areas of central New York,

widespread b e n t o n i t e beds in the base of the unit suggests that

the only remnant of the Tristates G r o u p consists of thin stringers

the Esopus is associated with a pulse of t e c t o n i s m that has been

of Oriskany quartz sand, s o m e of which extend downward as

referred to as the first m a j o r tectophase of the Acadian Orogeny.

m u c h as 50 cm as pipes or cavity fillings into the underlying eroded carbonates.

The

Esopus, for all

its

thickness

in

the

Hudson Valley

( > 1 0 0 m ) , appears to thin abruptly westward to a feather edge

T h e Oriskany Sandstone thickens t r e m e n d o u s l y in southern

west of C h e r r y Valley. It is apparent that a deep but rather local-

Pennsylvania and M a r y l a n d , where it c o m m o n l y is m i n e d as a

ized basin in the eastern New York and eastern Pennsylvania

102

THE

PALEOZOIC

GEOLOGY

OF

NEW

YORK

regions served as a sediment trap for the fine-grained m u d s and

m o r e calcareous and s o m e t i m e s c o n t a i n fairly abundant fossils.

silts that were being deposited o f f eroding m o u n t a i n s to the

However, the fossiliferous nature of the Schoharie is masked in

southeast or east. T h i s basin was created by the crustal b e n d i n g

m a n y o u t c r o p s by p r o m i n e n t slaty cleavage that was probably

forces produced in turn by the loading of thrust sheets as a result

developed during the later phases of the Acadian (Devonian)

o f m o u n t a i n - b u i l d i n g activity.

m o u n t a i n - b u i l d i n g episodes. Cleavage crosscuts bedding, m a k -

T h e Esopus F o r m a t i o n represents deep-water dysoxic envi-

ing collecting from the unit very difficult.

r o n m e n t s . At times the b o t t o m b e c a m e sufficiently well oxy-

A curious feature of the S c h o h a r i e is its absence in the central

genated that it was inhabited by a great a b u n d a n c e of w o r m l i k e

p o r t i o n of New York and the presence of deposits of this latest

animals

Zoophycos.

Early Devonian age b o t h east and west of the region centered on

Portions of the Esopus F o r m a t i o n are so very heavily c h u r n e d by

that

produced

the

distinctive

trace

fossil

Cayuga Lake. Recent work suggested that this may have been the

this swirly trace that in the early days of New York geology, the

result of arching of the seafloor that took place during late Early

unit was s o m e t i m e s referred to as the Cauda-galli or "roostertaiF'

D e v o n i a n t i m e , perhaps in response to the thrust loading that

grits. Relatively low oxygen, high turbidity, and possible sediment

o c c u r r e d in the Tristates tectophase of the Acadian Orogeny

trace-making/sediment-feeding

(Ver Straeten and Brett 2 0 0 0 ) . In areas west of Syracuse, the entire

worms apparently m a d e the Esopus a fairly inhospitable envi-

instability

produced

by

these

Tristates G r o u p , except for scattered thin stringers of Oriskany

r o n m e n t for m o s t shelly o r g a n i s m s . As s u c h , the unit is only very

S a n d s t o n e , has been removed at the Wallbridge Unconformity.

sparsely fossiliferous. A few layers do c o n t a i n assemblages of

W h e r e Lower D e v o n i a n strata are absent, the O n o n d a g a F o r m a -

relatively small, probably deep-water b r a c h i o p o d s such as the

tion of M i d d l e D e v o n i a n age (see below) rests directly on eroded

genus

beds of the Upper Silurian. T h e relief on this u n c o n f o r m i t y then

Pacificocoelia.

Some

mollusks,

occasionally

as

pyritized

specimens, are also k n o w n f r o m the Esopus and its equivalent

may represent at least two m a j o r episodes of erosion, o n e before

Beaver D a m Shale of Pennsylvania. However, as a whole the unit

and o n e after deposition of the Tristates G r o u p . T h i s c o m p o s i t e

is very sparse a n d has yielded little insight into the ecology of the

u n c o n f o r m i t y shows local sinkhole fillings, cavities that were dis-

t i m e , particularly with regard to trilobites.

solved out of the top of the Silurian beds prior to deposition of

Esopus shales are overlain by a s o m e w h a t m o r e silty to sandy unit, the Carlisle C e n t e r S a n d s t o n e , that c o m m o n l y contains

the overlying Lower or Middle Devonian strata (Figures 4 . 3 7 B and 4 . 3 8 A ) .

s o m e large quartz granules and the green clay m i n e r a l glauconite.

T h e u p p e r m o s t p o r t i o n o f the S c h o h a r i e , particularly near

T h i s unit locally c o n t a i n s large p h o s p h a t i c c o n c r e t i o n s near its

Albany and in the S c h o h a r i e Valley region itself, has been termed

base and displays a distinctive, sharp, s e q u e n c e - b o u n d i n g u n c o n -

the

formity at the top of the Esopus. T h e Carlisle C e n t e r seems to

is particularly n o t e d for its exquisitely preserved fossils that are

Richard

Hill

Member.

This

fossiliferous

skeletal

limestone

represent a c o n t i n u a t i o n and a c c e n t u a t i o n of coarser siliciclastic

c o m m o n l y weathered out. A rich fauna of brachiopods, corals,

sediment input into the Appalachian Basin. T h e basal c o n t a c t of

c e p h a l o p o d s , and over 15 species of trilobites, primarily d a l m a n -

this sandstone unit displays a r e m a r k a b l e assemblage of trace

itids, has been reported f r o m the S c h o h a r i e beds near Albany

fossils, which is beautifully s h o w n in cuts along U.S. Rte. 20 near

( G o l d r i n g 1 9 4 3 ) . T h i s unit represents e n v i r o n m e n t s again very

C h e r r y Valley, O t s e g o C o u n t y (Miller and R e h m e r 1 9 7 9 ) . A m -

similar to the older Glenerie and New Scotland F o r m a t i o n s . T h a t

ong other traces are distinctive r i b b o n - l i k e trails referred to as

is, the unit was deposited in low-energy offshore environments

Cruziana.

marks

that were subject to m i n o r wave agitation during storms but were

and are probably the work o f trilobites furrowing i n t o m u d s o f

well below the n o r m a l wave-base. T h i n hashes of shelly material

the underlying older and partially eroded Esopus F o r m a t i o n .

are c o m m o n in the S c h o h a r i e .

These

display V - s h a p e d

c h e v r o n - l i k e scratch

Such trilobite traces probably represent feeding activity. T h e s e

T h e S c h o h a r i e F o r m a t i o n was removed by erosion in areas

traces were produced in firm m u d s , and therefore even delicate

west of Syracuse. A thin, h e m a t i t i c , phosphate-rich sandy bed

scratch marks were preserved. However, despite these traces, there

near Syracuse m a y represent s o m e of the last vestiges of the unit

are few, if any, b o d y fossils of trilobites f o u n d in the Carlisle

in central New York. However, less silty argillaceous limestone,

C e n t e r F o r m a t i o n . To the west, the Carlisle C e n t e r b e c o m e s very

referred to as Bois Blanc Formation, is present intermittently in

t h i n , very rich in glauconite and p h o s p h a t e , and appears to over-

the area f r o m near Phelps, O n t a r i o C o u n t y ( n o r t h o f Seneca

step the thin Esopus shale. In the H u d s o n Valley region, the unit

L a k e ) , westward to Buffalo and into C a n a d a . T h e Bois Blanc

is overlain and grades laterally into the highest f o r m a t i o n of the

b e c o m e s a p r o m i n e n t unit in O n t a r i o and westward into the

Tristates G r o u p , the S c h o h a r i e

F o r m a t i o n , previously called

" S c h o h a r i e Grit."

M i c h i g a n Basin. T h i s unit is rich in b r a c h i o p o d s and corals that have species identical to those f o u n d in the S c h o h a r i e of eastern

T h e S c h o h a r i e F o r m a t i o n is dated as close to the e n d of

New

York.

A

few

the Early Devonian (the E m s i a n S t a g e ) . S c h o h a r i e beds range

anchiops,

also been o b t a i n e d from these rocks.

relatively

regular

cyclic

alternation

between

more

and

less

minuscula,

Burtonops

f r o m a b o u t 10 to over 3 0 c m (1 f o o t ) in thickness and display a c a r b o n a t e - r i c h , silty to sandy m u d s t o n e . C r e a m - c o l o r e d beds are

Maurotarion

trilobites, and

cristatus,

Crassiproetus

Anchiopella

species,

have

T h e c o m p l e t e S c h o h a r i e - B o i s Blanc trilobite listing is as follows:

FIGURE 4.37. New York d u r i n g the early M i d d l e D e v o n i a n . A. During d e p o s i t i o n of the O n o n d a g a Limestone. B. Lower a n d Middle Devonian stratigraphic chart for the Northeast. From C a s s a a n d Kissling (1982), N e w York State G e o l o g i c a l Association. R e p r o d u c e d with permission.

FIGURE 4 . 3 8 . U p p e r S i l u r i a n / O n o n d a g a Limestone. A. Silurian-Devonian Wallbridge Unconformity (arrow). Darker gray d o l o s t o n e (Akron Formation (a), U p p e r Silurian) at the b a s e of the picture is overlain along an irregular u n c o n formity by light gray O n o n d a g a Limestone (b) ( M i d d l e Devonian). O a k s Corners Quarry, O a k s Corners, Ontario County. B. M i d d l e D e v o n i a n O n o n d a g a Limestone, N e d r o w Member. Note the cyclic b a n d i n g of dark chert-rich limestone a n d lighter gray fossiliferous, n o n c h e r t y limestone. Quarry off Rte. 5, Leroy, G e n e s e e County.

DEVONIAN Anchiopella

105

PERIOD anchiops

Burtoiwps

Anchiopella

cristatus

anchiops

Calymene

Coniproetus

angustifrons

Coniproetus

Corycephalus

regalis

Crassiproetus

Echinolichas

hispidus

Maurotarion Phacops? Schoharia

Synphoria?

grandis

in the Acadian m o u n t a i n terrain and in the Appalachian foreland

calliccra

basin.

arenicolus

Pseudodechenella

emarginata

Terataspis

O n o n d a g a ash beds are a harbinger of renewed tectonic activity

schohariensis

Mystrocephala

clarksoni

this ash recently have been dated using u r a n i u m - l e a d dating, to yield a very precise date of 3 9 0 ± 0.5 million years ago. T h e

conradi

Kettneraspis

minuscula

sobrinus

platys

T h e base of the M i d d l e D e v o n i a n O n o n d a g a F o r m a t i o n is

hesionea

m a r k e d by a locally sandy, pinkish gray crinoidal limestone unit

concinnus

Trypaulites

in m a n y areas, a p o r t i o n of the Edgecliff M e m b e r . T h e Edgecliff

erinus

c o n t a i n s s o m e of the largest c r i n o i d c o l u m n a l s k n o w n in any unit in the Paleozoic. Trilobites, as well as diverse corals, are abundant and

Middle Devonian

represented

Crassiproetus

by

Viaphacops

bombifrons,

Calymene platys,

and

crassimarginatus.

Tectophase II of the Acadian O r o g e n y o c c u r r e d d u r i n g M i d -

T h e depositional e n v i r o n m e n t of the grainstone facies is

dle Devonian. A basal m i n o r sandstone and thick limestone

thought to represent offshore ( Y - z o n e ) shallow-water shoal envi-

(Onondaga

r o n m e n t s , similar to older units such as the Lower Devonian

Group)

were

deposited

in

quiescent

conditions

(Figure 4 . 3 7 A ) . A sudden shift to black shale (Marcellus F o r m a -

Becraft,

t i o n ) , then shallowing upward through siltstones and sandstones

L o c k p o r t G r o u p . However, in places, where the water was s o m e -

into red beds, records first tectonic deepening and then filling of

what deeper, at least the upper Edgecliff is c o m p o s e d of relatively

the foreland basin.

thick micritic or fine-grained l i m e s t o n e with extremely a b u n d a n t

Coeymans,

and

portions

o f the

still-older

Silurian

bluish gray to chalky white c h e r t . T h e source of this siliceous Onondaga Limestone

material is p o o r l y k n o w n . However, the c h e r t - r i c h beds may have

T h e Middle Devonian (Eifelian Stage) b o u n d a r y o c c u r s at

been derived from finely particulate organic silica, such as sponge

or near the base of the O n o n d a g a F o r m a t i o n in New York State

spicules, that m u s t have developed in e n o r m o u s quantity in the

and its equivalents in Pennsylvania. T h e O n o n d a g a is an e x -

s o m e w h a t quieter water areas of the Edgecliff deposition. Chert

tremely widespread unit that correlates with other limestones in

is not c o m m o n in the high-energy shoal facies, perhaps because

the Midwest, such as the Jeffersonville L i m e s t o n e of Indiana and

the fine-grained silica required for its f o r m a t i o n was w i n n o w e d

Kentucky and the C o l u m b u s

L i m e s t o n e o f O h i o . T h e early

Middle Devonian appears to have been a t i m e of very widespread,

from these areas and removed to the slightly deeper regions of the basin.

rather u n i f o r m topography. T h i s initial transgression of M i d d l e

Fossils are generally sparse in the O n o n d a g a cherty facies but

Devonian seas o c c u r r e d during a t i m e of t e c t o n i c quiescence.

include m o d e r a t e l y a b u n d a n t f r a g m e n t s and articulated speci-

Hence, there was little tendency for the d e v e l o p m e n t of deep

mens

of trilobites.

basins or m a j o r archlike swells at this t i m e . T h e O n o n d a g a there-

ifrons,

Kettneraspis

fore spread as a sheetlike unit that was deposited at relatively

slab

uniform depths of a few tens of meters over a vast tract of eastern

from the c h e r t y facies d u r i n g the c o n s t r u c t i o n o f the H u m b o l t

North America. T h e unit does grade laterally into shallow-water

Parkway in Buffalo.

of

The

trilobites

callicera,

articulated

and

found

are

Odontocephalus

Odontocephalus

humboltensis

Viaphacops bombaegeria. was

A

large

excavated

sands in regions of southern Pennsylvania and the southern

T h e Edgecliff M e m b e r also is n o t e d for the o c c u r r e n c e of

Appalachians. However, from the H u d s o n Valley to Buffalo, the

small to m e d i u m - s c a l e b i o h e r m s or reefs. In areas of eastern

O n o n d a g a displays considerable uniformity, varying primarily

New York

only in the relative a b u n d a n c e of c h e r t and skeletal-rich beds

New York, near Buffalo and A m h e r s t , Erie C o u n t y , these b i o -

(Figure 4 . 3 8 B ) .

h e r m s were developed as low m o u n d s , up to perhaps 1 km in

T h e basal Edgecliff M e m b e r is a coral-rich crinoidal grain-

near

Albany

and

Syracuse,

and

in

westernmost

diameter and generally a few meters to a b o u t 10 m in height.

stone that passes upward laterally into very c h e r t - r i c h , fine-

B i o h e r m s were c o m p o s e d

grained limestone. Shaly beds of the Nedrow M e m b e r probably

corals. T h i c k e t s of colonial rugose corals near their bases pass

primarily o f rugose and

tabulate

record m a x i m u m transgression. Upper p o r t i o n s o f the M o o r e -

upward to l i m e - m u d s t o n e m o u n d s with a b u n d a n t favositid and

house and the overlying Seneca M e m b e r b e c o m e increasingly

s o m e o t h e r colonial and solitary rugose corals. Trilobites and

cherty and micritic in c o m p o s i t i o n . T h e y also contain s o m e of

even b r a c h i o p o d s are scarce in these facies, which seem to have

the most widespread bentonite beds k n o w n in the Appalachian

been fully d o m i n a t e d by corals a n d crinoids. T h e source of the

Basin. Particularly notable in this cluster, which is s o m e t i m e s

l i m e m u d is a mystery, but it may represent algal deposition.

termed

to

However, shaly beds o n the margins o f s o m e o f the b i o h e r m s

as Onondaga Indian Nations Ash (Figure 4 . 3 9 A ) . T h i s unit is

evidently represent a type of protected quieter water environ-

locally up to 30 cm (1 foot) thick and contains a m i x t u r e of shale

m e n t , perhaps in the lee of the b i o h e r m s . W h i l e trilobites are

and actual volcanic ash beds. Extracted zircon crystals f r o m

not c o m m o n in the reef f r a m e w o r k of the Edgecliff b i o h e r m s ,

the

Tioga

Bentonite

cluster,

is

the

ash

referred

FIGURE 4.39. M i d d l e D e v o n i a n rocks. A. S h a r p c o n t a c t b e t w e e n the light gray O n o n d a g a Limestone (a) ( M i d d l e Devonian) a n d black B a k o v e n (Union Springs) Shale (b) of basal Hamilton G r o u p . Partings with plants mark the positions of bentonites (arrows). Kaaterskill Creek, b e l o w Rte. 23A, Catskill, Greene County. B. M i d d l e Devonian Mount Marion Formation s h o w s c o a r s e n i n g a n d t h i c k e n i n g u p w a r d from lower shaly b e d s to u p p e r s a n d s t o n e s . H i g h Falls, Kaaterskill Creek, near Saugerties, Ulster County.

DEVONIAN

PERIOD

107

interfingering shaly beds have yielded s o m e remarkable finds,

c h a n g e , and P h a c o p i d a e and H o m a l o n o t i d a e c o n t i n u e but in

including the e n o r m o u s spiny trilobite Terataspis grandis, o n e of

s o m e w h a t modified forms.

the largest k n o w n of all Devonian trilobites. F r a g m e n t s of this

A

unusual lichid were formerly rather a b u n d a n t in the Vogelsanger

follows:

complete

listing

of

the

reported

Onondaga

trilobites

Q u a r r y at East A m h e r s t , Erie County. T. grandis has also been found in the O n o n d a g a in O n t a r i o , and fragments have been

Acanthopyge

found in central New York.

Australosutura

T h e Edgecliff M e m b e r is sharply overlain in m a n y localities by

(Lobopyge)

Calymene

contusa

gemmaea

Asaphus?

acantholeurus

Bellacartwrightia

platys

pleione

Ceratolichas

dracon

a m u c h m o r e argillaceous, fine-grained, and n o n c h e r t y limestone

Ceratolichas

and calcareous shale, referred to as the Nedrow Member. In places

Coronura

the Nedrow contains very dark gray or almost black shale beds

Coronura

representing dysoxic m u d d y - b o t t o m c o n d i t i o n s . T h e s e beds, not

Crassiproetus

brevispinosus

Crassiproetus

greenish gray shaly limestones of the Nedrow are extremely rich

Crassiproetus

neoturgitus

Crassiproetus

stummi

not only in the solitary rugose and small tabulate corals b u t also

Echinolichas

Echinolichas

hispidiis

gryps

Coniproetus

aspectans myrmecophorus

a

diversity of b r a c h i o p o d s

proetids, small

Pseudodechenella

odontopleurid,

Viaphacops

clara

Kettneraspis

and and

trilobites, Coniproetus

callicera,

and

eriopsis

the

Harpidella

stephanophora

Harpidella

folliceps,

the

Kettneraspis

callicera

Mannopyge

the

phacopid

Mystrocephala

ing and deepening o n c e again. T h e M o o r e h o u s e M e m b e r records

Odontocephalus Otarion?

bifidus

Odontocephalus

coronatus

Odontocephalus

selenurus

humboltensis sp.

hybrida

from crinoidal packstone with a b u n d a n t rugose corals, albeit

Paciphacops

with no development of reefs, to shaly and c h e r t - r i c h limestone

Proetus

that contains very a b u n d a n t b r a c h i o p o d s and trilobites. T h e

Proetus

trilobites

Pseudodechenella

Odontocephalus selenurus as well

as

the

Otarion?

diadema minuscula

logani

Proetus

microgemma

Proetus

ovifrons

Proetus

tumidus

stenopyge canaliculata

delphinulus

Pseudodechenella

Synphoria

concinnus

Terataspis

o f the shaly beds o f the M o o r e h o u s e .

Trypaulites

erinus

Trypaulites

Viaphacops

aegeria

Otarion?

large synphoriid Coronura aspectans o c c u r in a b u n d a n c e in s o m e T h e f i n e - g r a i n e d limestone beds o f the upper M o o r e h o u s e

halli

Odontocephalus

Odontocephalus

conditions rather similar to p o r t i o n s of the Edgecliff. It varies

sp.

varicella

Odontocephalus

T h e upper two m e m b e r s of the O n o n d a g a record a shallow-

pygmaeus

crassimarginatus

including

bombifrons.

Viaphacops and

Helena

Corycephalus

surprisingly, are very sparse in fossils. However, s o m e of the

in

folliceps

Coronura

bombifrons

clara

grandis

Viaphacops

macrops pipa

and Seneca (and their equivalent in the Selinsgrove F o r m a t i o n of Pennsylvania) tend to be sparsely fossiliferous, but certain

Certain beds near the top of the Seneca M e m b e r are distinctive

bedding planes do c o n t a i n small b r a c h i o p o d s and, most notably,

in c o n t a i n i n g an a b u n d a n c e of fossil fish remains. In the area

an a b u n d a n c e of O. selenurus trilobites. T h i s synphoriid appears

between Syracuse and the H u d s o n Valley, the erosional top of

to have been a m o n g the m o s t tolerant of o r g a n i s m s of the low-

the O n o n d a g a L i m e s t o n e is m a r k e d by a very distinct b o n e bed

oxygen, l i m e - m u d sea b o t t o m . T h e facies o f the upper O n o n d a g a

with a b u n d a n t fish teeth ( k n o w n as Onychodus) and bones. T h e s e

resembles dalmanitid-rich p o r t i o n s of the Helderberg, such as

b o n e beds probably a c c u m u l a t e d during a period of very slow

the New Scotland and Port Ewen, and even the sparsely fossilif-

s e d i m e n t a t i o n on the seafloor. T h e y are abruptly overlain by the

erous calcareous m u d s t o n e s of the Rochester F o r m a t i o n in the

sooty black shales

of the

Union

Springs

F o r m a t i o n , which

Silurian. T h e s e facies t h r o u g h o u t the Silurian to M i d d l e D e v o n -

ushered in a new tectophase with abrupt deepening of the basin

ian time appear to have h a r b o r e d an a b u n d a n c e of dalmanitid

and input of a large a m o u n t of dark siliciclastic m u d that

trilobites.

evidently was being i m p o r t e d from uprising m o u n t a i n s of the

T h e highest beds of the O n o n d a g a in New York, b e l o n g i n g to the Seneca M e m b e r , overlie a very widespread ash b e d , the

second Acadian tectophase (Figure 4 . 2 1 ) . W i t h the U n i o n Springs F o r m a t i o n begins the M i d d l e Devonian H a m i l t o n G r o u p .

O n o n d a g a Indian Nations B e n t o n i t e . T h e Seneca is generally sparsely fossiliferous, dark micritic limestone in the Finger Lakes

Hamilton Group—General

area that grades to m o r e fossiliferous beds in western New York.

T h e M i d d l e Devonian H a m i l t o n G r o u p (Figure 4 . 4 0 ) is o n e

T h e Seneca typically contains b r a c h i o p o d s , small burrows (Chon-

of the m o s t richly fossiliferous of the New York Devonian. Its

drites),

and

a

few

scattered

fragments

of

Odontocephalus

trilobites.

fossil faunas have been well studied since the times of James Hall. Generally, the fossil assemblages are arranged in a series of asso-

At the close of O n o n d a g a deposition, m a n y families of trilo-

ciations, or b i o f a c i e s , that represent distinct environments from

bites disappeared from New York. Lichiids, o d o n t o p l e u r i d s , caly-

deeper-water black shales with low-diversity b r a c h i o p o d assem-

menids, dalmanitids, and synphoriids have never been reported

blages to shallow-water coral beds, and nearshore, sandy, clam-

from beds above the O n o n d a g a . However, proetids show little

d o m i n a t e d assemblages.

FIGURE 4.40. New York d u r i n g the M i d d l e D e v o n i a n Hamilton depositions. A. M a p d u r i n g the m i d d l e Hamilton time. B. Cross section s h o w i n g the e r o d i n g A c a d i a n Mountains. From Isachson et al. (1991). Printed with p e r m i s s i o n from the N e w York State M u s e u m , Albany, NY C. Stratigraphic cross section of the Hamilton formation d e p o s i t s . From Linsley (1994). R e p r o d u c e d with p e r m i s s i o n .

DEVONIAN

109

PERIOD

Lower H a m i l t o n Marcellus F o r m a t i o n

stones contains a rich, diverse fauna across the state. In the

T h e lower Marcellus or U n i o n Springs beds that overlie the

H u d s o n Valley region, this unit is a coral-rich bed that has been

Seneca M e m b e r are primarily black shales. D u r i n g deposition of

referred to as the Halihan Hill bed (Griffing and Ver Straeten

these sediments, oxygen levels were very low in the deeper parts

1 9 9 1 ) . Farther westward the corals b e c o m e less c o m m o n and are

of the seafloor (late Eifelian S t a g e ) . However, d u r i n g deposition

absent a r o u n d S c h o h a r i e , New York, but a diverse fauna of b r a -

of the upper portion of the U n i o n Springs, there was evidently a

c h i o p o d s , b r y o z o a n s , bivalves, and o t h e r fossils occurs from here

change. Higher beds of the U n i o n Springs in the Hudson Valley,

westward. Trilobites are scarce, but the first representatives of the

referred to as the Stony Hollow M e m b e r , are characterized by

Eldredgeops rana lineage, k n o w n in New York, o c c u r within the

calcareous

siltstones,

which

contain

a

relatively sparse

and

Halihan Hill bed and its lateral equivalent, the LeRoy bed in the

low-diversity fauna of auloporid corals, s o m e b r a c h i o p o d s , and

western part of New York. A Harpidella sp. has also been found.

notably, the trilobite Dechenella haldemani. C o m m o n pygidia of

T h e fauna o f this h o r i z o n m a r k s the i n c u r s i o n o f m a n y o f the

this trilobite and rare cephala o c c u r in a few beds of a p o r t i o n

typical H a m i l t o n species. T h e species that o c c u r within this bed

of the Stony Hollow. T h i s trilobite has been traced widely in rocks

are f o r m s that persist t h r o u g h o u t the entire r e m a i n d e r of the

that date from the late Eifelian Age. For e x a m p l e , it is f o u n d in

H a m i l t o n G r o u p . Moreover, individual assemblages within the

a thin ( 2 0 c m ) , pale gray limestone ( t h e C h e s t n u t Street b e d )

Halihan Hill/Leroy bed recur at multiple levels of the higher

that occurs just below the C h e r r y Valley L i m e s t o n e t h r o u g h o u t

H a m i l t o n succession. T h e fauna o f this b e d shows virtually

central and western New York. Very similar proetids also are

n o t h i n g in c o m m o n with similarly shallow-water, c o r a l - and b r a -

found in a c o m p a r a b l e position in the southern and central

c h i o p o d - r i c h faunas o f the U n i o n Springs/Stony Hollow m e m -

Appalachians as far south as M a r y l a n d . A related species is f o u n d

bers. A few species are recurrent O n o n d a g a taxa that seem to have

in the latest Eifelian of the Michigan Basin region. Dechenella

c o m e back into the Appalachian Basin following a period of

haldemani is just o n e of a suite of unusual species of fossils f o u n d

outage associated with the unusual Stony Hollow incursion.

in this assemblage.

The brachiopods,

the

proetid

trilobites,

In the Hudson Valley area, the Hallihan Hill bed is overlain by

crinoids, and other invertebrate fossils display few similarities

a thick (up to 5 0 0 m ) succession of silty shales, siltstones, and

with the older O n o n d a g a fauna and even fewer with those of the

sandstones o f the M o u n t M a r i o n F o r m a t i o n . T h e M o u n t M a r i o n

overlying Hamilton beds. T h e Stony Hollow fauna seems to rep-

F o r m a t i o n displays a series of small-scale cycles, a few tens of

resent the brief incursion of an assemblage of o r g a n i s m s that n o r -

meters in thickness, s u p e r i m p o s e d on a generally c o a r s e n i n g - and

mally lived in w a r m e r tropical areas to the northwest, represented

shallowing-upward trend. T h e gray m u d s t o n e s are sparsely fos-

in the present-day by the C a n a d i a n Arctic.

siliferous, but the caps of the small cycles are f o r m e d by shell beds unit,

with a n u m b e r of species of b r a c h i o p o d s and c l a m s . T h e trilobite

overlies the Union Springs F o r m a t i o n t h r o u g h o u t New York,

E. rana and asteropyge species have been reported from these

Pennsylvania, M a r y l a n d , and West Virginia. C h e r r y Valley is an

levels. Dipleura dekayi may o c c u r as well in s o m e of the sandy

unusually good example of a condensed bed that f o r m e d during

beds, but it is not c o m m o n .

T h e C h e r r y Valley L i m e s t o n e , a thin ( 0 . 5 to 3 . 0 m )

a period of sea-level rise. Following the shallowing Stony Hollow

Westward, the various units display a gradual transition from

conditions, there must have been a period of m i n o r seafloor

silty m u d s t o n e s into m e d i u m and dark gray shales. T h e lower

erosion, as the base of the C h e r r y Valley is typically sharp. T h e

p o r t i o n s of the M o u n t M a r i o n above the Halihan Hill bed grade

Cherry Valley itself is c o m p o s e d of the remains of small conical

into the C h i t t e n a n g o Shale M e m b e r o f the Marcellus F o r m a t i o n

pelagic organisms, referred to as styliolinids, and with c e p h a -

in central New York. T h i s black, rusty shale with c o n c r e t i o n s

lopods, for which it is particularly noted. S o m e of the earliest

c o n t a i n s very few fossils o t h e r than

abundant goniatitic a m m o n o i d s (Agoniatites vanuxemi) o c c u r

c e p h a l o p o d s , and styliolinid remains. However, it passes upward

scraps of w o o d , s o m e

within the C h e r r y Valley L i m e s t o n e . However, no trilobites are

into m e d i u m gray shales of the Bridgewater M e m b e r and the

known from the C h e r r y Valley proper.

overlying Solsville S a n d s t o n e and Pecksport Shale. T h e s e units

T h e C h e r r y Valley M e m b e r is overlain abruptly by O a t k a Creek

are noted for the o c c u r r e n c e of exceptionally well-preserved bra-

(Chittenago) black shale that resembles the underlying U n i o n

c h i o p o d and molluscan remains. A very few s p e c i m e n s of the

Springs F o r m a t i o n . Most of this unit represents deep-water a c c u -

trilobite E. rana showing primitive patterns in terms of eye struc-

mulation of anoxic muds. However, there are hints of a p r o f o u n d

ture ( 1 8 vertical files of lenses) have been recorded in these beds

faunal change within these rocks. Fossils are rare in the O a t k a

f r o m the region of the H a m i l t o n - t y p e area in the C h e n a n g o

Creek black shales. But a few gray layers c o n t a i n f o r m s typical of

Valley (Eldredge 1 9 7 2 ) . To the west only the upper two-thirds to

the higher Hamilton G r o u p and not the underlying U n i o n Springs

o n e - f o u r t h o f the O a t k a C r e e k (Marcellus) F o r m a t i o n represent

or O n o n d a g a . Most notable is a fossiliferous bed that occurs vari-

m e d i u m gray m u d s t o n e s ( C a r d i f f F o r m a t i o n ) ; these are typically

ably from just a few centimeters in western New York up to about

only very sparsely fossiliferous.

50 m ( 1 6 0 feet) in the east, above the C h e r r y Valley L i m e s t o n e .

T h e thick M o u n t M a r i o n F o r m a t i o n (Figure 4 . 3 9 B ) represents

This thin bed ( 1 0 to 5 0 c m ) of m e d i u m gray shale and thin lime-

m u d s , silts, and sands shed from Acadian uplifts into a rapidly

THE

110

PALEOZOIC

GEOLOGY

OF

NEW

YORK

subsiding foreland basin. T h i s succession thins abruptly westward

only sparsely fossiliferous. T h e Delphi Station and Pompey are

from m o r e than 5 0 0 m to less than 20 m in western New York,

relatively rich in small b r a c h i o p o d s and trilobites.

where thin m u d s of the O a t k a Creek Shale a c c u m u l a t e d deep

As with the Marcellus shales, the Skaneateles Formation tends

anoxic waters. Rapid a c c u m u l a t i o n o f sediments eventually o u t -

to pass westward into poorly differentiated, dark gray to black

stripped subsidence near the Hudson Valley, where the M o u n t

shales that generally contain tew f o s s i l s but are characterized in

M a r i o n shallows upward from deep basinal c o n d i t i o n s to shallow

m a n y areas by leiorhynchid b r a c h i o p o d fauna or small bivalves.

sandy shelf. T h e upper beds of the M o u n t M a r i o n F o r m a t i o n are

T h e s e deeper-water facies of the Levanna Shale yield relatively

sandstones with s o m e c o n g l o m e r a t e s . T h e latter contain quartz

a b u n d a n t E. rana and s o m e asteropyge specimens, but D. dekayi

and chert pebbles, s o m e of which m a y be reworked from older

is very rare. S o m e w h a t m o r e diversified b r a c h i o p o d s , auloporid

Devonian units uplifted during the Acadian Orogeny. T h e s e pass,

coral, and trilobite assemblages are found at levels that seem to

in turn, upward into gray flaggy siltstone and sandstone beds,

c o r r e s p o n d with the caps of the Delphi Station and Pompey

assigned to the Ashokan F o r m a t i o n , c o n t a i n i n g primarily plant

Members.

material and a few horizons of low-diversity b r a c h i o p o d a s s e m blages. T h e s e beds are interpreted as tidal-flat sands to n o n m a rine beds. T h e y are overlain gradationally by m a r o o n or red strata

Ludlowville F o r m a t i o n The

Centerfield

Member

at

the

base

of

the

overlying

o f the Plattekill and Manorkill F o r m a t i o n s . T h e s e n o n m a r i n e ,

Ludlowville F o r m a t i o n displays an abrupt shallowing trend. In

meandering river deposits typically show channeled sandstones

western New York, the Centerfield M e m b e r is a classic example

that fine upward through a few meters into red m u d s t o n e s c o n -

of a shallowing to deepening shale to c a r b o n a t e to shale cycle

taining p l a n t - r o o t marks and m u d cracks. Such evidence indi-

within the H a m i l t o n G r o u p . A thin basal succession of gray shales

cates that the relatively deep basins that o c c u p i e d the Hudson

passes upward into m u d s t o n e s and finally skeletal limestones. A

Valley region during Middle Devonian times were completely

nearly s y m m e t r i c a l transition back through calcareous m u d -

infilled with terrigenous detritus derived from the second tec-

stones to m e d i u m or dark gray shales of the Ledyard M e m b e r

tophase o f the Acadian O r o g e n y (Figure 4 . 3 4 ) .

o c c u r s in the upper half of the Centerfield. In places, a phosphatic pebble bed marks the t o p of the unit. The calcareous mudstone facies of the Centerfield pass eastward in central New York into

Skaneateles F o r m a t i o n In central to western New York, the Pecksport or C a r d i f f Shale

calcareous siltstones and cross-bedded sandstones, marking out

(upper Marcellus) is gradationally to sharply overlain by the

a m a j o r shallowing-up cycle that c o m m e n c e s with dark gray

second m a j o r H a m i l t o n l i m e s t o n e or calcareous siltstone, that is,

shales.

the Stafford and Mottville M e m b e r s at the base of the Skaneate-

A c o m p l e t e s p e c t r u m of H a m i l t o n biofacies is observable

les F o r m a t i o n . At this level a diverse H a m i l t o n fauna reappears

within the Centerfield and adjacent units. It overlies and under-

for the first t i m e above the Halihan Hill coral bed, and it displays

lies dark gray shales with leiorhynchid b r a c h i o p o d fauna that

m i n o r m o d i f i c a t i o n s , m o s t notably the loss of a few O n o n d a g a

probably represent deep offshore m u d s , well below the storm

holdover species and a greatly increased a b u n d a n c e of trilobites.

wave-base. T h e s e shales are transitional into gray shales charac-

Both Eldredgeops species and various f o r m s of astropygids, Ken-

terized by a a m b o c o e l i i d b r a c h i o p o d - r i c h fauna and very a b u n -

nacrypheus harrisae and a Greenops species (assigned

dant

in

the past

to G. boothi), are c o m m o n for the first t i m e in the Mottville beds

trilobites,

Harpidella

such

craspedota,

as

Bellacartwrightia jennyi,

Monodechenella

Eldredgeops

macrocephala,

and

rana, Mys-

of central New York. Joining t h e m is the h o m a l o n o t i d trilobite D.

trocephala baccata, and finally into the highly diversified coral and

dekayi. T h i s species o c c u r s in considerable a b u n d a n c e in s o m e of

b r a c h i o p o d assemblages that typify the calcareous mudstones

the silty beds of the Mottville, and especially in a siltstone capping

and limestones of the middle Centerfield. T h e s e beds are par-

a small cycle approximately 10.5 to 1 2 . 0 m above the top of the

ticularly noted in western

Mottville M e m b e r . T h i s latter unit, the C o l e Hill t o n g u e of the

abundant

Delphi Station Shale, is widely k n o w n as a source of these large

c o n c r e t i o n a r y limestone a b o u t 3 0 c m (1 foot) below the coral-

trilobites, particularly in

rich limestones of the middle Centerfield contains unusually

the

vicinity of Sangerfield, O n e i d a

proetid

New York as a source of rather

trilobites.

Pseudodechenella

In

rowi

particular, o n e thin

in

contorted

(10cm)

County, where large n u m b e r s of s p e c i m e n s have been o b t a i n e d

preserved

in beds rich in large bivalves and certain b r a c h i o p o d species.

which suggests these o r g a n i s m s were caught up in an unusually

orientations,

the

rapid s t o r m burial event. T h i s bed has been traced for over 80 km

Skaneateles c o r r e s p o n d t o three m e m b e r s o f central New York:

f r o m the Buffalo region westward to the type section at Center-

the

f i e l d , O n t a r i o County, near Canandaigua Lake. T h e C h e n a n g o

Three

higher,

Delphi

Station

major

shallowing-upward

(40m),

Pompey

(25m),

cycles and

in

Butternut

M e m b e r s (up t o 6 0 m ) . T h e top o f the P o m p e y c o n t a i n s l i m e -

M e m b e r siltstone and sandstones facies also display Dipleura

stone c o n c r e t i o n s that have been traced f r o m western New York

dekayi,

eastward into the C h e n a n g o Valley region. T h e upper Butternut

Formation.

as

do

similar

facies

in

the

underlying

Skaneateles

M e m b e r is typically the darkest shale of the Skaneateles F o r m a -

T h e bulk of the higher Ludlowville F o r m a t i o n is c o m p o s e d of

tion t h r o u g h o u t m o s t of western and central New York and is

black and dark to m e d i u m gray shales and mudstones of the

DEVONIAN

PERIOD

111

Ledyard and Wanakah M e m b e r s in western New York and their

to those seen in the older Centerfield M e m b e r . Again, well over 100

equivalents in central New York, the silty m u d s t o n e s of the O t i s c o

species of b r a c h i o p o d s , b r y o z o a n s , crinoids, mollusks, and trilo-

Shale and the siltstone of the overlying Ivy Point M e m b e r .

bites, including relatively large astropyges, Bellacartwrightia and

T h e Ledyard Shale in western New York is m e d i u m to dark

Greenops, species, and additionally E.

rana and M.

macrocephala

gray shale and m u d s t o n e . It is particularly noted for an o c c u r -

have been o b t a i n e d f r o m the Jaycox beds. T h e y also represent the

rence of an interval about 6 m ( 2 0 feet) above the Centerfield that

first

appearance

of the

trilobite Australosutura gemmaea.

is very rich in small spheroidal nodules of pyrite. T h e s e beds, termed the Alden Pyrite Beds, yield a moderately diverse fauna

Moscow Formation

dominated by b r a c h i o p o d s but also c o n t a i n i n g very a b u n d a n t remains of trilobites E.

rana and

Greenops grabaui,

T h e highest f o r m a t i o n of the H a m i l t o n G r o u p , the Moscow, is

typically as

b o u n d e d at its base by an unusually widespread skeletal limestone

enrolled individuals and often as the nuclei of pyrite c o n c r e t i o n s .

c o m p o s e d primarily o f ossicles o f crinoids and s o m e fragmentary

Babcock and Speyer ( 1 9 8 7 ) reasoned that these enrolled trilobite

or c o m p l e t e colonies of favositid and rugosan corals. T h i s unit,

beds reflect unusual c o n d i t i o n s on the seafloor under which

the T i c h e n o r M e m b e r , has been traced from Lake Erie eastward

storm disturbance stirred up hydrogen s u l f i d e - r i c h m u d s . Trilo-

to the S c h o h a r i e Valley region. It appears to represent a trans-

bites responded to the toxicity of the waters and perhaps their

gressive lag deposit f o r m e d in shallow, relatively sediment-starved

turbidity with the typical escape reaction of e n r o l l m e n t b u t were

waters. It overlies an erosional d i s c o n f o r m i t y f o r m e d during a

later buried by clouds of m u d suspended during the s a m e s t o r m

m a j o r regression at which beds of the Jaycox and subjacent units

event. T h e Alden beds c a n n o t be traced into the Finger Lakes,

o f the Ludlowville were locally t r u n c a t e d . S o m e o f the T i c h e n o r

where the Ledyard Shale is predominately fissile or platy black

L i m e s t o n e may actually be c o m p o s e d of fossils reworked from the

shale and represents low-oxygen e n v i r o n m e n t s . Trilobites, h o w -

older Ludlowville units. T h e T i c h e n o r passes upward into cal-

ever, are again c o m m o n in the gray silty m u d s t o n e facies of the

careous, sparsely fossiliferous m u d s t o n e of the Deep Run M e m b e r

equivalent Otisco M e m b e r that replaced the typical Ledyard

that is the o n l y o c c u r r e n c e of the trilobite Cyphaspis. T h e Deep

facies east of O w a s c o Lake. T h e O t i s c o is also n o t e d for the o c c u r -

R u n is overlain by a thin ( 3 0 to 5 0 c m ) silty M e n t e t h Limestone,

rence of two coral-rich s u b m e m b e r s , the Staghorn Point and the

which is m o s t n o t e d as a source of silicified fossils ( B e e c h e r 1893a)

Joshua coral beds. T h e s e are f o r m e d of thickets or b i o s t r o m e s of

that includes very early growth stages of m a n y species, such as

solitary rugose corals with s o m e tabulates. O t h e r fossils tend to

protaspides o f trilobites. T h e lowest part o f the M o s c o w F o r m a -

be rare within the coral thickets, but on the periphery of the

tion ( T i c h e n o r , D e e p R u n , M e n t e t h ) is also n o t e d as the source of

Joshua b i o s t r o m e , clusters of E. rana have been collected.

s o m e o f the largest s p e c i m e n s o f trilobites. T h e largest k n o w n

T h e Wanakah M e m b e r gray shales are exceptionally rich in

E.

rana,

Bellacartwrightia

phyllocaudata,

and

M.

macrocephala

are

fossils, at certain levels, including corals, b r a c h i o p o d s , bryozoans,

o b t a i n e d from the D e e p R u n , but similarly large individuals are

crinoids, trilobites, and others. Over 2 0 0 fossil species have

f o u n d in the M e n t e t h L i m e s t o n e and K a s h o n g Shale. T h e s e

been reported from the W a n a k a h Shale in western New York.

muddy-bottomed,

A m o n g these are about six or seven species of trilobites. T h e s e

favorable to the growth of these trilobites. However, an enigma

shallow-water

environments

were

highly

species are most a b u n d a n t in a series of thin argillaceous l i m e -

associated with these beds is the relative paucity of small individ-

stones that o c c u r low in the W a n a k a h from Lake Erie at least

uals. Because trilobites m o l t , o n e should see a record of these

to Canandaigua Lake. T h e s e are the famed "trilobite b e d s " of

various growth

Amadeus Grabau ( 1 8 9 8 - 1 8 9 9 ) . Along with large n u m b e r s o f

absence of these early stages may suggest that trilobites were rather

E.

G.

m o r e m o b i l e creatures and that the shallow-water m u d d y envi-

grabaui. Such trilobite bed facies, typically associated with small

r o n m e n t s represented by the D e e p Run and Kashong facies were

rana

are

found

P.

rowi,

Bellacartwrightia

whiteleyi,

and

stages observed as disarticulated

parts.

The

that

inhabited primarily by m a t u r e individuals. S o m e m o d e r n crus-

occupied an offshore mud b o t t o m during times of low net sedi-

taceans are k n o w n to undergo widespread m i g r a t i o n s of this sort.

solitary

(Stereolasma)

corals,

represent

a

distinctive biota

ment input. T h e s e thin limestones have m u c h in c o m m o n with

Overall, the T i c h e n o r - D e e p Run succession represents a gradual

the Browns Creek Bed of the Centerfield. Like the latter bed, they

deepening f r o m near wave-base to offshore subtidal m u d - b o t t o m

show evidence for both rapid e n t o m b m e n t of trilobites and a

e n v i r o n m e n t s influenced strongly by intermittent storms.

longer-term signature ot a cyclical increase and decrease in c a r -

T h e blue-gray m u d s t o n e s o f the overlying Kashong M e m b e r

bonate within the sediment. Trilobites frequently o c c u r in clus-

generally are rather sparsely fossiliferous but contain an a b u n -

ters of up to 100 individuals. Small-scale cyclicity, apparent in

dance of trace fossils. However, local patches within these m u d -

the lower Centerfield and in the lower W a n a k a h trilobite beds,

stones

suggests possible climatic oscillations that controlled the c a r b o n -

b r a c h i o p o d s of the

ate content of the offshore m u d s .

c h i o p o d bivalves, crinoids, bryozoans, and trilobites. Probably the

display

exceptionally

well-preserved

fossils,

including

Tropidoleptus fauna, various species of bra-

T h e highest unit of the Ludlowville F o r m a t i o n in western New

m o s t f a m o u s p o r t i o n of the Kashong is the " R e t s o f b e d s " found

York is the Jaycox M e m b e r , a richly fossiliferous m u d s t o n e . T h e s e

in the excavations for a railroad near the f o r m e r Retsof salt mines

beds are sources of high-diversity fossil assemblages very similar

in Livingston C o u n t y . T h e s e beds have been a prolific source of

THE

112 crinoids and blastoids a n d , again, relatively large s p e c i m e n s of the trilobites

Eldredgeops,

Greenops,

and

PALEOZOIC

GEOLOGY

OF

NEW

YORK

T h e Tully was preceded by an interval ot substantial erosion of the older seafloor sediments. Evidence from the u n c o n f o r m i t y

Monodechenella.

T h e highest m e m b e r o f the H a m i l t o n G r o u p , the W i n d o m

surface itself suggests that the seafloor was buckled into a series

Shale, has m a n y features similar to the m i d Ludlowville. It has

of low folded areas that b e c a m e erosionally truncated prior to and

a n u m b e r of small-scale cycles capped by beds rich in fossils of

during Tully deposition.

the typical diverse H a m i l t o n biofacies. Again, trilobites, Greenops barberi,

E.

rana,

Bellacartwrightia

sp.

and

P.

rowi,

occur

in

T h e lower p o r t i o n of the Tully L i m e s t o n e , in western New

a

York, is unusually clean, fine-grained limestone that apparently

n u m b e r of levels and are exceptionally a b u n d a n t in cyclically

accumulated in very-shallow-water c o n d i t i o n s . It contains an

bedded, calcareous m u d s t o n e s a n d argillaceous limestones that

unusual assemblage of b r a c h i o p o d s , most species of which are not

form a n o t h e r series similar to the " t r i l o b i t e b e d s " of the lower

c o m m o n to the H a m i l t o n G r o u p below. In addition, the typical

Wanakah. O t h e r p o r t i o n s of the W i n d o m Shale display the low-

H a m i l t o n trilobites and a few o t h e r species are f o u n d rarely in the

diversity, leiorhynchid b r a c h i o p o d - r i c h , dark shale facies, and

lower part of the Tully. An undescribed m e m b e r of Asteropyginae

Ambocoelia biofacies in m e d i u m gray m u d s t o n e s that are often

has been collected from this lower p o r t i o n of the Tully. It is not

highly enriched in phacopid trilobites, and c o r a l - r i c h beds that

a Greenops species, as previously reported. However, it is very

display a diversity of f o r m s including proetids, the unusual trilo-

similar to a species f o u n d in the C e d a r Valley Limestone of Iowa.

bite

A m i n o r u n c o n f o r m i t y separates these lower limestone beds from

Australosutera

gemmaea,

and

the

occurrence

of

Phacops?

iowensis.

the upper Tully. At Bellona, Yates County, apparently truncated

T h e trilobite distribution in the H a m i l t o n shows b o t h stasis, little change over a long period of t i m e , and significant change in

algal stromatolites have been found at this surface, suggesting a substantial period of shallowing, followed by erosion.

Bellacartwrightia

T h e upper portion of the Tully, a relatively clean limestone

genera show species c h a n g e , often after a transgression (Lieber-

resembling the m u c h older O n o n d a g a , displays a fauna of recur-

the

case

of

the

Asteropyginae.

Greenops

and

m a n n and Kloc 1 9 9 7 ) . O n e Kennacrypheus species makes only a

rent H a m i l t o n f o r m s . M o s t of the c o m m o n species within the

b r i e f appearance, and there are n o w still undescribed species to

upper Tully are f o r m s also present to abundant within the Hamil-

be accommodated.

ton G r o u p shales below. T h e return of trilobite bed facies is quite

T h e c o m p l e t e listing o f H a m i l t o n G r o u p trilobites follows:

evident.

The

trilobites

P.

rowi,

Bellacartwrightia

sp.,

Eldredgeops

norwoodcnsis, and Greenops? sp., as well as small rugose corals that Australosutura Bellacartwrightia

gemmaea

Bellacartwrightia

jennyi

Bellacartwrightia

calderonae

appears to be associated with a small patch reef facies found near

phyllocaudata Bellacartwrightia Cyphaspis Dipleura

Dechenella

sp.

Harpidella Phacops?

macrocephala

Pseudodechenella

Mystrocephala Proetus

iowensis arkonensis

the Tully, in total, are as follows: harrisae

ornata

baccata

jejunus

Pseudodechenella

to represent the last stand for most c o m m o n Hamilton genera and for their particular associations of biofacies. T h e trilobites of

grabaui

Kennacryphaeus

craspedota

Monodechenella

crassituberculatus rana

Greenops

barberi

in o t h e r beds in the upper part of the Tully. T h e upper Tully seems

haldemani

Eldredgeops

norwoodcnsis

Skaneateles at B o r o d i n o , O n o n d a g a County, but may o c c u r rarely

sp.

Eldredgeops

dekayi

Eldredgeops Greenops

Bellacartwrightia

whiteleyi

typify the H a m i l t o n calcareous "trilobite beds," o c c u r in several beds of the upper Tully. T h e unusual trilobite Scutellum tullius

rowi

New Asteropyginae referred to as Greenops Bellacartwrightia sp.

Eldredgeops

Harpidella spinafrons

Monodechenella

norwoodcnsis

Pseudodechenella rowi

Scutellum

macrocephala

tullius

In western New York west of Canandaigua Lake, the Tully

Tully L i m e s t o n e T h e shales o f the M o s c o w F o r m a t i o n are u n c o n f o r m a b l y over-

L i m e s t o n e has been removed, probably by deep seafloor erosion

lain throughout central New York by the unusual fine-grained

and c o r r o s i o n of the carbonates in undersaturated water. In these

( m i c r i t i c ) limestone o f the Tully F o r m a t i o n (Figures 4 . 4 1 , 4 . 4 2 A

areas, the black G e n e s e o Shale rests u n c o n f o r m a b l y on the upper

and 4 . 4 3 ) . 'The Tully is a rather e n i g m a t i c l i m e s t o n e , as it

beds of the H a m i l t o n G r o u p . However, in most localities local-

f o r m e d at a t i m e of general substantial siliciclastic input to the

ized small lenses, up to 10 or 2 0 c m thick, of reworked fossil b o n e

Appalachian Basin. It is suggested that the d e v e l o p m e n t of m i n o r

and pyrite material are observed intermittently at this contact.

folds on the sea b o t t o m in central New York ( n e a r C h e n a n g o

T h e s e beds of the Leicester Pyrite do contain occasional enrolled

Valley, C h e n a n g o C o u n t y )

served to e n t r a p m o s t siliciclastic

trilobites. W h a t is m o s t unusual about these trilobites is not

sediment that was still being shed from the second tectophase of

simply that they are pyritized, but that they are probably clasts

the Acadian O r o g e n y and to prevent these s e d i m e n t s from m o v -

removed by erosion of the underlying shale and reworked into

ing westward.

the lag deposits represented by the Leicester Pyrite.

FIGURE 4 . 4 1 . D e v o n i a n s u c c e s s i o n s . A. Devonian s u c c e s s i o n at Lake Erie. Lowest b e d s are W a n a k a h Shale (a) ( M i d d l e D e v o n i a n Ludlowville Formation). A distinctive limestone l e d g e , Tichenor M e m b e r (b), marks the b a s e of the M o s c o w Formation, w h i c h is overlain by gray W i n d o m Shale (c). A s e c o n d thin limestone, G e n u n d u w a (d), marks the a p p r o x i m a t e position of the M i d d l e - U p p e r D e v o n i a n b o u n d a r y dark gray to black shale (e) at a b o u t a third of the cliff height. Higher b e d s s h o w an alternation of black West

River-Middlesex-medium

gray,

concretion-bearing

Cashaqua

Shale

(f),

and

finally

black

Rhinestreet Shale (g) at the top of the cliff. Lake Erie Shore south of Eighteen Mile Creek, Evans, Erie County. B. M i d d l e Devonian Ludlowville a n d M o s c o w Formations (Hamilton G r o u p ) . Main cliff b e l o w the falls is the W a n a k a h a n d J a y c o x shales. Lower limestone of the falls c a p is the Tichenor M e m b e r (a) (marking the b a s e of the M o s c o w Formation), w h i c h is overlain by 2 m of D e e p Run Shale (b). The falls are c a p p e d by the Menteth Limestone (c). The b a n k a b o v e the falls is gray K a s h o n g Shale (d). Wheeler Falls, J a y c o x Creek, north of G e n e s e o , Livingston County.

FIGURE 4.42. M i d d l e D e v o n i a n / U p p e r Devonian s u c c e s s i o n s . A. M i d d l e Devonian s u c c e s s i o n . W i n d o m Shale (a) ( M o s c o w Formation, Hamilton G r o u p ) , b e l o w l e d g e s , is u n c o n f o r m a b l y overlain by t h i c k - b e d d e d Tully Limestone (b). T a u g h a n n o c k Creek, T r u m a n s b u r g , Tompkins County. B. M i d d l e - U p p e r Devonian s u c c e s s i o n . The b a s e of the falls is slightly a b o v e the Tully limestone. The main falls f a c e is G e n e s e o Shale (a). The falls are c a p p e d by the Lodi b e d s (b) of the S h e r b u r n e Formation, near the M i d d l e - U p p e r D e v o n i a n boundary. Higher cliffs are in the Penn Yan (c) (Sherburne) a n d Renwick Shale of the U p p e r D e v o n i a n . T a u g h a n n o c k Falls, T r u m a n s b u r g , Tompkins County.

DEVONIAN

PERIOD

115

FIGURE 4.43. Stratigraphy of the U p p e r Devonian a n d the u p p e r M i d d l e Devonian of N e w York. From Sevon a n d W o o d r o w (1985), after Rickard (1975).

Late Devonian Strata

prograded or built seaward into deepened basins of central New York a n d elsewhere. T h e deep basin again implies a period of

During tectophase III in the late M i d d l e - e a r l y Late D e v o n i a n ,

tectonic thrust loading that caused flexure of the crust through-

the basal c a r b o n a t e (Tully L i m e s t o n e ) gave way to black shales

out m u c h of western and central New York. T h a t basin center

(Genesee facies). T h i s was followed by a general progradation of

migrated abruptly westward f r o m its position in late Middle

siltstone, sandstone (prodelta, Portage facies; deltaic platform;

D e v o n i a n (Tully) t i m e , w h e n it lay close to the C h e n a n g o Valley

C h e m u n g facies), and red beds (subaerial delta p l a t f o r m ; Catskill

region. T h e black shales of this tectophase are actually still of

facies) (Figures 4 . 3 4 and 4 . 4 3 ) .

M i d d l e D e v o n i a n (Givetian) age in western and central New York.

Upper Devonian strata o c c u p y m o s t of the southern tier of

T h i s black m u d deposition represents the greatest deepening

New York State and are up to 2 km thick. To the east they are rep-

during the entire D e v o n i a n an event referred to as the Taughan-

resented by red siliciclastic m u d s , silts, and coarse c o n g l o m e r a t e s

nock onlap or transgression. T h e basal G e n e s e o Shale is charac-

that cap s o m e of the high peaks in the Catskill E s c a r p m e n t . T h e s e

terized by the black shales b u t displays intervals of gray, marly,

muds and conglomerates represent both m e a n d e r i n g and braided

calcareous m u d s t o n e s and thin limestones. Fossils tend to be

stream facies that accumulated rapidly in a subsiding basin in

quite scarce in these beds, presumably because of the strongly

front of a rising set of Acadian M o u n t a i n s . T h e abrupt increase

dysoxic

in siliciclastics near the base of the Upper D e v o n i a n , in associa-

prevailed on the m u d d y seafloor through most of this time.

(reduced

oxygen

fragments,

level)

goniatites,

to

anoxic

nautiloids,

conditions and

that

tion with the abrupt deepening of the basin to the west and the

Driftwood

occurrence of very widespread black shales, signals the onset

are c o m m o n in s o m e beds. Trilobites are extremely rare in the

conodonts

of the third and largest tectophase of the Acadian Orogeny.

Genesee and higher f o r m a t i o n s o f the Upper Devonian.

This m a j o r m o u n t a i n - b u i l d i n g pulse was the source of the vast

T h e base o f the Frasnian Stage o f the Upper Devonian occurs

Catskill deltaic c o m p l e x , an e n o r m o u s set of clastic wedges that

high within the Genesee F o r m a t i o n . T h e basal beds of the Frasn-

THE

116

PALEOZOIC

GEOLOGY

OF

NEW

YORK

ian are typically siltstones alternating with m e d i u m gray m u d -

Acadian Orogeny. Eventually it was sorted out that these facies

stones. T h e s e beds, like the G e n e s e e below, pass eastward into

were d i a c h r o n o u s , older to the east.

m u c h coarser-grained siltstone and sandstone facies within the

W h y did discrete tectophases o c c u r and why did the locus

Finger Lakes that, in t u r n , pass into massive m a r i n e sandstones

of basins shift southwestward? T h e Laurentia-Avalonia collision

with c o q u i n a (shell a c c u m u l a t i o n s ) . T h e Sonyea and West Falls

was mainly c o m p l e t e d by Middle to early Late Devonian, with

( I r o u p s make up the r e m a i n d e r of the Frasnian Stage. S o m e beds

rotational scissor-like closure and different p o r t i o n s of the Avalon

within the silty facies contain a b u n d a n t c o q u i n a s of b r a c h i o p o d s

t e r r a n e s hitting different p r o m o n t o r i e s of the Laurentian margin.

and clams. However, corals, b r y o z o a n s , and trilobites are only rarely seen within these beds.

O n l y a few fragments of phacopids, possibly E. rana, have been f o u n d in the G e n e s e o . T h e s e black shales pass eastward into gray

Most environmental interpretations o f the facies o f the Upper

m u d s t o n e and siltstone, with a somewhat m o r e diverse b r a c h i o -

Devonian follow the m o d e l of a delta. In the deepest most off-

pod fauna. Trilobites were never again c o m m o n within the

shore setting, fine-grained siliciclastic m u d s and a fairly large

Devonian of New York.

a m o u n t of organic detritus settled out in quiet waters. Black shale facies record these settings. Eastward of this, the seafloor sloped

T h e r e are o n l y two trilobites unique to the Upper Devonian in New York:

upward from deep water to near s t o r m wave-base (a few tens of meters of w a t e r ) , and this area is s o m e t i m e s termed the prodelta

Scutellum senescens

Otarion? laevis

region. T h i s sloped area e x p e r i e n c e d generally quiet water c o n ditions with settle-out o f f i n e m u d s , b u t episodically s t o r m o r

Reports

seismic s h o c k p h e n o m e n a generated sediment-filled turbidity

because the beds in which they were found are now possibly part

currents that laid down a series of flaggy and fine-grained sand-

o f the upper Middle Devonian.

of Eldredgeops

and

Greenops

species

are

questionable

stones with flute casts and drag marks on their lower surfaces.

C h e m u n g - s h e l f e n v i r o n m e n t s appear very similar to silty and

Such marks indicate that current directions were mainly out of

sandy p o r t i o n s of the older H a m i l t o n G r o u p . Therefore, it is

the southeast.

s o m e w h a t surprising that m a n y characteristic Hamilton species

Still farther east, the equivalent sandstones with shell c o q u i n a s

including the trilobite D. dekayi are completely absent from the

suggest deposition near or slightly above s t o r m wave-base and

Upper Devonian p o r t i o n s of the successions. Indeed, trilobites are

approaching n o r m a l wave-base. T h e s e facies have been termed

rare in almost all facies of the Upper D e v o n i a n . An extinction near

the "Chemung facies" and are interpreted as representing a s u b -

the end of the M i d d l e Devonian eliminated many of the typical

marine delta platform. O b v i o u s l y the red beds with their c h a n n e l

H a m i l t o n species and permitted an abrupt overturn to the typical

sands ("Catskill f a c i e s " ) , which are the final facies to the east, rep-

Genesee faunas of the latest M i d d l e Devonian to earliest Late

resent a n o n m a r i n e , subaerially exposed alluvial plain, perhaps a

Devonian age. A m o n g the o r g a n i s m s that were decimated locally

tidal-flat setting, in part.

by the M i d d l e Devonian e x t i n c t i o n s were the trilobites and many,

T h e westward m i g r a t i o n of these facies through the Upper

if not m o s t , of the associated rugose corals. H e n c e , the gray silty

Devonian is quite d r a m a t i c , with the red beds eventually c o m -

a n d sandy sandstone and m u d s t o n e facies that occupy so m u c h

ing to be deposited as far westward as the Genesee Valley region.

of the southern tier, although a rich source of brachiopods,

T h e fact that these individual facies transcend or cut time lines

bivalves, and o t h e r mollusks, are very p o o r for trilobite material.

established within the deltaic c o m p l e x indicates that the delta

Trilobites were clearly on the wane by the end of the Devonian,

was prograding or building forward into the seaway. As it did so,

and that last part of their history is obscure in New York State.

each successively m o r e shoreward facies built " p i g g y b a c k " over

M a r i n e ecosystems show intervals of relative stability p u n c -

the top of the next most-seaward facies, yielding a generally

tuated by abrupt turnovers at several apparently global events,

shallowing-up pattern. However, this simplistic m o d e l of a p r o -

each associated with widespread anoxia and possible climatic

grading delta must be modified in s o m e ways. For e x a m p l e , we

changes in Earth's history. D u r i n g the Late Devonian (Frasnian-

know there were intervals, probably associated with m a j o r events

F a m e n n i a n stage b o u n d a r y ) , o n e such mass extinction wiped out

causing a rise in sea level, when dark shales were spread widely

a b o u t 2 5 % o f m a r i n e families; decimated reef-building corals and

both over the prodelta slope facies and over the C h e m u n g - s h e l f

s t r o m a t o p o r o i d s ; and caused extinction of cystoids and pen-

environments.

tamerid and atrypid (orders) b r a c h i o p o d s , most a m m o n o i d s , and

T h e Appalachian Basin shifted southwestward as progressively

most r e m a i n i n g trilobites. T h e terrestrial system was not so dras-

Albany-Chattanooga)

tically affected. T h e causes of the events remain unclear. Like

spread into the Midwest. T h i s pattern was recognized in the m i d

o t h e r mass e x t i n c t i o n episodes, the Late Devonian crisis seems to

1900s as the pattern of basin filling-overfilling by deltaic p r o -

have involved sea-level

gradation of the great Catskill Delta, the flysch-molasse of the

climate stress.

younger

black

shales

(Cleveland-New

fluctuation, widespread hypoxia, and

5

The Trilobites

In this chapter, all the trilobites of New York State k n o w n to us

h o l o t y p e , such as c o t y p e , appear as they are on the label. W h e n -

are listed by family. T h e listing is first by order, with the orders

ever geographic data such as the presence of the species outside

appearing in the same sequence used in the classification chapter

New York are k n o w n to us, they are given.

of the Treatise (revised): Agnostida, Redlichiida, C o r y n e x o c h i d a ,

W h e n the t e r m type species is given at the b e g i n n i n g of the

Lichida, Phacopida, Proetida, Asaphida, and Ptychopariida (see

descriptive paragraph, it indicates that this species was used to

also Fortey, 2 0 0 1 ) . T h e families are listed alphabetically within

define the genus. In those instances where there m a y be difficul-

their respective order. S o m e New York trilobites m e n t i o n e d in the

ties in identifying similar trilobites, the diagnostic characteristics

literature did not have the a u t h o r or publication listed, and a

are presented in tabular f o r m . An asterisk b e f o r e the n a m e indi-

limited search for this i n f o r m a t i o n was unsuccessful. T h e s e trilo-

cates that the n a m e is no longer valid. T h e s e n a m e s were included

bites are listed, however, for completeness.

because they are represented in m u s e u m s or often listed in the

T h e location

information

includes

the

county,

and

only

literature.

New York counties are m e n t i o n e d . We did not a t t e m p t to m a k e this location i n f o r m a t i o n all-inclusive; thus, for m o s t species, it is only representative. M a n y New York trilobites can be f o u n d wherever the appropriate rock unit is exposed. We identified the trilobites by surveying the literature and by going through the collections of a few m a j o r m u s e u m s . T h e referenced m u s e u m s are the A m e r i c a n M u s e u m of Natural History ( A M N H ) ; Canadian Geological Survey ( O t t a w a )

(GSC);

Carnegie M u s e u m i n Pittsburgh ( C M ) ; M u s e u m o f C o m p a r a t i v e Zoology

at

Harvard

History

(USNM),

Natural

History

Museum

(MCZ);

sometimes Museum

(Natural History))

National

Museum

called just " t h e

of

London

o f Natural

Smithsonian";

(formerly

the

British

( B M ) ; New York State M u s e u m

( N Y S M ) ; Paleontological Research Institution ( P R I ) ; Peabody

5.1 ORDER AGNOSTIDA T h e agnostids are small trilobites, usually less than 12 mm (0.5 inch) long, characterized by having cephala and pygidia of a b o u t the s a m e size and never m o r e than two or three thoracic segments. T h e r e are two suborders, Agnostina and Eodiscina. In the past, s o m e workers considered the Agnostida as a different a r t h r o p o d class than trilobites, but current thinking is that they are indeed part of the class Trilobita. Agnostids are found from the C a m b r i a n through the O r d o v i c i a n , but in New York they have only been reported f r o m the C a m b r i a n rocks, primarily the a l l o c h t h o n o u s rocks on the western edge of the Taconics. T h e o r d e r is significantly revised in Treatise (revised).

Museum at Yale ( Y P M ) ; Rochester M u s e u m and Science C e n t e r ( R M S C ) ; Royal O n t a r i o M u s e u m ( R O M ) ; Buffalo M u s e u m o f

Suborder Agnostina

Science ( B M S ) ; O h i o State University ( O S U ) ; San Diego Natural History

Museum

(SDMNH);

and

University

of

Michigan

T h e agnostins have no eyes, two t h o r a c i c segments, and no facial sutures. T h e pygidium has three or fewer axial rings. As is

M u s e u m o f Paleontology ( U M M P ) . W h e n k n o w n , the location

so

of the holotype is given, but in most instances only the location

are u n k n o w n . Table 5.1 lists the families and species within this

of representative specimens is given. Any designations o t h e r than

suborder.

often

the

case

with

agnostids,

the

thoracic

segments

117

118

THE

TRILOBITES

Table 5 . 1 . Trilobites of the suborder Agnostina FAMILY

NAME

SPECIMENS

LOCATION

Diplagnostidae

Baltagnostus angustilobus (Rasetti, 1967) Baltagnostus stockportensis (Rasetti, 1967)

Holotype USNM 156565 Holotype USNM 156567

Middle Cambrian, Nutten Hook, Columbia County; see Bird and Rasetti (1968, p. 32). Middle Cambrian, Stockport Station, Columbia County; see Bird and Rasetti (1968, p. 26).

Peronopsidae

Peronopsis evansi (Rasetti and Theokritoff, 1967) Peronopsis primigenea (Kobayashi, 1939)

Holotype MCZ 8546 Lectotype USNM 18328

Lower Cambrian, Washington County, New York.

Ptychagnostidae

Ptychagnostus gibbus (Linnarsson, 1869) Ptychagnostus punctuosus (Angelin. 1851)

Plesiotypes USNM 156552, 156553 Plesiotypes USNM 156551

Middle Cambrian, Columbia County; see Bird and Rasetti (1968. p. 11). Type species. Middle Cambrian, Columbia County; see Bird and Rasetti (1968, p. 28).

Spinagnostidae

Eoagnostus acrorachis (Rasetti and Theokritoff, 1967) Eoagnostus primigeneus (Kobayashi, 1939) Hypagnostus parvifrons (Linnarsson, 1869)

Holotype MCZ 8544

Lower Cambrian, West Castleton Formation, Washington County, New York.

Cotype USNM 18328 Plesiotypes USNM 156561 to 156563

Lower Cambrian.

Suborder Eodiscina Plate 1 T h e eodiscins have two or three t h o r a c i c s e g m e n t s and four o r m o r e axial s e g m e n t s o n the pygidium, and m a y b e w i t h o u t eyes or facial sutures. In the Treatise (revised), the s u b o r d e r has been significantly t a x o n o m i c a l l y revised, a n d new family struc-

Lower Cambrian, Washington County, New York.

Type species. Middle Cambrian. Columbia County; see Bird and Rasetti (1968, p. 68). The holotype is from Sweden.

5.3 ORDER CORYNEXOCHIDA Family Dolichometopidae Athabaskiella cf. A. proba

(Walcott)

Middle C a m b r i a n , S t o c k p o r t Station, C o l u m b i a County. See Bird and Rasetti ( 1 9 6 8 , p. 2 8 ) .

tures assigned. Table 5.2 lists the families and species within this Bathyuriscidella cf.

suborder.

B.

socialis

(Rasetti)

Middle C a m b r i a n , S t o c k p o r t Station, C o l u m b i a County. See Bird and Rasetti ( 1 9 6 8 , p. 2 8 ) .

5.2 ORDER REDLICHIIDA T h e redlichiids are the m o s t primitive and earliest k n o w n of the trilobites. T h e y generally have a relatively large, semicircular cephalon with long genal spines, n u m e r o u s t h o r a c i c segments, and a very small pygidium. T h e o n l y well-known m e m b e r of this order in New York is Elliptocephala asaplwides, a Lower C a m b r i a n trilobite from the s u b o r d e r Olenellina, a s u b o r d e r representing the earliest o f the k n o w n trilobites. T h e holaspids o f the olenellins do not show facial sutures.

eboracensis

(Rasetti,

1967)

Holotype U S N M 156654 Middle C a m b r i a n , S t o c k p o r t Station, C o l u m b i a County. See Bird and Rasetti ( 1 9 6 8 , p. 2 6 ) . Bathyuriscus cf. B.

fibriatus

(Robison)

M i d d l e C a m b r i a n , S t o c k p o r t Station, C o l u m b i a County. See Bird and Rasetti ( 1 9 6 8 , p . 2 8 ) .

Family Holmiidae Elliptocephala asaphoides E m m o n s ,

Bathyuriscus

Corynexochides? 1 8 4 6 Plate 2

Type N Y S M 4 9 5 4

expansus

(Rasetti,

1967)

H o l o t y p e U S N M 156651 Middle C a m b r i a n , S t o c k p o r t Station, C o l u m b i a County. See

Type species. T h i s trilobite is f r o m the Lower C a m b r i a n ,

Bird and Rasetti ( 1 9 6 8 , p. 2 6 ) .

Nassau F o r m a t i o n , Troy, Rensselaer C o u n t y . It also is reported f r o m n u m e r o u s Lower C a m b r i a n l i m e s t o n e sites in C o l u m b i a

Family Dorypygidae

C o u n t y (see Bird and Rasetti

Fordaspis nana ( F o r d , 1 8 7 8 )

1 9 6 8 ) . T h i s is an apparently

deep-water trilobite f o u n d in Lower C a m b r i a n a l l o c h t h o n o u s dark shales. T h e s p e c i m e n in Plate 2 is rust colored on a black matrix.

Hypotypes N Y S M 1 1 0 4 7 , 1 1 0 4 8 Type

species.

Goldring ( 1 9 4 3 ) .

Lower

Cambrian,

Nassau

Formation.

See

Table 5.2. Trilobites of the suborder Eodiscina FAMILY Calodiscidae

NAME Calodiscus agnostoides

(Kobayashi, 1943) Calodiscus

fissifrons

(Rasetti, 1966) Calodiscus

lobatus

(Hall, 1847) Calodiscus meeki (Ford,

1876) Calodiscus

occipitalus

(Rasetti, 1966) Calodiscus

reticulatus

(Rasetti, 1966) Calodiscus

schucherti

(Matthew, 1896) Calodiscus

theokritoffi

(Rasetti, 1967) Calodiscus

walcotti

(Rasetti, 1952) Chelediscus

chathamsis

(Rasetti, 1967) Eodiscidae

Pagetia bigranulosa

(Rasetti, 1967) Pagetia

connexa

SPECIMEN

LOCATION

Holotype USNM 116356 Holotype USNM 146004 Syntype AMNH 210 Holotype NYSM 4587 Holotype USNM 146003 Holotype USNM 146006 Syntype ROM 138 Holotype GSC 105 Holotype USNM 26710 Holotype USNM 156584

Lower Cambrian, Schodack Formation, Salem, Washington County Lower Cambrian, Columbia County. Type species. Lower Cambrian, Nassau Formation, found at Troy, Rensselaer County, and in Washington County. Lower Cambrian, Schodack Formation. Troy, Rensselaer County. Lower Cambrian, Columbia County. Lower Cambrian, Columbia County. Lower Cambrian, Schodack Formation, Troy, Rensselaer County. Lower Cambrian, Maiden Bridge roadcut, Columbia County; see Bird and Rasetti (1968, p. 11). Lower Cambrian, Schodack Formation, near Greenwich, Washington County. Lower Cambrian, Maiden Bridge roadcut, Columbia County; see Bird and Rasetti (1968, p. 11).

Holotype USNM 1566 Holotype USNM

Lower Cambrian, Griswold Farm, Columbia County; see Bird and Rasetti (1968, p. 5). Lower Cambrian, Washington County.

Holotype USNM 156615 Holotype USNM 156613 Holotype USNM 156610 Plesiotypes USNM 156632, 156633 Plesiotypes USNM 156618 Plesiotypes USNM 156626 to 156628 Plesiotypes USNM 156621 to 156625 Plesiotypes USNM 156629 to 156631

Middle Cambrian, Griswold Farm, Columbia County; see Bird and Rasetti (1968, p. 5). Middle Cambrian, Griswold Farm, Columbia County; see Bird and Rasetti (1968, p. 5). Lower Cambrian, Riders Mills and Griswold Farm, Columbia County; see Bird and Rasetti (1968, p. 5). Lower Cambrian, Griswold Farm, Columbia County; see Bird and Rasetti (1968, p. 5). Type species. Lower Cambrian, numerous sites in Columbia County; see Rasetti (1967). Lower Cambrian, Griswold Farm, Columbia County; see Bird and Rasetti (1968, p. 5). Lower Cambrian, numerous sites in Columbia County; see Rasetti (1967). Lower Cambrian, Griswold Farm, Columbia County; see Bird and Rasetti (1968, p. 5).

Holotype USNM 156637 Holotype USNM 156634

Lower Cambrian, 1.6km (1 mile) east of Salem, Washington County. Lower Cambrian, Griswold Farm, Columbia County; see Bird and Rasetti (1968, p. 5).

Holotype USNM 145987 Holotype USNM 145989 Holotype USNM 145991 Holotype USNM 145093 Holotype USNM 156575 Holotype USNM 145955

Type species. Lower Cambrian, Griswold Farm, Columbia County; see Bird and Rasetti (1968, p. 5). Lower Cambrian, Columbia County.

(Walcott, 1891) Pagetia

clytioides

(Rasetti, 1967) Pagetia erratica (Rasetti,

1967) Pagetia laevis (Rasetti,

1967) Pagetides

amplifrons

(Rasetti, 1945) Pagetides

elegans

(Rasetti, 1945) Pagetides

leiopygus

(Rasetti, 1945) Pagetides

minutus

(Rasetti, 1945) Pagetides

rupestris

(Rasetti, 1948) Hebediscidae

Hebediscus marginatus

(Rasetti, 1967) Neopagetina

taconica

(Rasetti, 1967) Weymouthiidae

Acidiscus bird! (Rasetti, 1966) Acidiscus

hexacanthus

(Rasetti, 1966) Acimetopus

bilobatus

(Rasetti, 1966) Analox

bipunctata

(Rasetti, 1966) Analox obtusa (Rasetti,

1967) Bathydiscus dolichometopus

Type species. Lower Cambrian, Columbia County. Type species. Lower Cambrian, Columbia County. Lower Cambrian, Griswold Farm, Columbia County; see Bird and Rasetti (1968, p. 5). Type species. Lower Cambrian, Columbia County.

(Rasetti, 1966) Bolboparia

elongata

(Rasetti, 1966)

Holotype USNM 146001

Lower Cambrian, Columbia County.

120

THE

TRILOBITES

Table 5.2. Continued FAMILY

NAME Bolboparia

superba

(Rasetti, 1966) Leptochilodiscus

punctulatus

(Rasetti,

SPECIMEN

LOCATION

Holotype USNM 145998 Holotype USNM 146009

Type species. Lower Cambrian, Columbia County.

Holotype USNM 146012 Holotype USNM 18327

Type species. Lower Cambrian, Columbia County.

Lower Cambrian, Griswold Farm, Columbia County; see Bird and Rasetti (1968, p. 5); also found in Quebec.

1966) Litometopus

longispinus

(Rasetti, 1966) Mallagnostus

desideratus

(Walcott,

Washington County, New York. See Rasetti and Theokritoff (1967) for a discussion of this species.

i o y i)

Microdiscus?

Lower Cambrian, Nassau Formation; the genus Microdiscus is no longer used so this species is probably Eodiscus.

(Eodiscus)

connexus (Walcott,

1890) Oodiscus

binodosus

(Rasetti, 1966) Oodiscus

longifrons

(Rasetti, 1966) Oodiscus

subgranulatus

(Rasetti, 1966) Serrodiscus

griswoldi

(Rasetti, 1967) Serrodiscus

latus

(Rasetti, 1966) Serrodiscus

speciosus

(Ford, 1873) Serrodiscus

spinulosus

(Rasetti, 1966) Serrodiscus

subclovatus

(Rasetti, 1966) Stigmadiscus

gibbosus

(Rasetti, 1966) Stigmadiscus

stenometopus

(Rasetti,

Holotype USNM 146016 Holotype USNM 146018 Holotype USNM 146014 Holotype USNM 156596 Holotype USNM 146024 Lectotype NYSM 4588 (Rasetti, 1952) Holotype USNM 14602 Holotype USNM 146022 Holotype USNM 146031 Holotype USNM 146029

Lower Cambrian, Columbia County. Lower Cambrian, Columbia County. Lower Cambrian, Columbia County. Lower Cambrian, Griswold Farm, Columbia County; see Bird and Rasetti (1968, p. 11). Lower Cambrian, Griswold Farm, Columbia County; see Bird and Rasetti (1968, p. 5). Type species. Lower Cambrian, Schodack Formation, Troy. Rensselaer and Washington Counties. Lower Cambrian, Maiden Bridge roadcut, Columbia County; see Bird and Rasetti (1968, p. 11). Lower Cambrian, Columbia County. Lower Cambrian, Griswold Farm and Maiden Bridge, Columbia County; see Bird and Rasetti (1968, p. 5, 11). Lower Cambrian, Griswold Farm and Maiden Bridge, Columbia County; see Bird and Rasetti (1968, p. 5, 11).

1966) Weymouthia

nobilis

(Ford, 1873)

Kootenia fordi

Plesiotype MCZ 105039

(Walcott)

Lower Cambrian, Nassau Formation, Troy, Rensselaer County. The type is from Massachusetts.

is in the Lower Silurian Rochester Shale. T h e family is characterized

Lower C a m b r i a n , Nassau F o r m a t i o n .

by a s m o o t h , vaulted cephalon with no glabellar furrows. T h e posterior of the glabella is often outlined by weakly depressed furrows.

Olenoides

stissingensis

Specimen N Y S M

(Dwight)

T h e s e furrows rarely extend to the anterior portion of the c r a n i d i u m . T h e facial sutures are o p i s t h o p a r i a n , and the eyes are broadly

17011

Stissing L i m e s t o n e , Stissing M o u n t a i n , Dutchess C o u n t y , New

set near the cephalic m a r g i n s . T h e r e are eight to ten unfurrowed

York. T h e specimen is a s a n d s t o n e slab with m a n y disarticulated

t h o r a c i c s e g m e n t s . T h e pygidium is similarly vaulted and s m o o t h .

trilobite parts.

T h e pygidium, when f o u n d separately, often resembles a dark t h u m b n a i l . Lane and T h o m a s (1983) moved a n u m b e r of f o r m e r

Olenoides stockportensis

(Rasetti,

illaenids into the family Styginidae. A large n u m b e r of species have

1967)

H o l o t y p e U S N M 156668 Middle

Cambrian,

Stockport

been described from New York, but this may well be oversplitting, Station,

Columbia

County.

particularly in the Trenton species, which need r e d e s c r i p t i o n . S h a w

See Bird and Rasetti (1968, p. 26).

(1968) redescribed most of the Chazy material.

Family lllaenidae

Bumastoides aplatus

Ulaenids are first f o u n d in the Lower O r d o v i c i a n and disappear

(Raymond,

1925)

H o l o t y p e M C Z 101150

by the end of the Silurian. In New York they are first f o u n d in the

T h i s illaenid is from Middle Ordovician Chazy. For location

lower M i d d l e Ordovician Chazy G r o u p , and the last representative

i n f o r m a t i o n , see Shaw (1968). T h e c r a n i d i u m is semicircular in

ORDER

CORYNEXOCHIDA

121

dorsal view and about half as long as wide. T h e axial furrows are

the internal cast. T h e s e pits have n o t been seen on specimens

faint. T h e t h o r a x is u n k n o w n . T h e pygidium is s m o o t h , vaulted,

f r o m l o c a t i o n s o t h e r than the W a l c o t t - R u s t Quarry. T h e speci-

and without furrows. T h e s m o o t h cephalon and pygidium differ

m e n in Plate 4 is partially exfoliated and shows, on the left side,

from all other Chazy illaenids. R a y m o n d also listed it as f r o m

the lunette and its position relative to the eye. Plate 5 is a side

Vermont and Tennessee.

view of a n o t h e r s p e c i m e n f r o m the s a m e collection, also showing the lunette.

Bumastoides?

bellevillensis

(Raymond

and

Narraway,

1908)

Type C M 1900; s p e c i m e n s M C Z 7 2 0 , 7 1 9 Both

MCZ

specimens

are

from

the

Bumastoides milleri Middle

Ordovician.

N u m b e r 7 2 0 is from the Trenton L i m e s t o n e at Sugar River, Lewis

(Billings,

1859)

Plate 6

Holotype G S C 1319b; specimens U S N M 72265; M C Z 7 2 1 , 722; PRI 6455

County, and 7 1 9 is from the Black River Limestones at Buck's

T h e h o l o t y p e is f r o m O n t a r i o . T h e s p e c i m e n s in the U S N M

Quarry near Poland, H e r k i m e r C o u n t y . B o t h are cranidia in

are f r o m the M i d d l e O r d o v i c i a n Lowville M e m b e r of the Black

C. D. Walcott's collections.

River G r o u p . T h e y are listed f r o m W a t e r t o w n , Lewis County. O t h e r s p e c i m e n s are f r o m quarries near N e w p o r t , H e r k i m e r

Bumastoides billingsi

(Raymond

and

Narraway,

1908)

County. S p e c i m e n s in the M C Z are f r o m Walcott's collections and

Type C M 5 4 7 2 , hypotype G S C 331

are labeled f r o m the Black River L i m e s t o n e s at Buck's Q u a r r y

T h e type of this species is from Hull, Q u e b e c . T h e species dif-

near Poland, H e r k i m e r C o u n t y , and f r o m the lower Trenton at

ferentiation from other similar Trenton s p e c i m e n s is based pri-

Rawlin's Mills ( n e a r Saratoga, Saratoga C o u n t y ) . D e M o t t ( 1 9 8 7 )

marily on size. T h e length, 60 and 83 m m , is m u c h greater than

listed s p e c i m e n s from Illinois and W i s c o n s i n . T h e s p e c i m e n in

that of B. trentonensis and B.

milleri; the dorsal furrows on the

cephalon are also stronger and those on the t h o r a x are wider

Plate 6 is f r o m W a t e r t o w n and was listed on the label from the Trenton G r o u p .

apart. Bumastoides porrectus Bumastoides

gardenensis

(Shaw,

1968)

(Raymond,

1925)

Plate

7

Holotype M C Z 101147

Holotype N Y S M 12456

T h e type for this M i d d l e O r d o v i c i a n trilobite is from the

This small illaenid from the Middle O r d o v i c i a n Chazy is very

W a l c o t t - R u s t Quarry, H e r k i m e r C o u n t y , in the Rust M e m b e r of

similar to B. aplatus. For location i n f o r m a t i o n , see Shaw ( 1 9 6 8 ) .

the T r e n t o n G r o u p . T h e species was described to replace B. tren-

Bumastoides globosus

definition. T h e cephalon has faint dorsal furrows, and the eyes

tonensis because, in the o p i n i o n of R a y m o n d , the latter has a p o o r (Billings,

1859)

Plate

3

Lectotype G S C 1 0 9 0 B (Shaw, 1968)

are situated far b a c k and wide apart. T h e t h o r a x has a wide axial

This Middle Ordovician Chazy species is defined as having

lobe and ten t h o r a c i c s e g m e n t s . T h e pygidium is s h o r t and

a wide axis, well-developed cephalic axial furrows, and a b r o a d

without a trace of an axial l o b e . T h e entire exoskeleton is s m o o t h .

s m o o t h pygidium. F o r location i n f o r m a t i o n , see Shaw ( 1 9 6 8 ) .

T h e h o l o t y p e is figured in Plate 7. D e M o t t ( 1 9 8 7 ) also listed B.

T h e specimen in Plate 3 is a rare, articulated s p e c i m e n from

porrectus f r o m W i s c o n s i n and Iowa. B o l t o n ( 1 9 6 6 ) listed speci-

the Chazy G r o u p . Articulated trilobites f r o m the Chazy are

m e n s from O n t a r i o and Q u e b e c .

rare, probably because the Chazy c o m m o n l y represents a highenergy e n v i r o n m e n t not conducive to the preservation of articu-

* Bumastoides

lated specimens.

Plastotype A M N H 8 4 7 ; hypotypes N Y S M 4 1 5 8 , 1 0 7 5 7

trentonensis

(Emmons,

1842)

N Y S M 4 1 5 8 is labeled as the " T y p e of G e o l o g y of New York, Bumastoides holei (Foerste,

1920)

Plates 4 and 5

Report o f the 2 n d District, 1 8 4 2 , p . 3 9 0 " and " G e o l o g i c a l Survey

Hypotype M C Z 1 0 1 1 4 8

of M i n n e s o t a , 1 8 9 6 , p. 7 2 0 , Figure 3 2 . " T h e r e is also a label with

T h e type of this species is from the Middle Ordovician Kimmswick

Limestone

of M i s s o u r i .

It

was

redescribed

by

the

specimen

for

Bumastus porrectus

Raymond.

NYSM

10757

is listed from the R o c k l a n d ( N a p a n e e ) M e m b e r of the Trenton

R a y m o n d ( 1 9 2 5 ) with material from the W a l c o t t - R u s t Quarry,

at Wells, H a m i l t o n C o u n t y ( F i s h e r ) . T h i s M i d d l e Ordovician

Herkimer

a

Trenton species was a b a n d o n e d b y R a y m o n d ( 1 9 2 5 ) because o f

cephalon m u c h larger than the pygidium. T h e cephalon is evenly

its p o o r definition. Given the existence of the hypotypes, there is

convex, with a slight longitudinal m e d i a n depression. T h e eyes

reason to question R a y m o n d ' s decision.

County.

The

specimens

from

New York

have

are small, wide apart, and close to the posterior margin. T h e r e is a small median tubercle just in front of the posterior cephalic

Illaenus

margin. T h e axial lobe of the t h o r a x is very wide. T h e t h o r a x has

Holotype N Y S M 4499

arcturus

(Hall,

1847)

ten thoracic segments. T h e pygidium has no trace of an axial lobe.

T h e type of this species, labeled from the Middle Ordovician

T h e entire exoskeleton is granulose with c o r r e s p o n d i n g pits on

Chazy G r o u p , was studied by Shaw ( 1 9 6 8 ) , w h o concluded that

122

THE

TRILOBITES

the s p e c i m e n was in too p o o r c o n d i t i o n for c o m p a r i s o n with

H e r k i m e r C o u n t y , and in the Wells Outlier, Hamilton County,

o t h e r illaenids of the Chazy. He did believe it had definite

by Fisher ( 1 9 5 7 ) . T h e specimen in Plate 9 is labeled from the

nanillaenid character and the m a t r i x was unlike any of those he

Bowmanville Q u a r r y in O n t a r i o . This would place it high in

was familiar with in the Chazy. Chazy s p e c i m e n s assigned by

Trenton age rocks.

Raymond Thaleops

(1910b)

longispina

as

Thaleops

(Shaw,

arctura

became

the

basis

for

1968).

Nanillaenus?punctatus

(Raymond,

1905)

H o l o t y p e C M 1 2 7 8 , s p e c i m e n N Y S M 17015 Illaenus consimilis ( B i l l i n g s , 1 8 6 5 )

T h i s rare middle Chazy species is o n e of the most easily char-

Specimens U S N M 72319, 72317

acterized, as the entire surface of the cephalon is covered with

U S N M 7 2 3 1 9 is from the M i d d l e O r d o v i c i a n Trenton Walcott-

small pits or p u n c t a , and the anterior slope of the cephalon is

Rust Quarry, H e r k i m e r C o u n t y , and U S N M 7 2 3 1 7 is f r o m the

covered with terrace lines so distinct that R a y m o n d referred to

Trenton at Ellisburg, Jefferson C o u n t y . T h e types are from Table

t h e m as c o n c e n t r i c wrinkles. For location i n f o r m a t i o n , see Shaw

Head, N e w f o u n d l a n d ( B o l t o n , 1 9 6 6 ) .

(1968).

Nanillaenus americanus (Billings,

1859)

Plate 8

Nanillaenus? raymondi (Shaw,

Specimens N Y S M 17013, 17014 This

Middle

Ordovician

1968)

Plate

10A

H o l o t y p e N Y S M 12491

trilobite

is

well

represented

in

Nanillaenus? raymondi from

the Middle Ordovician Chazy is

N Y S M , U S N M , and M C Z collections f r o m W a l c o t t - R u s t Q u a r r y ,

characterized as being very similar to N.? punctatus, with the

Herkimer C o u n t y , in the Middle Trenton Rust L i m e s t o n e . T h e

exception that the cephalic outline in dorsal view is subtriangu-

cephalon on this small trilobite is considerably larger than the

lar rather than semicircular and the f o r m e r possesses a spine on

pygidium. Axial furrows on the cephalon are only developed on

the tree cheek. For location i n f o r m a t i o n , see S h a w I 1968).

the posterior region. T h e eyes are set well b a c k and far apart. T h e free cheeks have a p r o m i n e n t blunt angle. T h e furrows on

Thaleops longispina

the thorax are well defined. T h e r e are eight t h o r a c i c s e g m e n t s .

H o l o t y p e N Y S M 12922

T h e pygidium has a similarly well-defined axis over half the length of the pygidium. T h e s p e c i m e n in Plate 8 is from the M C Z

(Shaw,

1968)

Plate

10B

T h i s trilobite is from the Middle Ordovician Chazy limestones.

F o r location

i n f o r m a t i o n , see

Shaw

(1968).

Thaleops

and illustrates the difference between these trilobites and Bumas-

longispina

toides s p e c i m e n s f o u n d in the s a m e rocks.

cephalon and pygidium. T h e glabella is outlined by deep furrows,

is a

short, wide trilobite with

a

broadly rounded

which are parallel for half their length and then turn outward and Nanillaenus cf. N. conradi ( B i l l i n g s ,

1859)

down on the front of the c e p h a l o n . T h e eyes are raised on tapered

Syntypes G S C 1 3 2 0 , 1 3 2 0 a ; hypotype N Y S M 1 0 7 4 9 ; s p e c i m e n

stalks, which reach up and out at about a 4 5 - d e g r e e angle. T h e r e

N Y S M 17012

are long, narrow genal spines. T h e t h o r a x has ten segments. T h e

Type species. T h i s trilobite is listed from the M i d d l e O r d o v i -

pygidial axis is outlined by deep grooves and extends about half

cian Upper Black River C h a u m o n t L i m e s t o n e in Wells, H a m i l t o n

the length of the pygidium. B o t h the c r a n i d i u m and pygidium

County, by Fisher ( 1 9 5 7 ) . T h e syntypes are from the M i d d l e

are covered with small pits.

Ordovician Leray beds o f Q u e b e c ( B o l t o n 1 9 6 6 ) . Thaleops Nanillaenus latiaxiatus ( R a y m o n d a n d Narraway, 1 9 0 8 ) Plate 9 Type C M 5471

ovata

(Conrad,

1843)

Holotype A M N H 1011/3 Type species. T h e type is from W i s c o n s i n , in rocks with fossils

T h e type is from the M i d d l e O r d o v i c i a n Black River L i m e -

that are clearly Middle Ordovician Trenton age (Hall, 1 8 4 7 ) .

stones at Mechanicsville, near O t t a w a , C a n a d a . R a y m o n d and

Reports of T. ovata from the Chazy of New York are wrong (see

Narraway

Shaw 1 9 6 8 ) . R u e d e m a n n ( 1 9 0 1 ) found two pygidia in a gray crys-

suggested

that

many

of

the

Nanillaenus

americanus

specimens reported from the Black River are this species. T h e

talline limestone within the Rysedorph C o n g l o m e r a t e that agreed

species is similar to the latter trilobite except in the t h o r a x and

with the descriptions of 7! ovata. He also stated that specimens

the pygidium. T h e t h o r a x has ten segments, versus eight in N.

like those of T. ovata from other areas outside New York are found

americanus. T h e pygidium is about as long as the t h o r a x , s o m e -

in strata c o r r e s p o n d i n g to the Black River Lowville Limestone.

what rectangular in outline, three-fifths long as wide. T h e sides

D e M o t t ( 1 9 8 7 ) listed T. ovata from Illinois and W i s c o n s i n .

of the pygidium are abruptly t r u n c a t e d to right angles with the anterior margin. T h e axial lobe is strongly convex and outlined

Family Styginidae

by deep furrows on the sides. T h e axial lobe is a b o u t half the

Lane and T h o m a s ( 1 9 8 3 ) revised the family Styginidae to

length of the pygidium. T h i s trilobite is reported in the Black

include the family Thysanopeltidae and s o m e illaenids. T h e

River rocks at Pattersonville, Schenectady C o u n t y , and N e w p o r t ,

genus Bumastus is now considered a styginid. Holloway and Lane

ORDER

CORYNEXOCHIDA

123

( 1 9 9 8 ) , however, consider that of the New York trilobites assigned

genus Illaenoides and the trilobites he describes from Wisconsin

to Bumastus, only Bumastus ioxus is assigned with

do not differ from those f o u n d in the Rochester Shale.

confidence.

Styginids are rarely e n c o u n t e r e d in New York. In general, the glabella expands strongly forward, the genal angle is acute, the

Platillaenus

pleurae have narrow spines beyond the edge of the t h o r a x ,

L e c t o t y p e Y P M 7 4 1 0 A (Shaw, 1 9 6 8 )

and the pygidium is large and the back of the a n t e r i o r edge is

erastusi

(Raymond,

1905)

T h i s trilobite a n d the following P.

limbatus are from the

oval. T h e y are f o u n d from the Middle O r d o v i c i a n to the Upper

Middle O r d o v i c i a n Chazy G r o u p . See Shaw ( 1 9 6 8 ) for detailed

Devonian.

descriptions and locations.

Bumastus ioxus (Hall, 1 8 5 2 ) Plate 11

Platillaenus

Holotype A M N H 1821/1

L e c t o t y p e Y P M 2 3 3 0 1 (Shaw, 1 9 6 8 )

T h e holotype for B. ioxus is from W i s c o n s i n , a n d the specimens from the Lower Silurian Rochester Shale in western New

limbatus

(Raymond,

1910)

Middle O r d o v i c i a n Chazy G r o u p . For location i n f o r m a t i o n , see Shaw ( 1 9 6 8 ) .

York have long been assigned to this species. Small whole specimens are often found, s o m e t i m e s in groups, in the lower parts of

Scutellum

the Lewiston M e m b e r in Niagara C o u n t y (Tetreault 1 9 9 4 ) . T h i s

Type N Y S M 4 1 4 9

trilobite is s m o o t h and oval. T h e cephalon has widely spaced eyes. T h e axial furrows are faint and fade toward the front. T h e pygid-

barrandi

(Hall,

1859)

An undisclosed location in the Lower D e v o n i a n C o e y m a n s Limestone.

ium has a semicircular shape. T h e specimen in Plate 11 is m u c h larger than those usually f o u n d . T h e large s p e c i m e n s and the

Scutellum

smaller ones are found in different h o r i z o n s within the R o c h e s t e r

H o l o t y p e A M N H 1830

Shale. Compression due to the weight of the overlying sediments has flattened the s p e c i m e n , causing the edges of the cephalon and pygidium to crack.

niagarensis

Scutellum

(Hall,

1852)

Plate

16

niagarensis was originally f o u n d in a float boulder

at Niagara Falls, Niagara C o u n t y . O n l y the pygidium was originally described. T h e pygidium is very b r o a d and semicircular. Plate 16 also shows the previously undescribed c e p h a l o n . It is also

Eobronteus lunatus (Billings,

1857)

Plate

reported from the M i d d l e Silurian Reynales L i m e s t o n e in Wayne

12

Holotype G S C 1 7 8 1 , hypotype N Y S M 4 1 5 0 , s p e c i m e n N Y S M

C o u n t y (Gillette 1 9 4 7 ) .

17016 Ruedemann ( 1 9 0 1 ) reported this species f r o m M i d d l e O r d o v i cian Trenton pebbles in the Rysedorph C o n g l o m e r a t e , Rensselaer County. It is geographically widely distributed, being reported

Scutellum

pompilius

(Billings,

1863)

G o l d r i n g ( 1 9 4 3 ) listed this species as f r o m the Lower Devonian Kalkberg in C o l u m b i a C o u n t y .

from C a n a d a , M i n n e s o t a , and New Jersey. T h e h o l o t y p e is f r o m the Middle Ordovician of O n t a r i o . T h e specimen in Plate 12 is

Scutellum rochesterense (Howell a n d S a n f o r d ,

from Snake Hill Shales in Saratoga C o u n t y .

H o l o t y p e Princeton University 5 7 6 9 6 a ( n o w U S N M ) Lower

Failleana

indetermitiata

(Walcott,

1877)

Plate

13

Silurian

Irondequoit

Limestone

1946)

Plate 2 6 B

of the

Rochester,

M o n r o e C o u n t y , area.

Holotype M C Z 1 0 4 9 2 8 T h e holotype is from the Middle O r d o v i c i a n Black River Group limestone at Buck's Q u a r r y , Poland, H e r k i m e r County.

Scutellum senescens ( C l a r k e ,

1889)

Plate

17

H o l o t y p e N Y S M 4 1 5 1 ; hypotypes N Y S M 4 1 5 2 , 4 1 5 3

T h e relatively large type specimen was figured for the first t i m e

Upper Devonian C h e m u n g o f western New York. T h e hypo-

by R a y m o n d ( 1 9 1 6 ) and is shown in Plate 13. T h e s p e c i m e n is

type s p e c i m e n s were f o u n d while recovering the glass sponge

from the Walcott collection at M C Z . W i l s o n ( 1 9 4 7 ) reported the

Hydnoceras

trilobite from the lower Trenton Rockland beds of C a n a d a .

County. Trilobites are very rare in the Upper Devonian of New

from

a

Chemung

outcrop

near

Avoca,

Steuben

York, and the o n e illustrated in Plate 17 is an excellent example Illaenoides cf. /. trilobita (Weller, 1 9 0 7 ) Plates 14 a n d 15

of a very u n c o m m o n species.

Hall and Clarke ( 1 8 8 8 , plate 6 6 , Figures 1 - 5 ) T h e presence of a second illaenid in the Lower Silurian Rochester Shale, other than Bumastus ioxus, was long u n r e c o g nized.

Illaenoides

trilobita

is

easily

differentiated

Scutellum tullius (Hall a n d C l a r k e , 1 8 8 8 ) Plate 18 Syntypes N Y S M 4 1 5 4 , 4 1 5 5

by the c o m -

Middle Devonian Tully L i m e s t o n e . N Y S M 4 1 5 4 is from Kings-

paratively larger cephalon and the distinctive b o r d e r on the

ley's Hill near Otisco, O n o n d a g a C o u n t y . S p e c i m e n s are reported

pygidium, and the axial furrows on b o t h the cephalon and the

f r o m a q u a r r y near Spafford, O n o n d a g a County. C o o p e r and

pygidium are well defined. Weller ( 1 9 0 7 ) first recognized the new

W i l l i a m s ( 1 9 3 5 ) described the trilobite and listed a n u m b e r of

THE

124

TRILOBITES

locations. T h e illustrated s p e c i m e n s were f o u n d by Professor

William Rust. It is probable that the specimen is from the

Wells of Cornell University and the r e c o n s t r u c t i o n is an u n p u b -

W a l c o t t - R u s t Q u a r r y , H e r k i m e r County. R u e d e m a n n c o m p a r e d

lished drawing of his.

this s p e c i m e n to A. halli ( U p p e r O r d o v i c i a n , O h i o ) and found significant differences. He m a d e no c o m p a r i s o n s with any of

Scutellum wardi (Howell and S a n f o r d ,

1947)

the New York amphilichids. R u e d e m a n n did report evidence that

Holotype U S N M 488132

the h o l o t y p e c r a n i d i u m was covered with thin spines, an obser-

T h e type is a single pygidium f r o m the Upper Silurian O a k Orchard

M e m b e r o f the L o c k p o r t G r o u p

vation not reported in any of the other New York amphilichids

i n the Rochester,

n o r does it appear to be supported by our own examination of

M o n r o e County, area. T h e axis is very s h o r t , and the entire

the h o l o t y p e and o t h e r specimens. T h e glabella has a low

surface is s m o o t h .

rounded shape quite different from that of A. cornutus. T h e illustrated pygidium from R u e d e m a n n ( N Y S M 9 6 0 8 ) differs from A.

Family Zacanthoididae Prozacanthoides

eatoni

cornutus in that the pygidal lappets closest to the axis are drawn

(Walcott,

1891)

as forked on their ends. ( C l o s e e x a m i n a t i o n of the paratype does

Holotype U S N M

not appear to support this c o n c l u s i o n that the pygidial lappets

Lower C a m b r i a n , W a s h i n g t o n C o u n t y , New York.

are forked.) T h e h o l o t y p e is identical to specimens in the M C Z , f r o m the W a l c o t t - R u s t Q u a r r y , c o n f i r m i n g that N Y S M 9 6 0 7 is a

5 . 4 ORDER LICHIDA Family Lichidae

different species than A. cornutus.

Trilobites of the family Lichidae are first f o u n d in the Lower Ordovician and disappear at the end of the D e v o n i a n . In New

Amphilichas cornutus

(Clarke,

1894)

Plate

19

Holotype N Y S M 4533; specimens U S N M 2 6 3 4 1 , 72629

York they range f r o m the M i d d l e O r d o v i c i a n to the M i d d l e

T h e h o l o t y p e , illustrated in Plate 19, is an articulated speci-

D e v o n i a n . Lichids are very distinctive in their glabellar outline

m e n that was badly damaged during the preparation. It does

with two p r o m i n e n t lateral lobes, which because they are so dis-

have a p r o m i n e n t , c o n e - s h a p e d glabella. T h e pygidium is intact,

tinctive are given their o w n n a m e , bullae. Figure 5.1 shows lichid

however, and serves, along with the glabella shape, as a p r i m a r y

cephala with the distinctive bulla. Lichids are c o m m o n n o w h e r e ,

identifying feature. A c r a n i d i u m with this n a m e in the U S N M

b u t in certain h o r i z o n s their characteristic exuviae can be f o u n d

( U S N M 2 6 3 4 1 ) is pustulose. T h e location for the holotype is

by carefully searching. T h e lichids range in size f r o m the quite

given as Trenton Falls, which encompasses the entire middle

small Hemiargespaulianus ( 1 0 to

15 m m ) to the large and heavily

T r e n t o n ; however, the location label indicates the specimen was

o r n a m e n t e d Terataspis grandis (> 30 c m ) . W h o l e s p e c i m e n s of the

purchased from William Rust. Since most of Rust's material

lichids are rare and very prized by b o t h m u s e u m s and collectors.

c a m e f r o m the M i d d l e Ordovician Trenton Walcott-Rust Quarry,

T h o m a s and Holloway ( 1 9 8 8 ) extensively reviewed the classifica-

H e r k i m e r C o u n t y , and o t h e r s p e c i m e n s have been f o u n d there, it

tion and phylogeny, b u t the New York species need revision.

is likely that the h o l o t y p e is from that location. T h e U S N M speci m e n 7 2 6 2 9 has a " m u s e u m label" n a m e . It is a p r o m i n e n t glabella

Acanthopyge

(Lobopyge)

consanquinea

(Clarke,

1894)

f r o m the Middle Ordovician Trenton Limestone near Trenton

Figure 5 . I D

Falls. T h e p r o m i n e n t glabella indicates it is most likely A. cornu-

Holotype N Y S M 4 5 3 0

tus. Labels of material like this from " n e a r Trenton Falls" often

A lichid f r o m the Lower D e v o n i a n New Scotland L i m e s t o n e

m e a n the W a l c o t t - R u s t Quarry, H e r k i m e r County.

in Schoharie County. Amphilichas Acanthopyge

(Lobopyge)

contusa

(Hall

and

Clarke,

1888)

minganettsis

(Billings,

1865)

Lectotype G S C 1332a (Shaw, 1 9 6 8 ) , hypotypes N Y S M 1 2 2 1 9 - 3 4

Figure 5 . 1 C

Amphilichas

Types N Y S M 4 5 3 1 , 4 5 3 2

minganensis

is

reported

from

the

Middle

Ordo-

vician Chazy limestones and is the earliest lichid reported from

Hall and Clarke reported this trilobite f r o m the Upper Helder-

New York. F o r location i n f o r m a t i o n , see Shaw ( 1 9 6 8 ) . O n l y crani-

berg (Lower D e v o n i a n ) of eastern New York, Albany and O t s e g o

dia and pygidia are k n o w n f r o m m a t u r e specimens. T h i s is o n e of

Counties, and from O n o n d a g a ( M i d d l e D e v o n i a n ) f l o a t boulders

the few trilobites in New York from which significant i n f o r m a t i o n

in west-central

of growth stages is k n o w n f r o m silicified material. R a y m o n d

New York,

Ontario

County.

The

illustrated

specimen is f r o m Hall and Clarke ( 1 8 8 8 ) .

( 1 9 2 5 , p. 125) reported it to be also found in Q u e b e c and Virginia.

Amphilichas

Amphilichas

conifrons

(Ruedemann,

1916)

H o l o t y p e N Y S M 9 6 0 7 ; paratype N Y S M 9 6 0 8 ; s p e c i m e n s M C Z Amphilichas conifrons was described from

the

(Conrad,

1842)

T h e type is from Middle Ordovician Trenton age rocks in

1560, M C Z 1561 NYSM

trentonensis

Plesiotype M C Z 4 4 1 1

Middle

from a specimen

Ordovician

Trenton

in

collections

the

Pennsylvania. S p e c i m e n s f r o m New York that were referred by

of

Hall to this species are f r o m the lower Trenton at Middleville,

FIGURE 5 . 1 .

Lichids from the lower a n d lowest M i d d l e Devonian of New York. A. Ceratolichas dracon from the

O n o n d a g a Limestone in G e n e s e e County. The f i g u r e d c e p h a l o n is a reconstruction from Hall a n d Clarke (1888). B. Ceratolichas gryps from the O n o n d a g a Limestone at Schoharie, S c h o h a r i e County. The f i g u r e d c e p h a l o n is a reconstruction from Hall a n d Clarke (1888). C. Acanthopyge contusa from the O n o n d a g a Limestone in Ontario County. The figured g l a b e l l a is from Hall a n d Clarke (1888). D. Acanthopyge consanquinea from the New Scotland Limestone in Schoharie County. The f i g u r e d g l a b e l l a is from Clarke (1894). E. Echinolichas hispidus from the "Schoharie Grit," Schoharie, Schoharie County. The f i g u r e d p y g i d i u m is from Hall a n d Clarke (1888). F. Oinochoe bigsbyi from the shaly limestones of the lower H e l d e r b e r g G r o u p . D r a w i n g s 1 a n d 2 s h o w side a n d dorsal views of the glabella. D r a w i n g 3 s h o w s a partially r e c o n s t r u c t e d p y g i d i u m . The figures are from Hall ( 1 8 6 1 b ) .

126

THE

H e r k i m e r County. T h e whole s p e c i m e n figured by Hall ( 1 8 4 7 ) is

Dicranopeltis fragosa

from O h i o and probably a different species. A specimen in the

Holotype M C Z 100865

U S N M ( U S N M 6 3 0 3 ) i s from Pennsylvania.

(Phleger,

TRILOBITES

1937)

Lower Silurian Rochester Shale. T h i s trilobite is k n o w n only from a single c r a n i d i u m and may be Dicranopeltis nereus.

Arctinurus boltoni (Bigsby, 1 8 2 5 )

Plates 20 a n d 21

H o l o t y p e B M I t 1 5 6 9 0 ; hypotype N Y S M 9 6 3 1 ; s p e c i m e n s U S N M 4 9 9 5 4 3 , PRI 4 2 0 9 5 Arctinurus boltoni is f o u n d in the lower half of the Lower Silurian Rochester Shale in western New York. Arctinurus boltoni is o n e of the premier trilobites from New York. T h i s large, flat ovate trilobite has a b r o a d axis. T h e cephalon has a distinctive anterior tongue-shaped prow a n d h o o k - s h a p e d longitudinal furrows on the glabella. T h e pygidium is large and has three pairs of lobate spines. T h e large size ( 1 0 0 to 1 5 0 + m m ) and the pustulated exoskeleton make a striking display. T h e s e trilobites are very rare as whole, articulated s p e c i m e n s , and the types were only discovered during the digging of the Erie Canal in L o c k p o r t , Niagara County. Recently, large areas of the trilobite-rich layers of the Rochester Shale were uncovered in a shale q u a r r y near M i d d l e p o r t in Orleans C o u n t y , f r o m which sizable n u m b e r s of whole specim e n s have been taken. T h e s p e c i m e n i n Plate 2 0 , U S N M 4 9 9 4 5 3 , from the R o c h e s t e r Shale has e p i b i o n t s adhered to the surface, suggesting that the trilobite was m a t u r e and had not molted since the b r a c h i o p o d spat and o t h e r larvae lodged on the surface. T h e r e are two different b r a c h i o p o d s , b r y o z o a n s and Cornulites, species on

Dicranopeltis nereus (Hall,

1863)

Plates 22 a n d 23

Type A M N H 1 8 2 5 , s p e c i m e n PRI 4 9 6 2 3 Lower Silurian

Rochester Shale. Dicranopeltis nereus is found

in the lower R o c h e s t e r Shale in its western exposures (Tetreault 1 9 9 4 ) and at M i d d l e p o r t , Niagara County. T h e postaxial lobe of the pygidium has a rounded outline with a small median notch. T h e c r a n i d i u m of D. nereus has never been described. However, the c r a n i d i u m of D. fragosa described by Phleger (see above) could b e l o n g to D. nereus. T h e specimen in Plate 23 is from near M i d d l e p o r t and shows extensive healed damage to the left side, while the specimen in Plate 22 has healed damage to the right upper t h o r a x .

Echinolichas eriopsis

(Hall,

1863)

Plate 24

Syntypes N Y S M 4 5 3 7 t o 4 5 3 9 T h e illustrated s p e c i m e n s are from the O n o n d a g a Limestone and reported in Hall and Clarke ( 1 8 8 8 ) from the upper Helderberg at S c h o h a r i e , S c h o h a r i e County, and " d e c o m p o s e d chert b o u l d e r s " at C a n a n d a i g u a , O n t a r i o County.

the dorsal surface. T h e rhynchonellid b r a c h i o p o d apparently shows four growth stages, indicating a t i m e interval since the last

Echinolichas hispidus

m o l t . T h e trilobite in Plate 2 1 , PRI 4 2 0 9 5 , shows healed d a m a g e

Holotype N Y S M 4553

to the left side, possibly as a result of predator attack. T h r e e size

(Hall

and

Clarke,

1888)

T h e trilobite is reported from the Schoharie F o r m a t i o n at Clarksville, Albany C o u n t y , and O n o n d a g a L i m e s t o n e at LeRoy,

classes of b r a c h i o p o d s are evident on the surface.

Genesee County. Autoloxolichas?

inconsuetus

(Raymond,

1925)

Holotype M C Z 101164

Hemiarges paulianus

T h e h o l o t y p e , and only s p e c i m e n we are aware of, is a cranidium

Middle

Ordovician

Glens

Falls

1894)

Plate

25

Limestone

T h i s small lichid is from the Middle Ordovician, early Trenton

(basal T r e n t o n ) at the ( f o r m e r ) bridge at the falls of Flat Creek,

in New York. It has a wide geographic distribution west to M i n -

1.6 km (1

from

(Clarke,

Lectotype U S N M 4 2 4 3 a (Rudkin et al. 1994)

mile) south of Sprakers, M o n t g o m e r y County. No

c o m p a r i s o n s can be m a d e with o t h e r Trenton lichids. Ceratolichas dracon

(Hall a n d C l a r k e ,

1888)

Figure 5 . 1 A

Types N Y S M 4 5 3 4 t o 4 5 3 6 T h e illustrated s p e c i m e n is f r o m the O n o n d a g a L i m e s t o n e in Hall and Clarke ( 1 8 8 8 ) . Hall and Clarke reported the trilobite f r o m the upper Helderberg, Lower D e v o n i a n , at S c h o h a r i e , S c h o h a r i e County, and the M i d d l e Devonian at LeRoy, Genesee C o u n t y . Ceratolichasgryps (Hall

and Clarke,

1888)

Figure 5 . I B

Syntypes N Y S M 4 5 5 0 t o 4 5 5 2

nesota and n o r t h into C a n a d a . In New York cranidia and pygidia are c o m m o n l y f o u n d in the upper part of the Kings Falls Form a t i o n of the Trenton G r o u p , particularly in exposures just east of W a t e r t o w n in Lewis County. T h e trilobite in Plate 25 is from Trenton age quarries in O n t a r i o .

Lichid sp. Plate 26A Pygidium

of

an

unidentified

lichid

from

the

Middle

Devonian O n o n d a g a L i m e s t o n e in the Cheektawaga Quarry, Erie County. T h e specimen in Plate 26A differs from the known lichids in the O n o n d a g a .

T h e illustrated s p e c i m e n is f r o m the O n o n d a g a L i m e s t o n e and is in Hall and Clarke ( 1 8 8 8 ) . T h e trilobite is reported from

Oinochoe bigsbyi (Hall,

the upper Helderberg of Clarksville, Albany C o u n t y ; C h e r r y

Type A M N H 2 6 1 0 / 1

Valley, O t s e g o c o u n t y ; and " d e c o m p o s e d chert b o u l d e r s " at C a n a n d a i g u a , O n t a r i o County.

1859)

Figure 5 . I F

T h e illustrated specimen is from Hall and Clarke ( 1 8 8 8 ) and is in the New Scotland L i m e s t o n e .

ORDER

LICHIDA

Oinochoepustulosus

(Hall,

127 1859)

Plate 27

vature is greater anteriorly, but it is not strongly accentuated

Syntypes N Y S M 4 5 2 9 , 4 5 5 8 t o 4 5 6 4

anterodorsally. Viewed f r o m the dorsal side, the anterior part of

Oinochoe pustulosus is f o u n d in the New Scotland L i m e s t o n e

the m e d i a n lobe is less p r o m i n e n t . T h e furrow separating the

o f east-central New York. T h e c r a n i d i u m s h o w n , N Y S M E - 9 7 5 ,

third lateral lobes f r o m the c o m p o u n d anterior lateral ones

illustrates the source of the species n a m e pustulosus.

diverges m o r e to the front laterally. T h e specimen in Plate 30 is exceptional. T h e glabella of this s p e c i m e n is missing, probably as

Richterarges ptyonurus (Hall and Clarke, 1 8 8 8 ) Plate 28

a result of m o l t i n g . Note the Cornulites w o r m tubes on the right

Types N Y S M 4 5 5 5 t o 4 5 5 7

pygidial pleural surface. An e x a m p l e of the c r a n i d i u m , which is

Richterarges ptyonurus is reported by Hall a n d Clark from the "coralline limestone," now k n o w n as the Cobleskill F o r m a t i o n , in the area o f S c h o h a r i e , S c h o h a r i e County. T h e m e d i a n part o f the glabella, particularly in front of the level of the lateral glabellar

missing f r o m Plate 3 0 , is shown in Plate 3 1 . T h i s specimen is from Wayne County. Trochurus phlyctainoides

(Green,

1837)

furrows, S I , is flattened; the palpebral lobes are short and the

Trochurus phlyctainoides is a small o r n a t e lichid reported from

anterior branches of the facial sutures converge slightly forward.

the Rochester Shale. T h e species n a m e m e a n s having the form o f

T h e pygidium has a long axis and b r o a d e r postaxial ridge.

blisters or pustules, which is an apt description. T h e type is from

Richterarges trilobites are almost entirely restricted to n o r t h e r n

O h i o , and its actual presence in New York is q u e s t i o n a b l e . T h e

Laurentia. T h e only exception is R. ptyonurus.

reported material we are aware of is T. halli above.

Family Odontopleuridae

Terataspis grandis (Hall, 1 8 6 1 ) Plate 29

O d o n t o p l e u r i d s are f o u n d in New York f r o m the Middle

Holotype N Y S M 4 5 4 3 Type species. Onondaga

Terataspis grandis is f o u n d in both the lower

Limestone of western

New York, particularly the

former Fogelsanger Q u a r r y in Williamsville, Erie C o u n t y , and the upper Schoharie F o r m a t i o n of eastern New York. T h e large size and spiny nature of this trilobite make it o n e of the m o r e spectacular ones. A n u m b e r of models have been m a d e and are featured in Devonian reef d i o r a m a s , such as the o n e at the R o c h e s t e r Museum and Science ('enter, Rochester, New York. Only o n e specimen is known from New York; it is c o m p l e t e e n o u g h for a reasonable reconstruction. T h i s specimen is upside d o w n , and half, longitudinally, is missing. It is in the Buffalo M u s e u m of Natural History, Buffalo, New York. Plate 29 illustrates a genal spine from a large Terataspis s p e c i m e n . T h e An Eldredgeops specimen is included for scale. T h e drawing f r o m the Treatise shows where the genal spine appears on the exoskeleton. Using the relative scale of the drawing and the size of the genal spine, we can estimate an axial length, excluding pygidial spines, of a b o u t 38 cm ( 1 4 . 8 inches).

Trochurus bulbosa

(Phleger,

Ordovician to the base of the M i d d l e D e v o n i a n . W i t h the exception of the genus

Dicranurus, they are small

trilobites, easily

overlooked. T h e glabella tapers slightly forward, and the glabellar lobes are p r o m i n e n t . T h e genal spines are long, and short spines project d o w n , rakelike, from the lateral edges of the free cheeks. O f t e n there is o n e or m o r e occipital spines, which can be curved. T h e t h o r a c i c pleura end in long spines. T h e pygidium has a long pair of b o r d e r spines, with o n e or two pairs of s h o r t e r ones inside. Apianurus

narrawayi

(Raymond,

1910)

Topotype M C Z 7 6 9 7 Apianurus

narrawayi

is

an

uncommon

Middle

Ordovician

Chazy species. T h e type is lost, a n d Shaw ( 1 9 6 8 ) redescribed the species based on silicified material. B o t h A. narrawyi a n d Ceratocephala triacanthaspis f r o m the Chazy have two diverging o c c i p ital spines. Ceratocephala triacanthaspis is distinguished in that its c r a n i d i u m is covered with s h o r t spines. All the silicified material is f r o m very small s p e c i m e n s . For location i n f o r m a t i o n , see Shaw (1968).

1937)

Holotype M C Z 1555 Lower Silurian Clinton G r o u p , f o u n d in C l i n t o n drift (i.e., displaced rocks of Clinton age probably moved by glacial a c t i o n ) near Trenton Falls, Oneida County.

Ceratocara shawi ( C h a t t e r t o n , E d g e c o m b e , Vaccari, and Waisfeld, 1 9 9 7 ) Holotype N Y S M 15482 T h i s species is f r o m silicified material in the C r o w n Point Form a t i o n o f Valcour Island, C l i n t o n C o u n t y . Ramskold ( 1 9 9 1 ) f i r s t

Trochurus halli (Foerste, 1 9 1 7 ) Plates 30 and 31

noticed, in illustrations by Shaw ( 1 9 6 8 ) , that the remains of Cer-

Holotype A M N H 1826

atocera shawi were m i x e d

This trilobite from the Silurian Rochester Shale was originally designated

as

Trochurus phlyctainoides by

Hall

(1852).

theis.

Ceratocara

shawi

in with

differs

from

those of Ceratocephala C.

triacantheis

in

triacanlacking

Trochurus

sculpture on the glabella, o t h e r than the m a j o r pairs of spinose

halli species differs chiefly from T. phlyctainoides in the curvature

tubercles on the m e d i a n lobe, and in lacking sculpture on the

of the median lobe of the glabella, from front to rear. T h i s c u r -

lateral glabellar lobes.

128

THE

Ceratocephala

triacantheis

(Whittington

and

Evitt,

1954)

Meadowtownella trentonensis (Hall,

T h i s species is a Middle O r d o v i c i a n , middle Chazy trilobite

1847)

TRILOBITES

Plates 37 and 38

H o l o t y p e A M N H 8 5 3 / 2 , specimen M C Z 1 1 1 7 1 7

that Shaw ( 1 9 6 8 ) identified f r o m silicified material. For location

T h e type is from the M i d d l e Ordovician Trenton of Belleville,

i n f o r m a t i o n and illustrated s p e c i m e n s , see Shaw ( 1 9 6 8 ) . T h e type

O n t a r i o , and although it is not a good specimen, Ross ( 1 9 7 9 )

is from Virginia and is probably in the U S N M .

believed it to be a different trilobite from the Meadowtownella

Diacanthaspis parvula

been taken in reasonable n u m b e r s from the middle Trenton

specimen given this n a m e in New York. T h e New York species has (Walcott,

1877)

Plate 32

W a l c o t t - R u s t Quarry, H e r k i m e r C o u n t y , and is well represented

H o l o t y p e M C Z 4 3 7 2 , paratype M C Z 4 8 7 2 In New York D. parvula is primarily k n o w n f r o m the Middle Ordovician,

middle

Trenton

Walcott-Rust

Quarry,

in m a n y collections. Often the matrix with this trilobite contains

Herkimer

bryozoan and cystoid colonies. T h e trilobite is ornate, small, and

Diacanthaspis parvula

rarely over 2 . 5 c m (1 i n c h ) long. It makes an attractive specimen.

is found along with Meadowtownclla trentonensis. B o t h are small

Plates 37 and 38 show the dorsal and ventral exoskeletal a n a t o m y

trilobites with similar general shapes. T h e f o r m e r can be readily

of this trilobite.

County.

It is, however, fairly u n c o m m o n .

distinguished

from

M.

trentonensis because of its significantly

m o r e pustulose character and the presence of p r o m i n e n t pustules

Odontopleura

on the axis a n d pleural regions of the t h o r a c i c s e g m e n t s . It is

Hypotype N Y S M 9803

widely distributed geographically, being reported from Q u e b e c , Pennsylvania, and M i n n e s o t a .

ceralepta

(Anthony,

1838)

T h e type for this species is from the Upper Ordovician of O h i o . It has been reported from the Upper Ordovician W h e t s t o n e G u l f Shales near R o m e , O n e i d a County.

Dicranurus hamatus ( C o n r a d ,

1841)

Plate 33 Odontopleura sp.

Hypotypes N Y S M 4 1 9 0 t o 4 1 9 4 Lower D e v o n i a n New Scotland beds. T h i s trilobite is only

(Fisher,

1953)

Specimen B M S E16735

k n o w n from disarticulated parts in New York, but a close relative,

Lower Silurian M a p l e w o o d Shale, Rochester, M o n r o e County.

D. clegantus, f r o m O k l a h o m a is c o m p l e t e . Plate 3 3 , f r o m an O k l a -

Fisher illustrated a small articulated specimen and referred to it

h o m a s p e c i m e n , shows how D. hamata must have looked. T h e

as an Odontopleura species. Ludvigsen ( 1 9 7 9 b , p. 6 2 ) illustrated a

O k l a h o m a species is similar e n o u g h to be considered a subspecies

trilobite referred to as Leonaspis, which is n o w known as Exallaspis

by C a m p b e l l ( 1 9 7 7 ) . T h e curved hornlike occipital spines are very

( R a m s k o l d and C h a t t e r t o n 1 9 9 1 ) , and reported from the Cataract

distinctive.

by a variety of

G r o u p of C a n a d a . T h e M a p l e w o o d Shale is younger than the

epibionts such as bryozoa, b r a c h i o p o d s , c r i n o i d s , corals, and

Cataract G r o u p (Brett et al. 1 9 9 5 ) . T h i s trilobite may be Exallaspis,

w o r m tubes, as well as b o r i n g s referred to as endoliths. T h e r e

but m o r e material is needed to make identification possible.

T h e spines

are often

encrusted

is evidence that these encrusters were on the trilobite while it was alive ( K l o c 1 9 9 2 , 1 9 9 3 , 1 9 9 7 ) .

Primaspis (Miraspis?) crosota ( L o c k e ,

1 8 3 8 ) Plate 39

Hypotypes N Y S M 9 8 0 4 t o 9 8 0 6 , U S N M 3 4 6 1 7 Kettneraspis callicera (Hall and Clarke, 1 8 8 8 ) Plate 34

Primaspis crosota is an O h i o species from the Upper O r d o v i -

Hypotypes N Y S M 4 1 8 6 t o 4 1 8 9 Upper Clarksville,

Lower/lower Albany

Canandaigua,

Middle

County,

Ontario

cian. It has been reported from the Middle Ordovician Trenton Devonian,

and

County.

Schoharie

Onondaga

Note

in

Grit,

Limestone

Plate

34

how

age, C a n a j o h a r i e and Dolgeville Shales, M o n t g o m e r y County, to

at

the Upper Ordovician Lorraine G r o u p shales at Totman G u l f in

the

Jefferson County. Plate 39 is U S N M 2 3 6 0 0 from the Upper

genal spine ends with a " h o o k " shape.

Ordovician Frankfort F o r m a t i o n in O n e i d a County.

Kettneraspis tuberculata ( C o n r a d ,

5.5 ORDER PHACOPIDA

1 8 4 0 ) P l a t e 35

Hypotypes N Y S M 1 0 7 0 4 , 1 0 7 0 5 , 4 1 9 6 t o 4 2 0 0

This

post-Cambrian

order

contains

many

of

the

more

Lower Devonian New S c o t l a n d beds. Disarticulated parts of

c o m m o n trilobites from the Ordovician through the Devonian o f

this species are c o m m o n in s o m e of the limestones and shales of

New York. T h e suborder Phacopina contains the only trilobite

the New Scotland F o r m a t i o n . Articulated s p e c i m e n s such as the

families with schizochroal eyes.

o n e in Plate 35 are rare. Note the a b u n d a n c e of p r o m i n e n t t u b e r cles on the exoskeleton, which p r o m p t e d the n a m e .

Family Acastidae

Kettneraspis sp. Plate 36

c o m b e ( 1 9 9 3 ) and includes Greenops and related species that are

T h e family Acastidae ( D e l o 1934) was resurrected by EdgeT h i s s p e c i m e n has been collected f r o m the New Scotland

popular with trilobite collectors in New York. In New York the

L i m e s t o n e . It is distinguished from k n o w n material by the very

family is primarily restricted to the M i d d l e Devonian and then

long cephalic b o r d e r spines.

mostly to the H a m i l t o n G r o u p . T h e s e trilobites have schizochroal

ORDER

PHACOPIDA

129

eyes, which, because they are raised above the plane of the

greater n u m b e r of axial rings in the pygidium c o m p a r e d to

cephalon, are often damaged or lost during the collecting process.

Greenops species. Because the h o l o t y p e is lost and no neotype

T h e subfamily Astropyginae, which includes Greenops, currently

from Pennsylvania has been designated, the presence of this trilo-

is under revision because of the observation that m a n y m o r e

bite is u n k n o w n in New York. M o s t s p e c i m e n s in New York pre-

species apparently are represented in the s p e c i m e n s in m u s e u m s

viously assigned to G. calliteles have been reassigned to other

and private collections than are currently recognized. A revision

species ( L i e b e r m a n and Kloc 1 9 9 7 ) .

(Lieberman and Kloc 1997) divides the f o r m s k n o w n in New York as Greenops boothi and G. calliteles into new genera and species.

Bellacartwrightia jennyae

Tables 5.3 and 5.4 give descriptive i n f o r m a t i o n not included

Plates 4 2 a n d 4 3

below.

Holotype A M N H

(Lieberman

45312,

and

Kloc,

paratype A M N H

1997)

4 5 3 1 0 , specimen

NYSM 4235 Type species. T h i s trilobite is f o u n d in the Centerfield L i m e -

Subfamily Asteropyginae Plate 40

s t o n e M e m b e r o f the H a m i l t o n G r o u p i n Livingston County. This

Specimen in private collection ( G . K l o c ) T h e specimen is from the Tully L i m e s t o n e in Groves Creek o f f

type species is characterized by the s m o o t h pygidial lappets

Cayuga Lake. It is characterized by b r o a d e n i n g of the anterior

a n d their triangular cross section. Plate 42 is the paratype. T h e

border in front of the glabella, S2 meeting the glabellar furrow,

cluster in

prominently pustulose a cephalon, and rounded pleural s e g m e n t s

and

on the pygidium.

by Hall a n d Clarke ( 1 8 8 8 , Plate 2 4 . 1 5 ) and is from Centerfield in

two

Plate 43 of three

(one hidden)

Harpidella craspedota

Bellacartwrightia jennyae s p e c i m e n s was

first

illustrated

O n t a r i o County. T h e smaller B. jcnnyi has small pustules on the Bellacartwrightia

calderonae

(Lieberman

and

t h o r a c i c pleural lobes and axis that are not f o u n d on the larger

Kloc,

specimen.

1997) Plate 41 Holotype A M N H 4 5 2 7 3 W i n d o m M e m b e r , Hamilton G r o u p , O n t a r i o County. T h e

Bellacartwrightia phyllocaudata

cephalon has a broad flat anterior m a r g i n , axial nodes on the

1 9 9 7 ) Plate 4 4

thorax, and pustules on the lappets.

Holotype A M N H 4 5 2 3 0

(Lieberman

and

Kloc,

W i n d o m and D e e p Run M e m b e r s , H a m i l t o n G r o u p , LivBellacartwrightia

calliteles

(Green,

1837)

ingston C o u n t y . T h e s p e c i m e n in Plate 44 is the h o l o t y p e . T h e pygidial lappets on this species are pustulose, flat, and sharply

Holotype lost It is evident from Green's ( 1 8 3 7 a ) description that Cryphaeus calliteles

would

be

assigned

to

Bellacartwrightia,

owing

to

the

pointed with a thin sharp extremity, and the axial lappet is b r o a d e r at the base than the o t h e r lappets.

Table 5.3. Defining features of the New York asteropygins Bellacartwrightia

Greenops

Kennacryphaeus

Moderate to broad cephalic border

Narrow cephalic border

Eye: maximum of 8 to 10 lenses in a dorsoventral file Posterior border furrow is deflected backward on the genal spine

Eye: maximum of 6 lenses in a dorsoventral file Posterior border furrow is straight. ending halfway across the genal spines

Cranidial anterior border lengthened slightly medially, developed as a narrow lip Eye: maximum of 8 lenses in a dorsoventral file Posterior border furrow is deflected backward on the genal spine

Thorax

Axial spines or nodes on thoracic segments

No axial thoracic spines, sometimes nodes

Thoracic axial spines

Pygidium

14 to 16 pygidial axial rings Tops of pygidial pleural segments rounded in anteroposterior view Posterior portion of pygidial axis prominently excavated

11 pygidial axial rings Tops of pygidial segments flat in anteroposterior view Posterior portion of pygidial axis faintly excavated

Posterior portions of pygidial pleural segments elevated above anterior portion

Interior and posterior portions of pygidial pleural segments of equal elevation

14 pygidial axial rings Tops of pygidial pleural segments rounded Pygidial pleural field flanking posterior portion of pygidial axis faintly excavated Interior and posterior portions of pygidial pleural segments of equal elevation

Cephalon

Table 5 . 4 .

Horizon

Features of the genera Bellacartwrightia and Greenops

B. jennae

B. whiteleyi

B. calderonae

B.

Hamilton,

Hamilton, Wanakah

Hamilton, Windom

Hamilton, D e e p

Axial furrow narrow a n d shallow, nearly straight anterior of SO, diverging forward at about 25 degrees

B. pleione

G. boothi

G. barberi

G. grabaui

Onondaga

Frame Group in Pennsylvania

Hamilton.

Hamilton,

U. Wanakah, Windom Faint or absent

Centerfield, Ledyard, Wanakah Faint or absent

Run, Windom

Centerfield Cephalon

phyllocaudata

Axial furrow narrow a n d shallow, nearly straight anterior of S 1 . diverging forward at about 35 degrees

Axial furrow narrow and shallow, nearly straight anterior of S 1 , diverging forward at about 35 degrees

Axial furrow narrow and shallow, diverging more strongly anterior of S 1 , diverging forward at about 45 degrees

Unknown

Prominent axial tubercle on LO

axial tubercle on LO

axial tubercle on LO

Numerous and large circular perforations on glabellar and palpebral lobes Thorax

Has circular perforations Axial spines

Pygidium

Pygidial lappets are triangular in cross section 14 pygidial axial rings Pygidial lappets lack, or have very fine, prosopon of small granules

Has circular perforations Axial spines

No circular perforations Axial nodes

Pygidial lappets are oval in cross section 14 pygidial axial

Pygidial lappets are oval in cross section 14 pygidial axial

rings Pygidial lappets have prosopon of

rings Pygidial lappets have prosopon of

No circular

Unknown

perforations Axial spines

Pygidial lappets are flat 15 to 16 pygidial axial rings Pygidial lappets have prosopon of small granules

small granules

small granules

Terminal pygidial lappet narrow

Terminal pygidial lappet narrow

Terminal pygidial lappet narrow

Terminal pygidial

Circular perforations in the pleural area

Circular perforations in the pleural area

No circular perforations in the pleural area

No circular perforations in the pleural area

lappet broad

Pygidial lappets are oval in cross section 15 pygidial axial

Two transverse rows of circular perforations on anterior b a n d of pleural segments

One transverse row of circular perforations on anterior b a n d of pleural segments

One transverse row of circular perforations on anterior b a n d of pleural segments

No axial nodes or spines

No axial nodes or spines

No axial N o d e s or spines

Tips of lappets developed as blunt triangles

Tips of lappets

Tips of lappets d e v e l o p e d as blunt triangles

Terminal pygidial lappet broad anteriorly, subrectangular, convex posteriorly Medial margins of

Terminal pygidial lappet developed as a narrow, sharp triangle

Terminal pygidial lappet subrectangular

Medial margins of lappets curved, lateral margins curved

Medial margins of lappets straight, lateral margins curved

pointed

rings Pygidial lappets have prosopon of small granules Terminal pygidial lappet narrow

Circular perforations in the pleural area

lappets curved, lateral margins curved

ORDER

PHACOPIDA

Bellacartwrightia pleione

131

(Hall

and

Clarke,

1888)

H a m i l t o n , indicating their capability to live in poorly oxygenated

Holotype A M N H 4 2 4 8

waters. In the Ledyard pyrite beds, Genesee County, o n e finds

This species is found from the Middle Devonian O n o n d a g a

whole,

pyritized

G.

"boothi"

specimens.

Greenops

"boothi"

is

Limestone through the Tully F o r m a t i o n in n u m e r o u s localities in

reported f r o m the U p p e r D e v o n i a n beds of south-central New

western New York. T h e holotype is f r o m Kentucky.

York, T o m p k i n s C o u n t y , b u t little work has been d o n e on these o c c u r r e n c e s . In the N Y S M there is an exfoliated pygidium from

Bellacartwrightia

whiteleyi

(Lieberman

and

Kloc,

an

1997)

acastid,

possibly

Greenops,

from

the

Upper

Devonian

Plates 45 and 145

Rhinestreet or Cashagua Shale, Erie C o u n t y . T h e Pennsylvania

Holotype A M N H 4 5 3 1 3 , paratype A M N H 4 5 3 1 4

trilobite shown in Plate 51 ( t h e n e o t y p e f r o m the type locality) is

Wanakah M e m b e r , H a m i l t o n G r o u p , Genesee County. Plate

included for c o m p a r i s o n . P r i o r to the paper by L i e b e r m a n and

45 illustrates the paratype. Bellacartwrightia whiteleyi has pygidial

Kloc ( 1 9 9 7 ) , all the New York acastids were l u m p e d under G.

lappets, which are covered with small pustules and are semicir-

boothi or G. calliteles. Greenops boothi has a d o u b l e row of perfo-

cular in cross section. T h e axial lappet is n a r r o w and sharply

rations on each of the t h o r a c i c pleural segments and a broad axial

pointed.

pygidial lappet with a triangular t e r m i n a t i o n .

Bellacartwrightia

sp.

Plate

46

Greenops grabaui ( L i e b e r m a n a n d K l o c , 1 9 9 7 ) Plates 5 2 , 5 3 ,

USNM 89959

and 5 4

This undescribed species from the Tully L i m e s t o n e is c h a r a c terized by the very broad anterior b o r d e r and the triangular pygidium.

Holotype B M S E25857 Centerfield, Ledyard, and W a n a k a h M e m b e r s o f the H a m i l t o n G r o u p in Genesee C o u n t y . T h e pygidial lappets of G. grabaui are short and b r o a d , with the a n t e r i o r edge curved posteriorly and

Bellacartwrightia? sp.

Plates 47

and

48

the posterior edge straight. T h e terminal lappet is short, broad,

T h e specimen in Plate 47 c a n n o t be identified by the internal exoskeletal

anatomy.

It

was

prepared

to

s h o w the

internal

and subrectangular. Plate 53 illustrates a meraspid (degree 10) of this c o m m o n

Greenops species.

exoskeletal characteristics. T h e illustrated s p e c i m e n in Plate 48 is undescribed but has s o m e characteristics similar to B. whiteleyi.

Greenops sp. Plates 55 a n d 56

It differs in the broad shape of the pygidium and wider spacing

U n d e t e r m i n e d species f r o m the upper H a m i l t o n .

between the lappets. Kennacryphaeus Asteropyginae aff. Greenops Plate 49

harrisae

(Lieberman

and

Kloc,

1997)

Holotype A M N H 4 5 2 9 8

T h e specimen in Plate 49 is a small trilobite f r o m the P o m p e y M e m b e r in central New York.

Mottville M e m b e r and Stafford L i m e s t o n e , H a m i l t o n G r o u p , Onondaga County.

Greenops barberi ( L i e b e r m a n a n d K l o c , 1 9 9 7 )

Family Calymenidae

Plate 50

Holotype PRI 4 1 9 4 7 , paratype A M N H 4 5 2 7 7

T h e family C a l y m e n i d a e arose in the Early O r d o v i c i a n in

Upper Wanakah and W i n d o m M e m b e r s , H a m i l t o n G r o u p ,

Europe and migrated to N o r t h A m e r i c a during the early Middle

Erie County. T h e pygidial lappets on G. barberi are relatively long

O r d o v i c i a n . In general, the c e p h a l o n is semicircular, usually with

and narrow, and both the anterior and posterior edges are curved

no genal spines. T h e glabella is p r o m i n e n t l y convex and narrows

posteriorly. T h e axial lappet is narrow, relatively long, and trian-

anteriorly, yielding an o u t l i n e that can range f r o m bell shaped to

gular. Plate 50 illustrates the paratype.

parabolic. T h e r e is usually a distinct preglabellar area, or "lip," the shape of which has s o m e species significance. T h e r e are three

Greenops boothi ( G r e e n ,

1837)

Plate 51

or four distinctive lateral glabellar lobes. T h e posterior pair of

Holotype lost, neotype Y P M 3 5 8 0 7 L i e b e r m a n and Kloc, 1997

lobes, L I , are the largest. T h e pygidium is s o m e w h a t triangular

Type species. T h e long lost type for G. boothi is f r o m the

to semicircular with a s m o o t h edge. T h e N o r t h A m e r i c a n caly-

Middle Devonian F r a m e M e m b e r o f the H a m i l t o n Shales o f

menids have 13 t h o r a c i c s e g m e n t s . T h e exoskeleton of the caly-

central Pennsylvania. In describing the New York species, Hall

menids is robust, and clearly recognizable pieces are often found

accepted all asteropygins with short, r o u n d e d pleural lappets as

in fossil lag deposits. Because of this, and their presence in a wide

G. boothi and all with long, spinelike lappets as G.

callitelcs.

variety

of p a l e o e n v i r o n m e n t s ,

Greenops "boothi" is a c o m m o n fossil of the H a m i l t o n Shales, pri-

species

the

marily as whole cephalon and pygidial exuviae. W h o l e s p e c i m e n s

O r d o v i c i a n trilobites e n c o u n t e r e d in the field. E d g e c o m b e and

are infrequently e n c o u n t e r e d . Along with Eldredgeops rana,

Adrain ( 1 9 9 5 ) reviewed the Silurian calymenids of the United

G.

"boothi" is o n e of the trilobites f o u n d in the dark shales of the

States.

distinction

calymenids

o f being

the

most

share

with

common

Isotelus Middle

132

THE

Calymene camerata

(Conrad,

1842)

Plate

57

Calymene singularis (Howell a n d S a n f o r d ,

Hypotypes N Y S M 4 1 6 3 t o 4 1 6 5

1947)

TRILOBITES Plate 61

Holotype U S N M 4 8 8 1 3 9 Upper

T h e type for this c a l y m e n i d is from the Upper Silurian " O a k

Silurian Cobleskill L i m e s t o n e in the S c h o h a r i e Valley, S c h o h a r i e

O r c h a r d M e m b e r " of the L o c k p o r t G r o u p in M o n r o e County. It

County. T h i s trilobite is characterized by the deep furrow in front

was originally described as Cheirurus singularis. Holloway ( 1 9 8 0 )

of the glabella. T h i s feature is interpreted to indicate that the

recognized it as a c a l y m e n i d .

Calymene camerata

is

reported

from

the top

of the

preglabellar area is steeply u p t u r n e d , similar to the familiar Flexicalymene

Calymene?

meeki.

conradi

This

(Emmons,

1855)

senaria

for

the

Calymene

species

is

from

the

eastern

eyes, a m o r e tapered anterior p o r t i o n of the glabella, and the

T h i s species was described by E m m o n s to replace the use Flexicalymene

P l a t e 62

unidentified

Rochester Shale in Wayne County. It is characterized by smaller

Specimen U S N M 78402 of

Calymene sp.

Upper

Ordovician

Lorraine

o r n a m e n t a t i o n on the c e p h a l o n . C a l y m e n i d sp. P l a t e 6 3

Shale calymenids of New York. It was described as follows: " S m a l l ,

T h e r e are at least two calymenids of the Upper Ordovician

wide across the cheeks, cheek angles o b t u s e or r o u n d e d ; poste-

f o u n d in New York. T h e y have been referred to as Flexicalymene

rior

lobes

of the

glabella

comparatively

large

and

globu-

lar; t h o r a c i c lobes very convex, with a row of tubercles in the furrow or between the axis and the lateral lobes." It was f o u n d in the L o r r a i n e Shales f r o m an i n d e t e r m i n a t e location in central New York.

meeki a n d F. granulosa.

C a l y m e n i d sp. Specimen O S U 22763, 4 Leutze

Calymene niagarensis ( H a l l ,

1843)

(1961)

illustrated

Plates 58 a n d 59

although it has been reported f r o m rocks above and below. Calymene niagarensis has a bell-shaped glabella. T h e anterior b o r d e r

( E d g e c o m b e a n d Adrain 1 9 9 5 ) . Diacalymene

Lectotype S D S N H 8 6 8

best

known

defined

of the

axial

rings.

fine granules. Lower

Silurian

The

Calymene

exoskeleton niagarensis is

calymenids

the

F o r m a t i o n s , there are c a l y m e n i d species that may be the same

to the cephalon is s h o r t and strongly convex. T h e preglabel-

dense,

from

cific identification. In M a r y l a n d in the Will Creek and Toholoway

lar area is a b o u t 1 0 % of the cranidial length. T h e pygidium has completely

collected

O n o n d a g a C o u n t y . T h e specimens are too f r a g m e n t a r y for spe-

T h i s species is f r o m the Lower Silurian R o c h e s t e r Shale,

covered with

specimens

Camarotoechia zone in the Upper Silurian Syracuse F o r m a t i o n in

Holotype A M N H 31063

seven

M o r e work needs to be d o n e on these

specimens

because

is the

rostrata

T h e type from

the

(Vogdes,

is f r o m

1879)

Georgia.

Diacalymene rostrata

Lower Silurian, lower Clinton

in

is

reported

Oneida County

the

(Gillette 1 9 4 7 ) . Vogdes wrote: " D i s t i n c t projecting process in

quarrying activities in the R o c h e s t e r Shale near M i d d l e p o r t in

front of the glabella. T h e facial lines cut the anterior b o r d e r at the

Orleans C o u n t y have uncovered large n u m b e r s . T h e original

apex, giving the frontal limb a triangular f o r m ; at their j u n c t u r e

material was u n d o u b t e d l y f r o m the digging of the Erie Canal

the marginal b o r d e r is raised and forms a triangular process

in L o c k p o r t , Erie C o u n t y . T h e r e are at least three calymenids in

which s u p p o r t s the projection." There is no b a s i s to d i s t i n g u i s h

the

most

New York material as different from that f r o m Georgia. T h e

c o m m o n . Plate 58 shows an individual of the species. Plate 59

a n t e r i o r b o r d e r of the cephalon is moderately long and c o m e s

shows a cluster of C.

niagarensis s p e c i m e n s f r o m M i d d l e p o r t ,

to a p o i n t . T h e pygidial axis has eight or nine distinct interring

o n c e again d e m o n s t r a t i n g the gregarious nature of s o m e trilo-

furrows and a long terminal piece. See E d g e c o m b e and Adrain

bites. Clusters of this kind have been described as m o l t i n g or

( 1 9 9 5 ) for a recent description of the species.

Rochester

Shale,

and

C.

niagarensis

is

easily

the

breeding assemblages.

Calymene platys

(Green,

Diacalymene 1832)

Plate 60

Plastotype N Y S M 4 1 6 8 Calymene platys represents the latest o c c u r r e n c e of calymenids in New York. It is f o u n d in the top of the Lower Devonian S c h o h a r i e Grit and the base of the O n o n d a g a in S c h o h a r i e , Albany and Erie C o u n t i e s . T h e cast of Green's type in the U S N M is pustulose. T h e s p e c i m e n shown in Plate 6 0 , from the O n o n d a g a

vogdesi

(Foerste,

1887)

Holotype U S N M 84790a T h i s Silurian trilobite from O h i o has been reported from the Lower Silurian Rochester Shale of New York. T h i s o c c u r r e n c e c a n n o t be verified. See E d g e c o m b e and Adrain ( 1 9 9 5 ) for m o r e information. Diacalymene sp. Two

Plates 6 4 , 65

undescribed Diacalymene species are k n o w n

from

the

of O n t a r i o , has a s m o o t h surface; however, this may be due to

R o c h e s t e r Shale in M o n r o e and Wayne C o u n t i e s . T h e o n e illus-

weathering.

trated in Plate 64 has a triangular anterior cephalic margin. T h e

ORDER

133

PHACOPIDA

other, in Plate 6 5 , has a m o r e r o u n d e d margin. T h e s e will be

Trenton G r o u p , H e r k i m e r County. T h i s trilobite, part of the revi-

described as different species.

sion m e n t i o n e d above, has a very pustulose exoskeleton and short genal spine on the fixed cheeks. T h e facial sutures are proparian.

Flexicalymene granulosa

(Foerste,

1909)

T h i s species has been observed t h r o u g h o u t the Rust Limestone in

Hypotype N Y S M 9 6 4 9

the Trenton Falls area.

R u e d e m a n n ( 1 9 2 6 ) identified pustulose calymenids f o u n d in the Upper Ordovician W h e t s t o n e G u l f Shale in Jefferson C o u n t y

Gravicalymene

as

and 72

Calymene

granulosa.

Foerste

(1924)

described

C.

granulosa

as follows: "size, relatively small. A n t e r i o r b o r d e r of the c e p h alon less abruptly elevated than in C. meeki. Surface covered by n u m e r o u s granules, larger and m o r e c o n s p i c u o u s than those in the latter species." Hughes and C o o p e r ( 1 9 9 9 ) illustrated Flexicalymene cf. F. granulosa from Kentucky. Flexicalymene meeki ( F o e r s t e ,

1910)

Flexicalymene

meeki

as

follows:

"glabella

relatively short, with a tendency towards t r u n c a t i o n anteriorly. Anterior border of cephalon turned up abruptly and separated from the front of the glabella by a narrow groove. Genal angles with a short, acute, pointed extremity. Ribs of the pygidium with only a very faint trace of an impressed zone along their m e d i a n line." T h e

USNM

specimen

is

from

1926)

Plates

71

Holotype N Y S M 9650 T h i s M i d d l e O r d o v i c i a n trilobite, first figured by R u e d e m a n n as Flexicalymene senaria, was given subspecies rank in

1926. Ross

( 1 9 6 7 ) pointed o u t in s o m e New York calymenids that not only senaria being parabolic) b u t also the a n t e r i o r b o r d e r was thick-

Plate 66

USNM 23627 described

(Ruedemann,

was the glabella bell shaped in outline (vs. the glabella in F.

Holotype U S N M 7 8 8 2 2 ( O h i o ) , hypotype N Y S M 9 6 5 5 , specimen Foerste

magnotuberculata

the

U p p e r Ordovician

"Pulaski Drift" from north o f Utica, O n e i d a County. Similar material is in the N Y S M and the M C Z . T h e s p e c i m e n in Plate 66 is from C i n c i n n a t i , O h i o , the type area for the species. Flexicalymene senaria ( C o n r a d , 1 8 4 1 ) Plates 6 7 , 6 8 , 6 9 , a n d 70 Neotype A M N H 2 9 4 7 4 (Ross 1967) Flexicalymene senaria was o n e of the earlier New York trilobites recognized as being different f r o m its European c a l y m e n i d counterparts. It is f o u n d nearly everywhere that the M i d d l e Ordovician limestones are exposed in New York. T h e n e o t y p e , Plate 67, is from Middleville, H e r k i m e r C o u n t y , and is probably

ened and

rolled c o m p a r e d

to the standards for Flexicalymene.

Ross did n o t , however, m e n t i o n R u e d e m a n n ' s subspecies, and the assignment as Gravicalymene is based on Ross's general observations for the species and o u r e x a m i n a t i o n of s p e c i m e n s . T h e genal angle is very r o u n d e d . T h e facial suture is g o n a t o p a r i a n . Ruedemann's s p e c i m e n s

came

from

the T r e n t o n

age, C a n a j o h a r i e

Shales, and we have observed the s a m e trilobite in Dolgeville-like facies within the Sugar River F o r m a t i o n of the T r e n t o n . Plates 71 and 72 illustrate the dorsal and ventral exoskeletal surfaces. Liocalymene clintoni

(Vanuxem,

1842)

Plate

73

Hypotype M C Z 104689 T h e location of the original type is u n k n o w n . Liocalymene clintoni is listed f r o m the Lower Silurian, lower and middle C l i n t o n G r o u p in O n e i d a C o u n t y ( D a l e 1 9 5 3 ) . T h e trilobite has a bell-shaped glabella with very large first glabellar lobes ( L I ) . T h e glabellar lobes are m u c h less inflated than those in Calymene species. It is easily distinguished from o t h e r calymenids in that the pleural region of the pygidium is s m o o t h , without pleural grooves. See R a y m o n d ( 1 9 1 6 ) and W h i t t i n g t o n ( 1 9 7 1 a ) .

from the lower Trenton. T h e illustrated s p e c i m e n in Plate 68 is from the lower Poland L i m e s t o n e from Trenton Falls, H e r k i m e r

Liocalymene

County. T h e trilobite in Plate 69 is from the W a l c o t t - R u s t Q u a r r y

Lectotype U S N M 1 6 4 0 6 4 ( E d g e c o m b e and Adrain 1 9 9 5 )

in the Rust F o r m a t i o n of the Trenton G r o u p ; Ross ( 1 9 6 7 ) suggested this was a separate species owing to its unusually pustulose appearance. T h e specimen in Plate 70 is f r o m the u p p e r m o s t Trenton, the Hillier M e m b e r , and is less pustulose. It is interesting, however, that in spite of the n u m b e r of trilobite workers splitting o f f new species from early New York discoveries, it was not

cresapensis

(Prouty,

1923)

Liocalymene cresapensis was originally described

f r o m the Sil-

urian of M a r y l a n d . Dale ( 1 9 5 3 ) reported the trilobite from the Lower Silurian, upper C l i n t o n G r o u p shale o f O n e i d a County.

Family Cheiruridae C h e i r u r i d s are c o m m o n trilobites o f the Middle Ordovician

recognized a " s u b s p e c i e s " of F.

of New York. T h e y are also m o r e rarely f o u n d in the Silurian.

senaria. In 1967 Ross similarly pointed out that there are at least

Generally, the glabella expands forward and there are genal

four different trilobites in New York called F. senaria. Revision of

spines. T h e t h o r a c i c pleurae have short spines, although s o m e -

this group is presently in progress.

times these are b l u n t . T h e r e is an o b l i q u e furrow on the thoracic

until

1926 that R u e d e m a n n

pleura next to the axis. T h e pygidium is small and usually with Flexicalymene sp.

(Ross,

marginal

1967)

Ross identified the specimen from the W a l c o t t - R u s t Q u a r r y in

the

Rust

Limestone

spines.

Pribyl, Vanek,

and

Pek

(1985)

extensively

reviewed and modified the cheirurids in a work that is not readily

Specimen N Y S M 17004 Member

of the

Middle

Ordovician

available in most libraries. T h e genera referred to in the following are f r o m their paper.

134

THE

Acanthoparypha

trentonensis

Cerauropeltis

Holotype N Y S M 4766

(Raymond,

1916)

Plate

84C-E

H o l o t y p e N Y S M 9 6 8 9 , hypotype M C Z 101171

R a y m o n d ( 1 9 2 5 ) initially identified A.

trentonensis as Kawina,

with two cranidia from the M i d d l e O r d o v i c i a n material in the Walcott collection

ruedemanni

TRILOBITES

Type species.

Cerauropeltis

ruedemanni from

the base of the

Middle O r d o v i c i a n , upper Chazy resembles C. plcurexanthemus

( M C Z ) , probably from Herkimer County.

with the following differences. A crease j o i n s the proximal ends

R a y m o n d ( 1 9 2 5 , p. 145) additionally listed the species f r o m the

of the glabellar furrows, giving the glabella a trilobed appearance,

Black River of New Jersey.

and the second pleural spines on the pygidium are elongated. All of the k n o w n material is f r o m a single location (Shaw 1 9 6 8 ) . T h e

Acanthoparypha?

sp.

(Shaw,

fixed cheek has a wrinkled look. S p e c i m e n s are huge. O n e in the

1968)

M C Z has a glabella 3.7 cm long.

Specimens N Y S M 12435 to 12438 This Middle O r d o v i c i a n Chazy trilobite is only k n o w n f r o m a few pieces. For location i n f o r m a t i o n , see Shaw ( 1 9 6 8 ) .

Ceraurus

montyensis

(Evitt,

1953)

Holotype U S N M 116693a Ceraurinella

(Ceraurinella)

latipyga

(Shaw,

1968)

Plate

This

86C

Middle

Ordovician

Trenton

cheirurid

from

north-

eastern New York near the town of Chazy, Clinton County, is

Holotype N Y S M 12442 A Middle O r d o v i c i a n Chazy trilobite that was first described

very similar to C. pletirexanthemus.

T h e silicified material Evitt

studied has a less elevated eye on the free cheek, and the pygid-

by Shaw. For location i n f o r m a t i o n , see Shaw ( 1 9 6 8 ) .

ium appears to be m o r e scalloped or dentated than that of C. Ceraurinella

(Arcticeraurinella)

scofieldi

(Clarke,

plcurexanthemus.

1894)

Plate 7 4 Hypotype M C Z 100814

Ceraurus pleurexanthemus

T h e M C Z s p e c i m e n i s f r o m the M i d d l e O r d o v i c i a n Black

(Green,

1832)

Plates 7 6 , 7 7 , and 78

Holotype N Y S M 4 2 0 3 ; specimens M C Z 111708, M C Z 111715

River L i m e s t o n e near Poland, H e r k i m e r C o u n t y , and is part of

Type

species.

Ceraurus

pleurexanthemus

is

a

common

and

the Walcott collection. T h i s trilobite is also reported f r o m the

widely distributed trilobite of Middle Ordovician Trenton age

C h a u m o n t L i m e s t o n e in the W a t e r t o w n Town Q u a r r y , W a t e r -

rocks in central New York. T h e distinctive cephalon with its long

t o w n , Lewis C o u n t y . T h e original described material is from the

divergent genal spines and the two long marginal pygidial spines

Midwest; see D e M o t t ( 1 9 8 7 ) .

m a k e it easy to identify. Articulated specimens are u n c o m m o n in m o s t exposures, as it was not as robust as Isotelus gigas or Flexi-

Ceraurinus

marginatus

(Barton,

1913)

Plate

calymene senaria f o u n d in the s a m e rocks. T h e exception is the

75

W a l c o t t - R u s t Q u a r r y , H e r k i m e r County, where large n u m b e r s of

Holotype M C Z 100813 T h e h o l o t y p e is f r o m the Hillier M e m b e r ,

w h o l e , articulated s p e c i m e n s of all sizes are found in and on a

Middle O r d o v i c i a n Trenton G r o u p , Jefferson C o u n t y . T h i s is a

single layer. T h i s s a m e layer yielded specimens with appendages,

reasonably c o m m o n trilobite f r o m the C o b o u r g o f southern

which Walcott used in his first description of trilobite ap-

O n t a r i o but rarely reported in New York. T h e r e are u n n u m b e r e d

pendages. Plate 76 provides an excellent example of the species.

s p e c i m e n s in the U S N M , three small pieces a n d a very large

Plate 77 shows the ventral exoskeletal anatomy. T h e a p o d e m e s of

Type species.

glabella, 2.3 cm long. T h e y are f r o m 3 m ( 1 0 feet) b e n e a t h the

Plate 77 are clublike at the ends. T h e specimen in Plate 78 shows

top o f the M i d d l e O r d o v i c i a n Trenton o n the N o r t h Fork o f

a ferriginous trace of the gut from the midpoint of the t h o r a x to

Sandy Creek,

the end of the pygidium.

7.2 k m

(4.5

miles)

south

of Adams,

Jefferson

County. T h e s p e c i m e n in Plate 75 is f r o m the T r e n t o n age rocks of Ontario.

Ceraurus? sp. Plates 79 a n d 80 T h e s p e c i m e n shown in Plate 79 is from a flooding-surface

Ceraurinus

sp.

lag

Specimen U S N M 9 2 5 3 6 The

two

cranidia

deposit

over

the

Middle

Ordovician

Hillier

Limestone

M e m b e r o f the Trenton G r o u p and under the Upper Ordovician from

the

Middle

Ordovician

Black

Utica Shale. T h e species has s o m e distinct differences from

River, H e r k i m e r C o u n t y , are part of the H u r l b u r t collection

C.

and are quite possibly f r o m the s a m e exposures, Buck's Quarry,

Ceraurus? from a q u a r r y in the middle T r e n t o n , near Water-

from

town,

which Walcott got m o s t

of his

Black River trilobites.

pleurexanthemus. Jefferson

Plate County.

80

illustrates

These,

and

another some

unidentified

o f the

museum

An u n n u m b e r e d s p e c i m e n in the U S N M is f r o m the M i d d l e

materials designated as Ceraurus, need to be redescribed. T h e

Ordovician Lowville (Black River) or basal Trenton at a n o w -

s p e c i m e n s differ f r o m C. plcurexanthemus in the larger eye, the

a b a n d o n e d railroad cut 3.2 km (2 miles) b e l o w Poland, H e r k i m e r

m o r e p r o m i n e n t tubercles on the glabella, and inward-curving

County.

genal spines.

ORDER

PHACOPIDA

135

Cheirurus sp. (Hall, 1 8 6 7 ) Plate 81

Gabriceraurus

Specimen N Y S M 9 6 9 3

f r o m C. pleurexanthemus in that the f o r m e r has raised tubercles

Lower

Silurian

Rochester Shale.

Rochester

Shale

was

Hadromeros

niagarensis,

previously a

Wisconsin

The

cheirurid

assigned

to

species.

the

from

(Pribyl

et

al.

1985).

Gabriceraurus

hudsoni

differs

the

on the fixed cheeks, whereas the latter free cheek is pitted. For

cheirurid

location i n f o r m a t i o n , see Shaw ( 1 9 6 8 ) . R a y m o n d ( 1 9 2 5 , p. 139,

Holloway

(1980)

140) reported the species also f r o m Virginia and Tennessee.

noted that the New York s p e c i m e n s are of the genus Cheirurus and are different from the W i s c o n s i n specimens. T h e trilobite has

Heliotnera

a long, inflated glabella that expands toward the front where it

Holotype Y P M 2 3 3 2 6

overhangs the anterior border. T h e glabellar furrows are straight,

(Heliomeroides)

Hcliomera

akocephala

akocephala

is

an

(Shaw,

uncommon

1968)

trilobite

from

the

and the basal lobe is isolated. T h e pygidium has a single m e d i a n

Middle O r d o v i c i a n , u p p e r m o s t lower and lowermost middle

spine and three pairs of long, curved, pointed lateral spines.

Chazy. O n l y cranidia are clearly identified. For location i n f o r m a tion, see Shaw ( 1 9 6 8 ) .

Deiphon pisum (Foerste, 1 8 9 3 ) Plate 8 4 B

Kawina? chazyensis

Specimen U S N M 8 8 6 4 8 T h e U S N M specimen is f r o m L o c k p o r t , Niagara C o u n t y , and labeled D. forbesi, an English trilobite not k n o w n from New York. T h e glabella is greatly inflated and covered with pustules. T h e fixigenae are reduced to long genal spines. T h i s genus is not b e n t h i c but lived in the water c o l u m n (pelagic). Forteyopsl(?)

approximus

(Raymond,

T h i s trilobite is k n o w n o n l y from cranidia in the Middle (1968). 1865)

Lectotype G S C 6 6 9 ( W h i t t i n g t o n 1 9 6 3 )

1905)

Type species. Kawina vulcanus is identified as a New York trilo-

This trilobite is k n o w n f r o m two cranidia f r o m the Middle Ordovician Chazy G r o u p . F o r location i n f o r m a t i o n , see Shaw (1968). (Raymond and

1905)

O r d o v i c i a n Chazy L i m e s t o n e . F o r location i n f o r m a t i o n , see Shaw

Kawina vulcanus ( B i l l i n g s ,

Holotype Y P M 2 3 3 0 0

Gabriceraurus dentatus

(Raymond,

H o l o t y p e C M 1277

Barton,

bite f r o m a single s p e c i m e n , n o w lost, described by R a y m o n d ( 1 9 0 5 ) . T h e type is from N e w f o u n d l a n d . Shaw ( 1 9 6 8 ) questioned that this is a M i d d l e O r d o v i c i a n Chazy trilobite. Nieszkowskia? satyrus

1913)

(Billings,

1865)

H o l o t y p e G S C 1087

Plates 8 2 and 8 3

T h i s distinctive c h e i r u r i d o f the M i d d l e Ordovician Chazy

Holotype G S C 1775 is lost; paratype M C Z 1 0 0 8 0 2 T h e paratype is from Watertown, Jefferson County. Gabriceraurus dentatus is a large cheirurid f r o m the M i d d l e Ordovician Trenton. Specimens are f o u n d mostly in the lower Trenton but have been collected well up into the group. It is n o w h e r e as c o m m o n as C. pleurexanthemus. It is distinguished by its significantly larger size and the eyes, which are set farther b a c k on the cranidium than they are in the m o r e c o m m o n C. pleurexanthemus. T h i s trilobite is also found in the B o b c a y g e o n F o r m a t i o n of O n t a r i o and in the upper Esbataottine F o r m a t i o n , District of

L i m e s t o n e has a raised, c o n e - s h a p e d glabella similar to those on s o m e lichids. F o r location i n f o r m a t i o n , see Shaw ( 1 9 6 8 ) . Sphaerexochus

(Parvixochus)

parvus

1863)

Type species. Sphaerexochus parvus is widely distributed in the Middle O r d o v i c i a n , lower a n d middle Chazy L i m e s t o n e o f the C h a m p l a i n Valley. T h e small trilobite has an inflated glabella and long genal spines. F o r location i n f o r m a t i o n , see Shaw ( 1 9 6 8 ) .

Mackenzie, Canada. S p e c i m e n s are also f o u n d in the Midwest; see

Sphaerocoryphe goodnovi

D e M o t t ( 1 9 8 7 ) . T h e specimen in Plate 83 is f r o m the upper

Lectotype Y P M 2 3 3 0 4 (Shaw 1 9 6 8 )

Trenton Lindsay F o r m a t i o n in O n t a r i o and is flattened, as o n e

(Billings,

H o l o t y p e G S C lost, hypotype G S C 1330

(Raymond,

Sphaerocoryphe goodnovi,

from

the

1905) Middle

Plate

86A

Ordovician

Chazy,

often finds specimens on bedding planes. Plate 82 illustrates a

as with all trilobites of this genus, has a highly inflated glabella,

specimen from the lower Trenton of Fulton C o u n t y with a m o r e

which stands well above the plane of the body. T h e specimen

three-dimensional aspect.

figured by Shaw ( 1 9 6 8 ) differs f r o m others in the genus in that the glabella appears oval in a dorsal view, while o t h e r New York

Gabriceraurus hudsoni ( R a y m o n d ,

1905)

Plate 8 4 A

Sphaerocoryphe

Holotype C M 1271

species

have

a

spherical

glabella.

For

location

i n f o r m a t i o n , see Shaw ( 1 9 6 8 ) .

Shaw ( 1 9 6 8 ) identified G. hudsoni as the only cheirurid of the genus Ceraurus in the Middle Ordovician Chazy and the

other

two

species

reported,

Ceraurus

pompilius

placed Billings,

Sphaerocoryphe

major

(Ruedemann,

1901)

Holotype N Y S M 4813

R a y m o n d , 1 9 0 5 , and C. granulosus R a y m o n d and B a r t o n , 1 9 1 3 ,

T h i s is o n e of the unusual trilobites f o u n d in Middle O r d o -

in synonymy. Later investigators placed this trilobite in the genus

vician Trenton pebbles within the Rysedorph Hill C o n g l o m e r a t e ,

136

THE

Rensselaer County. It is larger than S. robusta but resembles it in general.

TRILOBITES

Family Dalmanitidae Dalmanitids are characterized as follows: T h e y have flattened bodies. T h e genal spines are often present. T h e abaxial end of the

Sphaerocoryphe robusta

(Walcott,

1875)

t h o r a c i c segments is well defined, often f o r m i n g small, pointed

P l a t e 85

Holotype M C Z 111709, specimen M C Z 110901

lappets. T h e glabellar lobes are well defined. Dalmanitids have

Walcott ( 1 8 7 5 b ) first described this small trilobite f r o m his

large cephala and pygidia and schizochroal eyes, which in most

collecting in the W a l c o t t - R u s t Q u a r r y , H e r k i m e r C o u n t y , located

cases are large. In New York they are found in the Silurian

in the Middle O r d o v i c i a n Rust M e m b e r , Trenton G r o u p . T h e

through the Middle Devonian. M a n y trilobites listed in the Trea-

trilobite is u n m i s t a k a b l e , with its spherical glabella raised well

tise as dalmanitids were assigned to the family Synphoriidae

above the plane of the body. It is not c o m m o n in the quarry, but

(Lesperance 1 9 7 5 ) . A defining difference between Dalmanitidae

the work by Walcott and later by Rust and H u r l b u r t resulted in

and Synphoriidae is the ratio of the distance from the cephalic

it being represented with fine s p e c i m e n s at M C Z , N Y S M , P R I ,

a p o d e m a l pit SO and SI and the distance between SI and S2

and U S N M . In New York S. robusta is f o u n d on o n l y o n e bedding

(Figure 5 . 2 ) .

plane in o n e l o c a t i o n , the W a l c o t t - R u s t Quarry. T h i s is probably due to its very small size and low c o n c e n t r a t i o n s , requiring a

Corycephalus? pygmaeus

significant area to be searched to be successful. T h e distinctive

Cotypes NYSM 4357 to 4358

glabella is also f o u n d in the Verulam ( T r e n t o n ) of O n t a r i o .

(Hall

and Clarke,

1888)

T h i s species is k n o w n from only two very small fragmentary cephala from Middle Devonian O n o n d a g a float boulders near

Staurocephalus sp.

Plate 9 1 B

Canandaigua,

Undescribed s p e c i m e n s have been f o u n d in the Rochester Shale. Presently they are o n l y k n o w n f r o m their free cheeks.

FIGURE 5 . 2 . Key c e p h a l i c differences

between

Ontario

County.

The

two

have an

elongated

glabella, and crenulations can be seen on the margins. T h e fragm e n t s are probably juveniles and even possibly meraspids.

Dalmanitidae a n d S y n p h o r i i d a e ( C a m p b e l l

1977).

A.

Glyptambon

amsdeni from Tennessee, a d a l m a n i t i d , w h e r e the ratio in d i s t a n c e b e t w e e n the a p o d e m a l pits at S2-S1 a n d S1-SO is about 1.1. This trilobite w a s u s e d b e c a u s e the a p o d e m a l pits s h o w up well in the p h o t o g r a p h . B. Anchiopella anchiops, a s y n p h o r i i d , from Ontario, C a n a d a , w h e r e the ratio in d i s t a n c e b e t w e e n the a p o d e m a l pits S2-S1 a n d S1-SO is about 1.6. This trilobite is also f o u n d in New York. Both s p e c i m e n s are in the G e r a l d Kloc collection.

ORDER

137

PHACOPIDA

Corycephalus regalis

(Hall,

1876)

i u m is triangular with 10 or 11 furrowed pleurae and 15 axial

Figure 5 . 3 A

rings with axial nodes.

Holotype A M N H 2 8 9 4 , paratype A M N H 2 9 2 4 7 T h i s trilobite, of the S c h o h a r i e Grit, Albany C o u n t y , is distinguished by the high convexity, large size, long genal spines, spat-

Dalmanites

ulate marginal denticles, and coarse t u b e r c u l a t i o n .

sp.

Plate 9 1 A

T h e s p e c i m e n is f r o m Lower Silurian R o c h e s t e r Shale found in an u n n a m e d creek in the S o d u s area, Wayne County.

Dalmanites aspinosus

(Weller,

1903)

Plate 87

Holotype Walker M u s e u m 1 0 2 4 2 This Silurian trilobite is f r o m the D e c k e r Ferry F o r m a t i o n . It was found in the Nearpass Q u a r r y 3.2 km (2 miles) south of Tristates, O r a n g e County. Dalmanites

bisigmatus

F.

russelli

(Lesperance,

1975)

Specimen A M N H unnumbered T h e referenced pygidium is f r o m the Lower Devonian Central Valley S a n d s t o n e , in O r a n g e C o u n t y , and is the only specimen

(Clarke,

k n o w n f r o m outside Q u e b e c . T h e r e are 12 pleural ribs, which

1900)

reach the margin. T h e r e are 20 axial rings and a small postaxial

Holotype N Y S M 13367/1 Lower

Forillonaria cf.

Devonian

Oriskany/Glenerie

Formation.

Only

the

pygidium has been characterized, although there is a glabella with this label in the U S N M ( U S N M 5 2 6 9 9 ) . T h e pygidium is triangular with 14 or 15 axial rings. T h e r e are p r o m i n e n t axial tubercles. T h e r e are 10 or 11 pairs of pleural ribs, which curve backward near the margins. Dalmanites limulurus limulurus

ridge. T h e surface is granular.

Neoprobilium

nasutus

(Conrad,

1841)

Figure

5.3B

Hypotypes N Y S M 4 3 4 2 t o 4 3 4 7 Type species. T h i s species is f r o m the Lower D e v o n i a n New Scotland F o r m a t i o n . T h e c e p h a l o n has a long anterior, median process that terminates in two divergent r o u n d e d spines. T h e

(Green,

1832)

Plates

88,

89,

and 9 9

genal spines are long and slender. T h e pygidium is subtriangular with 13 or 14 axial rings and 10 or 11 pleural ribs, which b e n d posteriorly toward the m a r g i n . T h e r e is a terminal spine equal

Neotype N Y S M 13381 Dalmanites limulurus limulurus is c o m m o n

in

the Lower Sil-

urian Rochester Shale of western New York in Niagara, O r l e a n s , and M o n r o e Counties (Tetreault

1 9 9 4 ) . T h e c e p h a l o n has a

distinct flattened b o r d e r and long tapering genal spines. T h e pygidium is triangular; the ribs are almost equal in width and terminate in a long slender spine. T h i s species is possibly the m o s t c o m m o n trilobite of the Rochester Shale. T h e exoskeleton is thin and often dissolved away. T h i s subspecies is f o u n d in the western exposures while D. I. lunatus, with a s h o r t e r pygidial spine, is found in the m o r e eastern exposures of the R o c h e s t e r Shale. B o t h

or greater in length than the pygidium. T h e spine is narrow, r o u n d e d in cross section, and c o m e s to a sharp point. T h e surface of the pygidium is granulose.

Neoprobilium

tridens

(Hall,

1859)

Figure

5.3C

Type A M N H 2 6 0 8 , hypotype Y P M 6 6 5 9 O n l y cephala are k n o w n of this species f r o m the Lower D e v o n ian New Scotland F o r m a t i o n . T h e cephala have a long anterior process that ends in two r o u n d e d divergent spines separated by a short, blunt, triangular process.

the specimens illustrated in Plates 88 and 89 are from the s a m e Odontochile

quarry in Orleans County.

litchfieldensis

(Delo,

1940)

Cotype U S N M 78089 Dalmanites

limulurus

lunatus

(Lambert,

Lower

1904)

Devonian,

Sallsburg

Quarry,

Litchfield,

Herkimer

County. O n l y two pygidia are k n o w n . T h e y are as wide as long

Cotypes U S N M 5 0 4 5 9 , 7 9 1 2 0 This subspecies is similar to D. I. limulurus, but the frontal

with a short acute t e r m i n a t i o n . T h e r e are 17 c o m p l e t e axial rings

process is wider and longer, the cheeks are narrower, the terminal

and 2 or 3 i n c o m p l e t e o n e s . Each ring bears an irregular row of

spine width and length are equal, and the posterior rib b r a n c h e s

tubercles. T h e r e are 14 pleural furrows, each lobe with a row of

are larger. This trilobite is f o u n d farther east in the R o c h e s t e r

tubercles along the crest. T h e b o r d e r is granulose.

Shale, in Oneida County, than the m o r e c o m m o n D. I. limulurus. Odontochile Dalmanites

(Synphoroides?)

pleuroptyx

(Green,

1832)

(Green,

1832)

Plate

92

T h i s species from the Lower D e v o n i a n C o e y m a n s Limestone

Plate 9 0 Plastotype U S N M 6 2 4 8 6

micrurus

Holotype N Y S M 13385 in

Herkimer

County

may

be

part

of

the

genus

Huntonia

T h i s trilobite from the Lower Devonian Helderberg G r o u p is

( C a m p b e l l 1 9 7 7 ) . T h e surface o f the c e p h a l o n i s o r n a m e n t e d

listed from both the New Scotland Beds and the Kalkberg L i m e -

with small tubercles. T h e r e are moderate-sized genal spines. T h e

stone in Albany and S c h o h a r i e C o u n t i e s . T h e cephalon has a

pygidial axis has 17 rings and there are 13 or 14 pleural ribs. T h e

broad crenulated frontal expansion and genal spines. T h e pygid-

pygidium terminates in a short spine.

FIGURE 5.3. Trilobites of the families D a l m a n i t i d a e ( A - D ) a n d S y n p h o r i i d a e ( E - G ) from the Lower a n d lower M i d d l e D e v o n i a n . A. Corycephalus regalis from the "Schoharie Grit" of A l b a n y County. The f i g u r e d c e p h a l o n is from Hall a n d Clarke (1888). B. Neoprobilium nasutus from the New S c o t l a n d Formation. The figured c e p h a l o n a n d p y g i d i u m are from Hall ( 1 8 6 1 b ) . C. Neoprobilium tridens from the New Scotland Formation. The f i g u r e d s p e c i m e n is from Clarke (1908) a n d is YPM 6 6 5 9 . D. Phalangocephalus dentatus from the Port Jervis Limestone in O r a n g e County. All three figures, a nearly c o m p l e t e trilobite a n d a c e p h a l o n a n d p y g i d i u m , are from Hall a n d Clarke (1888). E. Synphoria stemmata stemmata from the Oriskany/Glenerie Formations, C o l u m b i a County. The three s p e c i m e n s , a c e p h a l o n in dorsal a n d front view a n d a p y g i d i u m , are from Clarke (1900). F. Coronura myrmecophorus from the O n o n d a g a Limestone at Kingston, Ulster County. The p y g i d i u m f i g u r e d is from Hall a n d Clarke (1888). G.

Trypaulites calypso from the

C o l u m b u s Limestone, Sandusky, Ohio. The trilobite is also reported from N e w York. The illustration is from Hall a n d Clarke (1888).

ORDER

PHACOPIDA

Odontochilephacoptyx

(Hall

139 and

Clarke,

1888)

p o o r state of preservation of the s p e c i m e n s available to Edge-

Type N Y S M 4 3 5 1

c o m b e and C h a t t e r t o n m a d e proper identification impossible. A

Only the pygidium is k n o w n f r o m this Lower Devonian

s p e c i m e n now at the PRI ( P R I 4 9 6 2 8 ) , illustrated in Plate 9 5 ,

Oriskany trilobite. Delo ( 1 9 4 0 ) also listed this trilobite from the

suggests a new species m a y be involved (Greg E d g e c o m b e 1999,

lower O n o n d a g a of C a n a d a . T h e pygidium is triangular with a

private c o m m u n i c a t i o n ) .

terminal spine. T h e r e are 13 axial rings and 16 pleural ribs. T h e surface is covered with spines or tubercles, which are m o r e closely spaced on the pleura. T h e r e are tubercles of two sizes on the axial rings: the smaller are m o r e a b u n d a n t and the larger entirely

Encrinurus sp.

Plate 96

T h e unidentified s p e c i m e n s in Plate 96 are from the Lockport G r o u p o f Wayne C o u n t y .

obstruct the furrows. Erratencrinurus vigilans Odontochile? sp. Plate 93 T h e specimen is from the Lower D e v o n i a n , upper M a n l i u s F o r m a t i o n , Cobleskill, S c h o h a r i e County. Phalangocephalus dentatus

1847)

Plate 94

(Barrett,

1876)

vigilans

is

found

in

the

lower

half of the

Figure 5 . 3 D

pygidium.

Type species. T h i s species is characterized by the n u m e r o u s dant in the Port Jervis L i m e s t o n e southeast of Port Jervis in O r a n g e C o u n t y that the locality has been referred to as Trilobite M o u n t a i n . T h e cephalic b o r d e r has 37 spines; the longest is medial and the shortest is on the flank of the genal spine.

trilobites.

The

glabella has near-parallel sides or expands forward. T h e t h o r a x has 10 to 12 segments. T h e t h o r a c o p y g i d i u m is generally well tapered and may appear subtriangular. T h e small

Erratencrinurus

cybeleform

(Raymond

1921),

listed

by Fisher ( 1 9 6 5 ) f r o m the M i d d l e O r d o v i c i a n , lower Trenton Larrabee L i m e s t o n e , and E.

trentonensis

(Walcott

1 8 7 7 ) , des-

cribed with material f r o m W i s c o n s i n and Illinois, are j u n i o r s y n o n y m s of E. vigilans. T h e r e is u n n u m b e r e d material in the U S N M , all f r o m the M i d d l e O r d o v i c i a n , lower T r e n t o n , labeled Encrinurus

trentonensis.

Also

the

ROM

has

an

entire

specimen

( R O M 1 8 7 3 5 ) s o labeled.

Family Encrinuridae pustulose

Herkimer

C o u n t y . It is a small very pustulose trilobite with a highly tapered

triangular marginal spines. Pieces of this trilobite are so a b u n -

are generally small

Erratencrinurus

Middle O r d o v i c i a n Trenton G r o u p , particularly in

Hypotypes N Y S M 4 3 1 0 t o 4 3 1 1

Encrinurids

(Hall,

Lectotype A M N H 3 6 0 7 0 ( D e M o t t 1 9 8 7 ) , s p e c i m e n N Y S M 17008

pygidium

usually has very-well-defined pleural ribs, and the pygidial axis has significantly m o r e lobes than there are pleural ribs.

Physemataspis insularis (Shaw,

1968)

Plate 8 6 D

H o l o t y p e N Y S M 12331 Physemataspis

insularis

is

found

in

the

Middle

Ordovician,

lower middle Chazy t h r o u g h o u t the C h a m p l a i n Valley. For location i n f o r m a t i o n , see Shaw ( 1 9 6 8 ) . It is a small trilobite described from silicified material with very g o o d detail. T h e c r a n i d i u m is very pustulose on the glabella and palpebral area, while the genal area is pitted. It has a spherical glabella and eyes raised on stalks

Cybeloides ella ( R a y m o n d and Narraway)

well above the plane of the body.

Specimen M C Z 5 0 9 3 T h e listed specimen is from the Middle O r d o v i c i a n Black River Group at Buck's Q u a r r y northeast of Poland, H e r k i m e r County.

Family Homalonotidae T h e h o m a l o n o t i d s as a family are k n o w n from the Lower Ordovician to the end of the M i d d l e D e v o n i a n . All currently

Cybeloides prima ( R a y m o n d , 1 9 0 5 ) Plate 8 6 B

k n o w n New York species b e l o n g to the subfamily H o m a l o n o t i n a e

Lectotype C M H I 2 8 6 (Shaw 1968) Cybeloides prima is a small e n c r i n u r i d trilobite of the M i d d l e

that is represented from the Lower Silurian through the Middle

Ordovician, lower and middle Chazy. It apparently is geographi-

D e v o n i a n . T h e h o m a l o n o t i n s are characterized by a largely fea-

cally restricted to the area of Valcour and the southern end of

tureless c e p h a l o n and a r o u n d e d , subtriangular pygidium. There

Valcour Island, Clinton County. T h e cephalon has long curved

are facial sutures, but the c e p h a l o n on the New York h o m a -

genal spines and a medial occipital spine. T h e pygidium is dis-

lonotids is always f o u n d intact, indicating that the free cheeks

tinctive, as the anterior pleurae curve posteriorly and b a c k toward

were fused and not lost d u r i n g the m o l t i n g process.

the axis. Specimens described by Shaw are silicified r e m a i n s . No Brongniartella

articulated specimens are k n o w n .

trentonensis

(Simpson,

1890)

S p e c i m e n N Y S M 17017 Encrinurus cf. E. raybesti ( E d g e c o m b e a n d C h a t t e r t o n , 1 9 9 3 )

This

is a

Middle Ordovician

Trenton

age trilobite from

Plate 95

Pennsylvania. A l t h o u g h S i m p s o n reported it, Collie ( 1 9 0 2 ) first

PRI 4 9 6 2 8

described it. T h i s trilobite is f o u n d locally a b u n d a n t in the Salona

Lower Silurian, Reynales L i m e s t o n e , Niagara County. T h i s limestone is m u c h older than that c o n t a i n i n g E.

raybesti. T h e

F o r m a t i o n limestones at the Rte. 3 2 2 bypass at State College, Pennsylvania.

The

position

of these

limestones

is

possibly

140

THE

TRILOBITES

equivalent to the Kings Falls F o r m a t i o n of the T r e n t o n G r o u p in

however, disarticulated pieces are not u n c o m m o n . T h e specimen

New York. T h e Pennsylvania limestones were deposited in deeper

shown

water than those of New York, indicating that the presence of this

Trimeras delphinocephalus is also

trilobite is facies controlled. T h e r e is no reason why B. trento-

E n g l a n d , suggesting that protaspis was pelagic.

in

Plate

99

is

accompanied found

by

in

Dalmanites

limulurus.

the Silurian beds

in

nensis might not be an occasional m i g r a n t into the New York rocks.

Trimerus

vanuxemi

(Hall,

1859)

Type A M N H 2 6 1 4 / 1 , 2 Dipleura dekayi ( G r e e n , 1 8 3 2 ) Plates 97 a n d 98

T h i s large h o m a l o n o t i d is from the Lower Devonian, lower

Hypotypes N Y S M 4 4 7 8 t o 4 4 8 7 Type

species.

Dipleura

Helderberg and the Oriskany in O r a n g e County. Only pieces are in

k n o w n , but Hall and Clarke's ( 1 8 8 8 ) reconstruction 2 7 . 9 c m is (11

Middle Devonian, H a m i l t o n siltstone deposits. In s o m e areas

dekayi

is

most

often

found

inches) long. It is not at all clear what differentiates this trilobite

the cephala and pygidia are c o m m o n . W h o l e , articulated speci-

from

Homalonotus

major.

m e n s are far less c o m m o n , b u t in certain central New York m u d s t o n e s they are quarried successfully. T h i s m u c h - s o u g h t -

Family Phacopidae

after trilobite has been f o u n d in significant n u m b e r s f r o m the

Phacopids are the best k n o w n of all New York trilobites

famous " C o l e Hill Road b e d s " in M a d i s o n C o u n t y . T h e p a r t i c u -

because of the widespread availability of Eldredgeops rana in New

lar specimen shown in Plate 97 is from m o r e western exposures

York M i d d l e D e v o n i a n rocks. T h e family occurs from the Lower

of Kashong Shale and shows healed d a m a g e on the right side.

Silurian through the Upper D e v o n i a n , but the Lower and Middle

T h e r e is no o t h e r H a m i l t o n trilobite that can be c o n f u s e d or m i s -

Devonian trilobites are the best k n o w n . T h e glabella is rounded

taken for D. dekayi. Dipleura dekayi can be f o u n d in s p e c i m e n s

and expands forward. Phacopids have schizochroal eyes. T h e

up to 15.2 cm (6 inches) or longer. In size, however, it c a n n o t

genal angle is usually r o u n d e d , but short spines have been

compete

Homalonotus

observed on s o m e of the Lower Devonian species. T h e facial

major). T h e s p e c i m e n illustrated in Plate 98 shows large, spar-

sutures are fused, and molted cephala are c o m p l e t e . M u c h of

filled t h o r a c i c perforations that e x t e n d through to the internal

the diagnosis of phacopids relies on cephalic features such as

mold.

glabellar furrows and p r o s o p o n . T h e glabellar furrow SI can be

with

its

Lower

Devonian

cousin

(i.e.,

c o m p l e t e across the glabella, f o r m i n g a preoccipital ring; it can Homalonotus

major

(Whitfield,

1885)

extend back to the occipital ring ( S O ) , cutting o f f the first glabel-

Hypotype N Y S M 4 4 9 3

lar lobe ( L I ) into a n o d e ; or it can be a crease that does not cross

Two large, i n c o m p l e t e s p e c i m e n s of a h o m a l o n o t i d were

the glabella or j o i n the S O . T h e S2 and m o r e anterior glabellar

discovered in the upper part of the Lower D e v o n i a n Oriskany

furrows may be faintly expressed or absent. T h e thoracic pleurae

Sandstone near Kingston, D u t c h e s s C o u n t y . T h e larger s p e c i m e n

have rounded ends and the pygidium is semicircular. Maximova

is in the N Y S M and the smaller was given to a local, Kingston

( 1 9 7 2 ) erected a new genus, Paciphacops, and two new subgenera,

m u s e u m . Whitfield, when describing the new species, calculated

Paciphacops

that the smaller of the two, if c o m p l e t e , would have m e a -

Phacops logani and Phacops pipa,

and

sured 3 9 . 4 c m ( 1 5 . 5 inches) l o n g b y 1 4 c m ( 5 . 5 inches) wide.

We have elected

Hall and Clarke ( 1 8 8 8 ) pictured this s p e c i m e n as it might be

labels rather than subgeneric ones. Struve ( 1 9 9 0 ) differentiated

c o m p l e t e , and added the additional c o m m e n t s that the smaller

Phacops rana f r o m the type species Phacops latifrons and erected

specimen was from the lower O r i s k a n y and the larger, type spec-

the new genus Eldredgeops for the "Phacops" species of eastern America;

Viaphacops, to

with

two

as the

New

use Paciphacops and

consequently the

York

phacopids,

respective type species. Viaphacops as generic

imen was from the upper. We are not aware of any additional

North

specimens.

listed here may be referred to Eldredgeops when this genus is

Middle

Devonian

Phacops?

b e t t e r defined for N o r t h A m e r i c a . Struve ( 1 9 9 0 ) also reassigned Trimerus delphinocephalus

(Green,

1832)

Plate 99

Hypotypes N Y S M 4 4 9 0 t o 4 4 9 2 Type species.

Trimerus delphinocephalus is a w e l l - k n o w n trilo-

o n e of the Viaphacops species to Burtonops. Tables 5.5 and 5.6 list the I eat u res ol the Lower and Middle I levonian phacopids in New York.

bite of the Lower Silurian Rochester Shale. Gillette ( 1 9 4 7 ) , in his faunal list, restricted it in New York to the upper C l i n t o n G r o u p ,

Burtonops cristatus

and it is f o u n d across the state in o u t c r o p s of this age. In the

Lectotype N Y S M

Rochester Shale it is mostly f o u n d in the upper, deeper-water

4612

(Hall,

1861)

13883/1

Figure 5 . 4 F

(Eldredge

1 9 7 3 ) , hypotype N Y S M

facies (Tetreault, 1 9 9 4 ) . T h i s large inflated trilobite has a trian-

Type species. T h i s phacopid is from the Lower Devonian

gular cephalon and small eyes. T h e axial lobe on the t h o r a x is very

S c h o h a r i e F o r m a t i o n . Exposures are found in S c h o h a r i e County.

wide and faint. T h e pygidium has a distinct axial lobe, triangular

T h e c e p h a l o n has large genal spines and usually an occipital

and tapering to a point. T h i s trilobite is rarely f o u n d whole;

spine. T h e t h o r a x has axial spines. T h e r e are 14 dorsoventral rows

ORDER

PHACOPIDA

141

Table 5.5. Features of the Lower Devonian phacopids from New York

Cephalon Glabellar shape in "standard orientation" Posterior region of the glabella

Glabellar ornamentation

Dorsoventral files in the eye Ornamentation of the cephalic doublure

Genal spine Occipital spine Thorax Thoracic axial spines Axiallateral lobes Stratigraphic unit

Paciphacops logani

Paciphacops hudsoniscus

Paciphacops clarkei

Paciphacops subspecies A

Phacops? clarksoni

Burtonops cristatus

High (tumid)

High

Flattened

Flattened

Flattened

Relatively tumid

Deeply incised and connected 1S glabellar furrows; forms conspicuous intercalating ring with distal nodes and a median node, which is recurved slightly anteriorly

Deeply incised and connected 1S glabellar furrows; forms conspicuous intercalating ring with distal nodes and a median node, which is recurved slightly anteriorly

Deeply incised and connected 1S glabellar furrows; forms conspicuous intercalating ring with distal nodes and a median node, which is recurved slightly anteriorly

Deeply incised and connected 1S glabellar furrows; forms conspicuous intercalating ring with distal nodes and a median node, which is recurved slightly anteriorly

Glabellar lobes 1L are present distally as nodes; the intercalating either is wholly absorbed into the composite glabellar lobe or is depressed, with the medial position of glabellar furrow 1S generally obsolescent

Ground mass of small granules that cover the large tubercles and spaces between them 17, occasionally 18

Ground mass of small granules that cover the large tubercles and spaces between them 15 or 16

Small tubercles and ground mass of granulation much finer

Large simple tubercles, generally of different size classes

Intercalating ring depressed distally; medial lobes reflected anteriorly and incorporated into composite grabellar lobe; glabellar furrow 1S confluent with occipital furrow distally, then reflected anteromedially, becoming obsolescent medially Large simple tubercles, generally of different size classes

17

14

Granules covering the entire surface proximal to the furrow

Granules covering the entire surface proximal to the furrow

Present Node

Absent ?

Present Absent

Absent 7

Large Absent

Retains granules anteromedially but develops connected granules posterolaterally Large Present

Absent

?

Absent

?

?

Spines or nodes

Well developed

?

?

?

9

Faint

Kalkberg and New Scotland Formations

Kalkberg and New Scotland Formations

Glenerie Formation

Bee raft Formation

Schoharie Formation

Schoharie Formation

18

15

Source: From Eldredge, 1973; Campbell, 1977; Delo, 1940.

in the eyes, with a total of 48 to 81 lenses. T h e illustrated lectotype is from Eldredge ( 1 9 7 2 ) .

quarries near Silvania, O h i o . S p e c i m e n s of this trilobite were identified f r o m the Solsville M e m b e r ( n o w recognized as the Pecksport M e m b e r ) o f the H a m i l t o n G r o u p i n M a d i s o n C o u n t y

Eldredgeops crassituberculatus ( S t u m m , 1 9 5 3 ) Plates 1 0 0 ,

(Eldredge 1 9 7 2 ) . T h i s trilobite has 18 dorsoventral files, with six,

H O D , a n d 111

rarely seven, lenses per file. T h e interlensar sclera is well devel-

Holotype U M M P 2 5 5 3 7

o p e d , and the lenses are generally flush with the scleral surface.

This Middle Devonian phacopid is f o u n d in great n u m b e r s along with E. milleri (Plates 110F, 111) in the f a m o u s Silica Shale

Cephalic tubercles are large and often elongated. Plate 100 shows a specimen f r o m O h i o .

THE

142

TRILOBITES

Table 5.6. Features of the Middle Devonian phacopids of New York Viaphacops bombifrons

Viaphacops canadensis

Phacops? iowensis

Eldredgeops rana

Relatively tumid

Flattened

Flattened

Flattened

Intercalating ring depressed distally; medial lobes reflected anteriorly and incorporated into composite grabellar lobe; glabellar furrow 1S confluent with occipital furrow distally, then reflected anteromedially, becoming obsolescent medially Large simple tubercles, generally of different size classes

Intercalating ring depressed distally; medial lobes reflected anteriorly and incorporated into composite grabellar lobe; glabellar furrow 1S confluent with occipital furrow distally, then reflected anteriomedially, becoming obsolescent medially

Deeply incised and connected 1S glabellar furrows; forms conspicuous intercalating ring with distal nodes and a median node, which is recurved slightly anteriorly

1S deeply incised

Large simple tubercles, generally of different size classes

Rounded tubercles becoming transversly elongate at the anterior margin of the glabella

Dorsoventral files in the eye

14, rarely 13, 15, 16

13 or 14

13

18 in E. r. crassituberculata

Ornamentation of the cephalic doublure

Retains granules anteromedially but develops connected granules posterolaterally Short Absent

Large Absent

Absent Absent

Absent Absent

Sometimes nodes

Absent

Absent

Absent

Faint

?

Absent

Absent

Onondaga Formation

"Lower Onondaga Limestone," Port Colborne, Ontario

Hamilton Group

Hamilton Group

Cephalon

Glabellar shape in "standard orientation" Posterior region of the glabella

Glabellar ornamentation

15, rarely 16 or 17 in E. r. norwoodensis 17 in E. r. rana

Genal spine Occipital spine

Shows only terrace lines

Thorax

Thoracic axial spines Axial-lateral lobes Stratigraphic unit

Source: From Eldredge, 1972, 1973; Delo, 1940. Eldredgeops rana ( G r e e n , 1 8 3 2 ) Plates 1 0 1 , 1 0 2 , 1 0 3 , 1 0 4 , 1 1 0 C ,

103 are of trilobite clusters f o u n d in trilobite-rich beds, all in

and 111

western New York. Clusters such as these have been described as

Holotype N Y S M 4 6 4 5 Eldredgeops rana is the single most c o m m o n trilobite f o u n d and collected in New York, being widely distributed in the Middle

m o l t i n g or breeding assemblages. Plate 104 illustrates an E. rana with c o l o r centers that may reflect underlying muscle a t t a c h m e n t areas.

Devonian H a m i l t o n G r o u p shales and limestones and reported up into the Upper D e v o n i a n C h e m u n g rocks. T h e eye has 17

Eldredgeops

dorsoventral files. T h e most productive localities are in the

a n d 111

norwoodensis

(Stumm,

G r a b a u Trilobite Beds in the W a n a k a h Shale. T h e s e r e m a r k a b l e

Holotype U M M P 25524

1953)

Plates

110E

beds are well exposed in Erie, G e n e s e e , and Livingston C o u n t i e s .

T h i s is a trilobite of the late Middle D e v o n i a n . In New York

T h e exuviae, cephala, and pygidia are ubiquitous in the H a m i l -

it is only f o u n d in the Tully F o r m a t i o n , T o m p k i n s County. T h e

t o n G r o u p , and entire s p e c i m e n s are c o m m o n . Plate 101 shows

eye with usually has 15, but rarely 16 or 17, dorsoventral files.

the holotype (positive) and its m o l d (negative). Plates 102 and

T h i s species is distinguished f r o m E. rana by the narrower, less

FIGURE 5.4. Lower Devonian a n d lower M i d d l e D e v o n i a n p h a c o p i n s . All the figures are c e p h a l a s h o w n in dorsal a n d side views. The 1-cm scale bar is the s a m e for all the i m a g e s . A. Phacops? clarksoni from the Schoharie Formation, S c h o h a r i e County. The illustrated c e p h a l o n is A M N H 2 9 2 4 4 , the holotype. B. Paciphacops hudsoniscus, the s m a l l - e y e d form from the K a l k b e r g - N e w S c o t l a n d Formations, H u d s o n , C o l u m b i a County. The illustration is A M N H 2613. C. Paciphacops logani, the l a r g e - e y e d form from the New Scotland Formation near Schoharie, Schoharie County. D.

Paciphacops logani clarkei

from the Murailles Formation, Perce, Q u e b e c . This s u b s p e c i e s is also f o u n d in the Glenerie Formation, H u d s o n , C o l u m b i a County. Illustrated is A M N H 2 9 2 4 0 , the holotype. E.

Viaphacops bombifrons from

the O n o n d a g a Formation, w e s t e r n N e w York. The illustrated s p e c i m e n is A M N H 4077/2A, the lectotype. F. Burtonops cristatus from the S c h o h a r i e Formation, N e w York. Illustrated is A M N H 1 3 8 8 3 / 1 , the lectotype. A - F are from E l d r e d g e (1973), R e p r o d u c e d with p e r m i s s i o n of the author.

144

THE

TRILOBITES

e x p a n d i n g forward glabella and by the s m o o t h pygidial pleura.

distal

T h e interpleural furrows on the pygidium are deeply incised.

Eldredge ( 1 9 7 3 ) described a large-eyed and a small-eyed form.

p o r t i o n s of the t h o r a c i c

rings are large and distinct.

A l t h o u g h Eldredge ( 1 9 7 2 ) did not c o m m e n t on it, he illustrated

Further work has the large-eyed f o r m , with 17 or 18 dorsoven-

what could be considered a large- and small-eyed f o r m , with the

tral files and an average of 94 individual lens, described as

New York specimen being small-eyed.

P. logani (Plate 1 0 7 ) , and the small-eyed f o r m , with 15 or 16 dorsoventral files and with 46 to 48 lens, described as P. hud-

Eophacops

(Acernaspis?)

trisulcatus

(Hall,

1843)

Plates

105

soniscus ( R a m s k o l d and Werdelin 1 9 9 1 ) . T h i s species is reported

and 106

from the Kalkberg and New Scotland F o r m a t i o n s ot Schoharie

Holotype A M N H 1594

and C o l u m b i a C o u n t i e s , and also in Q u e b e c . Plate 107 shows a

T h i s trilobite is found in the Lower Silurian shales in M o n r o e

partially disarticulated specimen from the Helderberg G r o u p . SI

County. Ludvigsen ( 1 9 7 9 b ) figured a Silurian p h a c o p i d , referred

extends across the glabella, leaving LI as a ring on the posterior

to as an Acernaspis species, f r o m the Cataract G r o u p and the

of the glabella just anterior to the occipital ring. T h e specimen

T h o r n l o e F o r m a t i o n of C a n a d a . T h e C a n a d i a n phacopid has a

also has acute genal angles. In addition, note the p r o m i n e n t cir-

weakly inflated glabella with three pairs of t h i n , curving lateral

cular lobes on the t h o r a x where the axial and pleural lobes meet.

furrows. T h e pygidium is small and lenticular, with few furrows.

S p e c i m e n s illustrated by Hall ( 1 8 6 1 a , b ) have genal angles from

New York s p e c i m e n s are usually poorly preserved a n d are not

rounded to acute.

inconsistent with this description. F u r t h e r research is needed to properly classify the New York s p e c i m e n s . T h i s p h a c o p i d is not

Paciphacops logani s u b s p . A

u n c o m m o n in the W i l l i a m s o n or Sodus shales underlying the

Specimen A M N H 29243

(Eldredge,

1973)

Irondequoit L i m e s t o n e in M o n r o e C o u n t y . Plates 105 and 106 are

Lower Devonian Becraft F o r m a t i o n near S c h o h a r i e , Schoharie

examples of this trilobite. Preservation of the exoskeleton is u n i -

County. T h i s species is based on a single cephalon with a dis-

formly poor.

tinctive eye. T h e r e are 15 dorsoventral files with a total of 73 lenses.

Paciphacops

hudsoniscus

(Hall,

1859)

Figure

5.4B

Type A M N H 2 6 1 3

Phacopina

T h i s trilobite is reported f r o m the Lower Devonian Helderberg

Group

at

"Becraft's

Mountain"

1890)

County.

Middle Devonian O n o n d a g a L i m e s t o n e , Cayuga, O n t a r i o . T h e h o l o t y p e is a small, exfoliated c e p h a l o n . T h e presence in New

logani, the small-eyed

York is suspected b u t not k n o w n .

Ramskold

Columbia

(Clarke,

Eldredge ( 1 9 7 3 ) s y n o n y m i z e d the species with Paciphacops logani form.

in

anceps

Holotype NYSM 4 6 0 9

and

Werdelin

(1991)

rejected this, and P. hudsoniscus is n o w considered a legitimate species.

Phacopina?

correlator

(Clarke,

1900)

Holotype N Y S M 13882/1 Paciphacops clarkei

(Eldredge,

1973)

Figure

5.4D

O n l y the holotype is k n o w n from the Glenerie F o r m a t i o n at

Holotype A M N H 2 9 2 4 0 A phacopid of the Lower D e v o n i a n Glenerie

Becraft M o u n t a i n . It is a m o l d of the left half of the cephalon. Formation,

Becraft M o u n t a i n , C o l u m b i a C o u n t y . T h e glabella is s o m e w h a t

Phacops? clarksoni (Eldredge,

flatter than in o t h e r P. logani subspecies. T h e genal spines are well

Holotype A M N H 29244

developed. Glabellar furrow SI generally is indistinct medially,

1973)

Figure 5.4A

A species based on seven distinctive cephala from the Lower

and the intercalating ring tends to be i n c o r p o r a t e d medially into

Devonian

the glabellar l o b e . T h e eyes have 17 or 18 dorsoventral files with

S c h o h a r i e County. T h e r e are large genal spines and no occipital

Schoharie

Formation

of

the

Schoharie

Valley,

eight or nine lenses per c o m p l e t e file. O r n a m e n t a t i o n is fine

n o d e . T h e eye has 17 dorsoventral files and m o r e than 80 lenses.

tubercles over the entire test that are m u c h smaller than those on

T h e lenses protrude farther beyond the interlensar sclera than is

the other subspecies.

c o m m o n for phacopids. T h e area under the visual surface is devoid of o r n a m e n t a t i o n . Eldredge believed that the specimens

Paciphacops logani ( H a l l , 1 8 5 9 ) Figure 5 . 4 C a n d Plates

107,

c a n n o t be assigned to either Paciphacops or

Viaphacops.

1 1 0 A , and 111 Lectotype N Y S M 1 3 8 8 5 / 2 (Hall a n d Clarke 1 8 8 8 ; see Eldredge

Phacops? iowensis alpenensis

1973)

a n d 111

Type species. T h i s species is a widely distributed Lower D e v o n i a n , lower Helderberg trilobite. T h e occipital n o d e is vari-

(Stumm,

1953)

Plates

108,

110F,

Holotype U M M P 25516 Eldredge ( 1 9 7 2 ) f o u n d s p e c i m e n s in the Middle Devonian

ably developed, and genal spines are usually present but m a y be

Pecksport

absent, particularly in the small-eyed f o r m . T h e nodes on the

W i n d o m M e m b e r o f the H a m i l t o n G r o u p i n Madison County.

Member.

Later Steve

Pavilski

found s o m e in the

ORDER

PHACOPIDA

145

T h e SI glabellar furrow is deeply incised. Moderately conical

resembles a dalmanitid. T h e family was reviewed by Delo ( 1 9 4 0 )

tubercles are all over the exoskeleton. T h e facial suture over the

and m o r e recently by Ludvigsen and C h a t t e r t o n ( 1 9 8 2 ) .

ocular platform is moderately deeply incised. T h i s trilobite is relatively c o m m o n in Michigan and very u n c o m m o n in New York.

Achatella achates (Billings, 1 8 6 0 ) P l a t e 115

Plate 108 is from the upper W i n d o m beds in Livingston County.

Hypotype N Y S M 4257

Viaphacops bombifrons (Hall a n d C l a r k e , 1 8 8 8 ) Figure 5 . 4 E

bite is f r o m O t t a w a , C a n a d a . T h e general outline resembles dal-

Type species. T h e h o l o t y p e of this M i d d l e Ordovician triloand Plates 1 0 9 , 1 1 0 B , a n d 111

manitids. T h e cephalon is semicircular in outline with long genal

Lectotype A M N H 4 0 7 1 / 2 A (Eldredge 1973)

spines. T h e glabella expands forward and the La lobe is pustu-

This species is widely distributed in the Middle Devonian

lose. T h e eyes are schizochroal and elevated well above the plane

O n o n d a g a Limestones and their equivalent in New York, O n t a r i o ,

of the c e p h a l o n . T h e b o d y tapers toward the rear, ending with a

and O h i o . T h e eye usually has 14 dorsoventral files, although 13

p o i n t e d t e r m i n a t i o n on the pygidium. W h o l e articulated speci-

to 16 are known. Four or five lenses per row are also the n o r m .

m e n s are f o u n d in the middle T r e n t o n , W a l c o t t - R u s t Quarry,

T h e area under the visual surface is coarsely tuberculate. T h e r e

H e r k i m e r County. It is also reported f r o m Pennsylvania and

are short genal spines and s o m e t i m e s an occipital n o d e but no

M i n n e s o t a . Plate 115 shows a s p e c i m e n f r o m the Walcott-Rust

occipital spine. Normally there are no t h o r a c i c axial nodes or

Quarry. T h i s trilobite is m o s t often f o u n d as cephala on bedding

spines.

planes where the high, schizochroal eyes are distinctive.

Family Pliomeridae

Calyptaulax annulata

T h e only pliomerid from New York is Pliomerops canadensis. T h e cephalon is semicircular with a p r o m i n e n t glabella. T h e glabella expands forward uniformly. T h e SI

(Raymond,

1905)

Lectotype C M H - 1 2 9 3 (Shaw 1 9 6 8 ) ; hypotypes N Y S M 1 2 3 6 8 t o 12392

and S2 glabellar

Calyptaulax annulata is f o u n d t h r o u g h o u t the M i d d l e O r d o v i -

furrows are deep and extend about o n e - t h i r d of the way across

cian Chazy G r o u p . In general shape and characteristics, it closely

the glabella. T h e t h o r a x tapers to the rear with 18 s e g m e n t s . T h e

resembles

pygidium is semicircular and curves sharply down all a r o u n d .

s p e c i m e n s with and without short genal spines. T h e protaspids

T h e r e are five pygidial axial rings and five pleurae separated by

and meraspids are also k n o w n (Shaw 1 9 6 8 ) . It is the only ptery-

deep interpleural furrows.

g o m e t o p i d k n o w n f r o m the New York Chazy.

C.

callicephalus f r o m

the T r e n t o n .

Pliomerops canadensis (Billings, 1 8 5 9 ) Plates 1 1 2 , 1 1 3 ,

Calyptaulax callicephalus ( H a l l , 1 8 4 7 )

and 114

Holotype A M N H 848

Lectotype G S C 1101 ( W h i t t i n g t o n 1961) Type species.

Pliomerops canadensis is f o u n d

Calyptaulax throughout

callicephalus

is

Plates

found

Shaw

illustrated

1 1 6 and

throughout

the

117 Middle

the

O r d o v i c i a n Trenton G r o u p of New York and is also reported in

Middle Ordovician Chazy in New York (for locations, see Shaw

O n t a r i o , M a n i t o b a , New Jersey, Kentucky, and M i n n e s o t a . It is

1968) and in Chazy age rocks in Q u e b e c , Tennessee, and Virginia.

especially c o m m o n in the Kings Falls L i m e s t o n e at Kings Falls on

Articulated specimens are not rare in New York and may reflect

the Deer River, Lewis County. At first glance this trilobite appears

this species's exceptionally robust exoskeleton, as this is generally

to be a p h a c o p i d . T h e m a i n differences are the c e p h a l o n , which

not the case with other Chazy trilobites. In most of the s p e c i m e n s ,

in C. callicephalus is not r o u n d e d but rather c o m e s to a blunt

the medial area is very rounded and the distal parts of the pleurae

point in front, and the pygidium, which is subtriangular rather

are perpendicular to the m a t r i x . Plate 112 shows an articulated

than r o u n d e d as in m o s t p h a c o p i d s . T h e pygidium could be mis-

specimen. T h e very robust exoskeleton c o n t r i b u t e d to its preser-

taken for that of calymenids f o u n d in the s a m e h o r i z o n s , but o n c e

vation in a high-energy e n v i r o n m e n t . Plate 113 is a side view of

again the pygidium of C. callicephalus is m o r e triangular and has

the same s p e c i m e n , showing the vaulted pleural area and the

m a n y m o r e axial rings and pleurae. A s p e c i m e n in the M C Z is

cephalic structure, which is difficult to see from the top.

labeled with this n a m e f r o m the Black River L i m e s t o n e Quarries

Family Pterygometopidae

trilobite resembling C. callicephalus f r o m the Upper Ordovician

near Poland, H e r k i m e r C o u n t y . R u e d e m a n n ( 1 9 2 6 ) reported a T h e pterygometopids, in New York, are f o u n d in the Middle Ordovician. T h e glabella expands forward, and the eyes are

Indian Ladder Shales. Plates 116 and 117 illustrate the dorsal and ventral exoskeletal a n a t o m y of this trilobite.

schizochroal. T h e genal angle is often r o u n d e d to acute, b u t Achatella and Eomonorachus species have genal spines. T h e t h o -

Calyptaulax eboraceous

racic pleurae are rounded on the ends. T h e pygidium is s o m e -

Holotype N Y S M 4767

(Clarke,

1894)

what triangular with 8 to 13 axial rings. Calyptaulax species at

A M i d d l e O r d o v i c i a n , lower Trenton (Glen Falls Limestone)

first glance appear to be phacopids, and the Achatella species

trilobite from the quarries at Rawlins Mills, Saratoga County. It

146

THE

TRILOBITES

is also reported from the Trenton pebbles of the Rysedorph C o n -

10 are strongly expressed. T h e axial rings have faint medial nodes.

glomerate

Eomonorachus

T h e r e are eight pygidial ribs on the pleura, with o n e or two thin

intermedins in that the S2 and S3 glabellar furrows do not isolate

raised areas near the m e d i o p o s t e r i o r area. T h e first four most

the L2 and L3 lobes. It has genal spines.

anterior ribs have weak intrapleural grooves. T h e interpleural

(Ruedemann

1901).

It

differs

from

grooves do not reach the m a r g i n . Chasmops? (or Sceptaspis) bebryx ( B i l l i n g s ,

1860)

Plate

118

Holotype? PRI 4 9 6 3 1 , hypotype G S C 1 3 2 6 2 , s p e c i m e n U S N M 26361

Family Synphoriidae T h e family Synphoriidae was erected from the subfamily Syn-

T h e trilobite is listed as Trenton age from O t t a w a , C a n a d a .

p h o r i i n a e ( D e l o 1935, 1 9 4 0 ) of the Dalmanitidae by Lesperance

Billings's illustration, however, was f r o m a s p e c i m e n o w n e d by

( 1 9 7 5 ) because o f recognition o f a n u m b e r o f new trilobites

Colonel Jewett. T h i s s p e c i m e n is n o w at PRI and is designated as

within the then subfamily. T h e family was earlier restricted to the

the holotype?. It is from Trenton age rocks at J a c k s o n b u r g , M o n t -

Devonian and was almost exclusively North A m e r i c a n . Campbell

gomery

Monorachus

( 1 9 7 7 ) and Holloway ( 1 9 8 1 ) substantially modified the concept

bebryx, is from near W a t e r t o w n , Lewis C o u n t y , collected by the

of the Synphoriidae. Holloway extended the family into the Sil-

U S G S in 1897. D e l o ( 1 9 4 0 ) illustrated the P R I s p e c i m e n , by

urian. T h e family is characterized by the distance between the

copying B i l l i n g s , and designated it as the type of Chasmops bebryx

cephalic a p o d e m e s , SI and S 2 , which is m o r e than 1.5 times the

but does not list it in the text of his paper. Plate 118 illustrates

distance between S O and S I (Figure 5 . 2 ) .

the

County.

holotype?.

The

USNM

specimen,

Chasmops? bebryx differs

labeled

from

Eomonorachus con-

vexus (Plate 119) in the longer palpebral lobes, the m u c h m o r e triangular pygidium, and the m u c h less strongly incised SI on C? bebryx.

T h e specimen

is very similar to the genus Sceptaspis,

which is widely reported in the Midwest and C a n a d a as Sceptaspis lincolnensis. If this is the s a m e species, then the species n a m e bebryx has priority.

Middle O r d o v i c i a n Trenton Falls, H e r k i m e r C o u n t y . T h e r e are two exfoliated cranidia on the small rock with the s p e c i m e n s . T h e left cheek and genal area are c o m p l e t e on o n e of t h e m . It has short, thin genal spines. T h e eyes are missing. T h e m a t r i x of the rock is a j u m b l e of Prasopora. On the s a m e rock are Flexicalymene intermedins

Type

species.

This

trilobite

from

the

Lower

Devonian

S c h o h a r i e Grit in Albany C o u n t y is also referred to as Anchiopsis; however,

the

Treatise

supports

Anchiopella.

The

cephalon

has

terminal spine. It has seven or eight pairs of rounded, unfurrowed

T h e h o l o t y p e is an internal m o l d labeled from " p r o b a b l y " the

Eomonorachus

120

and large eyes. T h e pygidium is triangular with a sharp, upturned

H o l o t y p e U S N M 8 9 9 8 7 , specimen PRI 4 9 6 3 2

cranidia.

Plate

rounded tubercles of two sizes, and the occipital ring has a spine

1940)

Plate 119

Ceraurus

1832)

Holotype N Y S M 4264

slender genal spines, the glabella is sparsely covered with well-

Eomonorachus convexus ( U l r i c h a n d D e l o in D e l o ,

and

Anchiopella anchiops ( G r e e n ,

The by

species

was

synonymized

Ludvigsen

and

Chatterton

with (1982)

pleural lobes and eight or nine axial rings.

Anchiopella anchiops sobrinus (Hall and C l a r k e ,

1888)

Holotype N Y S M 4243 T h i s trilobite of the Lower Devonian S c h o h a r i e Grit, Albany C o u n t y , differs f r o m A. anchiops in having a m o r e - r o u n d e d anterior m a r g i n and in lacking genal and occipital spines. Only the holotype cephalon is k n o w n , according to Delo ( 1 9 4 0 ) .

without c o m m e n t . D e l o ( 1 9 4 0 ) stated that the species differs from

intermedins in the r o u n d e d front m a r g i n , smaller s e c o n d

glabellar lobes, larger eyes, and coarser o r n a m e n t a t i o n . Different specimens

are

USNM

79015

from

Rathbun

Brook,

Oneida

County, and U S N M 7 9 0 1 4 f r o m the lower T r e n t o n quarries a t

Coronura aspectans ( C o n r a d , 1 8 4 1 ) Plates 121 and 122 Type A M N H 4 0 6 5 / 1 , hypotype N Y S M 4 3 1 6 Type

species.

This

species,

from

the

Middle

Devonian

O n o n d a g a L i m e s t o n e , is characterized by furrowed ribs and

Rawlins Mills, Saratoga C o u n t y . A s p e c i m e n with this n a m e in

regular, rather fine, o r n a m e n t a t i o n on the pygidium. A whole

the M C Z is labeled as f r o m the basal T r e n t o n near Poland,

s p e c i m e n , Plate 1 2 1 , in N Y S M is from Leroy, Genesee County. It

H e r k i m e r County. S p e c i m e n s collected f r o m the Glens Falls

is a latex pull from the external m o l d , as it retains better features

Limestone near A m s t e r d a m , M o n t g o m e r y C o u n t y , PRI 4 9 6 3 2

than the c o u n t e r p a r t .

(Plate 1 1 9 ) , show the following characteristics: T h e cephalon is proparian and the free cheeks are missing. T h e glabella is pustu-

Coronura helena ( H a l l , 1 8 6 1 ) Plate

lose. T h e palpebral lobe is crescent shaped, with a groove sepa-

Holotype A M N H 4250/1

127B

rating it from the fixed cheek. T h e occipital ring has a m e d i a n

T h i s species f r o m M i d d l e Devonian O n o n d a g a Limestone is

n o d e . T h e pygidium is subtriangular. T h e tapered axis extends

characterized by weak to obsolete tuberculation, long slender

nearly to the m a r g i n , with tapering m o r e strongly for the m o s t

lateral pygidial spines, and horizontally bifid terminal pygidial

a n t e r i o r five axial rings; there are at least 14 axial rings; the first

spines.

ORDER

PHACOPIDA

147

Coroiuira myrmecophorus ( G r e e n ,

1835)

Odontocephalus

Figure 5 . 3 F

humboltensis

(Sargent,

1953)

Specimen B M S E-16674-5

Hypotypes N Y S M 4 3 3 5 , 4 3 5 0 This trilobite o f the Middle Devonian O n o n d a g a L i m e s t o n e , Genesee County, is characterized by its very large size, u n f u r -

This

Middle

Devonian

O n o n d a g a species was discovered

d u r i n g road c o n s t r u c t i o n in Buffalo, Erie County. It is character-

rowed ribs, scattered tuberculose o r n a m e n t a t i o n , and erect ter-

ized by having 11 denticles on the anterior cephalic border, short

minal spines ( D e l o 1 9 4 0 ) .

genal spines, and a distinct b o r d e r on the pygidium with no terminal pygidial spines.

Odontocephalus aegeria (Hall,

1861)

Plate

123

Odontocephalus selenurus

Hypotype N Y S M 4 2 5 8 T h i s species from the Middle Devonian O n o n d a g a L i m e s t o n e , Erie County, is characterized by 11 spatulate denticles on the anterior cephalic b o r d e r and sharp, slender genal spines that extend back to the fourth thoracic s e g m e n t . T h e r e are 10 pygidial pleurae.

(Eaton,

1832)

Plate

125

Hypotypes N Y S M 4 3 5 9 t o 4 3 6 8 Type species. T h i s trilobite is reported

from the Middle

Devonian O n o n d a g a limestones across the state. T h e species is in need of revision. It has been characterized as having nine spatulate denticles on the c e p h a l o n . Hall a n d Clarke ( 1 9 8 8 , Plate 12) illustrated s p e c i m e n s that m a y b e l o n g to two different species or

Odontocephalus bifidus (Hall, 1 8 6 1 )

Plate

m o r p h o t y p e s . O n e f o r m illustrated in Plate 125 has a cephalon

124

with ridges on the denticles and a slight forward protrusion of

Hypotype N Y S M 4 2 7 5 T h e type specimen is from quarries in the O n o n d a g a L i m e stone, Genesee County. It is a pygidium characterized by a b r o a d flat area posterior to the axial lobe and two stout, rapidly tapering, and close together, terminal axial spines. T h e r e are seven to eight pleurae. An entire specimen from the s a m e quarries is illustrated in Plate 124. T h i s is the only k n o w n whole s p e c i m e n f r o m New York. T h e cephalon has nine spatulate denticles and short genal spines.

the anterior cephalic border. T h e pygidium is oval with short pygidial spines. T h e o t h e r f o r m , illustrated in Plate 126, has a c e p h a l o n with flat denticles, a r o u n d e d a n t e r i o r cephalic border, and very s h o r t genal spines. An associated pygidium is m o r e triangular with relatively long pygidial spines. T h e r e are at least five species in this genus. T h e characteristics are listed in Table 5.7. Odontocephalus sp. This

specimen

Plate

is

from

126 the

Middle

Devonian

Moorehouse

M e m b e r o f the O n o n d a g a L i m e s t o n e i n the LeRoy Quarry, Odontocephalus

coronatus

(Hall,

1861)

Genesee C o u n t y .

Holotype A M N H 4 0 6 4 , hypotype N Y S M 4 3 0 9 T h i s trilobite is from the Middle Devonian O n o n d a g a L i m e stone of central New York, Cayuga County. T h e c e p h a l o n is u n k n o w n . It is characterized by the pygidium, which has no border and eight pleurae. T h e r e are no terminal spines, but where they are on other o d o n t o c e p h a l i d s , there are two

rounded

pygidial extensions.

Schoharia

emarginata

(Hall,

1876)

Holotype N Y S M 4 3 1 8 Type species.

O n l y the pygidium of this trilobite is de-

finitely k n o w n from the Lower D e v o n i a n S c h o h a r i e F o r m a t i o n , S c h o h a r i e C o u n t y . It is characterized by a posterior " n o t c h , " within which the most posterior pleural ribs t e r m i n a t e . T h e r e are

Table 5.7. Features of the genus Odontocephalus of New York

Cephalon Length to width Preglabellar dentations Genal spines Pygidium Border Terminal spines

Axial rings Pleura

O. aegeria

O. bifidus

1:2 11

9

Long

Short

None

None

2, short, well separated 9

2, short, close together, parallel 8

9 or 10

O.

coronatus

O.

huboltensus

O.

selenurus

Not known

1:2 11 Short

1:2 9 Short

None None

Distinct None

Distinct 2, short, well separated 8 or 9

7 (plus one indistinct) 12

8 or 9

148

THE

TRILOBITES

approximately 17 axial rings and 15 n o n f u r r o w e d pleural ribs.

Trypaidites calypso (Hall and C l a r k e ,

O r n a m e n t a t i o n consists o f scattered pustules.

Type A M N H 4 2 4 9 / 1

Schoharia

f r o m O h i o and S c h o h a r i e , S c h o h a r i e County. N o n e of the illus-

1888)

Figure 5 . 3 G

Hall and Clarke ( 1 8 8 8 ) listed this trilobite as Lower Devonian sp.

trations in Hall and Clarke's publication are specimens from New

Specimen NYSM 4309 A single pygidium illustrated by Lesperance ( 1 9 7 5 ) is from the

York, and all of the s p e c i m e n listings from Lesperance ( 1 9 7 5 ) are

Middle Devonian O n o n d a g a L i m e s t o n e , S c h o h a r i e County. It is

f r o m O h i o , Kentucky, M i c h i g a n , and Illinois. O n e must question

characterized by a shallow posterior n o t c h , a pseudo postaxial

if this species is truly f o u n d in New York. T h e cephalon has short

ridge, and low flattened ribs. O r n a m e n t a t i o n consists of very few

genal spines and large eyes. T h e r e are 11 thoracic segments. T h e

scattered pustules.

pygidium is rounded with a well-defined border and has 11 axial rings with a r o u n d e d n o d e and 10 or 11 broad, flat, furrowed

Synphoria?

concinnus

(Hall,

pleurae.

1876)

Types N Y S M 4 3 0 7 t o 4 3 0 8 Grit, Albany

Trypaulites erinus (Hall,

County, is k n o w n only f r o m pygidia. T h e pygidium is s u b t r i a n -

Holotype N Y S M 4320

This species o f Lower D e v o n i a n ,

Schoharie

gular and very convex. T h e b o r d e r is o b s c u r e laterally but widens

F r o m the Middle

1861)

Plate

127A

Devonian O n o n d a g a G r o u p o f western

posteriorly into a short, b l u n t , triangular t e r m i n u s . T h e surface

New York in O n t a r i o , Genesee, and Erie C o u n t i e s , this trilobite

is s m o o t h . T h e r e are seven or eight axial rings and seven or eight

is k n o w n only from the pygidium. It has 12 (13?) slightly fur-

wide flat pleurae, the m o s t a n t e r i o r of which is indistinctly

rowed pleural ribs and 16 axial rings with a postaxial ridge. T h e r e

furrowed.

is a border. T h e surface is covered with granules and the termi-

Synphoria

lected from the Bois B l a n c near LeRoy, Genesee County, New

nation is slightly u p t u r n e d . Pygidia of this species have been colsopita

(Lesperance,

1975)

York.

Paratype A M N H 2 9 2 4 7 T h i s species is f r o m the Lower D e v o n i a n O r i s k a n y / G l e n e r i e F o r m a t i o n , C o l u m b i a C o u n t y . T h e cephalon is triangular in

Trypaulites

outline with p r o t r u d i n g genal angles. T h e a n t e r i o r b o r d e r has at

Holotype NYSM 4327

least 15 c r e n u l a t i o n s , with perhaps up to 19 m o r e . T h e pygidium

macrops

(Hall,

1861)

T h i s trilobite is k n o w n f r o m a single incomplete, internal

has 14 or 15 axial rings and 9 or 10 pleural ribs. It is t e r m i n a t e d

cephalic

with a blunt spine u p t u r n e d at about 30 degrees.

S c h o h a r i e County. T h e eye is m u c h larger than that of T. calypso,

m o l d from

the O n o n d a g a

Limestone o f Schoharie,

with 37 dorsoventral files of 15 lenses each. Synphoria

stemmata

compacta

(Lesperance

and

Bourque, 1971)

5.6 ORDER PROETIDA

Holotype N Y S M 4371

T h i s p o s t - C a m b r i a n order lasted until the final extinction of

T h i s trilobite, from the Lower Devonian O r i s k a n y / G r e n e r i e

trilobites at the end of the Permian. T h e trilobites are generally

F o r m a t i o n s o f Becraft M o u n t a i n , C o l u m b i a C o u n t y , resembles S .

oval to suboval in o u t l i n e , with a m e d i u m - s i z e d pygidium. Genal

stemmata stemmata except the a n t e r i o r cephalic b o r d e r has 13 to

spines are c o m m o n l y present.

19 crenulations. T h e pygidium is n o n s p i n o s e and well r o u n d e d , with 13 axial rings and nine pleural ribs.

Family Aulacopleuridae T h o m a s and O w e n s ( 1 9 7 8 ) c o m b i n e d two trilobite families,

Synphoria

stemmata

stemmata

(Clarke,

1900)

Figure

5.3E

Aulacopleuridae and O t a r i o n i d a e , into o n e family, Aulacopleuri-

Lectotype N Y S M 4 3 7 2 ( L e s p e r a n c e and B o u r q u e , 1 9 7 1 ) Type

m e m b e r s of the subfamily Scharyiinae are reported from New

Oriskany/Glenerie F o r m a t i o n s , C o l u m b i a C o u n t y . T h e cephalon

York. T h e aulacopleurids are small trilobites with a forward-

large,

is

This

species

slightly convex,

is has

from seven

the

Lower

dae, with two subfamilies Aulacopleurinae and Scharyiinae. No

Devonian

is

species.

the

tapering glabella. T h e LI glabellar lobe is separated from the

anterior border, and has no genal spines. T h e pygidium is n o n -

crenulations

glabella by a groove. In m a n y respects, except for size, they resem-

spinose and bluntly r o u n d e d , with 13 axial rings and nine pleural

ble proetids and are a m e m b e r of the order Proetida. T h o m a s and

ribs.

on

O w e n s did not a t t e m p t to reclassify the large n u m b e r of North A m e r i c a n species represented by this family, so most of the names

Synphoroides

dolphi

(Clarke,

1893)

Holotype NYSM 4317 Helderbergian at Port Jervis, O r a n g e County.

listed are traditional. Adrain and C h a t t e r t o n ( 1 9 9 5 ) revised the genera Harpidella and Maurotarion. Species referred to as Otarion in New York are in need of revision.

O R D E R

149

P R O E T I D A

Cyphaspis

sp.

Otarion? (Maurotarion)

Specimen B M S E - 1 1 0 3 5

coelebs

(Hall

and C l a r k e ,

1888)

Plastotype N Y S M 4 2 3 3

S t u m m ( 1 9 6 7 , Plate II, no. 2 1 ) illustrated a trilobite identified

Otarion . coelebs is a Lower Devonian trilobite from the Lower

as an Otarion? species. An articulated s p e c i m e n collected in the

Helderberg of Albany and S c h o h a r i e C o u n t i e s . T h i s is likely a

Middle Devonian Deep Run Shale in Livingston C o u n t y has

Maurotarion species (Adrain and C h a t t e r t o n

7

1995).

been identified as a Cyphaspis species ( J o n Adrain 1 9 9 9 , private communication).

Otarion? diadema (Hall and C l a r k e ,

1888)

Plastotype N Y S M 4 2 3 8 T h i s M i d d l e Devonian trilobite is f r o m " d e c o m p o s e d chert

Harpidella craspedota (Hall a n d C l a r k e , 1 8 8 8 ) Plate 1 2 8

boulders in the n e i g h b o r h o o d of C a n a n d a i g u a , New York" (Hall

Lectotype N Y S M 4 2 3 6 Harpidella from certain

craspedota

is a

small,

relatively c o m m o n

of layers the Centerfield

trilobite

L i m e s t o n e in

Middle

and Clarke

1888).

T h e s e b o u l d e r s , in

O n t a r i o C o u n t y , are

glacially t r a n s p o r t e d O n o n d a g a L i m e s t o n e .

Devonian Hamilton exposures in O n t a r i o and Livingston C o u n ties

in western New York.

S p e c i m e n s of Harpidella that

may

belong to this species have been collected from the M o u n t M a r i o n

Otarion? hudsonicum

(Ruedemann,

1901)

Holotype N Y S M 4 2 3 6

trilobite

T h i s trilobite is f r o m the O r d o v i c i a n , upper Utica Shale of

is characterized by long genal spines and 12 t h o r a c i c s e g m e n t s .

Green Island near Albany, Albany C o u n t y . It was assigned to a

Formation

and

the

Stafford

Limestone.

This

T h e r e is a short, axial spine on the fourth t h o r a c i c segment

new species because of the rarity of aulacopleurids in the Utica

and a long one on the sixth. Plate 128 shows a small cluster of

Shale.

specimens. Otarion? hybrida (Hall a n d C l a r k e , 1 8 8 8 ) Harpidella spinafrons ( W i l l i a m s in C o o p e r and W i l l i a m s , 1 9 3 5 ) Plates 129 and 130 Holotype U S N M 8 9 7 5 1 , s p e c i m e n U S N M 8 9 9 8 0 (labeled H . craspedota) T h i s species is f r o m the M i d d l e Devonian Tully F o r m a t i o n , West

Brook

Other

Member

specimens

are

near listed

Sherburne, as

Chenango

4 . 8 km

(3

miles)

County. south

of

Sherburne. T h i s trilobite has a d o u b l e row of anterior spines along the cephalic border, a juvenile characteristic retained in the holaspid. Plate 129 shows an entire but d a m a g e d s p e c i m e n . T h e base of the thoracic spine on the sixth segment is clearly shown. Plate 130 is of a well-preserved cephalon of the same species.

T h i s M i d d l e Devonian trilobite is f r o m " d e c o m p o s e d chert boulders in the n e i g h b o r h o o d of Canandaigua,'' O n t a r i o County. These boulders are glacially t r a n s p o r t e d O n o n d a g a L i m e s t o n e . Otarion? laevis ( H a l l , Otarion

7

1876)

laevis is k n o w n from o n e cephalon from the Upper

Devonian " C h e m u n g Formation", C h e m u n g County. Otarion? matutinum

(Ruedemann,

1901)

Syntypes N Y S M 4 2 4 1 t o 4 2 4 2 T h i s trilobite was identified f r o m material in Middle O r d o v i cian Trenton age pebbles within the Rysedorph C o n g l o m e r a t e , Rensselaer C o u n t y . Shaw ( 1 9 6 8 ) believed that O. matutinum and

Harpidella stephanophora (Hall a n d C l a r k e ,

1888)

Hypotypes N Y S M 4 2 5 3 t o 4 2 5 6 This Middle Devonian trilobite is from " d e c o m p o s e d chert boulders in the n e i g h b o r h o o d of C a n a n d a i g u a , New York" (Hall and Clarke

1 8 8 8 ) . T h e s e boulders are O n o n d a g a L i m e s t o n e

glacially transported into O n t a r i o County. Adrain and C h a t t e r t o n (1995)

Holotype N Y S M 4240

assigned

Cyphaspis

stephanophora

to

Harpidella.

O. hudsonicum might not be aulacopleurids because of the n o n separate nature of the basal lobes. Otarion?

(Maurotarion)

minuscula

(Hall,

1876)

Hypotypes N Y S M 4 2 4 3 t o 4 2 4 9 Otarion? minuscula is a trilobite of the S c h o h a r i e Grit, Albany C o u n t y , and O n o n d a g a L i m e s t o n e , O n t a r i o , Genesee, and Erie C o u n t i e s , which places it in the upper Lower Devonian or lower Middle D e v o n i a n . T h e s p e c i m e n illustrated in the work by Hall

Harpidella sp. Plate 131 T h e trilobite in Plate 131 is an as yet, undescribed species from

and Clarke ( 1 8 8 8 ) shows no evidence of the axial thoracic spine often found in this genus. T h i s is likely a Maurotarion (Adrain

the O n o n d a g a Limestone.

and C h a t t e r t o n 1 9 9 5 ) .

Maurotarion sp. Plate 132

Otarion? spinicaudatum

Specimens have been found in the Upper Silurian L o c k p o r t Group near Sodus, Wayne County. T h e y c a n n o t be identified with any known New York species.

(Shaw,

1968)

Holotype N Y S M 12243 Otarion spinicaudatum is from the Middle Ordovician, lower Middle Chazy beds and was identified from silicified specimens.

150

THE

It is considered to be o n e of the oldest m e m b e r s of this family.

Bathyurus

For l o c a t i o n s , see Shaw ( 1 9 6 8 ) .

Syntypes N Y S M 9 6 3 4 t o 9 6 3 6

taurifrons

(Dwight,

TRILOBITES

1884)

Bathyurus taurifrons is reported f r o m the Lower Ordovician Roachdale

Family Bathyuridae Bathyurid trilobites are f o u n d in the Lower and Middle Ordovician of New Y o r k — m o s t , if not all, below the middle Trenton. T h e y have a robust, nearly semicircular c e p h a l o n with stout genal spines.

T h e glabella

is

p r o m i n e n t and expands

forward or is parallel sided. Glabellar furrows are faint. T h e t h o r a x has 9 or 10 s e g m e n t s and no c o n s p i c u o u s pleural spines. T h e pygidium is nearly semicircular, s o m e t i m e s with an axial pygidal spine.

Acidiphorus

(Brett

and

Westrop,

1996)

of

the

Fort

Cassin

Formation,

Washington

County. O n e should refer to the original publication for the description.

platypus

(Fortey,

Dutchess

striata

(Whitfield,

1897)

T h i s species is f r o m the Lower Ordovician Fort Cassin Form a t i o n in V e r m o n t . In all probability it is also found in New York (Brett and Westrop 1 9 9 6 ) . seeiyi

(Whitfield,

1889)

species.

Bolbocephalus

seeiyi

is

a

trilobite

from

the

lower part of the Spellman F o r m a t i o n (Lower Ordovician, lower B e e k m a n t o w n G r o u p ) a t B e e k m a n t o w n , C l i n t o n County. T h e c e p h a l o n is convex, narrowing anterior to the occipital ring and t h e n e x p a n d i n g forward. T h e r e are no glabellar furrows. Grinnellaspis

Bathyurelhis

the W a p p i n g e r Valley in

Holotype A M N H 35823

Type

T h i s bathyurid is f r o m the Lower O r d o v i c i a n Scotia L i m e Member

in

Holotype A M N H 396

Holotype U S N M stone

Benthamaspis

Bolbocephalus

whittingtoni

Limestone

County.

cf.

G.

marginiata

(Billings,

1865)

L e c t o t y p e G S C 6 4 6 ( W h i t t i n g t o n 1953)

1979)

Brett and Westrop ( 1 9 9 6 ) tentatively identified specimens

Holotype GSC 56847 T h i s bathyurid is from the Lower O r d o v i c i a n Scotia L i m e s t o n e M e m b e r of the Fort Cassin F o r m a t i o n , W a s h i n g t o n C o u n t y . A

f r o m the Lower Ordovician Scotia L i m e s t o n e M e m b e r of the Fort Cassin F o r m a t i o n , Washington County, as this species.

c r a n i d i u m and two pygidia were j u d g e d identical to material from N e w f o u n d l a n d (Brett and Westrop 1 9 9 6 ) .

Raymondites

ingalli

(Raymond,

1913)

Holotype G S C 4328 Bathyurus cf.

B.

angelina

(Billings,

1859)

Holotype G S C 1084c, specimen M C Z 3790 T h e h o l o t y p e i s f r o m the Lower O r d o v i c i a n o f Q u e b e c . T h e M C Z s p e c i m e n was collected by C. D. Walcott in 1867 from a drift block near T r e n t o n Falls in either H e r k i m e r or O n e i d a County. T h i s species was identified by P. R a y m o n d in 1 9 0 5 .

Bathyurus extans (Hall,

1847)

Plate

133

Lectotype N Y S M 4 1 3 9 ( W h i t t i n g t o n 1 9 5 3 ) Type species. Bathyurus extans is a characteristic trilobite f r o m the Lowville L i m e s t o n e M e m b e r o f the Middle O r d o v i c i a n Black River G r o u p . It is f o u n d wherever these rocks are exposed in New York and is also reported from M i n n e s o t a . Plate 133 is a specim e n f r o m the Black River of Lewis C o u n t y .

Type species. Raymondites ingalli is a trilobite usually associated with the M i d d l e Ordovician Kirkfield F o r m a t i o n of O n t a r i o . Fisher ( 1 9 6 2 ) listed it as characteristic of the lower Trenton Larrabee L i m e s t o n e . D e M o t t ( 1 9 8 7 ) stated that he can only place the holotype in this species with certainty. All other specimens he is aware of are R. spiniger. Raymondites

longispinus

(Walcott,

1877)

Holotype M C Z 107237 The

holotype

of

this

Middle

Ordovician,

upper

Black

River/lower Trenton trilobite is from o n e of the quarries operated for building stone near Poland, H e r k i m e r County, in the m i d to late 1800s. Kay ( 1 9 5 3 ) listed R. longispinus from the lower Trenton

Rockland

(Napanee)

M e m b e r . T h e Raymondites genus

differs from Bathyurus in that it has o n e pair of lateral glabellar furrows rather than two, and the surface of the cephalon is

Bathyurus johnsoni

(Raymond,

1913)

pustulose.

Specimen U S N M A trilobite with this n a m e , but with no inventory n u m b e r , is in the U S N M and is listed f r o m the Lowville M e m b e r of the

Raymondites

spiniger

(Hall,

1847)

Holotype A M N H 854

Middle Ordovician Black River G r o u p , Utica, O n e i d a County.

D e M o t t ( 1 9 8 7 ) reported the h o l o t y p e as G S C 4 3 1 8 , stating it

T h e r e are no Black River rocks in the i m m e d i a t e Utica area, so

is the s p e c i m e n figured by Hall. Hall clearly stated that his figured

this is probably from the Lowville M e m b e r at N e w p o r t , H e r k i m e r

s p e c i m e n , and h o l o t y p e , is f r o m New York but did not give a spe-

C o u n t y , in an area on West C a n a d a C r e e k .

cific location o t h e r than the M o h a w k Valley. He did report

ORDER

151

PROETIDA

another similar specimen belonging to a M r . Logan f r o m M o n -

Cordania

treal, which Logan o b t a i n e d in C a n a d a . (Logan is Sir William

Lectotype N Y S M 4 2 1 0 ( W h i t t i n g t o n 1 9 6 0 )

Logan, the f i r s t director o f the Geological Survey o f C a n a d a . ) T h i s may be the G S C specimen. Raymondites spiniger is reported f r o m

becraftensis

Cordania

Clarke,

becraftensis

is

1900

from

the

Lower

Devonian

Glenerie

L i m e s t o n e , Becraft M o u n t a i n , H u d s o n , C o l u m b i a County.

the Middle Ordovician, upper Black River C h a u m o n t L i m e s t o n e and the lower Trenton R o c k l a n d (Napanee) L i m e s t o n e . G e o -

Cordania cyclurus (Hall a n d C l a r k e , 1 8 8 8 )

graphically it is widely distributed into O n t a r i o , Q u e b e c , Ken-

Lectotype N Y S M 4 2 1 5 (Whittington 1960)

tucky, and Illinois.

Cordania cyclurus is a trilobite of the Lower Devonian New Scotland L i m e s t o n e in Albany C o u n t y .

Strigigenalis cassinensis

(Whittington,

1953)

Holotype location u n k n o w n ; s p e c i m e n s N Y S M 1 5 3 8 4 t o 1 5 3 9 0 Brett and Westrop ( 1 9 9 6 ) described this species from the Lower Ordovician Scotia L i m e s t o n e M e m b e r of the Fort Cassin F o r m a t i o n , Washington County. Strigigenalis caudatus

(Billings,

(1913)

1865)

Strigigenalis

caudatus

reported

from

the

T h e holotype is from N e w f o u n d l a n d . brevispinum

(Raymond,

cian, upper Chazy G r o u p k n o w n only from a poorly preserved cephalon, cranidia, and pygidia. For locations, see Shaw ( 1 9 6 8 ) . Uromystrum brevispinum has a long un fur rowed glabella.

T h i s trilobite f r o m the M i d d l e D e v o n i a n H a m i l t o n shales, in

(Hall a n d C l a r k e ,

1888)

T h i s species is reported to be f r o m the Centerfield L i m e s t o n e in O n t a r i o C o u n t y . Mystrocephala varicella (Hall a n d C l a r k e ,

1888)

Lectotype N Y S M 4 2 2 3 ( W h i t t i n g t o n 1 9 6 0 ) varicella

is

from

the

Middle

Devonian

O n o n d a g a L i m e s t o n e in O n t a r i o C o u n t y .

Holotype C M H - 1 2 8 4 U,

1876)

O n t a r i o C o u n t y , is p r o b a b l y different f r o m A. gemmaea.

Mystrocephala

1905)

Uromystrum minor is similar to

(Hall,

Syntypes N Y S M 4 2 5 1 , 4 2 5 2

Uromystrum brevispinum is a trilobite of the M i d d l e O r d o v i -

minor ( R a y m o n d ,

ornata

Hypotype N Y S M 4 2 5 0

Mystrocephala ornata baccata

1905)

Lectotype C M H - 1 2 8 7 (Shaw 1 9 6 8 )

Uromystrum

Mystrocephala arenicolus is f o u n d in the u p p e r Lower Devon-

Mystrocephala

Lower Ordovician B e e k m a n t o w n at T i c o n d e r o g a , Essex C o u n t y .

Uromystrum

1888)

Plastotype N Y S M 4 2 0 6 ian S c h o h a r i e G r i t , S c h o h a r i e County.

Holotype G S C 6 3 5 Raymond

Mystrocephala arenicolus (Hall a n d C l a r k e ,

brevispinum b u t is k n o w n

only from cranidia and pygidia. It is from the M i d d l e O r d o v i c i a n , middle Chazy G r o u p . T h e U. minor differs in that it has a low,

Radnoria sp. Plate 135 T h i s trilobite was formerly referred to as Proetus stokesii. It is

indistinct glabella. For locations, see Shaw ( 1 9 6 8 ) .

f o u n d in the Lower Silurian R o c h e s t e r Shale. T h e specimen

Family Brachymetopidae

described ( J o n Adrain 2 0 0 0 , private c o m m u n i c a t i o n ) .

in Plate 135 is f r o m O r l e a n s C o u n t y . T h i s trilobite is being

Brachymetopids are small trilobites in the Lower Silurian and Devonian in New York. T h e c e p h a l o n is nearly semicircular in

Family Dimeropygidae

outline, with genal spines with a distinct border. T h e glabella is

O n l y o n e representative of this family is k n o w n in New York.

short and tapers forward. T h e basal glabellar lobes ( L I ) stand

T h e s e small trilobites, 1 cm or less in length, are mostly k n o w n

alone, being cut o f f by glabellar furrow S I . T h e t h o r a x has 10 seg-

from

ments. T h e pygidium is semicircular with n u m e r o u s axial rings.

c e p h a l o n is convex and pustulose. T h e t h o r a x has eight segments.

T h e pygidiual margin may be s m o o t h or spined. T h e entire dorsal

T h e pygidium is convex with three to six s e g m e n t s . W h o l e , arti-

surface of the trilobite is covered with tubercles.

culated s p e c i m e n s are very rare

silicified

remains

etched

from

limestone

in eastern

blocks.

The

N o r t h America,

probably because they inhabited shallower, high-energy environAustralosutura gemmaea

(Hall,

1876)

Plate

134

Lectotype N Y S M 4 2 1 7 ( S t u m m 1 9 6 7 )

m e n t s where preservation is poor. F o r this s a m e reason they, would be difficult to find unless silicified.

This species is found in the Jaycox, D e e p R u n , K a s h o n g , and W i n d o m Shales. T h e illustrated s p e c i m e n , in Plate 134 is f r o m

Dimeropyge

Livingston County. S p e c i m e n s reported from the O n o n d a g a are

H o l o t y p e N Y S M 12357

an undescribed species. T h e genus assignment is f r o m an abstract (Scatterday 1 9 8 6 ) .

clintonensis

Dimeropyge

clintonensis

(Shaw, is

a

1968) small

trilobite

of

the

Middle

O r d o v i c i a n , middle Chazy and the only representative of the

152

THE

family in New York. For locations, see Shaw ( 1 9 6 8 ) . It is k n o w n

Coniproetus

f r o m silicified maraspids a n d holaspids. T h e c e p h a l o n has long

Lectotype A M N H 3 9 3 2 1

genal spines, and the transitory pygidium has a p r o m i n e n t axial

4706

conradi

(Hall,

TRILOBITES

1861) (Lieberman

1 9 9 4 ) , hypotype N Y S M

spine f r o m the second axial ring. T h i s pygidial spine is apparently

T h e lectotype is f r o m the Lower Devonian Schoharie Grit

lost in the holaspis. Dimeropyge clintonensis closely resembles D.

in Albany County. T h e N Y S M specimen is from Glenerie For-

virginiensis, from W h i t t i n g t o n and Evitt ( 1 9 5 4 ) . No articulated

mation,

s p e c i m e n s of the New York species are k n o w n . An articulated

cephalic features are very similar to those of C. angustifrons. T h e

Dimeropyge specimen

pygidium is r o u n d e d and 1.8 times wide as long. T h e r e are 10

is k n o w n

from

the Trenton

of C a n a d a

(Ludvigsen 1 9 7 9 b ) .

Becraft

Mountain,

Hudson, Columbia

County. T h e

axial rings. T h e pleural furrows are faint and b e c o m e indistinct posteriorly. T h e r e is a border.

Family Proetidae Proetids existed over m o r e geologic t i m e than any other trilobite family. According to Fortey and O w e n s ( 1 9 9 7 ) the family

Coniproetus folliceps (Hall a n d C l a r k e ,

1888)

Plate

136

Lectotype N Y S M 4 7 2 2 ( L i e b e r m a n 1994)

arose in the Early O r d o v i c i a n and lasted until trilobites b e c a m e

T h i s species is from the M i d d l e Devonian, upper O n o n d a g a

extinct during the great Late P e r m i a n e x t i n c t i o n event ( a b o u t 2 5 0

L i m e s t o n e near LeRoy, Genesee County. T h e cephalon is semi-

million years a g o ) . T h e order Proetida has m e m b e r s f r o m the Late

circular in outline without genal spines. T h e r e is a narrow border.

C a m b r i a n . Proetids have a r o u n d e d , inflated glabella that tapers

T h e surface is covered with low, coarse granules. T h e occipital

forward. T h e y have a well-developed cephalic b o r d e r and usually

ring has a faint axial n o d e . T h e lateral occipital lobes are c o n -

m e d i u m - l e n g t h genal spines. T h e t h o r a c i c pleurae have r o u n d e d

nected posteriorly to the occipital ring. T h e r e are no axial t h o -

ends. T h e pygidium is semicircular and often has a border. T h e

racic n o d e s . T h e pygidium has at least 10 axial rings and eitht or

first New York species are f o u n d in the M i d d l e O r d o v i c i a n and

m o r e pleurae. T h e r e is a narrow border. T h e surface is granulose.

are u n d o u b t e d l y i m m i g r a n t s f r o m European trilobite p o p u l a -

Plate 136 illustrates the lectotype.

tions.

These

early

representatives

did

not

last

past

the

Silurian b u t were replaced by a n o t h e r wave of proetids in the

Cornuproetus

Early Devonian ( L i e b e r m a n 1 9 9 4 ) . T h e proetids are nowhere as

H o l o t y p e Y P M , hypotype Y P M 2 7 8 1 0

abundant

as

Isotelus,

Dalmanites,

and

phacopids

respective periods, b u t their presence

is

known

exuviae. W h o l e , articulated s p e c i m e n s are

beecheri

(Ruedemann,

1926)

from

their

T h i s trilobite is part of Beecher's collections from Beecher's

from

their

Trilobite Bed in the Upper Ordovician Frankfort Shales n o r t h

uncommon, both

of R o m e , O n e i d a C o u n t y , the best s p e c i m e n s of which are in

because of low p o p u l a t i o n s and because the exoskeleton was

Y P M . N o n e of the New York Ordovician proetids have been

not very robust. In the M i d d l e D e v o n i a n , however, there are l o c a -

redescribed.

tions in the Centerfield L i m e s t o n e in Livingston C o u n t y where

must be considered tentative.

groups of whole Pseudodechenella rowi have been f o u n d . In

T h e assignment to

Cornuproetus by Cisne

(1973)

1994

L i e b e r m a n revised the proetids o f the D e v o n i a n o f eastern N o r t h

Crassiproetus

A m e r i c a including those in New York. T h e Silurian and O r d o v i -

Specimens A M N H 39329, 39337, 44700, 44707 to 44713

cian proetids need s o m e a t t e n t i o n . T h e features of the described proetids from New York are in Table 5 . 8 .

brevispinus

(Fagerstrom,

1961)

F r o m the M i d d l e Devonian O n o n d a g a Limestone and its equivalent in O n t a r i o and western New York and Albany County, this species is k n o w n f r o m cranidia and pygidia. It differs from

Basidechenella?

hesionea

(Hall,

1861)

C.

Holotype A M N H 2898 This

Lower

crassimarginatus by having a narrow cephalic border and, a

glabella that is wider and semicircular in the dorsal anterior view.

Devonian

species

from

the

Schoharie

Grit,

S c h o h a r i e C o u n t y , is k n o w n from two pygidia. T h e pygidium is

T h e r e is a small m e d i a n occipital n o d e . T h e pygidium has 18 axial rings and 15 pleural s e g m e n t s .

semicircular, with 13 axial rings and nine pleural s e g m e n t s . T h e r e are no tubercles on the axial rings.

Crassiproetus

crassimarginatus

(Hall,

1843)

Lectotype A M N H 3 9 3 2 8 ( L i e b e r m a n 1994) Coniproetus

angustifrons

(Hall,

1861)

Lectotype A M N H 2 9 0 0 ( S t u m m 1 9 5 3 b )

T h e lectotype is from Williamsville, Erie County. T h i s proetid is widely distributed from the Middle Devonian O n o n d a g a Lime-

T h i s species is f r o m the Lower D e v o n i a n S c h o h a r i e Grit of

stone and age-equivalent rocks of New York, O n t a r i o , Michigan,

Albany County. Apparently it is only positively k n o w n from

O h i o , and Kentucky. S p e c i m e n s have been reported from the

cranidia. Pygidia assigned to this species by Hall and Clarke are

Lower Devonian S c h o h a r i e Grit in S c h o h a r i e C o u n t y and the

not accepted by o t h e r a u t h o r s . T h e species is distinguished by the

Middle

larger than usual sagittal width of the cephalic border. T h e r e is

T h e c e p h a l o n is semicircular and has a wide b o r d e r and no genal

no medial occipital n o d e .

spines. T h e glabellar outline in dorsal anterior view is parabolic

Devonian

Onondaga

Limestone

in

Genesee County.

Table 5.8. Features of the described proetids of New York NAME

AGE,

Cornuproetus

beecheri

(Ruedemann, 1926) Proetus

(Proetus)

clelandi

STRATA

U. Ord.. Frankfort Shale M. Ord., Chazy?

LATERAL OCCIPITAL LOBE

OCCIPITAL NODE

GENAL SPINES

THORACIC AXIAL NODES

PYGIDIAL AXIAL NODES

PYGIDIAL AXIAL RINGS

PYGIDIAL PLEURAL SEGMENTS

SEP

Yes

Yes

No

No

7

5

No

Yes

(Raymond, 1905) Proetus

Ord.

parviusculus

(Hall, 1860) Proetus spurlocki (Meek,

Ord.

1872) Proetus

undulostriatulus

(Hall, 1847) Hedstroemia

pachydermata

(Barrett.

['Jo.

M. Ord., Snake Hill Shale Sil., Decker Ferry Limestone

1b

1878) Proetus artiaxis (Howell

and Sanford, 1947) Proetus

tenuisulcatus

(Howell and Sanford, 1947)

U. Sil., Oak Orchard Dolostone U. Sil., Oak Orchard Dolostone

No SEP

No

No

3^ 7

Faint

13

9

hesionea

L. Dev., Schoharie Grit

angustifrons

L. Dev.. Schoharie Grit

Faint

No

Yes

No

7 or 8

5 or 6

conradi (Hall,

L. Dev., Glenerie Formation L. Dev., Schoharie Grit

Faint

No

Yes

No

10

4 or 5

No

14

12

No

13

10

No

8 or 9

4 Faint

10 or 11 10

8

Yes

Basidechenella

(Hall, 1861) Coniproetus

(Hall, 1861) Coniproetus

1861) Crassiproetus

schohariensis

(Lieberman, 1994) Crassiproetus

L. Dev., Schoharie Grit

stummi

(Lieberman, 1994) Gerastos protuberans (Hall,

1859) Proetus hesione (Hall, Basidechenella

1861)

canaliculata (Hall, 1861)

L. Dev., New Scotland Limestone L. Dev.. Schoharie Grit M. Dev., Onondaga Limestone

No

No

SEP

Faint

No

No

Table 5.8.

Continued

NAME

AGE,

Basidechenella clara (Hall, 1861) Coniproetus folliceps (Hall and Clarke, 1888) Crassiproetus brevispinus (Fagerstrom, 1961) Crassiproetus crassimarginatus (Hall, 1843) Crassiproetus neoturgitus (Lieberman, 1994) Monodechenella halli (Stumm, 1953) Proetus microgemma (Hall and Clarke, 1888) Pseudodechenella arkonensis (Stumm, 1953) Pseudodechenella rowi (Green, 1838) Dechenella haldemani (Hall, 1861) Monodechenella macrocephala (Hall, 1861) Proetus jejunus (Hall and Clarke, 1888) Proetus marginalis (Conrad, 1839)

M. Dev., Onondaga Limestone M. Dev., Onondaga Limestone M. Dev., Onondaga Limestone M. Dev., Onondaga Limestone

STRATA

M. Dev., Onondaga Limestone M. Dev., Onondaga Limestone M. Dev., Onondaga Limestone M. Dev., Hamilton Group M. Dev., Hamilton Group M. Dev., Hamilton Group M. Dev., Hamilton Group

LATERAL OCCIPITAL LOBE

OCCIPITAL NODE

GENAL SPINES

THORACIC AXIAL NODES

PYGIDIAL AXIAL NODES

PYGIDIAL AXIAL RINGS

PYGIDIAL PLEURAL SEGMENTS

SEP

No

Yes

No

No

11

4 or 5

CON

Faint

No

No

No

10

8

Faint

Yes

18

15

Mo

No?

No

16

14

No

13

10

Yes

9

9

Yes

11

7 or 8

No

SEP

Yes

Yes

Yes

Yes

13

9

SEP

Faint

Yes

No

No to faint

11

8

SEP

No

No

No

No to faint

17

10

SEP

No

Yes

Faint

Yes

14

VA

Yes

10

8

M. Dev., Hamilton Group M. Dev., Hamilton Group

SEP, separated by a groove from the occipital ring; CON. connected to occipital ring.

i lo

ORDER

PROETIDA

155

or subsemicircular. T h e r e are about 16 pygidial axial rings and

lar furrows are deeply incised. T h e r e is no median occipital node

about 14 pleural segments. T h e r e is a pygidial border.

and the lateral occipital lobes are c o n n e c t e d posteriorly to the occipital ring. T h e r e are no axial t h o r a c i c nodes. T h e pygidium

Crassiproetus

neoturgitus

(Lieberman,

has 17 axial rings and 12 pleural s e g m e n t s . T h e r e is a pygidial

1994)

border, which widens posteriorly. Plate 138 is a whole specimen

Holotype A M N H 4 4 7 2 0 This species was described using two exfoliated pygidia f r o m

from the U n i o n Springs M e m b e r o f the Marcellus.

the Middle Devonian O n o n d a g a L i m e s t o n e in S c h o h a r i e County. There are 13 axial rings and ten pleural segments. A pygidial

Decoroproetus corycoeus ( C o n r a d ,

border is present.

Lectotype A M N H 1 8 2 9 (Holloway 1 9 8 0 ) , hypotype N Y S M 4 7 0 7

1842)

Plates

139 and

140

Found in the lower R o c h e s t e r Shale and reported from the Crassiproetus

sehohariensis

(Lieberman,

1994)

L o c k p o r t l i m e s t o n e , this trilobite is suboval and has long genal

Holotype A M N H 4 4 6 9 9

spines reaching the sixth t h o r a c i c s e g m e n t . T h e eyes are large and

T h e holotype exfoliated pygidium is from the Lower D e v o n ian Schoharie Grit of O r a n g e C o u n t y . O t h e r pygidia assigned to

r e n i f o r m . Plate 140 shows the s a m e s p e c i m e n as Plate 139 but shows an

associated

ophiuroid

(brittlestar Furcaster echinatus).

this species are either from the S c h o h a r i e Grit or f r o m the Middle Devonian O n o n d a g a o f Albany and S c h o h a r i e C o u n t i e s . T h e r e

Gerastos

are 14 axial rings and 12 pleural segments. No pygidial b o r d e r is

Lectotype A M N H 3 5 2 3 9 ( L i e b e r m a n 1 9 9 4 )

evident on the illustrations in L i e b e r m a n ( 1 9 9 4 ) .

protuberans

(Hall,

1859)

T h e lectotype is a pygidium from the Lower Devonian New Scotland L i m e s t o n e . A partial c e p h a l o t h o r a x was also figured by

Crassiproetus

stummi

(Lieberman,

1994)

Hall ( 1 8 5 9 b ) . T h e pygidium has eight axial rings and f o u r or five

Holotype U M M P 2 9 5 1 9

pleural segments. Pygidia with this description are k n o w n from

T h i s species, k n o w n only from pygidia, is f o u n d in

the

O n o n d a g a Limestone and S c h o h a r i e Grit o f S c h o h a r i e County.

the O n o n d a g a o f O n t a r i o C o u n t y and the Bois Blanc F o r m a t i o n of Michigan.

T h e holotype is from the Bois Blanc F o r m a t i o n of M i c h i g a n . There are 13 axial rings and ten pleural s e g m e n t s . T h e r e are no axial nodes, and a pygidial b o r d e r is present.

Hedstroemia

pachydermata

(Barrett,

1878)

T h i s genus is widespread in n o r t h e r n Laurentia, Fngland, and Baltica. It was first reported in eastern North A m e r i c a as H.

Cyphoproetus cf.

C.

wilsonae ( S i n c l a i r )

Plate

137

pachydermata in the Deckers Ferry F o r m a t i o n in O r a n g e C o u n t y

Specimen PRI 4 9 6 3 3

and in New Jersey.

This small proetid is from the M i d d l e O r d o v i c i a n , lower Trenton G r o u p . T h e genus is characterized by the large LI lobes

Mannopyge

isolated by the SI furrow. A C a n a d i a n specimen figured by Lud-

Holotype A M N H 4074

halli

(Stumm,

1953)

vigsen ( 1 9 7 9 b , Figure 3 1 C ) differs slightly from the PRI trilobite.

Type species. T h e h o l o t y p e of this trilobite is an incomplete

Another characteristic listed by O w e n s ( 1 9 7 3 , p. 2 7 ) , lateral lobes

t h o r a x and c o m p l e t e pygidium from the E d g e d iff M e m b e r of the

on the occipital ring, is not shown on the Ludvigsen illustration

O n o n d a g a L i m e s t o n e , Williamsville, Erie C o u n t y . T h e pygidium

but can just be made out on the left side of the PRI s p e c i m e n in

is very distinctive. T h e r e are nine pygidial axial rings and nine

Plate 137. T h e C a n a d i a n specimen appears to have a n a r r o w

pleural s e g m e n t s . A groove across the distal end of the pleural

preglabellar field. This is not evident on the PR] trilobite. Cypho-

segments separates the distal parts into n o d e s . T h e s e nodes are

proetus is a Silurian genus s o m e w h a t different from this species.

rounded and appear as part of an u n f o r m e d border. No other

T h e s e differences are under

proetid f r o m New York has these characteristics. T h i s trilobite

investigation

( J o n Adrain

1999,

private c o m m u n i c a t i o n ) .

has also been reported f r o m O n t a r i o . T h e genus was erected by Ludvigsen ( 1 9 8 7 ) .

Dechenella

haldemani

(Hall,

1861)

Plate

138

Lectotype A M N H 5 5 0 4 ( L i e b e r m a n 1994) T h i s trilobite is restricted to the M i d d l e Devonian Marcellus

Monodechenella

macrocephala

(Hall,

1861)

Plate

141

Lectotype A M N H 4 7 3 4 ( L i e b e r m a n 1 9 9 4 )

F o r m a t i o n , lower Hamilton G r o u p . S p e c i m e n s have been f o u n d

Type species. T h e lectotype is f r o m O n t a r i o County. A proetid

in Otsego and O n o n d a g a C o u n t i e s . T h e illustration from Hall

of the M i d d l e Devonian H a m i l t o n G r o u p and its equivalents, M.

and Clarke ( 1 8 8 8 ) is of a specimen from Pennsylvania, which was

macrocephala is often f o u n d in the s a m e horizons with Pseudo-

clearly designated to be the h o l o t y p e . T h e selection of a lectotype

dechenella

may be invalid. T h e cephalon is semicircular in outline with short

However, in the Deep Run and Kashong Shales it is the most

genal spines. T h e cephalic b o r d e r is b r o a d , and there is a narrow

c o m m o n proetid. T h e c e p h a l o n is semicircular in outline with

preglabellar field. T h e glabella narrows anteriorly and the glabel-

short genal spines. T h e glabella is inflated and pustulose and in

rowi,

although

in

significantly

reduced

numbers.

THE

156 dorsal view extends anteriorly over the wide cephalic border. SI

Proetusparviusculus

is deeply incised and extends perpendicular toward the m e d i a n

S p e c i m e n A M N H 1071

line, with a sharp dog-leg b e n d posteromedially, nearly to S O . T h e

(Hall,

TRILOBITES

1860)

Proetus parviusculus is an

Upper O r d o v i c i a n , O h i o

proetid.

occipital ring is wide, with lateral lobes separated by a shallow

T h e s p e c i m e n m e n t i o n e d is from Floyd, O n e i d a County, near

groove. T h e r e is no m e d i a n occipital n o d e . T h e pygidium is

R o m e . B o t h Middle O r d o v i c i a n Utica and Upper Ordovician

longer than wide and has 14 axial rings and 12 pleural s e g m e n t s .

F r a n k f o r t Shales are exposed in the area. A specimen in the

T h e r e is a pygidial border. T h e entire test is covered with g r a n u -

USNM

lations, coarsest on the glabella.

O r d o v i c i a n ) Utica Shale, Holland Patent, O n e i d a County, and is

(USNM 34490)

is a

proetid

from

(probably Upper

part of the Rust collection. Proetus artiaxis (Howell and Sanford, 1 9 4 7 ) Proetus spurlocki (Meek,

Holotype U S N M 4 8 8 1 2 7 T h i s trilobite is k n o w n f r o m a single pygidium f o u n d in the Upper Silurian E r a m o s a M e m b e r o f the L o c k p o r t G r o u p . T h e

1872)

Specimen U S N M 92544 Proetus spurlocki is an

Ohio

Upper Ordovician

proetid.

It

pygidium has a narrow axial lobe, which is almost parallel sided.

is included here because of a small pygidium in the National

T h e axis is rather highly convex and has three well-defined seg-

M u s e u m from Floyd, O n e i d a C o u n t y , labeled with this n a m e (Hurlburt Collection).

ments in its a n t e r i o r halt.

Floyd

is a town northeast of R o m e ,

O n e i d a County. B o t h the Middle Ordovician Utica and Upper Proetus

(Proetus) clelandi

(Raymond,

O r d o v i c i a n Frankfort Shales are exposed in the area.

1905)

Lectotype C o r n e l l M u s e u m 5 6 7 8 a (Shaw 1 9 6 8 ) T h i s trilobite was part of the Jewett Collection purchased by Cornell University in 1868 (Shaw 1 9 6 8 ) . T h e description a c c o m panying the only k n o w n s p e c i m e n was " C h a z y L i m e s t o n e , Chazy Village, New York" in C l i n t o n County. I n a s m u c h as b o t h Chazy and Trenton L i m e s t o n e s are f o u n d in the area and since no o t h e r s p e c i m e n s have been f o u n d in the Chazy, the exact stratigraphic horizon is in d o u b t .

Proetus tenuisulcatus (Howell and Sanford,

1947)

Holotype U S N M 488134 T h i s trilobite is f r o m the Upper Silurian Eramosa M e m b e r of the L o c k p o r t G r o u p in M o n r o e County. T h e glabella is subtriangular and reaches all the way to the b r i m in front. T h e glabellar furrows are very faint. T h e fixed cheeks are narrow, and the posterolateral p o r t i o n s are n a r r o w and end in sharp points. T h e pygidium is moderately convex. T h e axis is narrow; it tapers only

Proetus jejunus (Hall and Clarke,

a little and rises well above the pleural lobes. T h e r e are seven well-

1888)

T h e species is k n o w n f r o m a single exfoliated pygidium from the M i d d l e D e v o n i a n " s a n d y shales" o f the H a m i l t o n G r o u p , Albany C o u n t y . T h e pygidium is wider than long and has ten axial rings and eight pleural s e g m e n t s . T h e r e are p r o m i n e n t axial nodes.

defined axial s e g m e n t s . T h e pleural lobes are s m o o t h , with only faint traces of ribs. Proetus

undulostriatulus

(Hall,

1847)

Holotype? A M N H 3 0 1 0 1 , plastoholotype N Y S M 9 8 5 5 Hall first described this proetid from the Middle Ordovician

Proetus marginalis

(Conrad,

Snake Hill Beds, Saratoga County. Additional specimens from the

1839)

s a m e area have been described as Cyphaspis. T h e Snake Hill Beds

Hypotypes N Y S M 4 7 5 2 , 4 7 5 3 T h i s proetid trilobite was f o u n d in a D e v o n i a n b o u l d e r near

are an eastern New York equivalent of the lower Utica Shale.

Ithaca, T o m p k i n s C o u n t y . " T h i s has a m u c h less p r o m i n e n t front

Proetid sp. Plate 142

than the rowi, a deeper groove between the eye and middle lobe,

Specimens U S N M , M C Z 111714

and the tubercle which nearly j o i n s the lower angle of the eye is

Small

unprepared, u n n u m b e r e d , and undescribed

Middle

m u c h s m a l l e r " ( C o n r a d 1 8 3 9 ) . Hall and Clarke ( 1 8 8 8 ) ascertained

O r d o v i c i a n proetids are in collections from the Walcott-Rust

that the b o u l d e r referred to was f r o m the M i d d l e Devonian Tully

Q u a r r y in the Rust L i m e s t o n e M e m b e r of the Trenton G r o u p in

f o r m a t i o n . A n u m b e r of o t h e r proetids had been assigned to the

H e r k i m e r C o u n t y . B o t h the M C Z and the U S N M have speci-

species, and

m e n s . Plate 142 shows a prepared specimen from the Walcott-

Hall

synonymized

them

all

with

Pseudodechenella

rowi. T h e location of the type is u n k n o w n . T h e hypotypes are

Rust Q u a r r y n o w in the M C Z .

from the Tully F o r m a t i o n near O v i d , Seneca County. Pseudodechenella Proetus microgemma (Hall and Clarke,

1888)

Syntype N Y S M 4 7 4 0 T h i s species is k n o w n f r o m two pygidia f r o m the M i d d l e

arkonensis

(Stumm,

1953)

Holotype U M M P 25541 This

trilobite

is

described

from

the

Middle

Devonian

H a m i l t o n age rocks o f southwestern O n t a r i o . Lieberman ( 1 9 9 4 )

D e v o n i a n O n o n d a g a L i m e s t o n e o f O n t a r i o C o u n t y . I t quite pos-

reported

sibly is not a proetid.

H a m i l t o n G r o u p in central New York. S t u m m described it as

this

species

from

the

Ludlowville

M e m b e r of the

ORDER

157

A S A P H I DA there is no trace of

has also been reported in M i c h i g a n . Plate 147 shows a cluster

glabellar furrows, the genal spines reach to the sixth or seventh

similar to Pseudodechenella rowi except that

of individuals from the Tully F o r m a t i o n , revealing s o m e m o r -

thoracic segment, and there is a distinct occipital n o d e . T h e r e are

phological differences f r o m those lower in the H a m i l t o n . Pillet

axial nodes on the t h o r a x , m o r e strongly expressed on the m o r e

( 1 9 7 2 ) erected the new genus Pseudodechenella, with P.

posterior segments. T h e pygidium has a p r o m i n e n t axial n o d e on

the type species. Basse ( 1 9 9 7 ) agreed with Pillet that the New

the most anterior axial ring and lacks t u b e r c u l a t u m . In addition,

World

the pygidium has 13 axial rings and nine pleural segments.

Europe.

Pseudodechenella

5.7 ORDER ASAPHIDA Family Asaphidae

canaliculata

(Hall,

1861)

Holotype A M N H 4 2 5 3 , specimen Y P M 3 3 7 7 3

"Basidechenella"

species

are

different

from

rowi as

those

from

3 3 7 7 3 t o this

Asaphids are the m o s t n u m e r o u s s p e c i m e n s represented in the

species. It is an exfoliated pygidium labeled as c o m i n g from

New York O r d o v i c i a n . Although s o m e may be suspect by syn-

C h e r r y Valley, Otsego County, and is tentatively assigned to the

onymy, this will not displace t h e m f r o m " t h e most n u m e r o u s "

O n o n d a g a . T h i s is the only specimen f r o m New York. T h e h o l o -

title. We have f o u n d a total of 41 asaphids listed from the Lower,

type is from the Jeftersonville Limestone at the Falls of the O h i o ,

Middle, and Late O r d o v i c i a n of New York. Asaphids have plank-

Lieberman

(1994)

assigned specimen Y P M

Kentucky. T h e anterior cephalic b o r d e r has a medial transverse

tic protaspids, which makes for easy and widespread dispersal.

groove that is raised on each side, giving the a p p e a r a n c e of two

T h e meraspids and early holaspids usually have long genal spines,

transverse ridges on the border. O n e must question the identity

which often carries through to the adult. W h e n m a t u r e , the

of Y P M 3 3 7 7 3 until m o r e i n f o r m a t i o n is available.

asaphids have a s m o o t h , robust, u n o r n a m e n t e d body, which is well suited for plowing through and feeding in the surface mud

Pseudodechenella clara (Hall, 1 8 6 1 ) Plate 143

and debris of the sea b o t t o m . T h e holaspid has eight t h o r a c i c seg-

Lectotype A M N H 3 9 3 2 6 ( S t u m m 1953)

ments. T h e cephalic s u t u r e s are opisthoparian. The cephalon and

This

trilobite

is

described

from

the

Middle

Devonian

O n o n d a g a Limestone at Stafford in Genesee C o u n t y . A good

pygidium are often similar in size and shape, an observation that led to the genus n a m e Isotelus.

specimen is also in the U S N M ( U S N M 2 5 8 8 4 ) . T h e species has a subconical,

faintly

constricted

glabella

with

faint

glabellar

T h e oldest asaphids in New York are found in the Lower Ordovician B e e k m a n t o w n G r o u p , a n d then m o r e or less are

furrows. T h e cephalic b o r d e r is wide, flat, or slightly concave a n d

f o u n d c o n t i n u o u s l y upward t h r o u g h the Chazy, Black River,

has a distinctive raised o u t e r margin. T h e occipital ring has no

T r e n t o n , and L o r r a i n e G r o u p s . Asaphids geographically are very

medial node and has lateral lobes separated by a shallow furrow.

widely distributed in eastern North A m e r i c a ; therefore, it is not

T h e pygidium has 11 axial rings. T h e illustrated (Plate 143) spec-

likely that any straightforward evolutionary sequences will be

imen is from the M o o r e h o u s e M e m b e r of the O n o n d a g a L i m e -

found within the state. T h e family Asaphidae does not go beyond

stone in the Honeoye Falls Quarry, M o n r o e County. T h i s trilobite

the O r d o v i c i a n .

is widely distributed in the O n o n d a g a of New York and ageequivalent rocks ot O n t a r i o , Michigan, O h i o , and Kentucky.

* Basilicas romingeri

(Walcott,

1877)

H o l o t y p e M C Z , hypotype N Y S M 1 2 9 1 8 Pseudodechenella rowi ( G r e e n , 1 8 3 8 ) Plates 1 4 4 , 1 4 5 , 1 4 6 , and 147

Basilicas

romingeri

specimens

from

the

Middle

Ordovician

Black River G r o u p , H e r k i m e r C o u n t y , are in the N Y S M as N Y S M

Plastotype N Y S M 4 7 5 0

1 2 9 1 8 ( h y p o t y p e ) and the U S N M a s U S N M 6 1 2 7 7 . T h e genus

Type species. T h i s trilobite is f o u n d t h r o u g h o u t the M i d d l e

Basilicas differs

Devonian H a m i l t o n G r o u p , with the exception of the deeper-

than wide.

water black shales of the group. It is the m o s t c o m m o n l y f o u n d

B.

from

DeMott

wisconsensis

with

Basiliella (1987)

in that the pygidium

is longer

s y n o n y m i z e d Basilicas romingeri and

Basiliella

barrandi.

proetid of New York, with n u m e r o u s s p e c i m e n s f o u n d from Erie C o u n t y to east of Livingston County. T h e cephalon is s e m i c i r c u -

Basilicus ulrichi ( C l a r k e ,

lar in outline with genal spines. T h e cephalic b o r d e r has a n a r r o w

Specimen U S N M 61278

raised edge. T h e r e is no preglabellar field. T h e glabella is vaulted

1894)

T h e U S N M s p e c i m e n is f r o m the M i d d l e O r d o v i c i a n , upper

and tapers slightly forward. Glabellar tubercles are faint to absent.

Black

T h e occipital ring has a very slight to absent medial n o d e . T h e

Herkimer County.

River

Limestone,

1.6 km

(1

mile)

north

of Poland,

lateral occipital lobes are separated by a groove. T h e r e are no axial nodes on the s m o o t h t h o r a x . T h e pygidium has 11 axial rings and

Basilicus? vetustus (Hall,

eight pleural segments. Plate 144 shows a small group of indi-

Type A M N H 6 1 3

viduals from the W i n d o m Shale in Erie C o u n t y and Plate 145 is of a P.

rowi together with

Bellacartwrightia

whitelcyi. T h e species

1847)

T h e type of this Middle Ordovician Black River trilobite is from " t h e c o m p a c t Birdseye L i m e s t o n e of the M o h a w k Valley." In

THE

158

TRILOBITES

the U S N M a similarly labeled pygidium ( U S N M 4 7 7 9 ) has at least

o n e . T h e axis of the pygidium is not as p r o m i n e n t as the illus-

14 axial rings.

tration f r o m the Treatise suggests, but the posterior end of it is a well-defined r o u n d e d node. Homotelus is considered a question-

Basilicus

(Basiliella)

whittingtoni

(Shaw,

able genus and m a y be assigned to Isotelus.

1968)

Holotype NYSM 12535 T h i s species, from the Middle O r d o v i c i a n Chazy L i m e s t o n e , is only k n o w n f r o m cranidia and pygidia but is u n q u e s t i o n a b l y Basilicus and possibly Basiliella. Shaw equated this trilobite with Asaphus

marginalis

(abandon).

The

illustration

of the

f o r m e r A.

by

Raymond

Hyboaspis depressa

(Raymond,

1925)

Lectotype M C Z 1 0 1 1 3 8 (Shaw 1968) O n l y the pygidium of this Middle Ordovician Chazy species is k n o w n . However, R a y m o n d ( 1 9 2 5 ) considered these pygidia

The

as fairly c o m m o n . T h e r e is s o m e question of whether it is an

pygidium has paired, r o u n d e d p r o j e c t i o n s . For location i n f o r m a -

asaphid or an illaenid. See Shaw ( 1 9 6 8 ) for location i n f o r m a t i o n .

(1905)

is a

reconstruction

marginatus.

tion, see Shaw ( 1 9 6 8 ) . Isoteloides angusticaudus Basiliella barrandi

(Hall,

1851)

(Raymond,

1905)

H o l o t y p e C M 1285 Shaw ( 1 9 6 8 ) referred to this Middle Ordovician Chazy trilo-

Specimen M C Z 1 0 0 9 4 8 Type species. S p e c i m e n s of B. barrandi in the M C Z are from

bite as "Isotelus sp." because of its close similarity to Isotelus harrisi

the Middle O r d o v i c i a n Black River L i m e s t o n e s near Poland and

and the fact that only the pygidium, which was the original

Newport, H e r k i m e r County. M e m b e r s of the genera Basiliella and

figured s p e c i m e n , can be f o u n d . An entire specimen later figured

Basilicas

of

by R a y m o n d ( 1 9 1 0 c ) is lost. T h e Isoteloides species has well-

the facial suture in front of glabella" (Treatise). B o t h have genal

defined, flattened borders on the cephalon and pygidium. See

spines, a cephalic b o r d e r with a convex r i m , and a concave, well-

Shaw ( 1 9 6 8 ) for location i n f o r m a t i o n .

are

the

only

asaphids

"with

marginal

position

defined b o r d e r on the pygidium. Basiliella barrandi has a near Isoteloides canalis ( W h i t f i e l d , 1 8 8 6 ) Plate 149

semicircular pygidium. See also D e M o t t ( 1 9 8 7 ) .

L e c t o t y p e A M N H 3 5 2 7 6 (Brett and Westrop 1 9 9 6 ) Bellefontia

gyracanthus

(Raymond,

T h e species is from the Lower Ordovician Scotia Limestone

1910)

M e m b e r of the Fort Cassin F o r m a t i o n in Washington County.

Lectotype? ( W e s t r o p , K n o x , and Landing 1 9 9 3 ) Westrop et al. listed the family for genus Bellefontia from

T h e diagnosis from Brett and Westrop is "a species of Isoteloides

Lower O r d o v i c i a n as u n c e r t a i n . T h e Treatise placed it with the

with a relatively short axis that occupies up to about 80 percent

asaphids.

labeled Asaphus

of pygidial length a n d , consequently, relatively long border. Ante-

gyracanthus from Tribes Hill, C a n a j o h a r i e , M o n t g o m e r y C o u n t y .

rior b r a n c h e s of facial sutures are moderately divergent, so that

T h e r e are

specimens

in

the

MCZ

m a x i m u m frontal area width is equal to, or slightly greater than

T h e y are M C Z 3 4 7 8 and 3 4 7 9 .

glabellar length." T h e n a m e is u n f o r t u n a t e . T h e first record of ? Ectenaspis homalonotoides ( W a l c o t t ,

1877)

Plate

Asaphus canalis is in Hall's publication ( 1 8 4 7 ) . It is attributed to

148

C o n r a d and refers to material from the Chazy group. Whitfield

Syntypes F M N H 1 2 3 2 4 a , 1 2 3 4 1 b Walcott

( 1 8 8 6 b ) used the n a m e to refer to material from the Fort Cassin

based on s p e c i m e n s from Illinois, was said by R a y m o n d and

F o r m a t i o n . Later authors a b a n d o n e d the n a m e Isotelus canalis for

Narraway ( 1 9 1 0 ) to be fairly c o m m o n in the Middle O r d o v i c i a n

the Chazy material because of p o o r definition of the type speci-

Black River L i m e s t o n e s at Pattersonville, S c h e n e c t a d y C o u n t y .

m e n s . T h u s , o n e might argue that Isoteloides whitfieldi is now the

Later, R a y m o n d ( 1 9 2 5 ) withdrew this identification of the Black

proper n a m e .

?

Ectenaspis

homalonotoides,

originally

described

by

River specimens and equated the original with O n t a r i o material from just above the base of the T r e n t o n . T h i s later publication

Isoteloides peri (Fortey,

also

Holotype G S C 56799

assigned

it

to

his

new genus

Ectenaspis.

Ectenaspis

homa-

1979)

lonotoides has a long, tapering p r o j e c t i o n to the front of the

T h i s species is differentiated from /. canalis by a relatively

cephalon and a triangular pygidium. Plate 148 illustrates a spec-

longer pygidial axis, 85 to 9 0 % of the pygidial length. T h e species

imen

is f r o m the Lower Ordovician Scotia Limestone m e m b e r of the

from

Ontario

identified

as

Isoteloides

homalonotoides.

See

also D e M o t t ( 1 9 8 7 ) .

Fort Cassin F o r m a t i o n , Washington County. T h e species is also reported

Homotelus stegops

(Green,

1832)

from

Newfoundland

and

Pennsylvania

(Brett

and

Westrop 1 9 9 6 ) .

Hypotypes N Y S M 9 7 5 7 t o 9 7 6 5 T h i s trilobite is f o u n d in the U p p e r O r d o v i c i a n W h e t s t o n e

Isotelus

G u l f Shale o f the Lorraine G r o u p , O n e i d a C o u n t y . T h e cephalon

T h e genus Isotelus has not been properly revised, and species

has no trace of a border, and the pygidium has a poorly defined

identification, particularly in older m u s e u m specimens, can be

ORDER

159

A S A P H I DA

poor. Rudkin and Tripp ( 1 9 8 5 , 1 9 8 7 ) of the R O M have d o n e sig-

O n t a r i o retains its spines longer (i.e., at larger sizes) than those

nificant work with the Trenton and Upper Ordovician Isotelus

of the M o h a w k Valley. Plate 150 shows the neotype from the

species that o c c u r in O n t a r i o . Generally speaking, 7. platycephalus

W a l c o t t - R u s t Q u a r r y and is in the M C Z . Plate 151 is of a large,

is found in the Black River age rocks; /. gigas and /. walcotii,

near-perfect s p e c i m e n f r o m the s a m e location as the neotype.

in the middle Trenton; /. lotus and a n o t h e r isotelid informally

Plate 152 shows a cluster f r o m Trenton Falls. Plate 153 is the

known as "/. mafritzae" are found in the upper Trenton and lower

ventral view of a s p e c i m e n from Q u e b e c .

Upper O r d o v i c i a n ; and /. brachycephalus a n d I. maximus, in t h e Upper Ordovician. O t h e r u n n a m e d species have been identified,

Isotelus harrisi ( R a y m o n d ,

but similar careful e x a m i n a t i o n on the New York species has not

Lectotype Y P M 2 3 2 9 7 (Shaw 1 9 6 8 )

1905)

been done. Mature specimens of /. platycephalus, I. gigas, a n d /.

Isotelus harrisi is a fairly c o m m o n asaphid in s o m e Middle

latus do not have genal spines. Genal spines are f o u n d on m a t u r e

O r d o v i c i a n Chazy exposures. See Shaw ( 1 9 6 8 ) for location infor-

specimens

m a t i o n . It is a large trilobite b u t no articulated specimens are

of

/.

walcotti,

"I.

mafritzae?

I.

brachycephalus,

and

I. maximus. Although "/.

mafritzae" is not a formally published

name,

the

specimens

from

Lindsay

Formation

in

O n t a r i o are c o m m e r c i a l l y available with this n a m e and

Tripp

1985,

1987,

1989;

David

Rudkin

reported.

southern (Rudkin

1997,

private

communication).

Isotelus jacobus

(Clarke,

1894)

H o l o t y p e N Y S M 4 5 1 2 (lost) T h e type is listed f r o m C r o w n Point, Essex County. A large pygidium in the U S N M , U S N M 1 3 6 4 2 , is from this locality. It is

Isotelus annectans ( R a y m o n d ,

1920)

also listed from Middleville, H e r k i m e r C o u n t y , a Middle O r d o v i -

Holotype C M ?

cian, lower T r e n t o n area.

T h e holotype was originally described as Ectenaspis homalnotoiiles from New York but on further review was assigned to a new

Isotelus latus ( R a y m o n d , 1 9 1 3 )

species. R a y m o n d referred to this species as a link between Ecte-

Holotype GSC; specimens NYSM 17009, 17010

naspis and Isotelus. It is described as fairly c o m m o n in the Glens

T h e N Y S M s p e c i m e n s are f r o m M i d d l e O r d o v i c i a n , upper

Falls M e m b e r of the Middle Ordovician Trenton G r o u p at Pat-

Black River or lower T r e n t o n areas at Middleville and N e w p o r t ,

tersonville, Schenectady C o u n t y , and S m i t h s Basin, Washington

H e r k i m e r C o u n t y , respectively. O n e is a very large semicircular

County. T h e borders on the c e p h a l o n and pygidium are poorly

pygidium, 120 mm wide by 90 mm long. Given that /. latus is from

defined. Both the cephalic and pygidial axes are wide and poorly

higher up in the T r e n t o n / U p p e r O r d o v i c i a n , these s p e c i m e n s are

defined.

most

Isotelus giganteus ( R a y m o n d ,

1931)

platycephalus.

Isotelus cf. /. maximus ( L o c k e , 1 8 3 8 ) Plates 154, 1 5 5 , 1 5 6 ,

Holotype M C Z 1 0 4 9 8 2 T h e holotype, and only s p e c i m e n , is a

likely /.

and 157 huge h y p o s t o m e

Hypotypes N Y S M 4 3 1 3 , 4 3 1 5

from the upper Chazy Limestone at Tiger Point, Valcour Island,

R u e d e m a n n ( 1 9 0 1 ) f o u n d material in the Middle Ordovician

Clinton County. T h e h y p o s t o m e measures 8 0 m m across the pos-

Rysedorph C o n g l o m e r a t e , Rensselaer C o u n t y , that he assigned

terior points and about 100 mm at its widest. F r o m the size of the

to the U p p e r O r d o v i c i a n trilobite, f o u n d in O h i o and O n t a r i o .

hypostome and by knowledge of the relative size of the h y p o s t o m a

N Y S M 4 3 1 3 is a small, negative m o l d , which is not diagnostic.

of other species of the genus, R a y m o n d believed this s p e c i m e n was

On the s a m e m a t r i x are two pygidia and a c r a n i d i u m of a ptery-

6 0 0 to 6 7 5 mm ( 2 4 to 26 inches) long, m a k i n g it a truly giant trilo-

g o m e t o p i d . He believed the asaphid resembled /. maximus from

bite. It is not, however, likely to be a distinct species but a large

O h i o , which has a cephalon and pygidium with a very rounded

specimen of the large asaphids already k n o w n in the Chazy.

outline. T h e genal spines on O h i o s p e c i m e n s are long and thin. T h e y are kept through maturity. T h e New York s p e c i m e n s are

Isotelus gigas (DeKay, 1 8 2 4 ) Plates 1 5 0 , 1 5 1 , 1 5 2 , a n d 153

a q u e s t i o n a b l e a s s i g n m e n t . Plate 154 illustrates a specimen of

Neotype M C Z 1 0 0 9 3 8 (Rudkin and Tripp 1 9 8 9 )

/. maximus from O h i o and Plates 155 and 156 are the ventral

Type species. Isotelus gigas is a very well-known New York

view of a pyritized s p e c i m e n f r o m O h i o , with the posterior

trilobite because o f the n u m b e r s o f s p e c i m e n s , which were f o u n d

appendages possibly pyritized. Plate 157 is of a molt with the

in the Middle O r d o v i c i a n , middle Trenton Limestones of the

cephalon o v e r t u r n e d .

Trenton Falls area, H e r k i m e r County. I m m a t u r e holaspids have genal spines. T h e s e spines disappear as the trilobite grows,

Isotelus platycephalus

b e c o m i n g shorter with each successive molt. T h e size at which

Lectotype B M ( D a r b y and S t u m m 1965)

the genal spines disappear is different for /. gigas f r o m different localities. F o r example, /. gigas from the Lake S i m c o e area of

(Stokes,

1824)

T h e lectotype is from the Black River G r o u p of O n t a r i o and is f o u n d

in association with Basiliella barrandei and Bumastoides

160

THE

TRILOBITES

milleri. It differs f r o m /. gigas in that b o t h the cephalon and the

established that P.

pygidium are m o r e rounded and less triangular in outline. Black

L i m e s t o n e m e m b e r o f the t o p m o s t Middle Ordovician Trenton

River Isotelus species should be c o m p a r e d to /. platycephalus when

and in the base of the overlying shale. T h i s work also established

o n e is considering their validity.

the fact that P.

latimarginatus can be found in the Hillier

latimarginatus and P.

canadensis are the same,

and P. canadensis was a b a n d o n e d as a species. Both the cephalon Isotelus pulaskiensis

(Ulrich,

1926)

and pygidium have well-defined borders. T h e r e are short genal

Hypotype N Y S M 9 7 6 7

spines. T h e pygidium has n u m e r o u s , p r o m i n e n t pleurae that

T h e type of this species is f r o m Pennsylvania. T h e s p e c i m e n i n the U S N M , U S N M 2 3 6 2 8 , bearing this n a m e i s f r o m the

almost reach the margin. Plate 159 is a N Y S M specimen from Oneida County.

Pulaski drift ( U p p e r O r d o v i c i a n ) in the T r e n t o n Falls, H e r k i m e r County, area and is f r o m the Rust collection in a 1886 purchase.

Vogdesia

A small free c h e e k has long genal spines, longer than what is seen

N e o t y p e N Y S M 1 2 5 3 8 (Shaw 1968)

on i m m a t u r e /. gigas s p e c i m e n s .

bearsi

(Raymond,

1905)

Type species. T h i s trilobite is k n o w n from o n e area of the M i d d l e O r d o v i c i a n Chazy where it is considered abundant, Sloop

Isotelus simplex ( R a y m o n d a n d Narraway,

1910)

Bay, Valcour Island, C l i n t o n County. Strangely e n o u g h , similar

H o l o t y p e C M 1441

age exposures a short distance away do not yield this trilobite.

D e M o t t ( 1 9 8 7 ) listed this M i d d l e O r d o v i c i a n B l a c k River

T h e eyes are on short stalks. T h e pygidium has a concave border,

trilobite, originally described f r o m Pennsylvania, as f r o m Buck's

and the pleural field is flat. T h e t h o r a x , d o u b l u r e , and h y p o s t o m e

Q u a r r y near Poland, H e r k i m e r C o u n t y . It differs f r o m /. gigas

of V. bearsi are u n k n o w n .

in that the shields are less triangular and lack concave borders. S o m e asaphids f r o m the Black River Buck's Q u a r r y near Poland,

Vogdesia? obtusus

H e r k i m e r C o u n t y , bear the label /. iowensis ( M C Z 4 2 6 ) . T h e s e are

Neotype N Y S M 1 2 5 2 4 (Shaw 1968)

probably s p e c i m e n s of /. simplex.

(Hall,

1847)

T h i s fairly c o m m o n trilobite is f o u n d t h r o u g h o u t areas of the Middle Ordovician Chazy. T h e fragmentary nature o f most o f the

Isotelus walcotti U l r i c h , in ( W a l c o t t , 1 9 1 8 ) P l a t e 158

material prevents a m o r e exact placement within the asaphids.

Lectotype U S N M 6 1 2 6 1 a ( R u d k i n and Tripp 1 9 8 9 )

Additional s p e c i m e n s are M C Z 3 6 0 1 through 3 6 0 9 . R a y m o n d

Isotelus walcotti is f r o m the W a l c o t t - R u s t Q u a r r y , the source of all the s p e c i m e n s k n o w n to us. T h e q u a r r y is located in the

( 1 9 2 5 , p. 9 0 ) also reported this species f r o m V e r m o n t and Virginia. See Shaw ( 1 9 6 8 ) for location i n f o r m a t i o n .

lower Rust L i m e s t o n e o f the M i d d l e O r d o v i c i a n T r e n t o n G r o u p , H e r k i m e r C o u n t y . T h e lectotype is figured in Plate 158. T h e trilo-

Family Idahoiidae

bite bears a strong r e s e m b l a n c e to /. iowensis f r o m the Upper

Saratogia

O r d o v i c i a n of the n o r t h - c e n t r a l United States. T h e species differs

L e c t o t y p e U S N M 5 8 5 5 5 (Ludvigsen and Westrop 1983)

from the /. gigas f o u n d in the s a m e rocks in that it keeps its genal

Upper C a m b r i a n , Hoyt L i m e s t o n e , Saratoga County.

(Saratogia)

calcifera

(Walcott,

1879)

Plate

175B

spines t h r o u g h o u t its growth, and the a n t e r i o r and posterior ends of the c e p h a l o n and pygidium, respectively, are r o u n d e d in /.

Family Pterocephaliidae

walcotti while they have a m o r e p o i n t e d a p p e a r a n c e in /. gigas.

Cameraspis

Larger s p e c i m e n s of /. walcotti are rare. O n l y o n e a p p r o a c h i n g the

Specimens NYSM 14159, 14160

size of a m a t u r e /. gigas is in the M C Z , M C Z 4 2 2 , a n d it still has its genal spines.

convexa

(Whitfield,

1878)

Upper C a m b r i a n , Galway F o r m a t i o n , Saratoga County. See Ludvigsen and Westrop ( 1 9 8 3 ) for synonymies. T h i s species is also f o u n d in W i s c o n s i n , M i n n e s o t a , Pennsylvania, O k l a h o m a ,

Nileoides perkinsi

(Raymond,

1910)

M i s s o u r i , M o n t a n a , and W y o m i n g .

Lectotype U V M 2 - 6 6 (Shaw 1 9 6 8 ) Nileoides perkinsi is from the M i d d l e O r d o v i c i a n , upper Chazy of V e r m o n t . R a y m o n d ( 1 9 2 5 , p. 9 7 ) stated that he f o u n d a specimen from the Chazy o f C l i n t o n C o u n t y .

Cameraspis

sp.

Specimen M C Z 4810 Potsdam S a n d s t o n e , north edge of Battle Hill, near Fort A n n , W a s h i n g t o n County.

Pseudogygites

latimarginatus

(Hall,

1847)

Plate

159

Family Ptychaspididae

H o l o t y p e A M N H 1070 Hall described this species f r o m two isolated pygidia from an unspecified location near W a t e r t o w n , Jefferson C o u n t y . A similar species f r o m C a n a d a , f o u n d in a b u n d a n c e in the upper Middle Ordovician,

was

named

Pseudogygites

canadensis.

Fieldwork

Conaspis

whitehallensis

(Walcott,

1912)

Holotype U S N M 58579 Upper C a m b r i a n , Potsdam S a n d s t o n e , Whitehall, Washington County.

ORDER

A S A P H I DA

161

Idiomesus sp. (Bird and Rasetti, 1 9 6 8 )

Apatokephaloides sp.

Upper C a m b r i a n trilobite from a limited exposure in the East

(Bird

and

Rasetti,

1968)

An Upper C a m b r i a n species, f r o m C o l u m b i a County.

C h a t h a m quadrangle o f C o l u m b i a County. Hypodicranotus striatulus Keithiella

depressa

(Rasetti,

(Walcott,

1875)

Plates

160,

161,

a n d 162

1944)

Lectotype M C Z 1 0 0 9 8 6 ( R a y m o n d 1 9 2 5 )

Holotype G S C 71161 Upper C a m b r i a n , Hoyt L i m e s t o n e , Saratoga County. See Ludvigsen and Westrop ( 1 9 8 3 ) for synonymies. T h i s species is also found in Q u e b e c and N e w f o u n d l a n d .

Type

species.

Hypodicranotus striatulus

is

a

very

interesting

trilobite that was first described from the Middle Ordovician, upper T r e n t o n , W a l c o t t - R u s t Q u a r r y , H e r k i m e r County. In addition to the r e m o p l e u r i d c r a n i d i u m , the species has long genal spines r u n n i n g parallel to spinelike extensions of the occipital

Family Raphiophoridae All of the raphiophorids in New York are f o u n d in the Middle Ordovician. All are assigned to t h e genus Lonchodomas a n d are characterized by a glabellar m e d i o a n t e r i o r spine p r o j e c t i n g straightforward. T h e r e are also genal spines. T h e t h o r a x has five segments. T h e pygidium is small and semicircular and has a narrow border.

ring, giving the a p p e a r a n c e of a dual genal spine. T h e h y p o s t o m e is like no other. It is shaped like a tuning fork and extends to the e n d of the t h o r a x . T h e pygidium is very small. T h i s species has been reported f r o m New York, O n t a r i o , M i s s o u r i , Q u e b e c , and the District of M a c k e n z i e , C a n a d a . Plate 160 shows a specimen from the W a l c o t t - R u s t Q u a r r y . Plate 161 is of a n o t h e r specimen f r o m the W a l c o t t - R u s t Q u a r r y that split longitudinally, showing the long h y p o s t o m e . Plate 162 shows the small pygidium and

Lonchodomas

chaziensis

(Shaw,

the unusual, bifurcate lateral genal area. T h e genus has been

1968)

f o u n d in M i n n e s o t a , W i s c o n s i n , O k l a h o m a , Nevada, S c o t l a n d ,

Holotype N Y S M 12265 a

the central Ural M o u n t a i n s , and far n o r t h e a s t e r n Russia (see Lud-

long, four-sided glabellar spine projecting straight forward. It is

vigsen and C h a t t e r t o n 1 9 9 1 ) . Because of its shape it has been sug-

found in the Lower and Middle Chazy. See Shaw ( 1 9 6 8 ) for loca-

gested the trilobite might be pelagic, and its wide distribution

tion i n f o r m a t i o n .

goes along with this.

Lonchodomas

Lonchodomas

chaziensis

halli

is

a

(Billings,

trinucleoid

characterized

by

Remopleurides

1865)

In New York L. halli is f o u n d in the Upper Chazy. It is also found in Chazy age rocks in Virginia, Q u e b e c , and V e r m o n t . Shaw differentiated

the

two

Lonchodomas

species

from

the Chazy as follows: "L halli differs from L. chaziensis by p o s session of the following characters: ( 1 ) glabellar profile m o r e convex, with a m o r e definite keel present. ( 2 ) Glabellar furrows are extremely faint to absent. ( 3 ) Glabella tapers m o r e rapidly into glabellar spine, thus the glabella itself does not extend far beyond the fixed cheeks.

( 4 ) S-shaped genal spines.

(5)

Possession of a sight flat area on fixed cheek proximal to anterior portion of facial sutures." See Shaw ( 1 9 6 8 ) for location information.

Lonchodomas

(Billings,

1865)

H o l o t y p e G S C 1 7 6 0 (Shaw 1968)

Topotype N Y S M 1 2 2 7 9

(1968)

canadensis

Remopleurides

canadensis

is

found

throughout

the

Middle

O r d o v i c i a n Chazy. R e m o p l e u r i d s have a distinctive c r a n i d i u m , which can not easily be mistaken for any o t h e r genus. See Shaw ( 1 9 6 8 ) for location i n f o r m a t i o n . T h i s species is also reported f r o m Ottawa and Virginia. Remopleurides

linguatus

(Ruedemann,

1901)

Hypotypes N Y S M 4 7 7 0 t o 4 7 7 4 M i d d l e O r d o v i c i a n Trenton age pebbles in the Rysedorph Conglomerate. Remopleurides

tumidus

(Ruedemann,

1901)

Holotype N Y S M 4 7 7 5 hastatus

(Ruedemann,

1901)

Syntypes N Y S M 4 1 2 8 t o 4 1 3 5 Lonchodomas hastatus was f o u n d in Trenton age pebbles in the Rysedorp Hill C o n g l o m e r a t e , Rensselaer County.

Family Remopleurididae

Middle O r d o v i c i a n Trenton age pebbles in the Rysedorph C o n g l o m e r a t e , Rensselaer C o u n t y . Richardsonella sp.

( B i r d a n d Rasetti,

1968)

Upper C a m b r i a n , C o l u m b i a C o u n t y . Robergiella

cf.

R.

brevilingua

(Fortey,

1980)

Remopleuridids are known from the Upper C a m b r i a n to the

Brett and Westrop ( 1 9 9 6 ) reported a c r a n i d i u m and free cheek

Middle Ordovician in New York. T h e y are not c o m m o n any-

very similar to those of this species f r o m the Lower Ordovician

where. T h e family is characterized by long curved eye lobes. All

Scotia

species have genal spines and small pygidia.

W a s h i n g t o n County.

Limestone

member

of

the

Fort

Cassin

Formation,

THE

162

Family Saukiidae Hoytaspis speciosa

TRILOBITES

in North America during the latter part of the Middle Ordovi-

(Walcott,

1879)

cian (early C a r a d o c ) , likely due to the closing of the Iapetus

Lectotype U S N M 5 8 5 6 3 (Resser 1 9 4 2 a )

O c e a n and associated changes in currents and distances that

Type species. T h i s species is k n o w n f r o m the U p p e r C a m b r i a n ,

allowed the pelagic larvae to reach North A m e r i c a . Shaw and

Hoyt L i m e s t o n e , Saratoga C o u n t y , and also the Potsdam S a n d -

Lesperance ( 1 9 9 4 ) argued that all the Cryptolithus species repre-

stone drift near Trenton Falls, H e r k i m e r C o u n t y ( M C Z 3 8 5 8 ) .

sented in New York are part of a long-lived interbreeding popu-

Prosaukia

considered " m o r p h s " of Cryptolithus tessellatus. Since these trilo-

lation and as such do not hold species rank but should be briarcliffensis

(Lochman,

1946)

H o l o t y p e Y P M 17391

bites are clearly separated by time and stratigraphy in New York,

Upper C a m b r i a n f r o m rocks in D u t c h e s s C o u n t y referred to

we c h o s e to c o n t i n u e to list t h e m as separate species. T h e mature Cryptolithus trilobites are eyeless, while the tretaspids have lateral

as " H o y t D o l o s t o n e . "

eye tubercles. B o t h are considered to be b e n t h i c , living and feeding by plowing through the soft b o t t o m and ingesting the

Prosaukia hartti (Walcott, 1 8 7 9 ) Plate 1 7 5 A

m i c r o f a u n a or organic detritus. All have a characteristic, radially

Holotype U S N M 5 8 5 7 1 Upper C a m b r i a n , Hoyt L i m e s t o n e , Saratoga County. T h i s

pitted, cephalic b r i m or fringe. T h e pits are considered to have a sensory f u n c t i o n , but they also strengthen the fringe significantly

species is also f o u n d in W i s c o n s i n .

over a s m o o t h surface. T h e b r i m is divided horizontally into an Prosaukia

tribulis (Walcott,

upper part of the dorsal cephalic exoskeleton and a lower p o r t i o n ,

1912)

which

Holotype U S N M 58578

c o m e s free, probably during ecdesys.

Because of this

l a m i n a r nature, the upper b r i m and lower b r i m are called lamel-

Upper C a m b r i a n , Hoyt L i m e s t o n e , Saratoga County.

lae. T h e lower lamella has the genal spines.

Family Symphysurinidae T h i s family, o n c e considered a subfamily of Asaphidae, is r e p -

Cryptolithus bellulus ( U l r i c h , 1 8 7 8 ) Figure 5 . 5 C , D and

resented by two species, and no general family description is

Plate 163

given. T h e family is not listed in v o l u m e 1 of Treatise (revised).

Holotype USNM 41876

Symphysurina

Ordovician trilobite f o u n d in both limestones and shales. In New

Cryptolithus bellulus geographically is a widely distributed Late convexa

(Cleland,

1900)

Holotype PRI 5072

York State it is f o u n d in the Lorraine G r o u p shales in Oneida

T h i s trilobite is f r o m the Tribes Hill F o r m a t i o n of the Lower Ordovician in M o n t g o m e r y County. T h e glabella is vaulted,

County.

Cryptolithus

bellulus

with

preserved

appendages

was

f o u n d along with the m o r e f a m o u s appendaged Triarthrus eatoni

longer than wide, and the palpebral lobes are a b o u t m i d p o i n t .

in the Frankfort Shales of Beecher's Trilobite Bed. All we know of

T h e pygidium is semicircular to p a r a b o l i c , r o u n d e d with a well-

the soft tissue a n a t o m y of the cryptolithids is from the

defined axis. Axial segments are defined but not p r o m i n e n t .

pyritized, partial s p e c i m e n s k n o w n from this site. Cryptolithus

Symphysurina convexa

is characterized by a

pitted

prosopon

13

or

bellulus is very similar to C. lorettensis with the exception that the

o r n a m e n t a t i o n on external surfaces. See Westrop, K n o x , and

pits in E, and I, are radially aligned in C. lorettensis and alternat-

Landing ( 1 9 9 3 ) .

ing in C. bellulus. T h e r e are also statistical differences in the pit c o u n t s of the c o n c e n t r i c rows, but this is not diagnostic with

Symphysurina cf. S. woosteri U l r i c h , in ( W a l c o t t , 1 9 2 4 )

small sample sizes. Because of the observed c o - o c c u r r e n c e of C.

Specimens N Y S M 15209, 15210

bellulus and C. lorettensis in C a n a d a , it is questionable that these

Type species. T h i s trilobite is from the Lower Ordovician Tribes Hill

F o r m a t i o n , M o n t g o m e r y County.

is based on

O n e m u s t go outside the state to observe Cryptolithus species

two pygidia with stout medial spines. M o r e material is necessary

through the time sequence between the middle Trenton and the

for positive identification.

It

are distinct species. In New York, however, there is no intermix.

See Westrop, K n o x , and Landing

L o r r a i n e . Plate 163 shows a specimen from the Upper Ordovician

(1993).

shales in O n e i d a County.

Family Trinucleidae

Cryptolithus lorettensis ( F o e r s t e , 1924) Figure 5.5A, E and

Hughes, I n g h a m , and Addison ( 1 9 7 5 ) reviewed and revised trinucleids. T h e trinucleids are represented in New York by five species tolithus

or

subspecies:

tessellalus,

C.

Tretaspis

lorettensis, and

reticulata, C.

T.

bellulus.

diademata, The

Cryp-

Plates 164 a n d 165 Holotype G S C 10790 T h i s trilobite is f o u n d in the upper Sugar River Limestone,

trinucleids

R a t h b u n M e m b e r , or its equivalent limestones in New York. It is

are a family originating in the S o u t h e r n Trilobite Province Z o n e

f o u n d near the top of the m e m b e r where it replaces C. tessellatus.

of W h i t t i n g t o n ( 1 9 6 6 ) in the lower Arenig. T h e y first appeared

In s o m e areas in O n e i d a C o u n t y there is a narrow horizon where

ORDER

163

P T Y C H O P A R I IDA

both may be found, but this is not c o m m o n . In each of the U S N M

selaer C o u n t y . It differs f r o m T. reticulata in that the rows of pits

and N Y S M ( E - 9 2 0 ) collections there is a b o x of m i x e d C. tessel-

are arranged radially (aligned) and not just c o n c e n t r i c as they are

latus and C.

in

lorettensis s p e c i m e n s labeled

f r o m Trenton Falls,

T.

reticulata.

H e r k i m e r County. In the M o h a w k Valley, C. tessellatus is f o u n d in the middle Sugar River L i m e s t o n e , but in the R a t h b u n or upper

Tretaspis reticulata

m e m b e r of the Sugar River, C. lorettensis is the only Cryptolithus

Hypotypes N Y S M 4 8 2 0 t o 4 8 2 2

species (Vere 1 9 7 2 ) . T h e p r i m a r y distinguishing feature of C. lorettensis versus C.

tessellatus is that C.

lorettensis has an addi-

Tretaspis

(Ruedemann,

reticulata

was

1901)

described

from

remains

in

Middle

O r d o v i c i a n Trenton age pebbles in the Rysedorph C o n g l o m e r a t e ,

tional row of pits, I,, anterior to the glabella and genal area. T h i s

Rensselaer C o u n t y . T h e genus Tretaspis differs from Cryptolithus

row of pits is not always c o m p l e t e in front of the glabella but

primarily

always extends farther toward the median line than with C. tes-

expanding glabella, b u t Tretaspis species have three pairs of dis-

sellatus. Additionally, on

large s p e c i m e n s of C.

lorettensis,

in

the

glabella.

Both

have

a

bulbous,

forward-

the

tinct glabellar furrows, which are absent in Cryptolithus. T h e r e

exterior, median genal area is reticulated, and this area is s m o o t h

are three rows of pits a n t e r i o r to the glabella. T h e surface of the

on large specimens of C. tessellatus.

glabella is pitted and reticulated. T h e r e is no occipital spine. T h e pygidium is small and widely triangular. T h e n u m b e r of thoracic

Cryptolithus tessellatus (Green,

1832)

Figure 5 . 5 B and Plates

segments is u n k n o w n for T. reticulata, but six may be expected

166 and 167

by analogy. F o r a m o r e c o m p l e t e discussion of the trinucleids of

Holotype lost, neotype M C Z 1 0 6 4 9 2 (Shaw and Lesperance 1 9 9 4 ) Type species. T h e Middle O r d o v i c i a n C.

tessellatus in New

N e w York, particularly Cryptolithus, see W h i t t i n g t o n ( 1 9 4 1 , 1 9 6 8 ) and Vere ( 1 9 7 2 ) .

York is considered an index fossil of the Sugar River L i m e s t o n e of the Trenton G r o u p because it apparently first appears in New York in this limestone and is rarely, if ever, f o u n d in the overlying limestones. It is c o m m o n in s o m e h o r i z o n s and locations in the Sugar River in O n e i d a C o u n t y but is not u n i f o r m l y distributed anywhere. Although small, this trilobite has a distinctive and robust cephalon. T h e glabella is vaulted and s m o o t h , with only two shallow pits anterior to the occipital ring for glabellar furrows. T h e cephalon is r o u n d e d in outline and about twice as long as wide, including the long genal spines. Cephala are f o u n d with and without genal spines. T h o s e without genal spines have lost the lower lamella. T h e occipital ring has a central spine extending backward over the first few t h o r a c i c s e g m e n t s . T h e most characteristic feature of the trilobite is the a n t e r i o r b r i m or fringe, which has u n i f o r m rows of pits following the curvature of the anterior edge. T h e s e pits, their n u m b e r , and a r r a n g e m e n t are m a j o r factors in distinguishing the various species. Pit rows E, and I| have a thickened area called a girder, seen o n l y on the ventral

surface,

that

separates

them.

Cryptolithus

tessellatus

5.8 ORDER PTYCHOPARIIDA T h i s o r d e r includes trilobites primarily o f the C a m b r i a n and O r d o v i c i a n . In New York these trilobites are only represented in these periods. T h i s diverse o r d e r does not have any easily recognized defining features. W i t h i n the individual Ordovician families, however, there are distinctive features.

Family Conocoryphidae Atops trilineatus ( E m m o n s ,

Type species. Lower C a m b r i a n . Conocoryphe

verrucosa

(Whitfield,

Upper

Cambrian,

Potsdam

Sandstone,

Ausable

Chasm,

Keesville, Essex C o u n t y .

Family Dokimocephalidae

are only three rows of pits ( E , , I,, I ) immediately a n t e r i o r to the

Sulcocephalus

genal area. T h e t h o r a x has six t h o r a c i c segments, and the pygid-

H o l o t y p e N Y S M 10511

ium is rounded, being m u c h broader than it is long. W h o l e speci-

1884)

Syntypes A M N H 0 0 0 2 8 0 , 0 3 5 9 7 8 - 0 3 5 9 8 3

differs from the other New York Cryptolithus species in that there 2

1846)

Plastotype N Y S M 4 2 0 4

saratogensis

(Resser,

1942)

Lower C a m b r i a n , Theresa F o r m a t i o n .

mens from New York are rare. Plate 166 shows an u n c o m m o n , whole specimen from the Sugar River F o r m a t i o n of H e r k i m e r

Family Elviniidae

County. Plate 167 is included because it is listed f r o m Trenton

Calocephalites cf.

Falls, an area not usually included as exposing the Sugar River

minimus (Kurtz,

1975)

Ludvigsen and Westrop ( 1 9 8 3 ) .

rocks. Tretaspis diademata

(Ruedemann,

1901)

Dellea? landingi (Ludvigsen a n d Westrop, 1 9 8 3 )

Holotype N Y S M 4 8 1 9 Tretaspis

C.

Upper C a m b r i a n , Galway F o r m a t i o n , Saratoga County. See

diademata

is

Holotype N Y S M 14138 known

from

one

specimen

in

the

Middle Ordovician part of the Rysedorph C o n g l o m e r a t e , Rens-

Upper

Cambrian,

Hoyt

L i m e s t o n e , Saratoga County.

Ludvigsen and Westrop ( 1 9 8 3 ) .

See

164

THE

TRILOBITES

FIGURE 5.5. Features of New York Cryptolithus. The s p e c i m e n s are all about the s a m e size. For scale, see the plates. A.

Cryptolithus lorettensis from the u p p e r Sugar River Formation of the Trenton G r o u p , Jefferson

County. Note the four rows of pits anterior to the c h e e k area (NYSM). B. Cryptolithus tessellatus from the lower Sugar River Formation of the Trenton G r o u p , Herkimer County. Note that there are three rows of pits anterior to the

c h e e k area (TEW collection).

C.

Cryptolithus bellulus from the

Pulaski

M e m b e r of the

Lorraine G r o u p ,

O n e i d a County. There are four rows of pits anterior to the c h e e k area in this s p e c i m e n . D. Cryptolithus bellulus from the Pulaski M e m b e r of the Lorraine G r o u p , Lewis County. There are four rows of pits anterior to the c h e e k area. The radial a l i g n m e n t of the pits in rows E, a n d I, are not quite the s a m e as in C. The s p e c i m e n s in C a n d D are internal m o l d s a n d not as clearly d e f i n e d as those in A a n d B. The n u m b e r i n g system for the pit rows in Cryptolithus are as follows: R,, R , R , . . . are d e s i g n a t i o n s for the radially a l i g n e d rows starting with the medial 2

3

row; E, is the first circumferal row from the front e d g e of the c e p h a l o n ; I,, l , l 2

3

d e s i g n a t e the circumferal rows

after E,.

Dellea

saratogensis

(Resser,

1942)

Elvinia granulata

Holotype N Y S M 10511

(Resser,

1942)

Holotype U S N M 108815

Upper C a m b r i a n , Galway F o r m a t i o n , Saratoga C o u n t y . See Ludvigsen and Westrop ( 1 9 8 3 ) .

Upper C a m b r i a n , Galway F o r m a t i o n . Saratoga County. See Ludvigsen and Westrop ( 1 9 8 3 ) . T h e holotype is f r o m Nevada. T h e species is also f o u n d in Utah and Indiana.

Drabia cf.

D.

curtoccipita

(Wilson,

1951)

Upper C a m b r i a n , Galway F o r m a t i o n , Saratoga C o u n t y . See Ludvigsen and Westrop ( 1 9 8 3 ) .

Family Glaphuridae Glaphurids are best k n o w n from the two genera in eastern N o r t h A m e r i c a . Long considered trilobites of the Middle Ordovi-

Drabia cf. D.

menusa ( W i l s o n ,

1951)

U p p e r C a m b r i a n , Galway F o r m a t i o n , Saratoga C o u n t y . See Ludvigsen and Westrop ( 1 9 8 3 ) .

cian Chazy Limestones, they are currently k n o w n to have a longer t i m e range (Shaw 1 9 6 8 ) . Glaphurids are smallish trilobites f o u n d in reef facies. T h e i r exoskeleton is subelliptical, tapering

ORDER

165

PTYCHOPARIIDA

from the large cephalon to the small semicircular pygidium. T h e

County. T h e M C Z material is two specimens from the Middle

surface is either very pustulose or spiny. T h e glabella is suboval

O r d o v i c i a n Trenton L i m e s t o n e o f Port Jackson, Clinton County.

and p r o m i n e n t .

T h e s p e c i m e n in Plate 1 6 9 C is from a negative of a metal replica o f the holotype.

Glaphurina lamottensis ( U l r i c h , 1 9 3 0 ) Plate 1 6 8 B Holotype U S N M 8 0 5 5 3 Type species. Shaw ( 1 9 6 8 ) considered G. lamottensis from the upper part of the Middle O r d o v i c i a n , in the lower and the lower part of the middle Chazy, to be a considerably different trilobite from G. pustulosus. T h e exoskeletal p r o s o p o n is widely spaced tubercles, c o m p a r e d to the spines on G. pustulosus, and there are 12 thoracic segments instead of the 10 in G. pustulosus. Glaphurus pustulosus

(Walcott,

1877)

Plate

168A

Lectotype M C Z 7 5 6 6 B (Shaw 1 9 6 8 ) Glaphurus pustulosus is a trilobite of upper middle and basal upper Chazy G r o u p limestones. Disarticulated parts can be very abundant locally, but whole articulated s p e c i m e n s are rare. T h e o n e articulated and two partially articulated s p e c i m e n s reported by Shaw exhibit spines radiating f r o m the front of the cephalon,

Eoharpes

pustulosus

(Hall,

Eoharpes pustulosus is a

trilobite of the Middle Ordovician,

upper Black River G r o u p

in

the Watertown

area, Jefferson

County. Hibbertia valcourensis (Shaw,

1968)

Plate

169A, B

Holotype N Y S M 12293 Hibbertia

valcourensis

from

the

Middle

Ordovician,

from the Chazy by R a y m o n d ( 1 9 0 5 b , Eoharpes

ottawaensis

(both

1 9 1 0 b ) as Harpina anti-

quatus

and

(1859,

1865) f r o m C a n a d i a n s p e c i m e n s ) . T h e genus Hibbertia

described

S p e c i m e n N Y S M 12301

(Shaw,

1968)

T h i s trilobite is f r o m the M i d d l e O r d o v i c i a n , lower Chazy

specimen.

G r o u p . For location i n f o r m a t i o n , see Shaw ( 1 9 6 8 ) .

Family Harpidae

Scotoharpes cassinensis

(Whitfield,

1897)

Plate

Scotoharpes

cassinensis

is

a

Lower

Ordovician

reported from the B e e k m a n t o w n

of the cephalon, f o r m i n g a wide p l a t f o r m , t o o wide to call a genal

( 1 9 6 2 ) reported it also f r o m New York.

the trilobite. T h e fringe has a l a m i n a r structure that is separated into upper and lower lamellae by a suture a r o u n d the entire lateral edge. Separation is parallel to the plane of the fringe surface. During ecdysis the lamellae separate along this suture, and the trilobite crawls forward, leaving the m o l t e d exoskeleton behind. T h e eyes are small tubercles with two lenses each. T h e thorax has 12 to 29 segments. T h e pygidium is small with few segments. T h r e e of the six k n o w n harpids in New York are from the Middle Ordovician Chazy limestones. Dolichoharpes

sp.

(Shaw,

This trilobite is from the M i d d l e O r d o v i c i a n , middle and upper Chazy. D o l i c h o h a r p i d s have a narrower fringe that has three raised, serrated rows along the lateral edge of the upper fringe. For location i n f o r m a t i o n , see Shaw ( 1 9 6 8 ) .

Family Hystricuridae Hystricurids are o n l y f o u n d in the Lower O r d o v i c i a n in New York. T h e y are small pustulose trilobites with opisthoparian cephalic sutures. All have genal spines. Articulated s p e c i m e n s are u n k n o w n from New York. Hystricurus

conicus

(Billings,

1859)

Holotype GSC 516 Type species. T h e h o l o t y p e is f r o m the Lower Ordovician

Hystricurus

Plate

169C

crotalifrons

(Dwight,

1884)

Syntype N Y S M 9 7 6 6 F r o m the Lower O r d o v i c i a n Roachdale L i m e s t o n e , Dutchess County. Hystricurus

1865)

Fisher

Spellman F o r m a t i o n .

1968)

(Billings,

trilobite first

Group of Vermont.

B e e k m a n t o w n of Q u e b e c . It is also f r o m the Lower Ordovician

Specimens Y P M 2 3 2 9 4 , N Y S M 1 2 2 9 4 t o 1 2 3 0 0

Hibbertia ottawaensis

169D

Holotype U S N M 35817

wide fringe. T h e lateral fringe sweeps back posteriorly to the rear spine. T h i s genal platform extends close to the posterior end of

Billings

o r n a m e n t a t i o n . F o r location i n f o r m a t i o n , see Shaw ( 1 9 6 8 ) . Hibbertia sp.

T h e cephalon is semicircular in the anterior p o r t i o n , with a very

by

differs f r o m Dolichoharpes in the width of the fringe area and the

of the pleura. T h e single articulated specimen is 3.5 mm long and

Harpids are nearly impossible to mistake for any o t h e r family.

lower

Chazy was described by Shaw from material previously described

the genal angle, the axis of the t h o r a c i c s e g m e n t s , and the ends could be a late meraspid. T h e r e are ten thoracic s e g m e n t s on this

1847)

Holotype A M N H 841

ellipticus

(Cleland,

1900)

H o l o t y p e PRI 5 0 7 3

Holotype G S C 3 2 9 , hypotype N Y S M 9 7 3 6 , s p e c i m e n M C Z 1 2 8 5 6

This species is k n o w n f r o m n u m e r o u s cranidia and pygidia

T h e holotype is from the Middle Ordovician of O n t a r i o . T h e

from the Lower O r d o v i c i a n Tribes Hill F o r m a t i o n , M o n t g o m e r y

N Y S M specimen is from the Snake Hill beds, Snake Hill, Saratoga

C o u n t y . See Westrop, K n o x , and Landing ( 1 9 9 3 ) .

166

THE

Hystricurus cf. H.

oculilunatus ( R o s s ,

TRILOBITES

Family Menomoniidae

1951)

Bolaspidella fisheri ( R a s e t t i , 1 9 6 7 )

S p e c i m e n s N Y S M 1 5 2 3 0 , 15231 Tribes Hill F o r m a t i o n , M o n t g o m e r y C o u n t y . See Westrop, K n o x , and Landing ( 1 9 9 3 ) .

Holotype U S N M 156682 M i d d l e C a m b r i a n , S t o c k p o r t Station, C o l u m b i a County. See Bird a n d Rasetti ( 1 9 6 8 , p. 2 6 ) .

Family Kingstoniidae Kingstonia seeiyi ( W a l c o t t ,

Family Olenidae

1912)

Olenids are k n o w n in the Ordovician of New York from

Cotypes U S N M 5 8 5 8 2 t o 5 8 5 8 4 Upper C a m b r i a n , Potsdam S a n d s t o n e . See Resser ( 1 9 4 2 ) .

at least three, possibly five, species of Triarthrus. T h e s e are small trilobites with a semicircular cephalon. T h e glabella is rectangular, curving gently in front. T h e SI and S2 glabellar furrows

Family Komaspididae

are distinct and curve toward the rear. S3 is usually faint. T h e

Komaspidids are small o p i s t h o p a r i a n trilobites with forward-

free cheeks are "yoked," m e a n i n g they are attached together

narrowing glabella. T h e eyes are characteristic as they are quite

anteriorly to the front center of the glabella and are lost as a

long, extending m o r e than h a l f the length of the glabella. T h e r e

single unit during the m o l t i n g process. T h e fixed cheeks flare

are genal spines. T h e pygidium is semicircular and roughly the

o u t w a r d f r o m the rear end of the palpebral lobes, crossing

same size as the c r a n i d i u m . T h e r e are only two or three axial rings

the genal angle. T h e r e is an occipital n o d e . T h e t h o r a x has 12 to

and pygidial pleurae.

15 s e g m e n t s . Triarthrus beckii and the early T. eatoni have axial

Interpleural furrows do not reach the

margin. T h e family is n o r m a l l y f o u n d from the Upper C a m b r i a n

nodes on all the t h o r a c i c segments.

to

question

( u p p e r ) W h e t s t o n e G u l f Shale does not have axial nodes on the

whether the b e l o w - m e n t i o n e d trilobite is in the correct family.

m o s t a n t e r i o r segments. T h e pygidium is very small and can be

"Carrickia is probably a p r o e t a c e a n ; it is definitely not a k o m a s -

distinguished f r o m the t h o r a x by the absence of intrapleural

p i d i d " (R. Ludvigsen 1997, private c o m m u n i c a t i o n ) .

furrows. See Ludvigsen and Tuffnell ( 1 9 8 3 , 1994) for a complete

the

Lower

Ordovician

(Treatise).

There

is

some

Triarthrus eatoni from the

review. "Carrickia" setoni

(Shaw,

1986) Triarthrus beckii (Green, 1832) Plate 170

Holotype N Y S M 12246 "Carrickia" setoni was described f r o m silicified material f r o m the Middle O r d o v i c i a n , lower M i d d l e Chazy. Additional material

Hypotype N Y S M 9892 Type

species.

Triarthrus

beckii

is

widely

distributed

in

was f o u n d in the upper lower C h a z y as well. M o s t of the m a t e -

Middle O r d o v i c i a n Trenton equivalent shales such as the Flat

rial is very small silicified s p e c i m e n s . T h e glabella tapers forward

Creek,

and from the dorsal view is parabolic to semicircular. T h e r e are

County. It has also been reported in s o m e lower Trenton L i m e -

no glabellar furrows. T h e eyes are set wide apart and e x t e n d f r o m

stones. Triarthrus beckii is primarily distinguished from T. eatoni

about o n e - t h i r d b a c k on the c r a n i d i u m to nearly the posterior

by the position of the palpebral lobe. On T. beckii the lobe is short

cephalic border. T h e t h o r a x is u n k n o w n . T h e pygidium is s e m i -

and the posterior e n d is opposite the S2 glabellar furrow. On T.

circular with a well-defined axis with two axial rings. T h e r e are

eatoni the palpebral lobe is significantly longer and extends to the

two pleurae. T h e pleural furrows do not quite reach the margin.

SI glabellar furrow. T h i s distinction is usually clear. In addition,

lower

Utica,

and

Dolgeville

Shales

in

Montgomery

This trilobite is the only representative of this n o r m a l l y upper

the glabella length and width are nearly equal with T. beckii, while

Middle C a m b r i a n

the glabella of T. eatoni is longer than wide. On s o m e specimens,

to Lower O r d o v i c i a n

family.

F o r location

however, such as those f r o m the Holland Patent site (see T. spin-

i n f o r m a t i o n , see Shaw ( 1 9 6 8 ) .

osus), b o t h characteristics of T. beckii and T. eatoni can be found. Ludvigsen and Tuffnell ( 1 9 9 4 ) indicated that the ranges of T.

Family Lonchocephalidae

beckii and T. eatoni significantly overlap. Plate 170 enables o n e to

Lonchocephalus ( B r a d l e y , 1 8 6 0 )

see the short palpebral length c o m p a r e d to T. eatoni (Plates 171

Plesiotypes U S N M 5 8 5 6 7 t o 5 8 5 7 0 Upper

Cambrian,

Potsdam

Sandstone,

Keesville,

Essex

County.

and 1 7 2 ) . Triarthrus eatoni (Hall, 1 8 3 8 ) Plates 171 and 172 Hypotypes N Y S M 9 8 9 3 , 9 8 9 4

Family Marjumiidae Modocia punctata

(Rasetti,

Triarthrus 1967)

Holotype U S N M 156687 M i d d l e C a m b r i a n , S t o c k p o r t Station, C o l u m b i a C o u n t y . See Bird and Rasetti ( 1 9 6 8 , p. 2 6 ) .

eatoni

is

a

common

trilobite

of

the

Upper

O r d o v i c i a n , upper Utica Shales and overlying Lorraine G r o u p shales. Many, if not m o s t , of the s p e c i m e n s labeled as T. eatoni f r o m the M i d d l e Ordovician shales are T. beckii. A complete meraspid growth series of this trilobite is k n o w n from collections

ORDER

167

PTYCHOPARIIDA

made by Walcott and Rust in the Utica Shale overlying the

Plethopeltis saratogensis

Steuben Limestone near Holland Patent, O n e i d a County. B e -

Holotype U S N M 58558

(Walcott,

1890)

Plate

175C

cause of its presence in Beecher's Trilobite Bed with superbly

Type species. T h i s species is f r o m the Upper C a m b r i a n , Hoyt

pyritized appendages, a great deal has been written c o n c e r n i n g

L i m e s t o n e , Lester State Park, Saratoga County. See Ludvigsen and

the structure of this trilobite (see W h i t t i n g t o n and A l m o n d

Westrop ( 1 9 8 3 ) .

( 1 9 8 7 ) and the references t h e r e i n ) . T h e protaspid of this trilobite reported from these beds, however, may be that of a proetid

Family Ptychopariidae

(G.

Ptychoparia

Edgecombe

1990,

private

communication).

Triarthrus

eatoni lived in deep, poorly oxygenated waters. Plate 172 shows a Beecher specimen with the pyritized appendages. T h e specimen in Plate 171 has all the characteristics of T. eatoni except

minuta

(Bradley,

1860)

S p e c i m e n M C Z 1045 Upper C a m b r i a n , P o t s d a m S a n d s t o n e , High Bridge, Keesville, Essex C o u n t y .

it lacks the axial nodes on the eight m o s t - a n t e r i o r t h o r a c i c segments.

Ptychoparia

matheri

(Walcott,

1912)

Types U S N M 5 8 5 8 5 t o 5 8 5 8 7 Triarthrus glaber

(Billings,

Upper C a m b r i a n , Potsdam S a n d s t o n e , W h i t e h a l l , Washington

1859)

County.

Syntypes G S C 1936e, h ; specimen U S N M T h e syntypes are from the Upper O r d o v i c i a n o f Q u e b e c . U n n u m b e r e d specimens in the U S N M from L o r r a i n e , Jefferson

Family Shumardiidae T h i s is a family of very small, blind trilobites without facial

County, bear this n a m e .

sutures and oval in o u t l i n e . T h e c e p h a l o n is semicircular with Triarthrus spinosus (Billings, 1 8 5 7 ) Plates 173 a n d 1 7 4

deep lateral glabellar furrows. T h e occipital ring is p r o m i n e n t .

Holotype U S N M 9 6 2 3 5 , hypotypes N Y S M 9 8 9 7 t o 9 9 0 0

T h e pygidial shape is variable, as are the n u m b e r of axial rings

R u e d e m a n n ( 1 9 2 6 ) found this n o r m a l l y Upper O r d o v i c i a n

( f o u r to seven). T h e i r family relationship is in d o u b t .

Canadian trilobite in collections m a d e by Walcott and Rust. It was found in the Utica Shales overlying the S t u e b e n L i m e s t o n e

Shumardia pusilla

near Holland Patent, O n e i d a County. T h i s olenid is distinguished

Hypotype N Y S M 9857

by having genal spines, an occipital spine, and t h o r a c i c spines

(Sars,

1835)

Lower O r d o v i c i a n Deepkill Shales.

from the eighth, ninth, and tenth t h o r a c i c segments. T h e r e are no axial nodes on the thoracic segments. T h e s p e c i m e n in plate 173

Family Solenopleuridae

is the holotype. Plate

Rimouskia

174 shows a s p e c i m e n f r o m O t t a w a ,

typica

(Resser,

1938)

Ontario.

Plesiotype U S N M 1 5 6 6 9 4

Family Plethopeltidae

Hill and Judson Point, C o l u m b i a County. See Bird and Rasetti

Type species. T h i s species is f r o m the Lower C a m b r i a n , Ashley Plethometopus

knopfi

(Lochman,

( 1 9 6 8 , p. 2 8 ) . Rasetti ( 1 9 6 7 ) classified Rimouskia as "family u n d e -

1946)

t e r m i n e d . " T h e Treatise placed it within this family.

Holotype Y P M 1 7 3 9 4 Upper C a m b r i a n , f r o m rocks in Dutchess C o u n t y referred to

Family Uncertain

as " H o y t D o l o s t o n e . "

Clelandia Plethopeltis granulosa

(Resser,

(Cleland,

1900)

F r o m the Lower O r d o v i c i a n Tribes Hill F o r m a t i o n . Westrop,

Holotype U S N M 5 8 5 6 1 Upper C a m b r i a n , Hoyt

parabola

H o l o t y p e PRI 5 0 7 0

1942) L i m e s t o n e , Saratoga County.

Ludvigsen and Westrop ( 1 9 8 3 ) .

See

K n o x , and Landing ( 1 9 9 3 ) reviewed the trilobite. T h e species is also f o u n d in Idaho and O k l a h o m a .

Appendix A Trilobites and Their Environments

Environment

Ordovician Chazy

Lagoonal

Ordovician Black River

Ordovician Trenton

Ordovician

Lowville Bathyurus Bumastoides

Reef/shoals

Reef limestone Thaleops Glaphurus Glaphurina Paraceraurus Niloides Uromystrum Plattillaenus Hyboaspis Isotelus Bumastus

Shoal margins

Calcarenite Plattillaenus Glaphurina Bumastoides Cybeloides Lonchodomas Calyptaulax

Watertown Raymondites Bathyurus Bumastoides lllaenus Isotelus Eoharpes

Steuben//C/'ngs Falls Calyptaulax Primaspis Hemiarges Flexicalymene

Sugar River/Den/ey Isotelus Primaspis Flexicalymene Ceraurus Cryplolithus

Napanee Isotelus Flexicalymene

Pulaski Flexicalymene Cryptolithus

Distal ramp

Canajoharie Gravicalymene Isotelus Triarthrus

Whetstone/ Frankfort Homotelus Triarthrus Cryptolithus

Upper slope

Dolgeville Triarthrus

Lower slope

Utica Triarthrus

Basin

Utica Triarthrus

Proximal ramp

Silty limestone Calyptaulax Cybeloides Lonchodomas Ceratocephala

Information on trilobites and their environment from the work of Carlton Brett, Gerald Kloc, and Thomas Whiteley. 168

Lorraine

TRILOBITES

Silurian

AND

THEIR

Silurian

Clinton

Lockport

Devonian

Helderberg

Devonian

Onondaga

Gasport Calymenids

U. Irondequoit Dalmanites Scutellum Spathocalymene

Lowest Rochester L. Irondequoit Deiphon Bumastus Dicranopeltis Trochurus Liocalymene Encrinurus Eophacops Shales

Upper Rochester Shales Willowvale Dalmanites Trimerus Liocalymene

Eramosa (basal) Encrinurus Dalmanites Calymenids

Devonian

Hamilton

Tully (lower) Scuttelum Pseudodechenella Harpidella

Chrysler/Thacrier Eurypterids

Neahga/Sodus Eophacops Calymenids

Lower Rochester Trimerus Calymene Dalmanites Radnoria Arctinurus Decoroproetus Bumastus

169

ENVIRONMENTS

Coeymans/Becrarr Odontochile Scutellum Proetus

Edgecliff (western) Maurotarion Mystrocephala 'Calymene" Synphoria Trypaulites Terataspis

Tichenor Otarion

Kalkberg/Becraft Paciphacops Coniproetus Scutellum Synphoroides

Moorehouse/ Clarence Harpidella Coronura Odontocephalus Viaphacops

Centerfield/Kashong Basidechenella Monodechenella Eldredgeops Harpidella Bellacartwrightia

New Scotland Paciphacops Kettneraspis Dicranurus Oinchoe Acanthopyge Neoprobilium Dalmanites Cordania

Seneca Viaphacops

Wanakah/ Windom Eldredgeops Pseudodechenella Bellacartwrightia Greenops Dipleura Monodechenella

Esopus

Nedrow Viaphacops Odontocephalus Kettneraspis

Ledyard Eldredgeops Greenops

Levanna Eldredgeops Greenops

Williamson Liocalymene

Marcellus Eldredgeops?

Appendix B The Photography

A l l of the p h o t o g r a p h s for this b o o k were taken with a fairly standard, single-lens reflex, 3 5 - m m c a m e r a e q u i p p e d with a m a c r o

the exposure system of the c a m e r a to give proper exposure regardless of the aperture.

focusing lens. W i t h few e x c e p t i o n s , the c a m e r a was placed on a

• Film. T h e preferred film was Kodak 25-speed color negative

copy stand, and electronic flash was always used for exposure. T h e

film because of its very high resolution. W h e n it b e c a m e no

specimens, preferably, were set on a " l a b - j a c k " s u p p o r t so they

longer available, Kodak Gold 100 was used, as it is the next

could be raised or lowered for focusing independent of the

sharpest available c o l o r negative film. C o l o r negative film was

camera o n c e the proper c o m p o s i t i o n was reached. T h e flash was

preferred over black and white film (which can be sharper) and

as close to o n - a x i s as the setup p e r m i t t e d . T h e e x p o s u r e was

slide film (which has p o o r exposure latitude and is not as

d e t e r m i n e d through the lens by the electronics of the c a m e r a .

s h a r p ) . T h e c o l o r negative films are fine enough in grain so

An aperture of fl 1 was used for very flat s p e c i m e n s and f 2 2 ,

graininess is not a p r o b l e m and the sharpness of the p h o t o -

for t h r e e - d i m e n s i o n a l s p e c i m e n s . T h e preferred films were c o l o r

graphic image is well above that of the image when digitized

negative films selected for the highest sharpness available. P r o -

(i.e., it is not a limiting factor in image quality). High-quality

cessing and printing were p e r f o r m e d by c o m m e r c i a l l y available

c o l o r negative processing is available anywhere in the c o u n t r y

sources.

(world?), and the c o l o r print is very useful for cataloging.

Dark

specimens

ammonium

usually

chloride.

This

benefited procedure

from was

whitening not

available

with for

specimens in m u s e u m s .

• E x p o s u r e . Electronic flash was preferred because (1) it stops all m o t i o n and ( 2 ) most c o l o r films are balanced for daylight e x p o sure. T h e r e is a m e a s u r a b l e , and theoretically known, falloff in

With a Nikon L S - 1 0 0 0 3 5 - m m film scanner, the resulting c o l o r

sharpness as a c a m e r a lens is stopped down beyond about f 11.

negatives were s c a n n e d directly into a c o m p u t e r r u n n i n g Adobe

Apertures between fl 1 and f22 were chosen to give the neces-

P h o t o s h o p software. All of the s c a n n i n g was at a resolution of

sary depth of field. Aperture 22 was only used when the speci-

2 7 0 0 pixels/inch

m e n had a lot of t h r e e - d i m e n s i o n a l character.

( 1 0 6 p i x e l s / m m ) . T h e s c a n n e d images were

adjusted with the autolevels c o m m a n d in P h o t o s h o p ; treated with

• S c a n n i n g . T h e p h o t o g r a p h i c images were scanned into the

unsharp masking. Scratches on the negative were r e t o u c h e d in

c o m p u t e r , as digital images are m u c h easier to manipulate

P h o t o s h o p ; this was the only r e t o u c h i n g d o n e to the image.

than are optical images in the traditional d a r k r o o m . O n c e o n e

( T h e r e were rare exceptions to this " n o r e t o u c h i n g " statement.

gets

W h e n glue bubbles in a repaired s p e c i m e n were t h o u g h t to be

t i m e difference between using the c o m p u t e r and the traditional

distracting, they were r e t o u c h e d away using the " c l o n e " t o o l — t h e

d a r k r o o m is orders of m a g n i t u d e . S c a n n i n g was d o n e at 2 7 0 0

same tool used to eliminate s c r a t c h e s ) . T h e digital images were

pixels/inch in order to have the m a x i m u m a m o u n t of infor-

then stored as T I F F files.

m a t i o n to work with in the c o m p u t e r . Images can always be

T h e images in the b o o k were adjusted for c o m p o s i t i o n in

through

the

learning

curve

with

digital

images, the

sized down with little loss in quality but sizing up always intro-

P h o t o s h o p and the final images were stored as T I F F files at a

duces potential p r o b l e m s . Occasionally the prints, if good

resolution o f 3 0 0 pixels/inch ( 1 1 . 8 p i x e l s / m m ) .

e n o u g h , were s c a n n e d into the c o m p u t e r with a flat bed scanner. O n e should use the m a x i m u m optical resolution of the

Some Specifics • C a m e r a s . T h e two cameras used exclusively were O l y m p u s O M - 2 N and O M - 4 T .

scanner. • Software. Adobe P h o t o s h o p is the m o s t - u s e d image-processing p r o g r a m available. A limited edition that is now on the market

• Lenses. T h e m a c r o lenses used were the O l y m p u s 5 0 - m m f3.5

for significantly less m o n e y has all the capability most needed

and the Vivitar 9 0 - m m f2.5. ( T h e Vivitar was preferred because

for this type of work. T h e levels c o m m a n d evaluates the image

the longer focal length allowed better c o m p o s i t i o n . )

and adjusts it to o c c u p y the gray-scale space that P h o t o s h o p

• Flash. T h e flash used was an O l y m p u s T - 3 2 , which couples with 170

can

handle.

This

is

important.

The

autolevels

function

THE

PHOTOGRAPHY

171

generally does an excellent j o b , but occasionally o n e will wish

further work is going to be d o n e on t h e m . Since a 3 5 - m m T I F F

to additionally adjust the image for lightness or darkness. To do

c o l o r image can be about 25 megabytes in size, o n e should con-

this, use the levels c o m m a n d and m o v e the center slider to get

sider storing images on a C D - R O M , as CD " b u r n e r s " are readily

the preferred image. U n s h a r p m a s k i n g e n h a n c e s edges and is

available and writable C D s are inexpensive.

also i m p o r t a n t . A n y t i m e an image goes through a lens, it loses

Printing. T h e ink-jet printers on the market can give near-

sharpness. T h i s happens both in the c a m e r a and in the scan-

photographic-quality

ners. Unsharp masking will regain the edge sharpness desired

white. Various c o n s u m e r groups and c o m p u t e r magazines rate

in the image.

the printers. T h e i r advice is usually s o u n d . T h e price range is

prints

in

either

color

or

black and

Stored images. Most publishers want images that have not been

large and is driven m o r e by p r i n t i n g speed than by final print

compressed. All compression algorithms throw s o m e i n f o r m a -

quality. In o t h e r words, within o n e manufacturer's printers,

tion away as redundant.

For a o n e t i m e c o m p r e s s i o n and

there will be little if any difference in print quality between

decompression and printing, it is unlikely that anyone will

those selling for $ 1 5 0 and those selling for $ 3 0 0 but the print-

that

ing speed may be significantly different. If you do not m i n d

previously have been compressed and then modified can result

waiting 5 to 10 m i n u t e s for an 8 x 10 c o l o r print, buy the less

in

is

expensive m o d e l . No specific r e c o m m e n d a t i o n s can be given

inescapable. By far the safest m o d e is to keep images in an

because the t e c h n o l o g y is m o v i n g t o o fast and any r e c o m m e n -

uncompressed m o d e ( T I F F ) and only c o m p r e s s t h e m when n o

dations will be o b s o l e t e within a year.

notice

changes

compression

in

the

artifacts

image. that

Compressing

reduce

image

images quality.

It

Glossary

F o r the geological t e r m s we were assisted by the use of Keary ( 1 9 9 6 ) and for the trilobite t e r m s , by W h i t t i n g t o n and Kelly (1997).

a u t o c h t h o n o u s . A term describing rock units in place where they were deposited (i.e., not t r a n s p o r t e d ) , axis. T h e longitudinal center line of an organism, ball-and-pillow-type structures.

a b a t h o c h r o a l . Having schizochroal eyes with less lenses and lacking stellar p r o j e c t i o n s ,

underlying m u d .

abaxial. Away or farther from the axial line, a c c r e t i o n a r y wedge. A

complex

basis (plural, b a s e s ) . T h e most proximal part of the trilobite,

of sediments

with

multiple

thrust faults resulting from the s c r a p e - o f f of s e d i m e n t , o n t o the

overridding

plate,

from

the

oceanside

plate

during

subduction. acritarchs.

R o u n d e d sandstone structures

resulting from the soft sediment settling of sandstone into

appendage structure. The basis attaches to the trilobite, and the o t h e r two parts of the appendage b r a n c h o f f from it. benthic (benthonic).

Living on the seafloor.

b e n t o n i t e s . Clay layers consisting of altered volcanic ash useful

A g r o u p of microfossils consisting of hollow, organic-

walled, unicellular vesicles, mostly 20 to

1 5 0 | i m in size.

in tracing stratigraphic h o r i z o n s , biofacies.

R o c k s with distinctive and characteristic fossils,

Known f r o m the P r e c a m b r i a n to the recent, they are used in

b i o h e r m s . An organic m o u n d or reef.

stratigraphic correlation.

b i o m e r e s . A t e r m used to describe periods of time in the C a m -

adaxial. Toward or closer to the axial line.

brian when there was an extinction event with nearshore trilo-

a e r o b i c . Able to live only where free oxygen is available.

bites and the area was repopulated from deeper-water species

a l l o c h t h o n o u s . A t e r m describing rock units that have been transported f r o m the site of their original deposition.

with differing functions.

a m a l g a m a t e d . Closely j o i n e d , inseparable rock units. a n a e r o b i c . Able to live or can o n l y live where free oxygen is absent.

b o r d e r . F o r the trilobite, a distinctive area around the margin of the cephalon or pygidium.

a n o x i c . A term describing an e n v i r o n m e n t where the c o n c e n t r a tion of oxygen is t o o low to support o x y g e n - b r e a t h i n g life. antennae

that evolved to o c c u p y the now-vacant ecological niches. b i r a m o u s . Having appendages that b r a n c h into two branches

(singular, a n t e n n a ) . Modified

jointed

and

extend

from

the

front,

appendages that are ventral

part

of the

cephalon.

b o u n d s t o n e s . Limestones

the

grains

were

bound

b r e c c i a s . R o c k units with included angular pieces, or clasts, of o t h e r b r o k e n - u p units. o t h e r units.

a n t e r i o r cephalic b o r d e r . T h e b o r d e r o n the forward part o f the cephalon generally b o u n d e d by the a n t e r i o r cephalic sutures. a p o d e m e s . Paired

projections

on

the

inner

surface

o f the

exoskeleton along the axial groove. T h e r e is o n e pair for each

cephalic b o r d e r . chamositic.

C o n t a i n i n g the iron mineral c h a m o s i t e .

c h e l i c e r a t e . A subphylum of a r t h r o p o d s without antennae and with

appendage. A p o d e m e s are the a t t a c h m e n t points

(pinchers).

for the

appendages to the exoskeleton.

chert.

a p o m o r p h y . A derived characteristic.

appendages.

animal

first

pair of appendages

modified as chelicerae

Microcrystalline quartz f o u n d within limestones, taxonomic

methodology

studying

relationships

using shared characteristics,

arenites. Sandstones with grain sizes f r o m 0.1 to 2 m m . a r t h r o p o d . An

the

cladistics. A

See apodeme.

T h e b o r d e r a r o u n d the margin o f the cephalon.

c e p h a l o n (plural, c e p h a l a ) . T h e head o f the trilobite.

t h o r a c i c segment and a pair for each cephalic and pygidial

172

which

b r e c c i a t e d . C o n t a i n i n g breccia or distinctive inclusions from

anterior. Toward the front or in front of.

appendifer.

in

together by o r g a n i s m s .

with

an

exoskeleton

and

class. In biology, a grouping just after the phylum of plants or jointed

animals having a similar basic structure. Trilobites are in the phylum A r t h r o p o d a and class Trilobita.

173

GLOSSARY clasts.

epifaunal. A t e r m describing o r g a n i s m s that live on the sea

Pieces of b r o k e n - u p rock units.

cleavage.

b o t t o m , either m o v i n g freely or attached,

Preferred direction of splitting of rocks.

epipelagic.

c o m m i n u t e d . Broken down into fine particles.

Living at or very close to the surface of the sea.

animal

etymology. T h e origin and d e v e l o p m e n t of a word or n a m e ,

with chordate characteristics; widely used in stratigraphic

exfoliated. Loss of the actual fossil, leaving an internal mold,

correlation.

exite. T h e outer or brachial b r a n c h of a trilobite's appendage,

c o n o d o n t s . Phosphatic

teeth

of

an

extinct

marine

conterminant. A condition where the h y p o s t o m e is under the anterior glabella and attached to the a n t e r i o r d o u b l u r e by a suture. tire fossil c o m m u n i t y . tal material.

T h e line for o p e n i n g or separation of the free cheek

families. G r o u p i n g of o r g a n i s m s with very similar characteristics. In t a x o n o m y , family is the g r o u p i n g after order and before

cotype. W h e n two or m o r e s p e c i m e n s are used to define a species

genus. firmgrounds. Sea b o t t o m s that have consolidated enough to

(term is no longer used), coxa. T h e part of an a r t h r o p o d appendage attached to the body, cranidium (plural, cranidia).

T h e central p o r t i o n o f the trilobite

cephalon, b o u n d e d by the facial sutures; basically the fixed

support s o m e f o r m s o f direct a t t a c h m e n t s , fixigenae (singular, f i x i g e n a ) . T h e f i x e d cheeks; p o r t i o n s o f the cheek area not lost by the o p e n i n g of the facial suture, flooding surfaces.

cheeks and the glabella, cross-stratification. Inclined bedding structure resulting f r o m

S e d i m e n t - s t a r v e d areas at the interface of two

very different rock units due to a rapid rise in sea level or a transgression event,

water- or wind-deposited grains. A trace fossil attributed to trilobite tracks or trails,

fluidize. To convert a particulate substrate with stable, semisolid characteristics into a fluid that can flow,

cuticle. T h e exoskeleton of the trilobite. degree. A term used to describe the n u m b e r of t h o r a c i c segments

flute. A groovelike physical m a r k i n g on the base of a rock unit resulting f r o m erosion in the underlying unit,

in trilobite meraspid. dendroid. A highly b r a n c h e d inclusion often seen on bedding planes.

foreland basin. A basin or deepening of a sea between a stable c r a t o n and m o u n t a i n building due to plate tectonics,

desiccation cracks. Cracks

in

fine-grained

sediments

result-

ing from aerial drying out; usually seen as p o l y g o n - s h a p e d structures. d i a c h r o n o u s . A stratigraphic term describing a unit that varies in age over its geographic range, diagenesis. Process by which physical, biological, and chemical changes alter a sediment or fossil from the t i m e of deposition to the present. Diplichnites.

A fossil trace believed to be tracks f r o m the a p -

pendages o f a r t h r o p o d s , distal. Away from a reference point. dorsal. Toward the upper surface of an animal while in its life position. doublure. A c o n t i n u a t i o n , by folding under, of the dorsal e x o skeleton on the ventral side. down warp. T h e side of a fault displaced downward. dysaerobic. Able to live in low-oxygen c o n d i t i o n s . dysoxic. A term used to describe a low-oxygen e n v i r o n m e n t that poorly supports oxygen-breathing o r g a n i s m s . ecdysis. T h e process of shedding the exoskeleton in order to grow larger. Consisting primarily o f c r i n o i d material.

endites. Inwardly directed projections on a s e g m e n t , p o d o m e r e , of a trilobite's walking leg. endopod.

facial suture.

from the c r a n i d i u m .

coquina. Limestones with a high density of a c c u m u l a t e d skele-

encrinal.

appendage. exoskeleton. T h e external support structure for arthropods.

coordinated stasis. L o n g - t e r m evolutionary stability for an e n -

Cruziana.

e x o p o d . T h e upper or brachial, breathing, b r a n c h of a trilobite's

The lower or walking b r a n c h of a trilobite's appendage.

genae (singular, g e n a ) . T h e cheeks of a trilobite; the areas lateral f r o m the central area of the glabella, genal angle. T h e angle f o r m e d where the anterior margin of the cephalon turns toward the axis, genal

spine. A

spine

directed

posteriorly

from

the

genal

angle. genus (plural, g e n e r a ) . T h e t a x o n o m i c grouping after family that denotes an increasingly similar evolutionary relationship. It is the g r o u p i n g just b e f o r e the actual species. glabella. T h e central, axial, part of a trilobite's c e p h a l o n . glabellar furrow. A furrow along the sides of the glabella paralleling the axis of the trilobite. gnathobases. T h e most proximal p r o j e c t i o n s o n the p o d o m e r e s of a trilobite's appendages. g o n a t o p a r i a n . T h e c o n d i t i o n where the posterior end o f the facial suture emerges on the genal angle. gradient

currents. Underwater

currents

flowing

downslope,

often carrying sediment into deeper water. grainstones. G r a n u l a r limestones with no included muds. graptolites.

Extinct a n i m a l s with a characteristic, often sawtooth,

shape, used in stratigraphic correlation. graywacke. A sandstone with greater than 1 5 % clay minerals. groove-casts. Grooves on an underlying layer caused by the m o v e m e n t of a stone along the b o t t o m . T h e s e grooves are expressed as casts on the underside of the overlying rock.

174

GLOSSARY

h e m i p e l a g i c . A term describing a deposit of fine-grained sedim e n t that has flowed d o w n s l o p e within a gradient current and c o m e to rest, settling out. no

L I , . . . Sequential

designation

for

the

lateral

glabellar

furrows, starting with the occipital furrow, LO. lowstand. T h e lowest sea level following a regression,

h o l a s p i d . T h e final growth phase of a trilobite; in most cases, signifies that

LO,

m o r e t h o r a c i c s e g m e n t s are added during

molting.

lutites. Very-fine-grained limestones. MaBP.

Million of years before present.

m a g m a s . M o l t e n rocks forced to the surface from underground

h o l o c h r o a l . Having c o m p o u n d eyes with a s m o o t h external surface.

chambers. m a r g i n a l lappets. Lappets radially projecting from the pygidial

h o l o t y p e . T h e single specimen used to define a species, hypersalinity. Salt c o n t e n t above what o n e measures in the ocean.

margin. m a r g i n a l spines. Spines radially projecting from the pygidial margin.

h y p o s t o m e (plural, h y p o s t o m a ) . A mineralized tergite on the ventral cephalon under the glabella.

meraspid. A cephalon

h y p o t y p e . A specimen described in the literature.

no

Iapetus. An ocean lying between p r o t o N o r t h A m e r i c a and the

molting.

growth and

further

the

phase

of

trilobites

protopygidium

thoracic

from

when

are separated

segments

are

the

to when

added

during

African c r a t o n . T h e closing of this o c e a n resulted in m a j o r

m e r a s p i s . An individual specimen in the meraspid phase,

m o u n t a i n building, the C a l a d o n i a n Orogeny.

m e t a m o r p h i c . A t e r m to describe rocks altered by heat and

impendent.

Having a c o n d i t i o n where the a n t e r i o r edge of the

h y p o s t o m e is posterior to the a n t e r i o r edge of the glabella. infaunal. A term describing o r g a n i s m s that live just under the surface of the sea b o t t o m . instar.

Recognizable phase d u r i n g the protaspid phase of trilo-

cally organic structure; used here to indicate the mineral structure of a trilobite's exoskeleton.

M a p s showing lines o f equal thickness o f rock

units.

m o r p h o l o g i c a l . Having

to

do

with

physical

shape

or

morphology.

isostatic. A term describing b u o y a n c y forces. karstic.

C o n t a i n i n g very-fine-grained limestones that form the

m a t r i x to fossil deposits; see also lutites. m i n e r a l i z e d . W h e n inorganic materials b e c o m e part of a basi-

bite growth. Isopach m a p s .

pressure. micritic.

m u d s t o n e s . R o c k s c o m p o s e d of consolidated muds with few

Having surface characteristics due to subsurface solution

of rocks. M a j o r c a v e - f o r m i n g areas often have karstic surfaces. K o n s e r v a t - L a g e r s t a t t e n . Fossil

deposits

with

very

unusually

good preservation o f the o r g a n i s m s , lag. Deposit in which the finer particles have been w i n n o w e d or washed away. lamella (pleural, l a m e l l a e ) . T h e horizontally separable part o f the c e p h a l o n , of trinucleids and harpids. A suture runs a r o u n d the outer edge of the c e p h a l o n , separating it into an upper and lower lamella. lappets. S h o r t , r o u n d e d p r o j e c t i o n s from the ends of the pleura. lateral glabellar f u r r o w s . S y m m e t r i c a l furrows in the glabella

larger particles. n a t e n t . A c o n d i t i o n where the h y p o s t o m e is below the anterior glabella but u n a t t a c h e d to the d o u b l u r e . n e o t y p e . T h e single specimen used to define a known species when the original type is lost or poorly defined. n o d e s . Small circular or oval raised areas on the exoskeleton. o b d u c t e d . A term used to describe rocks that have been forced over and above when two plates collide. occipital ring. Raised area at the posterior of the glabella running transverse across the axis and b o u n d e d by the glabellar furrows. ontogenetic.

Distintive phases of an animal's growth,

that are roughly perpendicular to the axis and end or start,

o n t o g e n y . T h e processes o f the growth o f a n organism,

from the glabellar furrow.

ooids.

lateral glabellar l o b e s . Bilateral lobes on the glabella separated by the lateral glabellar furrows. Laurentia. A continental land mass c o m p o s e d of the C a n a d i a n shield, G r e e n l a n d , parts o f western Europe, and o t h e r parts o f what b e c o m e s North A m e r i c a . l e c t o t y p e . T h e single s p e c i m e n selected to define the species

oolitic.

Small particles c o m p o s e d of concentric layers, C o n t a i n i n g oolites.

o p i s t h o p a r i a n . T h e condition where the posterior end o f the facial suture emerges on the posterior cephalic margin (i.e., toward the axis from the genal angle). order. T h e t a x o n o m i c grouping after class. orogenesis.

T h e building o f m o u n t a i n s .

when, in the original definition, a g r o u p of s p e c i m e n s , syn-

orogenic.

types or cotypes, were used.

ossicles. T h e n a m e given to individual e c h i n o d e r m plates.

librigenae (singular, l i b r i g e n a ) . Free cheeks. load casts. Depressions in an underlying s e d i m e n t f r o m overloading by the overlying layers; expressed as r o u n d e d p r o t r u sions on the base of the overlying layer.

Resulting from m o u n t a i n building.

packstones. Granular

limestones

with

mud

between

the

granules. palpebral area. Portion of the fixed cheek that is immediately adaxial to the eye.

175

GLOSSARY paralectotypes. W h e n

a

lectotype

is

chosen

from

a

type

group, syntypes or cotypes, the r e m a i n i n g s p e c i m e n s are paralectotypes. paratypes. S p e c i m e n s

radiolarian. M a r i n e , single-cell a n i m a l with an ornate silica shell.

from

the s a m e locations and h o r i z o n

as the holotype that have been used in the original species definition.

regression. T h e lowering of sea level. ridges. Elongated raised areas or s o m e t i m e s elongated, abrupt raised areas as in terrace ridges.

parsimonious. Used in cladistics to describe the closest relationship or fit in a grouping. phaselus. A m i n u t e oval structure believed to be a pre-protaspid phase in a trilobite's life cycle. animals; indicates a basic shared characteristic. planktic. Floating free in the surface of the sea. See planktic.

b o u n d e d by sutures; not present on all trilobites. Rusophycus.

A trace fossil attributed to trilobites; considered a

trilobite resting pit; often seen on the base of sandstones as a wedge-shaped raised area.

plastotype. A cast or m o l d of the original type s p e c i m e n . Having shared primitive characteristics, m e a n -

ing they are primitive to the group

d e n c e o f water rippling. Rodinia. A proposed P r e c a m b r i a n s u p e r c o n t i n e n t . rostral plate. A part of the ventral, a n t e r i o r b o r d e r of a trilobite

phylum (plural, phyla). T h e first t a x o n o m i c division of plants or

plesiomorphic.

rifting. T h e separation or pulling apart of continental plates. ripple m a r k s . M a r k s on a bedding plane due to preserved evi-

pelagic. Living in the o p e n ocean or deep sea.

planktonic.

pyritized. Replaced by pyrite in diagenesis.

(e.g., b i r a m o u s a p -

schizochroal. Having

eyes

sclerites.

ancestor to arthropods not exclusive to trilobites).

scoured. A sea b o t t o m

today).

the

lenses

are

distinctly

sclera. T h e area between the lenses of the schizochroal eye.

pendages are p l e s i o m o r p h i c as they represent a c o m m o n plesiotype. A specimen very similar to the type ( t e r m is not used

where

separate. Individual skeletal parts of c o m p l e x fossils. m a r k e d by c u r r e n t - m o v e d particles;

expressed as grooves or channels, setae (singular, s e t a ) . Small hairlike p r o j e c t i o n s f r o m various

pleura (plural, pleural). Lateral p o r t i o n of each t h o r a c i c segments, or the raised area separated by a groove on the pleural area of the pygidium. pleural spines. Spines projecting from the t h o r a c i c pleura. podomeres. T h e sections of the trilobite walking leg. posterior. Toward the rear or rearward. preglabellar field. An area immediately in front of the glabella separated from the cephalic margin by a groove, progradation. T h e buildup and extension o f deltaic sediments

parts of a trilobite. silicified. A term describing exoskeletal material or appendages that has been replaced with silica, soft sediment d e f o r m a t i o n .

Uneven, wavy surfaces at rock-layer

interfaces due to the settling of the upper layer into the still soft layer b e n e a t h it. SO, S I , . . .

Designations used t o identify the lateral grooves o r

sulcus in the trilobite glabella, speciation.

T h e process o f evolution o f o n e species into another,

within a basin as the result of sediment washed f r o m the land.

species. T h e smallest t a x o n o m i c division of life,

T h e weight of the sediments can cause the basin axis to m o v e

spines. Elongated, often p o i n t e d , exoskeletal p r o j e c t i o n s . Spines

away from the sediment source, proparian. T h e condition where the posterior end of the facial suture emerges in front of the genal angle, prosopon.

Exoskeletal o r n a m e n t a t i o n ,

protaspid. First unequivocal stage of a trilobite's life cycle, protaspis. An individual trilobite at the protaspid stage. Proterozoic. T h e late P r e c a m b r i a n . protocephalon. T h e anterior part of the meraspid that represents the future cephalon. Protopangea.

ject dorsally. s t o r m wave base.

M a x i m u m depth of the alteration of the sea

b o t t o m by s t o r m waves, stromatolites. M o u n d - s h a p e d ,

laminar

structures

formed

by

algae and c y a n o b a c t e r i a . stromatoporoids. Extinct

reef-forming

sponges

with

layered

calcite skeletons, subaerial. Exposed to the air.

Precambrian supercontinent ( R o d i n i a ) .

protopygidium. T h e p o s t e r i o r - m o s t part o f the trilobite during the meraspid stage,

subduction zone. T h e area d u r i n g plate collision where an o c e a n i c plate is forced under the continental plate. subsiding. T h e deepening of a basin b o t t o m due to tectonics or

proximal. Near, close to. punctuated equilibria.

can c o m e o f f radially to parts of the exoskeleton or may pro-

Periods of l o n g - t e r m evolutionary stabil-

ity followed by abrupt evolutionary changes. pustule. Small rounded, raised area on the exoskeleton. W h e n pustules are n u m e r o u s , the specimen is often referred to as pustulose. pygidium (plural, pygidia). T h e posterior or tail of a trilobite.

the weight of the overlying sediments. sulcus. A furrow or groove. supratidal. A t e r m describing an area at the water's edge that is above n o r m a l high tides but s u b m e r g e d during exceptional tides. suture. A line in the c e p h a l o n where the parts separate during the m o l t i n g process.

GLOSSARY

176 synapomorphies.

trace

Shared derived characteristics,

s y n j a c e n t . A t e r m used to describe overlying and underlying

s y s t e m a t i c s . T h e orderly classification o f organisms,

in

sedimentary

layers

tectophases. Phases during m o u n t a i n f o r m a t i o n and erosion

Treatise

on

Invertebrate

Paleontology:

or

walking

branch

of

a

trilobites

Part

O,

Anthro-

poda I (first edition) by M o o r e ( 1 9 5 9 ) . trough and h u m m o c k y cross-stratification.

from plate tectonics,

Cross-stratification

where the b o u n d i n g surfaces of the stratification are both s p o o n shaped (lower) and raised in the center ( u p p e r ) .

appendage. t e m p e s t i t e s . S e d i m e n t a r y f o r m a t i o n s resulting f r o m deposition

trough cross-bedding.

Cross-stratification where the lower sur-

face of the stratification is curved upward on the ends.

of sediments t r a n s p o r t e d as the result of storms. tergite. A part of the dorsal exoskeleton that separates along sutures or articulations.

t s u n a m i s . Tidal waves. t u b e r c l e s . Small p r o j e c t i o n s on the exoskeleton; often used to

t e r m i n a l axial s p i n e . A spine on the pygidium that projects posteriorly from the axial region.

imply a structure larger than a pustule yet not a spine, t u r b i d i t e s . S e d i m e n t layers from water-born sediments flowing

t e r r a c e lines. Elongated structures on the exoskeleton that are f o r m e d by m i c r o s t e p s .

d o w n s l o p e and c o m i n g to rest, turbidity currents.

t e r r a n e s . G e o g r a p h i c areas inserted within larger areas during

Turbulent currents o f sediment-laded water

flowing downslope. u n c o n f o r m i t y . A t i m e gap in the stratigraphic c o l u m n during

plate m o v e m e n t and c o n s o l i d a t i o n . C o n t a i n i n g sediments derived f r o m the erosion and

which no sediment was deposited or other rocks were eroded, ventral. T h e lower or under surface,

w a s h - o f f f r o m land. segments. The

meraspid phase. Treatise.

from its death to its discovery,

inner

transgressive lag. C o n c e n t r a t e d deposit formed during times of t r a n s i t o r y p y g i d i u m . T h e most posterior unit o f the trilobite

t a p h o n o m y . T h e study of processes involved with an o r g a n i s m

thoracic

structures

low sediment deposition and erosion during transgression.

t e r m , no longer applied),

terrigenous.

or

t r a n s g r e s s i o n . Sea level rising.

rock units. s y n t y p e s . O r g a n i s m s used to define the species (a t a x o n o m i c

telepodite. T h e

fossils. M a r k i n g s

believed to be due to the activity of living creatures,

articulated

parts

of

a

trilobite's

thorax. t h o r a c o p y g i d i u m . Trilobite fossil recovered w i t h o u t the c e p h alon, probably as a result of m o l t i n g . t h o r a x . T h e central b o d y o f the trilobite between the c e p h a l o n and the pygidium. t o p o t y p e . A s p e c i m e n f r o m the type l o c a t i o n .

vugs. Hollows within rocks. w i n n o w e d . A t e r m describing deposits of coarse particulate material f r o m which the fine sediments have been removed. w i n n o w i n g . T h e process o f currents removing f i n e particles f r o m a r o u n d coarser ones. X Y Z . A series of rocks exhibiting l o w - t o - h i g h - t o - l o w - e n e r g y deposition.

References

Adrain, [. M., and 15. 1). E. C h a t t e r t o n . 1 9 9 5 . T h e o t a r i o n i n e trilobites

Harpidella

and

Maurotarion,

with

species

from

north-

western C a n a d a , the United States and Australia. Journal of Paleontology 6 9 : 3 0 7 - 3 2 6 .

T.

1876.

Description

of a

new trilobite, Dalman-

ites dentata. A m e r i c a n Journal of Arts and Science, 3rd ser. 11: 200. .

Allison, P. A. 1986. soft-bodied fossils: the role of decay in frag-

1878.

The

coralline,

or

Niagara

Limestone

of

the

Appalachian system as represented at Nearpass's Cliff, M o n taque, New Jersey. A m e r i c a n J o u r n a l of Arts and Science, 3rd

mentation during transport. Geology 14: 9 7 9 - 9 8 1 . .

Barrett, S.

1988a. Konservat-Lagerstatten: cause and classification.

ser. 15: 3 7 0 - 3 7 2 . B a r t o n , D. C. 1 9 1 3 . A new genus of the C h e i r u r i d a e , with descrip-

Paleobiology 14: 3 3 1 - 3 4 4 . . 1988b. Phosphatized s o f t - b o d i e d squids from the Jurassic

tions o f new species. Bulletin o f the M u s e u m o f C o m p a r a t i v e Zoology (Harvard) 54: 5 4 7 - 5 5 6 .

O x f o r d Clay. Lethaia 2 1 : 4 0 3 - 4 1 0 . . 1990. Decay processes. In D. E. G. Briggs and P. R. C r o w t h e r

Basse, M. 1997. Trilobiten aus M i t t l e r e m D e v o n des R h e n o h e r -

(eds.), Paleobiology: a synthesis, pp. 2 1 3 - 2 1 6 . O x f o r d : Black-

cynikums:

well Scientific.

Palaeontographica A 2 4 6 : 5 3 - 1 4 2 .

II.

Proetida

( 2 ) , Ptychopariida,

Phacopida

(1).

Allison, P. A., and C. E. Brett. 1 9 9 5 . In situ b e n t h o and paleo-

Beecher, C. E. 1 8 9 3 a . Larval f o r m s of trilobites from the Lower

oxygenation in the Middle C a m b r i a n Burgess Shale, British

Helderberg G r o u p . A m e r i c a n Journal o f S c i e n c e , 3rd ser. 4 6 :

Columbia, Canada. Geology 23: 1 0 7 9 - 1 0 8 2 .

142-147.

A l l i s o n , P. A., and I). E. G. Briggs. 1991a. T h e t a p h o n o m y of softbodied animals. In S. K. D o n o v a n , T h e Processes of fossilization, pp. 1 2 0 - 1 4 0 . L o n d o n : Belhaven Press. record. New York: P l e n u m . preservation through the Phanerozoic. G e o l o g y 2 1 : 5 2 7 - 5 3 0 . Angelin, N. P. 1 8 5 1 . Palaeontologia Scandinavica: Pars I, C r u s 1 8 3 8 . Crotocephala ceralepta. A m e r i c a n Journal of

Science 3 4 : 3 7 9 . phacopid trilobites from the Devonian of New York. In B. M a m e t and M. J. C o p e l a n d (eds.), T h i r d North A m e r i c a n Paleontological C o n v e n t i o n , Proceedings, vol. 1, pp. 1 7 - 2 2 . Toronto: Business and E c o n o m i c Services.

pygidium

of Triarthrus.

. 1 8 9 4 b . On the m o d e of o c c u r r e n c e , and the structure and d e v e l o p m e n t of Triarthrus beckii. A m e r i c a n Geologist .

13: 3 8 -

1895a. Structure and appendages of Trinucleus. American

Journal

o f Paleontology

. 1 8 9 5 b . T h e larval stages of trilobites. A m e r i c a n Geologist 16: 1 6 6 - 1 9 7 . . 1896. T h e m o r p h o l o g y of Triarthrus. A m e r i c a n Journal of S c i e n c e , 4 t h ser. 1: 2 5 1 - 2 5 6 . Bergstrom, J.

1993. Trilobite m a l f o r m a t i o n s and the fossil record of 67:

217-

229. Babcock, L. E., and S. E. Speyer. 1987. Enrolled trilobites from the Alden pyrite bed, Ledyard Shale ( M i d d l e D e v o n i a n ) of New York. Journal o f Paleontology 6 1 : 5 3 9 - 5 4 8 . Barrande, J. 1852. System Silurien du centre de la B o h e m e , 1: 226-230, 629.

T h e appendages of the

Journal o f S c i e n c e , 3rd ser. 4 9 : 3 0 7 - 3 1 1 .

Babcock, L. E. 1982. Original and diagenetic c o l o r patterns in two

asymmetry.

1894a.

A m e r i c a n Journal o f S c i e n c e , 3rd ser. 4 7 : 2 9 8 - 3 0 0 .

43.

tacea Formationis Transitionis. H o l m i a e , 24 p.

behavioral

o f Science, 3rd ser. 4 6 : 4 6 7 - 4 7 0 . .

. 1993. Exceptional fossil record: distribution of soft-tissue

.

1 8 9 3 b . A larval f o r m of Triarthrus. A m e r i c a n Journal of

. 1893c. On the t h o r a c i c legs of Triarthrus. A m e r i c a n Journal

. 1991b. T a p h o n o m y : Releasing the Data Locked in the fossil

Anthony, J. G.

.

Science, 3rd ser. 4 6 : 3 6 1 - 3 6 2 .

1 9 6 9 . R e m a r k s o n the appendages o f trilobites.

Lethaia 2 : 3 9 5 - 4 1 4 . .

1972. Appendage m o r p h o l o g y of the trilobite Cryptolithus

and its implications. Lethaia 5: 8 5 - 9 4 . . 1 9 7 3 . O r g a n i z a t i o n , life, and sytematics of trilobites. Fossils and Strata 2: 69 p. . 1 9 9 0 . H u n s r u c k slate. In D. E. G. Briggs and P. R. Crowther (eds.),

Paleobiology:

a

synthesis,

pp.

277-279.

Oxford:

Blackwell Scientific. 177

REFERENCES

178 B e r g s t r o m , J., a n d G. Brassel. 1 9 8 4 . Legs in the trilobite Rhenops f r o m the Lower Devonian H u n s r u c k Slate. Lethaia 17: 6 7 - 7 2 . Berner, R. A.

1981a. Authigenic mineral f o r m a t i o n resulting

f r o m organic m a t t e r d e c o m p o s i t i o n in m o d e r n sediments.

.

1 9 9 2 . C o o r d i n a t e d stasis and evolutionary ecology of

S i l u r i a n - D e v o n i a n m a r i n e biotas in the Appalachian Basin. Geological Society of A m e r i c a , Abstracts with Programs, 24: 139. . 1 9 9 3 . T a p h o n o m i c approaches to temporal resolution in

Fortschritte der M i n e r o l o g i e 5 9 : 1 1 7 - 1 3 5 . . 1 9 8 1 b . A new g e o c h e m i c a l classification of s e d i m e n t a r y

stratigraphy: examples f r o m Paleozoic m a r i n e mudrocks. In

e n v i r o n m e n t s . Journal o f S e d i m e n t a t i o n Petrology 5 1 : 3 5 9 -

S. M. Kidwell and A. K. B e h r e n s m e y e r (eds.), T a p h o n o m i c

365.

approaches

Bigsby. 1825. Description of a new species of trilobite. Journal o f the Academy o f Natural S c i e n c e , Philadelphia 4 :

365-

Billings, E. 1857. New species of fossils f r o m the Silurian rocks of Canada. Geological Survey of C a n a d a , report for 1856. . 1859. D e s c r i p t i o n s of s o m e new species of trilobites from the Lower and M i d d l e Silurian rocks of C a n a d a . C a n a d i a n

resolution

in

fossil

assemblages,

pp.

Paleontological Society. 1 9 9 5 . C o o r d i n a t e d stasis and evolutionary ecology of

Silurian to Middle Devonian faunas in the Appalachian basin. In D. H. Erwin and R. L. Anstey (eds.), New approaches to speciation in the fossil record, pp. 2 8 5 - 3 1 5 . New York: C o l u m b i a University Press. . 2 0 0 2 . Revised stratigraphy and facies relationships of the

Naturalist and Geologist 4 : 3 6 7 - 3 8 3 . .

time

2 5 0 - 2 7 4 . S h o r t courses in paleontology 6, Knoxville, Tenn.: .

368.

to

1 8 6 0 . D e s c r i p t i o n of s o m e new species of fossils from

upper part of the type area, central New York State: sedimen-

the Lower and M i d d l e Silurian rocks of C a n a d a . C a n a d i a n

tology and tectonics of a Middle Ordovician ( C a r a d o c i a n )

Naturalist 5 : 4 9 - 6 9 .

shelf-to-basin succession. Physics and C h e m i s t r y of the Earth,

. 1 8 6 3 . G e o l o g y of C a n a d a . Geological Survey of Canada . 1 8 6 5 . Paleozoic fossils: vol. 1. C o n t a i n i n g descriptions and f i g u r e s o f new o r little k n o w n species o f organic remains from the Silurian rocks. Geological Survey o f C a n a d a ( M o n t r e a l ) ,

stasis: an overview. Paleogeography, Paleoclimatology, Paleoecology 127: 1 - 2 0 . Brett, C. E., and A. Seilacher. 1 9 9 1 . Fossil Lagerstatten: a t a p h o a n o m i c c o n s e q u e n c e of event sedimentation. In G. Einsele, W.

pp. 3 9 5 - 4 2 6 . Bird, J. M . , and F. Rasetti. 1 9 6 8 . Lower, M i d d l e and U p p e r C a m brian faunas in the Taconic S e q u e n c e of eastern New York: stratigraphic

in press. Brett, C. E., L. C. Ivany, and K. M. Schopf. 1996. Coordinated

( M o n t r e a l ) , 9 8 3 p.

and

biostratigraphic

significance.

Geological

Society of A m e r i c a , special paper, 113. Boulder. B o l t o n , T. E. 1 9 6 6 . Catalogue of type invertebrate fossils of the

R i c k e n , A. and Seilacher (eds.), Cycles and events in stratigraphy, pp. 2 8 3 - 2 9 7 . Berlin: Springer-Verlag. Brett, C. E., D. H. Tepper, W. M. G o o d m a n , S. T. L o D u c a , and B. H. Eckert.

1 9 9 5 . Revised Stratigraphy and Correlations

of the Niagaran

Provincial

Series

( M e d i n c e , C l i n t o n , and

Geological Survey of C a n a d a , vol. 3: 2 0 3 p. Ottawa: Geological

L o c k p o r t G r o u p s ) in the Type Area of Western New York. U.S.

Survey o f C a n a d a .

Geological Survey Bulletin 2 0 8 6 , 66 p.

1 8 6 0 . D e s c r i p t i o n of a new trilobite f r o m the

Brett, C. E., T. E. Whiteley, P. A. Allison, and E. Yochelson. 1997.

Potsdam S a n d s t o n e . A m e r i c a n J o u r n a l o f Science and Arts,

T h e W a l c o t t - R u s t Q u a r r y : a Middle Ordovician Konservat-

Bradley, F. H.

2nd ser. 3 0 : 2 4 1 - 2 4 3 . Brandt, D. S. 1 9 8 5 . I c h n o l o g i c , t a p h o n o m i c , and s e d i m e n t o l o g i c clues to the deposition of C i n c i n n a t i a n shales ( U p p e r O r d o v i -

Lagerstatte. 2 n d International Trilobite C o n f e r e n c e , St. C a t h e rines, O n t a r i o , Abstracts, p. 11. .

1999. T h e W a l c o t t - R u s t Q u a r r y : a Middle Ordovician

cian) O h i o , U S A . In H. A. C u r r a n ( e d . ) , B i o g e n i c Structures:

Konservat-Lagerstatten.

T h e r e Use in Interpreting D e p o s i t i o n a l E n v i r o n m e n t . Society

305.

of E c o n o m i c Paleontologists and Mineralogists special publication 3 5 : 2 9 9 - 3 0 7 . .

1996. Epizoans on Flexicalymene (Trilobita) and i m p l i c a -

tions for trilobite paleoecology. Journal of Paleontology 7 0 : 442-449. Brett, C. E. 1 9 7 8 . Host-specific p i t - f o r m i n g epizoans on Silurian crinoids. Lethaia 11: 2 1 7 - 2 3 2 . .

1985. Tremichnus: a new i c h n o g e n u s of circular-parabolic

pits i n fossil e c h i u o d e r m s . Journal o f Paleontology 5 9 : 6 2 5 635. Brett, C. E., and G. C. Baird. 1 9 8 6 . C o m p a r a t i v e t a p h o n o m y : a key to p a l e o e n v i r o n m e n t a l interpretation based on the fossil preservation. Palaios 1: 2 0 7 - 2 2 7 .

Journal

o f Paleontology

73:

288-

Brett, K. D., and S. R. Westrop. 1996. Trilobites of the Lower Ordovician Valley

(Ibexian)

region,

Fort

New York

Cassin State

Formation,

and V e r m o n t .

Champlain Journal

of

Paleontology 7 0 : 4 0 8 - 4 2 7 . Briggs, D. E. G., S. H. Bottrell, and R. Raiswell. 1 9 9 1 . Pyritization of s o f t - b o d i e d fossils: Beecher's Trilobite B e d , Upper O r d o v i cian, New York State. G e o l o g y 19: 1 2 2 1 - 1 2 2 4 . Briggs, D. E. G., and P. R. Crowther. 1 9 9 0 . Paleobiology: a synthesis. O x f o r d : Blackwell Scientific. 5 8 3 p. Briggs, D. E. G., and G. D. E d g e c o m b e . 1 9 9 3 . Beecher's Trilobite Bed. Geology Today ( M a y - J u n e ) : 9 7 - 1 0 2 . Briggs, D. E. G . , and A. J. Kear. 1 9 9 3 . Fossilization of soft tissue in the laboratory. Science 2 5 9 : 1 4 3 9 - 1 4 4 2 .

179

REFERENCES Bromley, R. G.

1990. Trace fossils biology a n d t a p h o n o m y .

Burmeister, H.

1 8 4 3 . D i e O r g a n i s a t i o n der trilobiten. Berlin:

1846. T h e organization of the trilobites. L o n d o n : Ray

geologist, p. 57. . 1 8 9 0 . Archivos do Museu Nacional do Rio de Janeiro 9: 16.

Society, [An English translation of B u r m e i s t e r ( 1 8 4 3 ) . ] Butterfield, N. ). 1990. O r g a n i c preservation of n o n - m i n e r a l i z i n g organisms and the t a p h o n o m y of the Burgess Shale. Paleo-

. 1 8 9 1 . 10th report of the state geologist of New York for 1 8 9 0 , 1 8 9 1 , p. 6 9 , 7 1 . . 1 8 9 3 . Report of the assistant paleontologist. Annual Report

biology 16: 2 7 2 - 2 8 6 . Campbell, K. S. W. 1 9 7 5 . T h e functional m o r p h o l o g y of Cryp1977. Trilobites of the Haragan, Bois d'Arc and Frisco

Formations

(early D e v o n i a n )

Oklahoma.

Oklahoma

t o the Regents, N e w York State M u s e u m 4 6 : 1 9 1 - 1 9 5 . . 1894 T h e Lower Silurian trilobites of M i n n e s o t a . Geology

tolithus. Fossils and Strata 4: 6 5 - 8 6 . .

Americana 9: 9 9 - 1 4 0 . Clarke, J. M. 1 8 8 9 . Eighth a n n u a l report of the New York State

Georg Reimer, 147 p. .

. 1 9 8 1 . Triarthrus eatoni ( T r i l o b i t a ) : a n a t o m y of its exoskeletal, skeletomuscular, and digestive systems. Palaeontographica

L o n d o n : Unwin H y m a n .

Arbuckle Mountains

Geological

Survey

region,

Bulletin

123.

o f Minnesota, Paleontology 3 ( 2 ) : 6 9 5 - 7 5 9 . . 1 9 0 0 . O r i s k a n y fauna of Becraft M o u n t a i n . New York State M u s e u m M e m o i r 3. 128 p. .

N o r m a n : O k l a h o m a Geological Survey, 2 2 7 p. Canfield, D. E., and R. Raiswell. 1991 a. Pyrite f o r m a t i o n and fossil preservation. In P. A. Allison and D. E. G. Briggs (eds.), T a p h o n o m y : releasing the data locked in the fossil record, pp.

1 9 0 8 . Early D e v o n i c History of New York and Eastern

N o r t h A m e r i c a . New York State M u s e u m M e m o i r 9: Plate 5, n o . 1. Albany. C l a r k s o n , E. N. K. 1 9 7 5 . T h e evolution of the eye in trilobites. Fossils and Strata 4 : 7 - 3 2 .

3 3 7 - 3 8 8 , New York: P l e n u m . . 1 9 9 1 b . C a r b o n a t e precipitation and dissolution: its relevance to fossil preservation. In P. A. Allison and D. E. G. Briggs (eds.), T a p h o n o m y : Releasing the Data Locked in the Fossil

. 1 9 7 9 . Invertebrate p a l e o n t o l o g y and evolution. L o n d o n : G e o r g e Allen and Unwin. Cleland, H. F.

1 9 0 0 . T h e calciferous of the M o h a w k Valley.

Bulletin of A m e r i c a n Paleontology 3. 127 p.

Record, pp. 4 1 1 - 4 5 3 . New York: P l e n u m . Cassa, M. R., and D. L. Kissling. 1982. C a r b o n a t e facies of the O n o n d a g a and Bois Blanc F o r m a t i o n s , Niagara Peninsula, O n t a r i o . In E. J. Buehler and P. E. Calkin ( e d s . ) , G e o l o g y of the

Collie,

G.

L.,

1902.

Ordovician

section

near

Bellefonte.

Geological Society o f A m e r i c a Bulletin 14: 4 1 8 . C o n r a d , T. A. 1 8 3 9 . S e c o n d a n n u a l report of T. A. C o n r a d on the

northern Appalachian Basin, western New York, pp. 6 5 - 9 8 .

Paleontological D e p a r t m e n t of the Survey. Geological report

Field trips g u i d e b o o k for New York State Geological Associa-

o f N e w York, 1 8 3 9 - 4 0 , p . 5 6 - 6 6 . .

tion 54th annual meeting. C h a t t e r t o n , B. D. E., G. D. E d g e c o m b e , S. E. Speyer, A. S. H u n t , and R. A. Fortey. 1994. O n t o g e n y and relationships of T r i n u cleoidea (Trilobita). lournal o f Paleontology 6 8 : 5 2 3 - 5 4 0 . C h a t t e r t o n , B. D. E., G. D. E d g e c o m b e , N. E. Vaccari, and B. G. Waisfeld. 1997. O n t o g e n y and relationships of the Ordovician odontopleurid

trilobite

Ceratocara,

with

new

species

from

Argentina and New York. lournal of Paleontology 7 1 : 108— 125.

1 8 4 0 . Annual report of the New York State Geological

Survey. . 1 8 4 1 . D e s c r i p t i o n of new genera and species of organic r e m a i n s , Crustacea. New York Geological Survey, 5th report of the state paleontologist, p. 2 5 - 5 7 . . 1842. J o u r n a l of the A c a d e m y of Natural Sciences, Philadelphia 8: 2 7 7 . .

1 8 4 3 . Proceedings of the Academy of Natural Sciences,

Philadelphia 1: 3 3 2 .

C h a t t e r t o n , B. D. E., D. J. Siveter, G. D. E d g e c o m b e , and A. S. Hunt.

1990.

Larvae and

relationships of the C a l y m e n i n a

(Trilobita). Journal o f Paleontology 6 4 : 2 5 5 - 2 7 7 .

C o o p e r , G. A., and J. S. W i l l i a m s .

1 9 3 5 . Tully F o r m a t i o n of

New York. Geological Society o f A m e r i c a Bulletin 4 6 : 7 8 1 868.

Chatterton, B. D. E., and S. E. Speyer. 1 9 9 0 . Applications of the

Dale, N. C. 1 9 5 3 . Geology and mineral resources of the Oriskany

study of trilobite ontogeny. In D. G. Mikulic ( e d . ) , A r t h r o p o d

Q u a d r a n g l e ( R o m e Q u a d r a n g l e ) . New York State M u s e u m

paleobiology, pp. 1 1 3 - 1 3 6 . S h o r t courses in paleontology 3.

Bulletin 3 4 5 . 197 p. Albany.

Knoxville, Tenn.: Paleontological Society. . 1997. Ontogeny. In R. L. Kaesler ( e d . ) , Treatise on invertebrate paleontology: part O, A r t h r o p o d a 1, Trilobita, revised, pp. 1 7 3 - 2 4 7 . Boulder, Col.: Geological Society o f A m e r i c a . Cisne, J. L. 1973. Beecher's Trilobite Bed revisited: ecology of an Ordovician deep water fauna. New Haven: Postilla, Peabody M u s e u m , Yale University. 160 p. .

1975. A n a t o m y of Triarthrus and the relationships of the

Trilobita. Fossils and Strata 4: 4 5 - 6 3 .

Dalziel, I. W. D. 1997. N e o p r o t e r o z o i c - P a l e o z o i c geography and tectonics: Review, hypothesis, e n v i r o n m e n t a l speculation. G e o logical Society o f A m e r i c a Bulletin 109: 1 6 - 4 2 . Darby, D. G., and E. C. S t u m m . 1 9 6 5 . A revision of the Ordovician

trilobite

Asaphus

platycephalus

Stokes.

Contributions

f r o m the M u s e u m o f Paleontology, University o f Michigan 2 0 : 63-73. Davidek, K., E. Landing, S. A. B o w r i n g , S. R. Westrop, A. W A. R u s h t o n , R. A. Fortey, and J. M. Adrain. 2 0 0 0 . New uppermost

REFERENCES

180 C a m b r i a n U - P b date f r o m Avalonian Wales and age o f the C a m b r i a n - O r d o v i c i a n b o u n d a r y . Geological

Magazine

137:

alternative to phyletic gradualism. In T. M. S c h o p f (ed.), M o d e l s in paleobiology, pp. 8 2 - 1 1 5 . San Francisco: Freeman,

303-309. DeKay, J. E. 1824. O b s e r v a t i o n s on the structure of trilobites, and description of an apparently new genus. Annales of the

. 1 9 4 0 . Phacopid trilobites of N o r t h A m e r i c a . Geological . 1935. A revision of the phacopid trilobites. Journal of

E t t e n s o h n , F. R. 1987. Rates of relative plate m o t i o n during the Acadian O r o g e n y based on the spatial distribution of black

Paleontology 9 : 4 0 2 - 4 2 0 . 1987. Platteville and D e c o r a h trilobites from

Illinois and W i s c o n s i n . In R. E. Sloan ( e d . ) , Report of investiMinnesota

New York, 1: 371 p. . 1 8 5 5 . T h e Taconic System. A m e r i c a n Geologist 1: 2 3 6 .

Society o f A m e r i c a , special publication 2 9 .

35,

District. Albany. . 1846. Natural history of New York, part 5, agriculture of

New York. Journal of Paleontology 8: 2 4 7 - 2 4 9 .

D e M o t t , L. L.

Cooper. E m m o n s , E. 1842. Natural History of New York. Geology of New York part 2. C o m p r i s i n g the Survey of the Second Geological

Lyceum of Natural History, New York 1. p. 174. Delo, D. M. 1934. T h e Fauna of the Rust Q u a r r y , Trenton Falls,

gations

Eldredge, N., and S. J. G o u l d . 1972. Punctuated equlibria: an

Geological

Survey,

pp.

63-98.

St.

Paul.

shales. Journal o f G e o l o g y 9 5 : 6 3 0 - 6 3 9 . E t t o n s o h n , F. R., and C. E. Brett. 1 9 9 5 . Tectonic c o m p o n e n t s in Silurian cyclicity: examples from the Appalachian Basin and global implications. In E. Landing and M. E. Johnson

Dick, V. B., and C. E. Brett. 1 9 8 6 . Petrology, t a p h o n o m y and sedimentary e n v i r o n m e n t s of pyritic fossil

beds from

the

Hamilton G r o u p ( M i d d l e D e v o n i a n ) of western New York, pp. 1 0 2 - 1 2 8 . In C. E. Brett ( e d . ) , D y n a m i c stratigraphy and depositional e n v i r o n m e n t s o f the H a m i l t o n G r o u p ( M i d d l e D e v o n i a n ) in New York State, Part 1. N e w York State M u s e u m Bulletin 4 5 7 . Albany: New York State M u s e u m .

(eds.), Silurian Cycles: Linkages of D y n a m i c Stratigraphy with A t m o s p h e r i c , O c e a n i c , and Tectonic Changes. New York State M u s e u m Bulletin 4 9 1 : 1 4 5 - 1 6 2 . Albany. Evitt, W. R. 1 9 5 3 . O b s e r v a t i o n s on the Trilobite Ceraurus. Journal o f Paleontology 27: 3 3 . Fagerstrom, J. A.

1 9 6 1 . T h e fauna of the Middle Devonian

F o r m o s a Reef L i m e s t o n e o f southwestern O n t a r i o . Journal o f

D o n o v a n , S. K. ( e d . ) . 1 9 9 1 . T h e process of fossilization. New York: C o l u m b i a University Press. 3 0 3 p.

Paleontology 3 5 : 1 - 4 8 . Fisher, D. C.

Dwight, W. P. 1884. Recent e x p l o r a t i o n s in the W a p p i n g e r Valley limestones o f D u c h e s s C o u n t y , New York. A m e r i c a n Journal o f Science, 3rd ser. 27: 2 4 9 - 2 5 9 .

1 9 7 5 . S w i m m i n g and b u r r o w i n g in Litmdus and

Mesoliinulus. Fossils and Strata 4: 2 8 1 - 2 9 0 . Fisher, D. W. 1 9 5 3 . Additions to the stratigraphy and paleontology of the lower C l i n t o n of western New York. Buffalo Society

Eaton. 1832. Geological t e x t b o o k .

o f Natural Science Bulletin 2 1 : 2 6 p .

E d g e c o m b e , G. D. 1992. Trilobite phylogeny and the C a m b r i a n -

. 1957. M o h a w k i a n ( M i d d l e Ordovician biostratigraphy of

Ordovician " e v e n t " : cladistic reappraisal. In M. J. Novacek and

the Wells Outlier H a m i l t o n C o u n t y ) New York. New York State

Q . D . W h e e l e r ( e d s . ) , E x t i n c t i o n and phylogeny, pp. 1 4 4 - 1 7 7 .

M u s e u m and Science Service Bulletin 3 5 9 . Albany: University

New York: C o l u m b i a University Press.

o f the State o f New York.

E d g e c o m b e , G. D.

1 9 9 3 . Silurian acastacean trilobites of the

. 1962. C o r r e l a t i o n of the Ordovician Rocks in New York State. New York State M u s e u m and Science Service Geological

Americas. Journal o f Paleontology 6 7 : 5 3 5 - 5 4 8 . E d g e c o m b e , G. D., and J. M. Adrain. 1 9 9 5 . Silurian c a l y m e n i d trilobites f r o m the United States. P a l a e o n t o g r a p h i c a (A) 2 3 5 :

Survey, M a p and chart series: No. 3. Albany. Foerste, A.

F.

1887.

The Clinton

Group

of O h i o ,

part II.

Bulletin of the Science Laboratories, D e n i s o n University 2:

1-19. E d g e c o m b e , G. D., and B. D. E. C h a t t e r t o n .

1 9 9 3 . Silurian

( W e n l o c k - L u d l o w ) e n c r i n u r i n e trilobites f r o m the M a c k e n z i e

89-110. .

1893.

Fossils

of

the

Clinton

Group

in

Ohio

and

M o u n t a i n s , Canada and related species. Palaeontographica (A)

Indiana. Report of the Geological Survey of O h i o 7: 516—

229: 7 5 - 1 1 2 .

597.

Einsele, G., W. Ricken, and A. Seilacher ( e d s . ) . 1 9 9 1 . Cycles and events in stratigraphy. Berlin: Springer-Verlag. 9 5 5 p. Eldredge, N.

1972. Systematics and evolution of Phacops rana

. 1 9 0 9 . Preliminary notes on C i n c i n n a t i a n and Lexington fossils. Bulletin of the Science Laboratories, Denison University 14: 2 9 4 .

( G r e e n , 1832) and Phacops iowensis Delo, 1935 (Trilobita) f r o m

. 1 9 1 0 . P r e l i m i n a r y notes on C i n c i n n a t i a n and Lexington

the Middle Devonian o f N o r t h A m e r i c a . A m e r i c a n M u s e u m o f

fossils of O h i o , Indiana, Kentucky and Tennessee. Bulletin of

Natural History Bulletin 147: 4 5 - 1 1 4 .

the Science Laboratories, Denison University 16: 1 7 - 1 0 0 .

. 1 9 7 3 . Systematics of Lower and Lower M i d d l e D e v o n i a n species of the trilobite Phacops E m m r i c h in N o r t h A m e r i c a . A m e r i c a n M u s e u m o f Natural History Bulletin 335.

151: 2 8 6 -

. 1917. Notes on Silurian fossils f r o m O h i o and other central states. O h i o Journal o f Science 17: 1 8 7 - 2 6 4 . . 1 9 2 0 . T h e K i m m s w i c k and Plattin Limestones of n o r t h eastern M i s s o u r i . D e n i s o n University Bulletin, Journal of the

181

REFERENCES

Gillette, T. 1947. T h e C l i n t o n of western and central New York.

Scientific Laboratories 19: 1 7 5 - 2 2 4 . . 1924. Upper Ordovician faunas of O n t a r i o and Q u e b e c .

New York State M u s e u m Bulletin 3 4 1 . 191 p. Albany: New York State M u s e u m .

Geological Survey o f C a n a d a , M e m o i r 138. O t t o w a . Ford, S. W. 1873. Remarks on the distribution of fossils in the

G o l d r i n g , W. 1 9 2 3 . D e v o n i a n crinoids of New York. New York

Lower Potsdam rocks at Troy, New York, with descriptions of

State M u s e u m M e m o i r 16. 6 7 0 p. Albany: New York State

a few new species. A m e r i c a n Journal of Science 106: 1 3 4 - 1 4 0 .

Museum. . 1 9 4 3 . G e o l o g y of the Coxsackie Q u a d r a n g l e , New York.

. 1876. On additional species of fossils from the primordial of Troy

and

Lansingburg,

Rensselaer

County,

New York.

New York State M u s e u m Bulletin 3 3 2 . G o l u b i c , S., R. D. Perkins, and R. J. Lucas. 1 9 7 5 . Boring m i c r o o r -

American Journal of Science, 3rd ser. 1 1: 3 6 9 - 3 7 1 . . 1877. On s o m e e m b r y o n i c forms of trilobites from the pri-

ganisms and m i c r o b a r i n g s in c a r b o n a t e substrates. In R. W.

mordial rocks at Troy, New York. A m e r i c a n Journal of Science,

Frey ( e d . ) , T h e Study of Trace Fossils, pp. 2 2 9 - 2 5 9 . New York:

3rd ser. 13: 2 6 5 - 2 7 3 .

Springer-Verlag.

.

1878.

Note on

the development of Olenellus asaphoides.

. 1878. Descriptions of two new species of primordial fossils.

a c c u m u l a t i o n . Journal o f G e o l o g y 9 3 : 5 1 5 - 5 3 3 . G r e e n , J. 1 8 3 2 . A m o n o g r a p h of the trilobites of North America,

American Journal of Science, 3rd ser. 15: 1 2 4 - 1 2 7 . Fortey, R. A.

G o o d w i n , P. W., and E. J. A n d e r s o n . 1 9 8 5 . Punctuated aggradational cycles: a general hypothesis of episodic stratigraphic

American Journal of Science, 3rd ser. 15: 1 2 9 - 1 3 0 .

1975. Early Ordovician trilobite c o m m u n i t i e s .

93 p. Philadelphia: Joseph B r a n o . . 1 8 3 5 . A s u p p l e m e n t to the m o n o g r a p h of the trilobites of

Fossils and Strata 4: 3 3 1 - 3 5 2 . .

1979.

Formation

Early Ordovician (St.

Georges

trilobites

Group),

from

western

the

Cartoche

.

1980.

The

Ordovician

trilobites

of

.

Newfoundland. Spitsbergen.

formation.

. 1 8 3 7 b . Description of a new trilobite. A m e r i c a n Journal of

III.

Norsk

Science and Arts 3 2 : 1 6 7 - 1 6 9 . . 1838. D e s c r i p t i o n of a new trilobite. A m e r i c a n Journal of

Polarinstitutt Skrifter 171: 1 - 1 6 3 . . 1985. Pelagic trilobites as an example of deducing the life habits of extinct a r t h r o p o d s . Transactions of the Royal Society, . 1990a. Ontogeny, h y p o s t o m e a t t a c h m e n t and trilobite clas. 1 9 9 0 b . Cladistics. In D. E. G. Briggs and P. R. C r o w t h e r a

synthesis,

pp.

430-434.

Oxford:

. 2 0 0 1 . Trilobite systematics: the last 75 years. Journal of Fortey, R. A., and B. D. E. C h a t t e r t o n . 1 9 8 8 . Classification of the trilobite suborder Asaphina. Paleontology 3 1 : 1 6 5 - 2 2 2 . Fortey, R. A., and S. F. M o r r i s . 1 9 7 8 . Discovery of nauplius-like Fortey, R. A., and R. M. O w e n s . 1997. Evolutionary history. In Kaesler ( e d . ) , Treatise on invertebrate paleontology:

part O, A r t h r o p o d a 1, Trilobita, revised, pp. 2 4 9 - 2 8 7 . B o u l d e r : habits

in

trilobites.

Palaeontology 4 2 :

429-465. Fortey, R. A., and J. N. T h e r o n . 1 9 9 5 . A new O r d o v i c i a n a r t h r o pod Soomaspis, and the agnostid p r o b l e m . Palaeontology 37: 841-861. Fortey, R. A., and H. B. W h i t t i n g t o n . 1 9 8 9 . T h e Trilobita as a natural group. Historical Biology 2: 1 2 5 - 1 3 8 . Fortey, R. A., and N. V. W i l m o t . 1 9 9 1 . Trilobite cuticle thickness in relation to p a l e o e n v i r o n m e n t . Paleontologische Zeitschrift 65: 1 4 1 - 1 5 1 .

to

the

genus

Paradoxides.

American

Journal

of Science

33:

. 1 8 4 3 . Natural history of New York. Part IV, Geology of New York, c o m p r i s i n g the survey of the Fourth Geological District, 5 2 5 p. Albany. lower division of the New York System. Natural History of New York: Palaeontology, vol. I. 3 8 3 p. . 1 8 5 1 . Description of new and rare species of fossils from the Palaeozoic series. In Foster and W h i t n e y , Report on the

Geological Society o f A m e r i c a . Feeding

Association.

. 1847. C o n t a i n i n g descriptions of the organic remains of the

trilobite larvae. Palaeontology 2 1 : 8 2 3 - 8 3 3 .

1999.

Trip G u i d e b o o k 6 3 , pp. 2 0 5 - 2 4 9 . New York State Geological

139-142.

Paleontology 7 5 : 1 1 4 1 - 1 1 5 1 .

.

F o r m a t i o n ( M i d d l e D e v o n i a n ) in eastern New York State. In

Hall, J. 1 8 3 8 . Descriptions of two species of trilobites, belonging

Blackwell Scientific.

R. E.

Griffing, D. H., and C. A. Ver Straeten. 1 9 9 1 . Stratigraphy and

J. R. Ebert ( e d . ) , New York State Geological Association Field

sification. Palaeontology 3 3 : 5 2 9 - 5 7 6 . Paleobiology:

Science 3 3 : 4 0 6 - 4 0 7 . depositional e n v i r o n m e n t s o f the lower part o f the Marcellus

Edinburgh 7 6 : 2 1 9 - 2 3 0 .

(eds.),

1837a. Descriptions of several new trilobites. American

Journal o f Science 3 2 : 3 4 3 - 3 4 9 .

Geological Survey o f C a n a d a , Bulletin 3 2 1 : 6 1 - 1 1 4 . Remaining trilobites of the Valhallfonna

North A m e r i c a , 30 p. Philadelphia: Joseph B r a n o .

Lake S u p e r i o r land district: part 2, the iron region together with the general geology: U. S. Congress, 3 2 n d , Special Session, Senate Executive D o c u m e n t 4 , pp. 2 0 3 - 2 3 1 . . 1852. C o n t a i n i n g descriptions of the organic remains of the lower

middle divisions of the

New York System.

Natural

History of New York: Palaeontology, vol. II. 3 6 2 p. . 1859a. New York State C a b i n e t of Natural History, Annual report n o . 12, 72 p. . 1 8 5 9 b . C o n t a i n i n g descriptions and figures of the organic remains of the Lower Helderberg G r o u p and the Oriskany

REFERENCES

182 S a n d s t o n e . Natural History of New York: Palaeontology, vol.

phology, classification and evolution of the Trinucleidae (Trilo-

III. 5 3 2 p. Albany. . 1 8 6 0 . C o n t r i b u t i o n s to paleontology 1858 a n d 1 8 5 9 . 13th annual report to the regent of the University of the State of New York and the c o n d i t i o n s of the State C a b i n e t of Natural . 1861 a. Descriptions of new species of fossils from the upper Helderberg, H a m i l t o n and C h e m u n g G r o u p s . New York State

537-604. Hughes, N . C , and R . E . C h a p m a n . 1995. Growth and variation implications for trilobite paleobiology. Lethaia 2 8 : 3 3 3 - 3 5 3 . Hughes, N . C , and D . L . C o o p e r . 1 9 9 9 . P a l e o b i o l o g y and t a p h o n o m i c aspects of the "Granulosa' trilobite cluster, Kope For-

C a b i n e t of Natural History, annual report, 14. . 1861b. Preliminary notice of the trilobites and other c r u s taceans o f the upper Helderberg, H a m i l t o n and C h e m u n g G r o u p s . Report of the New York State C a b i n e t of Natural

mation

( U p p e r O r d o v i c i a n , C i n c i n n a t i region).

. 1863. Notes and c o r r e c t i o n s . 16th annual report of New

Journal o f

Paleontology 7 3 : 3 0 6 - 3 1 9 . I C Z N . 1 9 8 5 . International code o f zoological n o m e n c l a t u r e , 3rd edition.

History, 15, pp. 2 7 - 1 1 3 .

Berkeley,

Cal.:

International Trust

for Zoological

N o m e n c l a t u r e , University of California Press. 3 3 8 p. Irwin, M. L. 1 9 6 5 . General t h e o r y of epeiric clear water sedi-

York State C a b i n e t o f Natural History, pp. 2 2 3 - 2 2 6 . . 1867. A c c o u n t of s o m e new or little k n o w n species of fossils from the rocks of the age of the Niagara G r o u p . 20th annual report of New York State C a b i n e t of Natural History, pp.

mentation.

A m e r i c a n Association

o f Petroleum

Geologists

Bulletin 4 9 : 4 4 5 - 4 5 9 . Isachsen, Y. W., E. Landing, J. M. Lauber, L. V. Rickard, and W. B. Rogers (eds.). 1 9 9 1 . Geology of New York, a simplified account.

305-401. 1876.

b i t a ) . Philosophical Transactions of the Royal Society 2 7 2 :

in the Silurian proetide trilobite Aulacopleura koninki and its

History.

.

Hughes, C. P., J. K. I n g h a m , and R. Addison. 1975. T h e m o r -

Illustration

of

Devonian

fossils.

Gastropoda,

Pteropoda, C e p h a l o p o d a , C r u s t a c e a , a n d corals o f the upper Helderberg, H a m i l t o n and C h e m u n g G r o u p s , Albany, New

New

York

State

Museum/Geological

Survey

Educational

Leaflet, 2 8 . 2 8 4 p. Albany. Jell, P. A. 1 9 7 5 . T h e a b a t h o c h r o a l eye of Pagetia, a new type of trilobite eye. Fossils and Strata 4: 3 3 - 4 4 .

York. Hall, ]., and J. M. Clarke. 1 8 8 8 . C o n t a i n i n g descriptions of the

J o h n s o n , T. T. 1 9 8 5 . Trilobites of the T h o m a s T. J o h n s o n collec-

trilobites and o t h e r Crustacea of the Oriskany, upper Helder-

tion: h o w to find, prepare and p h o t o g r a p h trilobites. Dayton,

berg,

Hamilton,

Portage,

Chemung

and

Catskill.

Natural

History of New York: Palaeontology, vol. V I I . 2 3 6 p. Albany. Hall, J., and R. P. Whitfield. 1 8 7 5 . D e s c r i p t i o n s of invertebrate fossils, mainly f r o m the Silurian

System.

Report Geology

H e n n i n g s m o e n , G. 1 9 7 5 . M o u l t i n g in trilobites. Fossils and Strata

O,

Arthropoda

1,

Trilobita,

revised.

Boulder,

Col.:

Geological Society o f A m e r i c a . 5 3 0 p . 1 9 8 6 . Ecologic stability of the dysaerobic biofacies during the late Paleozoic. Lethaia 19: 1 0 9 - 1 2 1 .

4: 179-200. Hesselbro, S. P.

1987. T h e b i o s t r a t i n o m y of Dikclocephalus scle-

rites: implications for the use of trilobite attitude data. Palaios

Kay, M.

1937. Stratigraphy of the Trenton G r o u p . Geological

Society o f A m e r i c a Bulletin 4 8 : 2 3 3 - 3 0 2 . . 1 9 4 3 . M o h a w k i a n series on West Canada Creek, New York.

2: 6 0 5 - 6 0 8 . Holloway, D. J. 1 9 8 0 . M i d d l e Silurian trilobites from Arkansas and O k l a h o m a , U. S. A. Paleontographica Abt. A 1 7 0 : 1 - 8 5 . 1981.

part

K a m m e r , T. W, C. E. Brett, D. R. B o a r d m a n II, and R. H. Mapes.

Survey O h i o , 2 , part 2 , pp. 6 5 - 1 6 1 .

.

O h i o : L i t h o - p r i n t . 178 p. Kaesler, R. L. ( e d . ) . 1997. Treatise on invertebrate paleontology:

Silurian

dalmanitacean

trilobites

from

North

A m e r i c a and the origins o f D a l m a n i t i d a e and S y n p h o r i i n a e .

A m e r i c a n Journal o f Science 2 4 1 : 5 9 7 - 6 0 6 . . 1 9 5 3 . Geology of the Utica Q u a d r a n g l e , New York. New York M u s e u m Bulletin 3 4 7 . . 1 9 6 8 . O r d o v i c i a n f o r m a t i o n s in northwestern New York. Naturaliste C a n a d i e n 9 5 : 1 3 7 3 - 1 3 7 8 .

Palaeontology 2 4 : 6 9 5 - 7 3 1 . Holloway, D. J., and P. D. Lane. 1 9 9 8 . Effaced styginid trilobites from the Silurian o f New S o u t h Wales. Palaeontology 4 1 :

Keary, P. 1996. T h e new Penguin dictionary of geology. L o n d o n : Penguin B o o k s . 3 6 6 p. Kidwell, S. M . , and D. B o s e n c e . 1 9 9 1 . T a p h o n o m y and t i m e -

853-896. Howell, B. E, and J. T. S a n f o r d . 1 9 4 6 . Trilobites from the Silurian

averaging of m a r i n e shelly faunas. In P. A. Allison and D. E. G.

Irondequoit F o r m a t i o n of New York. Bulletin W a g n e r Free

Briggs (eds.), T a p h o n o m y : releasing the data locked in the fossil record, pp. 1 1 6 - 2 0 9 . New York: P l e n u m .

Institute o f Science 2 1 : 5 - 1 0 . . 1947. Trilobites f r o m the Silurian O a k O r c h a r d M e m b e r of

Klapper, G. 1 9 8 1 . Review of New York Devonian c o n o d o n t bios-

the L o c k p o r t F o r m a t i o n of New York. Bulletin W a g n e r Free

tratigraphy. In W. A. Oliver and G. Klapper (eds.), Devonian

Institute o f Science 2 2 : 3 3 - 4 2 .

biostratigraphy of New York, part 1, pp. 5 7 - 6 6 . Washington,

H u d s o n , J. A. 1982. Pyrite in a m m o n o i d - b e a r i n g shales from the

Jurassic of E n g l a n d and G e r m a n y .

639-667.

Sedimentology 27:

D.C.: International U n i o n o f Geological Sciences, S u b c o m m i t tee on D e v o n i a n Stratigraphy. K l o c , G. 1992. Spine f u n c t i o n in the o d o n t o p l e u r i d trilobites

183

REFERENCES Leonaspis and

Dicranurus

from

the

Devonian

of O k l a h o m a .

North American Paleontological C o n v e n t i o n Abstracts a n d P r o g r a m , Paleontological Society Special Publication 6: 167. . 1993. Epibionts on Selenopeltinae ( O d o n t o p l e u r i d a ) trilo-

History 2 2 3 . 176 p. New York: A m e r i c a n M u s e u m of Natural History. L i e b e r m a n , B. E., and G. K l o c . 1997. Evolutionary and biogeographic patterns in the Asteropyginae (Trilobita, D e v o n i a n ) .

bites. Geological Society o f A m e r i c a , 1 9 9 3 annual meeting,

Bulletin A m e r i c a n M u s e u m Natural History 2 3 2 . 127 p. New

Abstracts with p r o g r a m s 2 5 : 103.

York: New York M u s e u m of Natural History.

.

1997. Epibionts on Dicranurus and s o m e related genera.

Linnarsson, J . G . O .

In Second International Trilobite C o n f e r e n c e , St. C a t h a r i n e s ,

Siluriska

O n t a r i o , Abstracts with P r o g r a m , p. 2 8 .

Handligar 8: 87.

Kobayashi, T. 1939. Journal of the Faculty of S c i e n c e , Imperial University, Tokyo, sec. 2 5: 112.

D.

M.

1994.

K.

Svenska

Devonian

Vetenskapakadamiens

paleontology of New York.

Paleontological Research Institution special publication 2 1 .

Kurtz, V. E. 1975. F r a n c o n i a n ( U p p e r C a m b r i a n ) trilobite faunas from the Elvins G r o u p o f southeast M i s s o u r i .

Journal o f

Paleontology 4 9 : 1 0 0 9 - 1 0 4 3 . Lambert, A. E.

Linsley,

1 8 6 9 . O m Vestergotlands C a m b r i s k a o c h

Aflagringar.

4 7 2 p. Ithaca: Paleontological Research Institution. L o c h m a n , C . 1 9 4 6 . Two U p p e r C a m b r i a n ( T r e m p e a l e a u ) trilobites f r o m D u t c h e s s C o u n t y , New York. A m e r i c a n Journal of

1904. Description of Dalmanites lunatus. Bulletin

o f the Geological Society o f A m e r i c a 15: 4 8 0 - 4 8 2 .

Science 244: 5 4 7 - 5 5 3 . Locke.

Landing, E. 1988. Depositional tectonics and biostratigraphy of the western portion of the Taconic a l l o c h t h o n , eastern New

1838.

2nd

annual

report

geology

survey

of Ohio.

Columbia. L o D u c a , S. T. 1 9 9 5 . T h a l l o p h y t i c - a l g a e - d o m i n a t e d biotas from

York State. In E. Landing ( e d . ) , T h e C a n a d i a n paleontology

the Silurian L o c k p o r t G r o u p o f N e w York and O n t a r i o . N o r t h -

and biostratigraphy seminar, pp. 9 6 - 1 1 0 . N e w York State

eastern G e o l o g y and E n v i r o n m e n t a l Sciences 17: 3 7 1 - 3 8 2 .

Museum

Bulletin

462:

96-110.

Albany:

New

York

State

Museum.

Ludvigsen, R.

1977. T h e O r d o v i c i a n trilobite Ceraurinus B a r t o n

i n N o r t h A m e r i c a . Journal o f P a l e o n t o l o g y 5 1 : 9 5 9 - 9 7 2 .

Landing, E., S. A. B o w r i n g , K. L. Davidek, A. W. A. R u s h t o n ,

. 1979a. T h e O r d o v i c i a n trilobite Pseudogygites Kobayashi in

R. A. Fortey, and W. A. P. W i m b l e d o n . 1998a. C a m b r i a n -

eastern and arctic N o r t h A m e r i c a . Life sciences c o n t r i b u t i o n s

Ordovician b o u n d a r y age and d u r a t i o n of the lowest O r d o v i -

120. T o r o n t o : Royal O n t a r i o M u s e u m .

cian

Tremadoc

Series

based

on

U-Pb

zircon

dates

from

Avalonian Wales. Geological Magazine 137: 4 8 5 - 4 9 4 .

. 1 9 7 9 b . Fossils of O n t a r i o , part 1: the trilobites. Life sciences miscellaneous p u b l i c a t i o n s . T o r o n t o : Royal O n t a r i o M u s e u m .

Landing, E., S. A. B o w r i n g , K. L. Davidek, S. R. Westrop, G. Geyer,

. 1987. R e e f trilobites f r o m the F o r m o s a L i m e s t o n e (Lower

and W. Heldmaier. 1998b. D u r a t i o n of the Early C a m b r i a n :

D e v o n i a n ) o f southern O n t a r i o . C a n a d i a n Journal o f Earth

U - P b ages of volcanic ashes from Avalon and G o n w a n d a . Canadian Journal o f Earth Sciences 3 5 : 3 2 9 - 3 3 8 . Lane, P. D., and A. T. T h o m a s . 1983. A review of the trilobite s u b order Scutelluina. Palaeontological Association Special Papers in Palaeontology 3 0 : 1 4 1 - 1 6 0 . Lask, P. R. B. 1993. T h e hydrodynamic behavior of sclerites f r o m the trilobite Flexicalymene meeki. Lesperance, P. J.

Palaios 2: 2 1 9 - 2 1 5 .

1 9 7 5 . Stratigraphy and paleontology of the

Science 24: 6 7 6 - 6 8 8 . Ludvigsen, R., and B. D. E. C h a t t e r t o n . 1982. O r d o v i c i a n Pteryg o m e t o p i d a e (Trilobita) o f N o r t h A m e r i c a . C a n a d i a n Journal o f E a r t h Science 19: 2 1 7 9 - 2 2 0 9 . .

1991.

from

the

The

peculiar

Whittaker

Ordovician

Formation,

trilobite

District

Hypodicranotus

of

Mackenzie.

C a n a d i a n Journal o f Earth Science 2 8 : 6 1 6 - 6 2 2 . Ludvigsen, R., and P. A. Tuffnell. 1 9 8 3 . A revision of the O r d o v i -

Synphoriidae (Lower and Middle Devonian D a l m a n i t a c e a n

cian olenid trilobite

trilobites). Journal o f Paleontology 4 9 : 9 1 - 1 3 7 .

120: 5 6 7 - 5 7 7 .

Triarthrus G r e e n .

Geological

Magazine

Lesperance, P. J., and P.-A. B o u r q u e . 1 9 7 1 . T h e S y n p h o r i i n a e : an

. 1994. T h e last olenacean trilobite: Triarthrus in the W i t b y

evolutionary pattern of Lower and M i d d l e Devonian trilobites.

F o r m a t i o n ( U p p e r O r d o v i c i a n ) o f southern O n t a r i o . New York

Journal o f Paleontology 4 5 : 1 8 2 - 2 0 8 .

State M u s e u m Bulletin 4 8 1 : 1 8 3 - 2 1 2 .

Leutze, W. P. 1 9 6 1 . A r t h r o p o d s f r o m the Syracuse F o r m a t i o n , Silurian o f New York. Journal o f Paleontology 3 5 : 4 9 - 6 4 . Levi-Setti, R.

1975. Trilobites: a p h o t o g r a p h i c atlas. C h i c a g o :

University of Chicago Press. 2 1 3 p. .

1993.

Trilobites,

2 n d edition.

Ludvigsen, R., and S. R. Westrop. 1 9 8 3 . F r a n c o n i a n trilobites of New York State. New York State M u s e u m M e m o i r 2 3 : 83 p. Albany: New York State M u s e u m . . 1986. Classification of the Late C a m b r i a n trilobite Idiome-

Chicago:

University of

Chicago Press. 3 4 2 p. Lieberman, B. E. 1994. Evolution of the trilobite subfamily Proetinae Salter, 1864, and the origin, diversification, evolutionary

sus R a y m o n d . C a n a d i a n Journal o f Earth Science 2 3 : 3 0 0 - 3 0 7 . M a r t i n , R. E. 1 9 9 9 . T a p h o n o m y : a process approach. C a m b r i d g e : C a m b r i d g e University Press. M a t t h e w , G. F.

1896. Faunas of the Paradoxides beds of eastern

affinity, and extinction of the Middle Devonian proetid fauna

N o r t h A m e r i c a . New York Academy of Science Transactions 15:

of eastern North A m e r i c a . Bulletin A m e r i c a n M u s e u m Natural

192-247.

184

REFERENCES

Maximova,

Z.

A.

1972.

New

Devonian

trilobites

of

the

Donovan

( e d . ) . T h e processes o f fossilization, pp. 2 2 - 6 5 .

L o n d o n : Belhaven Press.

Phacopoidea. Paleontological j o u r n a l 1: 7 8 - 8 3 . M c N a m a r a , K. J., and D. Rudkin. 1984. Techniques of trilobite exuviation. Lethaia 17: 1 5 3 - 1 7 3 .

Phleger, F. B.

1937. New Lichidacea in the collection of the

M u s e u m of C o m p a r a t i v e Zoology. Bulletin of the Museum of

M e e k , F. B. 1872. Descriptions of new species of fossils from the Cincinnati G r o u p o f O h i o . A m e r i c a n Journal o f Science vol. 3 , 3rd ser: 4 2 6 .

C o m p a r a t i v e Z o o l o g y (Harvard) 8 0 : 4 1 5 - 4 2 3 . Pillet, J.

1972.

Les

trilobites du

Devonian

inferieur et du

Devonian moyen du sud-est du Massif armoricain. Societe

Middleton, G. V., M. Rutka, and C. J. Salas. 1987. G e o l o g i c setting of the n o r t h e r n Appalachian Basin during the Early Silurian. In W. L. Duke ( e d . ) , Sedimentology, stratigraphy, and i chnol ogy of the Lower Silurian M e d i n a F o r m a t i o n in New York and O n t a r i o , Society o f E c o n o m i c Paleontologists and M i n e r a l o gists, Eastern S e c t i o n .

1987 Annual Field Trip G u i d e b o o k ,

pp. 1 - 1 5 .

D'Etudes Scientifique de l'Anjou, M e m o i r e 1: 307 p., Angers France. Plotnick,

R.

E.

1986.

Taphonomy

of

a

modern

shrimp:

implications for the a r t h r o p o d fossil record. Palaios 1: 2 8 6 293. Pratt, B. R. 1998. Possible predation on Upper C a m b r i a n trilobites and its relevance for the extinction of soft-bodied Burgess

Mikulic, D. G., and J. Kluessendorf. 2 0 0 1 . M o u l t i n g behavior and disarticulation patterns ot Silurian calymenids: implications

Shale-type animals. Lethaia 3 1 : 7 3 - 8 8 . Pribyl, A., J. Vanek, and I. Pek. 1985. Phylogeny and t a x o n o m y of

for interpreting trilobite ecology and t a p h o n o m y , In Abstracts

family Cheiruridae (Trilobita). Acta Universitatis Palackianae

of papers lor the Third International (Conference on Trilobites

Olomucenis

and their Relatives, pp. 2 2 - 2 3 . New York: University of O x f o r d .

Geologica X X I V 83: 1 0 7 - 1 9 1 .

Miller, I. 1975. S t r u c t u r e and function of trilobite terrace lines,

Facultas

Rerum

Naturalium

Geographica-

Prouty, F. 1923. Systematic paleontology. Maryland Geological Survey: Silurian. Baltimore.

fossils and Strata 4: 1 5 5 - 1 7 8 . Miller, M. F., and J. Rehmer. 1 9 7 9 . Trace fossils in interpretation

R a m s k o l d , L. 1 9 9 1 . Pattern and process in the evolution of the

of sharp lithologic b o u n d a r i e s ; and e x a m p l e f r o m the D e v o n -

O d o n t o p l e u r i d a e ( T r i l o b i t a ) . T h e Selenopeltinae and Cerat-

ian of New York. Geological Society of A m e r i c a , Abstracts with

cephalinae. Transactions of the Royal Society of Edinburgh:

Program 1 1 : 4 5 .

Earth Science 8 2 : 1 4 3 - 1 8 1 .

M o o r e . R. C. ( e d . ) . 1 9 5 9 . Treatise on invertebrate paleontology:

R a m s k o l d , L., and B. D. F. C h a t t e r t o n . 1 9 9 1 . Revision and sub-

part O, A r t h r o p o d a 1. Boulder, C o l . : Geological Society of

division of the polyphyletic "Leonaspis" (Trilobita). Transac-

America and University of Kansas Press.

tions of the

M o r r i s , P., L. C. Ivany, K. M. Schopf, and C. E. Brett. 1995. T h e challenge of paleoecological stasis: reassessing sources of evolutionary stability. Proceedings of the National Academy of Sciences 9 2 : 1 1 2 6 9 - 1 1 2 7 3 . phylogeny. New York: C o l u m b i a University Press. 2 5 3 p.

fossils

from

I.

the C l i n t o n

Drennen. Group

1975.

(Silurian)

Trilobite

trace

of east-central

New York State. Bulletins o f A m e r i c a n Paleontology 67: 2 9 9 349.

Ramskold, L., and G. D. E d g e c o m b e . 1 9 9 1 . Trilobite monophyly revisited. Historical Biology 4: 2 6 7 - 2 8 3 . ered. Alcheringa 2 0 : 2 6 9 - 2 7 6 . tion of s o m e phacopid trilobites. Cladistics 7: 2 9 - 7 4 . glomerate, lournal o f Paleontology I S : 2 2 9 - 2 5 8 . . 1945. New Upper C a m b r i a n trilobites from the Levis C o n g l o m e r a t e , (ournal o f Paleontology 19: 4 6 2 - 4 7 8 . . 1946. Revision of s o m e late Upper C a m b r i a n trilobites

O w e n , A. W. 1985. Trilobite a b n o r m a l i t i e s . Transactions of the Royal Society, E d i n b u r g h , Earth S c i e n c e 7 6 : 2 5 5 - 2 7 2 .

f r o m New York, Vermont and Q u e b e c . America Journal of Science 2 4 4 : 5 3 7 - 5 4 6 .

Owens, R. M. 1973. British Ordovician and Silurian proetidae

. 1948. Lower C a m b r i a n trilobites from the conglomerates

(Trilobita). Palaeontographical Society M o n o g r a p h vol. 127,

of Quebec

no. 535: 1-98.

Paleontology 2 2 : 1 - 2 4 .

Palmer, A. R. 1965. B i o m e r e - a new kind of biostratigraphic unit. lournal o f Paleontology 3 9 : 1 4 9 - 1 5 3 . . 1984. T h e b i o m e r e p r o b l e m : evolution of an idea. lournal

and biases in m o d e r n m a r i n e e n v i r o n m e n t s : and actualistic fossil

assemblage

o f the

Ptychopariidae).

Journal

of

1952. Revision of the North A m e r i c a n trilobites of the

.

1966a. Revision of the North A m e r i c a n species of the

C a m b r i a n trilobite genus Pagetia. Journal of Paleontology 3 9 :

Parsons, K. M . , and C. E. Brett. 1 9 9 1 . T a p h o n o m i c processes on

.

(exclusive

family Eodiscidae. Journal of Paleontology 2 6 : 434—451.

o f Paleontology 5 8 : 5 9 9 - 6 1 1 .

perspective

Science 8 2 :

Rasetti, F. 1 9 4 4 . U p p e r C a m b r i a n trilobites from the Levis C o n -

o n t o g r a p h i c a A m e r i c a (v. 6 ) 4 1 : 2 8 1 - 4 3 9 . G., a n d W.

Earth

R a m s k o l d , L., and L. Werdelin. 1 9 9 1 . T h e phylogeny and evolu-

O s g o o d , R. G., )r. 1 9 7 0 . Trace fossils of the C i n c i n n a t i area. PaleR.

Society, Edinburgh:

. 1996. Trilobite appendage structure—Eoredlichia reconsid-

Novacek, M. L., and Q. D. W h e e l e r ( e d s . ) . 1 9 9 2 . E x t i n c t i o n and

Osgood,

Royal

333-371.

preservation.

In

S.

K.

502-511. .

1966b.

New

Lower C a m b r i a n

trilobite faunule

from

the Taconic S e q u e n c e of New York. Smithsonian Miscella-

185

REFERENCES neous Collections 148. 52 p. W a s h i n g t o n D.C.: S m i t h s o n i a n

Resser, C. E. 1 9 3 8 . C a m b r i a n system (restricted) of the southern Appalachians. Geological Society of A m e r i c a Special Paper 15:

Institution. . 1967. Lower and Middle C a m b r i a n trilobite faunas f r o m the Taconic S e q u e n c e of New York. S m i t h s o n i a n Miscellaneous Collections 152. no. 4: 135 p. W a s h i n g t o n D.C.: S m i t h s o n i a n

1 - 1 4 0 . Boulder. . .

Institution. Rasetti, E, and G. T h e o k r i t o f f . 1967. Lower C a m b r i a n agnostid trilobites o f North

America.

Journal

o f Paleontology 4 1 :

1942a.

New Upper

Cambrian

trilobites.

Smithsonian

trilobites.

Smithsonian

Miscellaneous C o l l e c t i o n s 1 0 1 : 1 - 5 8 . 1942b.

New

Upper

Cambrian

Miscellaneous C o l l e c t i o n s 103: 1 - 1 3 6 . Rickard,

L.

V.

1962.

Late

Cayugan

(Upper

Silurian)

and

Helderbergian (Lower D e v o n i a n ) stratigraphy in New York.

189-196. R a y m o n d , P. E. 1905a. T h e fauna of the Chazy L i m e s t o n e . A m e r -

New York State M u s e u m Bulletin 3 8 6 . Albany. . 1 9 7 5 . C o r r e l a t i o n of the Silurian and D e v o n i a n rocks in

ican Journal o f Science, 4 t h ser. 2 0 : 3 5 3 - 3 8 2 . . 1905b. T h e trilobites of the Chazy L i m e s t o n e . Annals of the

New York State. New York State M u s e u m , M a p and C h a r t Ser. 2 4 . Albany.

Carnegie M u s e u m 3 : 3 2 8 - 3 8 6 . 1910a. Trilobites of the Chazy F o r m a t i o n in V e r m o n t .

. 1 9 8 1 . T h e D e v o n i a n System of New York State. In W. A.

7th Report of the State Geologist, V e r m o n t , pp. 2 1 3 - 2 4 8 .

Oliver and G. Klapper ( e d s . ) , Devonian biostratigraphy of

Burlington.

New York, part 1, pp. 5 - 2 1 . W a s h i n g t o n , D.C.: International

.

. 1 9 1 0 b . Notes on Ordovician trilobites. IV. New and old species of trilobites from the Chazy. Annals of the Carnegie 1910c.

Notes

Stratigraphy. Ross, R. J. 1 9 5 1 . Stratigraphy of the G a r d e n City F o r m a t i o n in

M u s e u m 7: 6 0 - 8 0 . .

U n i o n o f Geological Sciences, S u b c o m m i t t e e o n Devonian

on

Ordovician

trilobites.

I.

Asaphidae

from the B e e k m a n t o w n . Annals of the Carnegie M u s e u m 7:

n o r t h e a s t e r n Utah, and its trilobite fauna. Peabody M u s e u m of Natural History Bulletin 6. .

35-45. . 1913. Notes on s o m e new and old trilobites in the Victoria

1967. C a l y m e n i d and o t h e r O r d o v i c i a n trilobites from

Kentucky and O h i o . Geological Survey Professional Paper 5 8 3 -

Memorial

B : B 1 - B 1 9 . W a s h i n g t o n D.C.: United States Geological Survey.

. 1914. Notes on the o n t o g e n y of Isotelus gigas Dekay. B u l -

lithospheric plates, a n d ocean currents. Fossils and Strata 4:

Memorial

Museum.

Bulletin

of

the

Victoria

M u s e u m , Geology Survey of Canada 1: 4 5 . Ottawa. letin o f the M u s e u m o f C o m p a r a t i v e Zoology, Harvard 6 3 : 1916. A new Ceraurus from the Chazy. New York State

M u s e u m Bulletin 189: 1 - 4 1 . Albany. . 1920a. T h e appendages, a n a t o m y and relationships of trilobites.

M e m o i r s o f the C o n n e c t i c u t Academy o f Arts a n d

Science 7: 169 p. New Haven, C o n n e c t i c u t . . 1920b. S o m e new O r d o v i c i a n trilobites. Bulletin of the M u s e u m o f C o m p a r a t i v e Zoology, Harvard 6 4 : 2 7 3 - 2 9 6 . . 1921. A c o n t r i b u t i o n to the description of the fauna of the Trenton G r o u p . C a n a d i a n Geological Survey M u s e u m Bulletin 3 1 . Ottawa. . 1925. S o m e trilobites of the Lower M i d d l e O r d o v i c i a n of eastern North A m e r i c a . Bulletin o f the M u s e u m o f C o m p a r a tive Zoology, Harvard 67 ( 1 ) : 1 - 1 8 0 . . 1 9 3 1 . An unusually large isoteloid h y p o s t o m a . Bulletin of the M u s e u m o f C o m p a r a t i v e Zoology, Harvard 5 5 : 2 0 5 - 2 0 9 . R a y m o n d , P. E., and D. C. B a r t o n . 1 9 1 3 . A revision of the A m e r ican species of Ceraurus. Bulletin of the M u s e u m of C o m p a r ative Zoology, Harvard 5 4 ( 2 0 ) : 5 2 3 - 5 4 3 . R a y m o n d , P. E., and J. E. Narraway. 1 9 0 8 . Notes on O r d o v i c i a n trilobites:

Illaenidae from the Black River L i m e s t o n e near

Ottawa, Canada. Annals o f the Carnegie M u s e u m 4 : 2 4 2 - 2 5 5 . . 1910. Notes on Ordovician trilobites. III. Asaphidae f r o m the Lowville and Black River. Annals of the Carnegie M u s e u m 7: 4 6 - 5 9 .

1975.

Early

Paleozoic

trilobites,

sedimentary

facies,

331-352. .

247-269. .

.

1979.

Additional

trilobites

from

the

Ordovician

of

Kentucky. Geological Survey Professional Paper 1 0 6 6 - D : D l D 1 3 . W a s h i n g t o n , D . C . : United States Geological Survey. Rudkin, D. M . , and R. P. Tripp. 1 9 8 5 . A reassessment of the O r d o v i c i a n trilobite Isotelus, part I: N o r t h A m e r i c a n species. C a n a d i a n Paleontology a n d Biostratigraphy Seminar, Q u e b e c City, S e p t e m b e r 1 9 8 5 . . 1987. A reassessment of the O r d o v i c i a n trilobite Isotelus, part II: O n t a r i o species. C a n a d i a n Paleontology and B i o s tratigraphy Seminar, L o n d o n , O n t a r i o , S e p t e m b e r 1987. . 1 9 8 9 . T h e type species of the O r d o v i c i a n trilobite genus Isotelus: I. gigas DeKay, 1 8 2 4 . Life Sciences C o n t r i b u t i o n 152. 18 p. T o r o n t o : Royal O n t a r i o M u s e u m . Rudkin, D. M . , R. P. Tripp, and R. Ludvigsen. 1994. T h e O r d o v i cian trilobite genus Hemiarges (Lichidae: T r o c h u r i n a e ) North America and Greenland.

New York State

from

Museum

Bulletin 4 8 1 : 2 8 9 - 3 0 6 . R u e d e m a n n , R. 1 9 0 1 . T r e n t o n c o n g l o m e r a t e of Rysedorph Hill Rensselaer C o . , N e w York and its fauna. New York State M u s e u m Bulletin 4 9 : 3 - 1 1 4 . .

1916a. A c c o u n t of s o m e little-known species of fossils,

mostly from the Paleozoic rocks of New York. New York State M u s e u m Bulletin 189: 1 - 1 1 2 . . 1 9 1 6 b . T h e presence of a m e d i a n eye in trilobites. New York State M u s e u m Bulletin 189: 1 2 7 - 1 4 3 .

REFERENCES

186 . 1926. T h e Utica and L o r r a i n e F o r m a t i o n s of New York. Part

.

1990c. E n r o l l m e n t in trilobites. In A. J. B o u c o t ( e d . ) ,

2 systematic paleontology, n o . 2 Mollusks, C r u s t a c e a n s and

Evolutionary

Eurypterids. New York State M u s e u m Bulletin 2 7 2 : 1 - 2 2 7 .

A m s t e r d a m : Elsevier.

paleobiology

and

coevolution,

pp.

450-456.

Sargent, J. D. 1 9 5 3 . A new trilobite f r o m the O n o n d a g a L i m e s t o n e

Speyer, S. E., and C. E. Brett. 1 9 8 5 . Clustered trilobite assem-

of New York. Buffalo Society Natural Science Bulletin 2 1 , n o .

blages in the Middle Devonian H a m i l t o n G r o u p . Lethaia 18:

2: 9 1 - 9 3 .

85-103. . 1986. Trilobite t a p h o n o m y and Middle Devonian taphofa-

Sars. 1 8 3 5 . O k e n s Isis, p. 3 3 3 . Scatterday, J. W.

1986. T h e Middle Devonian brachymetopid

cies. Palaios 1: 3 1 2 - 3 2 7 .

1 8 8 8 ) , close

. 1 9 8 8 . Taphofacies models for epeiric sea environments:

relatives, descendants, a n d ancestors. C a n a d i a n Paleontology

Middle Paleozoic examples. Palaeogeography, Palaeoclimatol-

and Biostratigraphy Seminar, Abstracts, pp. 2 9 - 3 0 .

ogy, Palaeoecology 6 3 : 2 2 5 - 2 6 2 .

trilobite Australosutura gemmaea

(Hall and Clarke,

Seilacher, A., W. E. Reif, and F. Westfal. 1 9 8 5 . S e d i m e n t o l o g i c a l ,

.

1 9 9 1 . Taphofacies c o n t r o l s — b a c k g r o u n d and episodic

ecological, and t e m p o r a l patterns of fossil Lagerstatten. P h i l o -

processes in fossil assemblage preservation. In P. A. Allison

sophical Transactions o f the Royal Society o f L o n d o n B 3 1 1 :

and

5-23.

data locked in the fossil record, pp. 5 0 1 - 5 4 5 . New York:

Sevon, W. D., and D. L. W o o d r o w . 1 9 8 5 . M i d d l e and Upper Devonian stratigraphy within the Appalachian Basin. In D. L. W o o d r o w and W. D. Sevon ( e d s . ) , T h e Catskill Delta, G e o l o g -

N e w York State

Museum

and

E.

G.

Briggs

(eds.),

Taphonomy:

releasing

the

Plenum. Stewart, G. A. 1927. F a u n a of the Silica Shale of Lucas County, O h i o . O h i o G e o l o g y Survey Bulletin, 4 t h . ser. 3 2 : 1 - 7 6 . Stokes, C. 1824. On a trilobite from Lake H u r o n . In J. J. Bigsby,

ical Society of A m e r i c a Special Paper 2 0 1 . 2 4 6 p. Shaw, F. C. 1 9 6 8 . Early Middle O r d o v i c i a n Chazy trilobites of New York.

D.

Science

Service

M e m o i r 17. 163 p. Albany.

Notes on the geography and geology of Lake H u r o n . Transactions Geological Society, ser. 2 1: 1 7 5 - 2 0 9 . S t o r m e r , L. 1 9 3 9 . Studies on trilobite morphology. Part I. T h e

Shaw, F. C, and P. J. Lesperance. 1994. N o r t h A m e r i c a b i o g e o g raphy and t a x o n o m y of Cryptolithus (Trilobita, O r d o v i c i a n ) .

t h o r a c i c appendages and their phylogenetic significance. Norsk G e o l o g y tidsskrift 19: 1 4 3 - 2 7 3 . . 1 9 5 1 . Studies on trilobite morphology. Part III. T h e ventral

Journal o f P a l e o n t o l o g y 6 8 : 8 0 8 - 8 2 3 . S h u , D . - G . , G. Geyer, L. C h e n , a n d X . - L . Z h a n g . 1995. Redlichiacean trilobites with preserved soft-parts from the Lower C a m brian C h e n g j i a n g fauna ( S o u t h C h i n a ) . In E. Landing and G. Geyer ( e d s . ) , M o r o c c o ' 9 5 : T h e L o w e r - M i d d l e C a m b r i a n standard o f western G o n w a n d a , pp. 2 0 3 - 2 4 2 . Beringeria Special Issue 2. W i i r z b u r g , G e r m a n y : Institiit fur Palaontologie der Universitat W i i r z b u r g .

cephalic structures with remarks on the zoological position of the trilobites. Norsk Geology tidsskrift 2 9 : 1 0 8 - 1 5 8 . Struve, W. 1 9 9 0 . Palaozoologie III ( 1 9 8 6 - 1 9 9 0 ) . Cour. Forsch.Inst. S e n c k e n b e r g 127: 2 5 1 - 2 7 9 . .

1992.

Neues zur stratigraphie und fauna des r h e n o -

typen M i t t e l - D e v o u i a n . Sencken bergiana Lethaea. 7 1 : 5 0 3 624.

Signor, P. W., and C. E. Brett. 1 9 8 4 . T h e m i d - P a l e o z o i c precursor

S t u m m , E. C. 1953a. Trilobites of the Devonian Traverse G r o u p

t o the M e s o z o i c m a r i n e revolution. Paleobiology 10: 2 2 9 -

o f M i c h i g a n . C o n t r i b u t i o n s o f the M u s e u m o f Paleontology,

245.

University o f M i c h i g a n 10: 1 0 1 - 1 5 7 .

Simpson.

1890.

Transactions

o f the A m e r i c a n

Philosophical

Society, n.s., 16: 4 6 0 . Sloss, S. L. 1 9 6 3 . S e q u e n c e s in the c r a t o n i c interior of N o r t h America.

Geological

Society o f A m e r i c a

Bulletin

74:

93-

1 9 5 3 b . Lower Middle Devonian proetid trilobites from

b u t i o n s o f the M u s e u m o f Paleontology, University o f M i c h i gan 1 1 : 1 1 - 3 1 . . 1967. Devonian trilobites from northwestern O h i o , n o r t h -

113. Smith, A. B. 1994. Systematics and the fossil record: d o c u m e n t -

. 1987. C o m p a r a t i v e t a p h o n o m y and paleoecology of trilo. 1990a. Gregarious behavior and r e p r o d u c t i o n in trilobites. In A. J. B o u c o t ( e d . ) , Evolutionary paleobiology and coevolution, pp. 4 0 5 - 4 0 9 . A m s t e r d a m : Elsevier.

A m s t e r d a m : Elsevier.

coevolution,

S t u r m e r , W., and J. B e r g s t r o m . 1 9 7 3 . New discoveries on trilobites by X-rays. Palaeontologische Zeitschrift 4 7 : 1 0 4 - 1 4 1 . Swirydczuk, K., B. H. W i l k i n s o n , and G. R. S m i t h . 1 9 8 1 . Synsed-

1 9 9 0 b . Trilobite m o l t patterns. In A. J. B o u c o t ( e d . ) , and

surprising results o f X-ray e x a m i n a t i o n o f Devonian slates. Science 170: 1 3 0 0 - 1 3 0 2 .

bite Lagerstatten. Alcheringa 11: 2 0 5 - 2 3 2 .

paleobiology

109-

122. S t u r m e r , W. 1 9 7 0 . Soft parts of cephalopods and trilobites: s o m e

Royal Society, E d i n b u r g h 7 6 : 2 2 1 - 2 2 3 .

Evolutionary

ern M i c h i g a n and western New York. C o n t r i b u t i o n s of the M u s e u m o f Paleontology, University o f Michigan 2 1 :

ing evolutionary patterns. Blackwell Scientific. 2 2 3 p. Speyer, S. E. 1 9 8 5 . M o u l t i n g in p h a c o p i d trilobites. T r a n s a c t i o n s

.

.

M i c h i g a n , southwestern O n t a r i o , and n o r t h e r n O h i o . C o n t r i -

pp.

491-499.

i m e n t a r y lacustrine phosphorites f r o m the Pliocene Glenns Ferry F o r m a t i o n o f southwestern Idaho. Journal o f S e d i m e n tation Petrology 5 1 : 1 2 0 5 - 1 2 1 4 .

187

REFERENCES Taylor, W. L, and C. E. Brett. 1996. T a p h o n o m y and paleoecol-

Vogdes, A. W. 1 8 7 9 . A s h o r t notice u p o n the geology of Catoosa

ogy of E c h i n o d e r m Lagerstatten from the Silurian ( W e n l o c k -

C o u n t y , Georgia. A m e r i c a n Journal of Science, 3rd ser. 18:

ian) Rochester Shale. Palaios 11: 1 1 8 - 1 4 0 .

475-477.

Tetreault, D. K. 1992. Paleoecologic implications of epibionts on

Vogel, K., S. G o b u l i c , and C. E. Brett. 1987. Endolith associations

the Silurian trilobite Arctinurus. N o r t h A m e r i c a n Paleontology

and their relation to facies distribution in the Middle Devon-

C o n v e n t i o n , abstracts and p r o g r a m , Paleontological Society

ian o f New York State. Lethaia 2 0 : 2 6 3 - 2 9 0 . Walcott, C. D. 1875a. D e s c r i p t i o n of a new species of trilobite.

special publication 6: 2 8 9 . . 1994. B r a c h i o p o d and trilobite biofacies of the Rochester

C i n c i n n a t i Q u a r t e r l y Journal o f Science 2 : 2 7 3 . . 1 8 7 5 b . New species of trilobite from the Trenton limestone

Shale (Silurian, Wenlockian Series) in western New York. New

at T r e n t o n Falls, N e w York. C i n c i n n a t i Quarterly Journal of

York State M u s e u m Bulletin 4 8 1 : 3 4 7 - 3 6 1 . T h o m a s , A. T., and D. S. Holloway. 1988. Classification and phy-

Science 2 : 3 4 7 - 3 4 9 . .

logeny of the trilobite order Lichida. Philosophical Transac-

1875c.

Notes on

Ceraurus pleurexanthemus Green.

Annals

o f the Lyceum o f Natural History, New York 1 1 : 1 5 5 - 1 5 9 .

tions o f the Royal Society, L o n d o n B 3 2 1 : 1 7 9 - 2 6 2 .

. 1 8 7 5 d . D e s c r i p t i o n of the interior surface of the dorsal shell

T h o m a s , A. T., and R. M. O w e n s . 1 9 7 8 . A review of the family Aulacopleuridae. Palaeontology 2 1 : 6 5 - 8 1 .

of

Tillman, C. G. 1 9 6 0 . S p a t h a e a l y m e n e , an unusual new Silurian trilobite genus. Journal o f Palaeontology 3 4 : 8 9 1 - 8 9 5 .

Ceraurus

pleurexanthemus

Green.

Annals

of

the

Lyceum

Natural History, New York 11: 1 5 9 - 1 6 2 . . 1876. P r e l i m i n a r y n o t i c e of the discovery of the remains of

Titus, R. 1982. Fossil c o m m u n i t i e s of the Middle Trenton G r o u p

the n a t a t o r y and brachial appendages of trilobites. Advanced

(Ordovician) o f New York State. Journal o f Paleontology 5 6 :

print, D e c . 1 8 7 6 . 2 8 t h Annual Report of the New York State

477-485.

M u s e u m o f Natural History 1 8 7 9 : 8 9 - 9 2 .

.

1986. Fossil c o m m u n i t i e s of the Upper Trenton G r o u p

.

1877a.

D e s c r i p t i o n of new species of fossils from the

(Ordovician) o f New York State. Journal o f Paleontology 6 0 :

Trenton L i m e s t o n e . Advanced print, Jan. 1877. 2 8 t h Annual

805-824.

Report New York State M u s e u m Natural History 1 8 7 9 : 9 3 - 9 7 .

Towe, K. M. 1 9 7 3 . Trilobite eyes: calcified lens in vivo. Science

.

1 8 7 7 b . Notes on s o m e sections of trilobites f r o m the

Trenton

179: 1 0 0 7 - 1 0 0 9 .

limestone.

Advanced

print,

Sept.

20,

1877.

31st

Treatise (revised). See Kaesler ( 1 9 9 7 ) .

Annual Report New York State M u s e u m Natural History 1879:

Ulrich, E. O. 1878. Descriptions of s o m e new species of fossils

61-63.

from the Cincinnati G r o u p . Journal of the C i n c i n n a t i Society of Natural History 1: 9 9 . . 1879. Description of a trilobite from the Niagara G r o u p of Indiana. Journal o f the C i n c i n n a t i Society o f Natural History . 1926. In R. R u e d e m a n n , T h e Utica a n d L o r r a i n e F o r m a tions of New York: Part 2 systematic paleontology: no. 2 M o l lusks, Crustaceans and Eurypterids. New York State M u s e u m . 1930. Ordovician trilobites of the family Telephidae and c o n c e r n e d stratigraphic correlations. United States National M u s e u m Proceedings 7 6 : 1 - 1 0 1 .

1 8 7 7 d . D e s c r i p t i o n s of new species of fossils from the

31st Annual

R e p o r t N e w York State M u s e u m

of Natural

History 1 8 7 9 : 6 8 - 7 1 . . 1879a. Description of new species of fossils f r o m the Cal-

bites of North A m e r i c a . Geological Society of A m e r i c a special paper 2 9 : 108. Boulder: Geological Society o f A m e r i c a .

131. Triarthrus becki. Advanced print, June

York. Part III. C o m p r i s i n g the survey of the T h i r d Geological District, 3 0 6 p. Albany. (Trilobita)

Ph.D.

in

New

dissertation,

York

Syracuse

State

and

University.

8 4 8 p.

1 8 8 1 . T h e trilobite: new a n d old evidence relating to

its organization.

Bulletin

o f the

Museum

o f Comparative

Zoology, Harvard 8 : 1 9 1 - 2 2 4 . .

Vere, V. K. 1972. T h e biostratigraphy, evolution and paleoaute-

1 8 7 9 . Transactions of

the Albany Institute 1 8 8 3 10: 1 8 - 3 8 . .

Vanuxem, L. 1842. Natural history of New York geology of New

of Cryptolithus

Report New York State M u s e u m Natural History 1 8 7 9 : 1 2 9 . 1 8 7 9 b . Fossils of the Utica Slate and the m e t a m o r p h o s e s of

Ulrich, E. O., and D. M. Delo. 1 9 4 0 . In D. M. Delo, P h a c o p i d trilo-

Vermont.

.

ciferous F o r m a t i o n . Advanced print Jan. 3, 1 8 7 9 . 3 2 n d Annual

Bulletin 2 7 2 : 128.

western

Natural History 1 8 7 9 : 6 6 - 6 7 . Chazy and Trenton limestones. Advanced print, Sept. 2 0 , 1877.

2: 131-134.

cology

. 1877c. N o t e on the eggs of the trilobite. Advanced print, Sept. 2 0 , 1877. 31st Annual Report New York State M u s e u m of

1890.

fossils.

Descriptions of new f o r m s of Upper C a m b r i a n

United

States

National

Museum

Proceedings

13:

267-279. . 1 8 9 1 . T h e fauna of the Lower C a m b r i a n or Olenellus zone. U.S. Geological Survey Tenth Annual R e p o r t , pp. 5 1 5 - 6 2 9 .

Ver Straeten, C. A., and C. E. Brett. 2 0 0 0 . Bulge m i g r a t i o n and

. 1 9 1 2 . C a m b r i a n geology and paleontology II, New York

pinnacle reef development, Devonian Appalachian foreland

P o t s d a m - H o y t fauna. S m i t h s o n i a n Miscellaneous Collections

basin. Journal o f Geology 108: 3 3 9 - 3 5 2 .

57: 269.

REFERENCES

188 . 1 9 1 8 . C a m b r i a n geology and paleontology, IV, appendages of trilobites. S m i t h s o n i a n Miscellaneous C o l l e c t i o n s 67: 115— 216.

. 1897. Descriptions of new species of Silurian fossils from

. 1 9 2 1 . C a m b r i a n geology and paleontology, IV, notes on the structure of Neolenus, s u p p l e m e n t a r y notes. S m i t h s o n i a n

near Fort Cassin and elsewhere on Lake C h a m p l a i n . American M u s e u m o f Natural History Bulletin 9 : 1 7 7 - 1 8 4 . Whittington,

Miscellaneous Collections 67: 3 7 7 - 4 5 6 . . 1924. C a m b r i a n and Lower Ozarkian trilobites. S m i t h s o n -

H.

B.

1941.

The

Trinucleidae—with

special

reference to N o r t h A m e r i c a n genera and species. Journal of Paleontology 15: 2 1 - 4 1 .

ian Miscellaneous Collections 7 5 : 5 3 - 6 0 . Weller, S. 1903. New Jersey Geological Survey: Paleontology 3:

. 1952. A u n i q u e remopleuridid trilobite. Breviora, Harvard 4: 1 - 9 .

252. .

. 1 8 8 9 b . Additional notes on Asaphus canalis, C o n r a d . A m e r ican M u s e u m o f Natural History Bulletin 11: 6 3 - 6 4 .

1907. T h e paleontology of the Niagaran L i m e s t o n e in

the C h i c a g o area: the Trilobita. C h i c a g o Academy o f Sciences

.

Bulletin 4, part II of the Natural History Survey, 281 p. Westrop, S. R. 1 9 8 3 . T h e life habits of the O r d o v i c i a n illaenine trilobite Bumastoidcs.

Lethaia

16:

.

14-24.

1953.

North American

Bathyuridae and

Leiostegiidae

( T r i l o b i t a ) . lournal o f Paleontology 27: 6 4 7 - 6 7 8 . 1957.

O n t o g e n y of Ellipsoccphala,

Paradoxides,

Sao,

Blainia,

and Triarthrus ( T r i l o b i t a ) . Journal o f Paleontology 3 1 : 9 3 4 946.

Westrop, S. R., L. A. K n o x , and E. Landing, 1 9 9 3 . Lower O r d o v i -

. 1 9 5 9 . Silicified Middle Ordovician trilobites: Remopleuri-

cian ( I b e x i a n ) trilobites f r o m the Tribes Hill F o r m a t i o n , central

dae, Trinucleidae, R a p h i o p h o r i d a e , E n d y m i o n i i d a e . Bulletin of

M o h a w k Valley, New York State. C a n a d i a n Journal of Earth

the M u s e u m o f C o m p a r a t i v e Zoology, Harvard 1 2 1 : 3 7 1 - 4 9 6 .

Sciences 3 0 : 1 6 1 8 - 1 6 3 3 . Whiteley, T.

E.,

C.

E.

.

Brett, and

D.

Lehmann.

1993.

The

W a l c o t t - R u s t Q u a r r y ; a u n i q u e O r d o v i c i a n trilobite K o n s e r -

1 9 6 0 . Cordania and o t h e r trilobites from the Lower and

M i d d l e D e v o n i a n . Journal o f Paleontology 3 4 : 4 0 5 - 4 2 0 . .

1961a. M i d d l e Ordovician Pliomeridae (Trilobita) from

vat-Lagerstatte. Geological Society o f N o r t h A m e r i c a , N o r t h -

Nevada,

eastern

Paleontology 3 5 : 9 1 1 - 9 2 2 .

Section,

28th

Annual

Meeting,

Abstracts

with

programs, 25: 89. York State 3: Caleb's Q u a r r y : Part I, the trilobites. A m e r i c a n Paleontologist 9, No. 1: 3 - 5 . fossils in the collections of the m u s e u m and c o r r e c t i o n of prespecies.

American

Museum

o f Natural

History M e m o i r 1: 146. i n the collections o f the m u s e u m , and c o r r e c t i o n s o f previously species.

American

Museum

o f Natural

History

Bulletin 5 : 1 4 9 - 1 5 3 . .

1885.

Notice

.

Newfoundland.

lournal

of

1963. Middle Ordovician trilobites from Lower Head, Newfoundland.

Museum

o f Comparative Zoology

( H a r v a r d ) Bulletin 129: 1 - 1 1 8 . . 1966. Phylogeny and distribution of Ordovician trilobites. lournal o f Paleontology 4 0 : 6 9 6 - 7 3 7 . .

. 1 8 8 4 b . N o t i c e of s o m e new species of p r i m o r d i a l fossils described

Quebec,

(August): 8 - 1 7 . western

Whitfield, R. P. 1884a. Notice of s o m e new species of primordial described

York,

. 1 9 6 1 b . A natural history of trilobites. Natural History 70

Whiteley, T. E., a n d K. S m i t h . 2 0 0 1 . Fossil Lagerstatten of New

viously

New

1968.

Cryptolithus

(Trilobita):

specific

characters

and

o c c u r r e n c e in O r d o v i c i a n of eastern North A m e r i c a . Journal of Paleontology 4 2 : 7 0 2 - 7 1 4 . . 1971a. Silurian calymenid trilobites from the United States, Norway, and Sweden. Palaeontology 14: 4 5 5 - 4 7 7 .

of a

very

large

species

of Homalonotus

. 1 9 7 1 b . T h e Burgess Shale: history of research and preser-

from the Oriskany sandstone f o r m a t i o n . A m e r i c a n M u s e u m o f

vation of fossils. Proceedings of the First North American

Natural History Bulletin 6: 1 9 3 - 1 9 5 .

Paleontological C o n v e n t i o n 1: 1 1 7 6 - 1 2 0 1 .

. 1886a. Notice of geological investigations along the eastern

. 1 9 8 0 . Exoskeleton, m o u l t stage, appendage with habits of

share of Lake C h a m p l a i n , c o n d u c t e d by Prof. H. Seely and

the M i d d l e C a m b r i a n trilobite Olenoides serratus.

Pres. Ezra Brainerd of M i d d l e b u r y College, with descriptions

ogy 2 3 : 1 7 1 - 2 0 4 .

of the new fossils discovered. A m e r i c a n M u s e u m of Natural History Bulletin 7: 3 3 6 . . 1886b. Notice of geological investigations along the eastern shore of Lake C h a m p l a i n c o n d u c t e d by Prof. H. M. Seely and Pres. Ezra Brainard of M i d d l e b u r y College, with descriptions

Palaeontol-

. 1 9 8 5 . T h e Burgess Shale. New Haven: Yale University Press. 151 p. . 1992. Trilobites. Rochester, N . Y : Boydell Press. 145 p., 120 plates. .

1993.

Anatomy

of the

Ordovician

trilobite

Placoparia.

of the new fossils discovered. A m e r i c a n M u s e u m of Natural

Philosophical Transactions of the Royal Society, L o n d o n 3 3 9 :

History Bulletin 8 : 2 9 3 - 3 4 5 .

109-118.

. 1889a. O b s e r v a t i o n s on s o m e imperfectly k n o w n fossils

. 1997a. Life m o d e , habits and o c c u r r e n c e . In R. L. Kaesler

from the calciferous sandrock of Lake C h a m p l a i n , and descrip-

( e d . ) , Treatise on invertebrate paleontology: part O, Arthro-

tions o f several new f o r m s . A m e r i c a n M u s e u m o f Natural

poda 1, Trilobita, revised, pp. 1 5 2 - 1 5 8 . Boulder: Geological

History Bulletin 1 1 : 4 1 - 6 3 .

Society o f A m e r i c a .

189

REFERENCES .

1997b.

Illaenidae

(Trilobita):

morphology

of t h o r a x ,

W i l s o n , A. E. 1947. Trilobita of the Ottawa F o r m a t i o n of the

classification, and m o d e o f life. Journal o f Paleontology 7 1 :

O t t a w a - S t . Lawrence lowland. Geological Survey Bulletin 9.

878-896.

C a n a d i a n D e p a r t m e n t of M i n e s and Resources. 86 p. Ottawa.

Whittington, H. B., and J. E. A l m o n d . 1987. Appendages and habits

of the

Upper

Ordovician

trilobite

Triarthrus

eatoni.

Philosophical Transactions of the Royal Society, L o n d o n B 3 1 7 : 1-46. W h i t t i n g t o n , H. B., and W. R. Evitt.

ans. Journal o f Paleontology 2 5 : 6 1 7 - 6 5 4 . W i t z k e , B. J. 1 9 9 0 . Palaeoclimate constraints for Palaeozoic palaeolatitudes of Laurentia a n d E u r o a m e r i c a . In W. S. McKerrow

1954. Silicified M i d d l e

Ordovician trilobites. Geological Society o f A m e r i c a M e m o i r 5 9 : 137. W h i t t i n g t o n , Fi. B., and C. P. Hughes. 1972. O r d o v i c i a n geography and faunal provinces deduced from trilobite distribution. Philosophical Transactions of the Royal Society, L o n d o n 2 6 3 : 235-278. W h i t t i n g t o n , H. B., and S. R. A. Kelly. 1997. M o r p h o l o g i c a l terms applied to Trilobita. In R. L. Kaesler ( e d . ) , Treatise on invertebrate paleontology: part O, A r t h r o p o d a 1, Trilobita, revised, pp. 3 1 3 - 3 2 9 . Boulder, Col.: Geological Society o f A m e r i c a a n d the University of Kansas.

W i l s o n , J. L. 1 9 5 1 . F r a n c o n i a n trilobites of the central Appalachi-

and C.

R. Scotese ( e d s . ) , Palaeozoic palaeogeography and

biogeography, pp. 5 7 - 7 3 . M e m o i r 12. L o n d o n : Geographical Society. Yochelson, E. L. 1987. Walcott in Albany, New York: James Hall's "special assistant." Earth Sciences History 6: 8 6 - 9 4 . Yochelson, E. L., and M. A. F e d o n k i n . 1 9 9 3 . Paleobiology of Climactichnites, an e n i g m a t i c late C a m b r i a n

fossil. S m i t h s o n i a n

C o n t r i b u t i o n s to Paleobiology 7 4 . pp. 1 - 7 4 . Young, F. P. 1943a. Black River stratigraphy and faunas, part I. A m e r i c a n Journal o f S c i e n c e 2 4 1 : 1 4 1 - 1 6 6 . .

1943b.

Black

River stratigraphy and

A m e r i c a n Journal o f Science 2 4 1 : 2 0 9 - 2 4 0 .

faunas, part

II.

Trilobite Index: Order-Family-Genus-Species T h e arrangement of the orders in this index reflects that in the trilobite Treatise (revised) (Kaesler 1 9 9 7 ) . Families, genera, and species are alphabetical.

ORPIR

FAMILY

GENUS

Agnostida

Diplagnostidae

Baltagnostus

angustilobus

118

Baltagnostus

stockportensis

56, 118

Peronopsis

evansi

56, 118

Peronopsis

primigenea

56, 118

Ptychagnostus

gibbus

56, 1 I 8

Ptychagnostus

punctuosus

56, 118

Peronopsidae Ptychagnostidae

Spinagnostidae

Calodiscidae

Eodiscidae

Hebediscidae Weymouthiidae

SPECIES

PAGE

Ptychagnostus

elegans

56, 118

Eoagnostus

acrorachis

56, 118

Eoagnostus

primigeneus

118

Hypagnostus

parvifrons

56, 1 18

Calodiscus

agnostoides

55, 119

Calodiscus

fissifrons

55, 119

Calodiscus

lobatus

55, 119

Calodiscus

meeki

55, 119

Calodiscus

occipitalis

55, 119

Calodiscus

reticulums

56,119

Calodiscus

schucherti

56, 119

Calodiscus

theokritoffi

56, 119

Calodiscus

walcotti

56, 119

Chelediscus

chathamsis

56, 119

Pagetia

bigranulosa

56, 119

Pagetia

connexa

56, 119

Pagetia

clytioides

56, 1 19

Pagetia

erratic

56, 1 19

Pagetia

laevis

119

Pagetides

amplifrons

56, 119 56, 119

Pagetides

elegans

Pagetides

leiopygus

56, 119

Pagetides

minutus

56, 119 56, 1 1 9

Pagetides

rupestris

Hebediscus

marginatus

119

Neopagetina

taconica

56, 119

PLATE

IE

Acidiscus

birdi

55, 119

Acidiscus

hexacauthus

55,119

1H

Acimetopus

bilobatus

55,119

1A

Analox

bipunctata

119

Analox

obtusa

119

Bathydiscus

dolichometopus

55, 119

Bolboparia

elongata

55,119

IF

191

192 ORDER

T R I L O B I T E

FAMILY

SPECIES

PAGE

V. ATI

Bolboparia

superba

55, 119

IE

Leptochilodiscus

punctulatus

56, 120

Litometopus

punctulatus

120

Mallagnostus

desideratus

120

Microdisctis

connexus

120

Oodiscus

binodosus

56, 120

GENUS

Oodhcus

longifrons

120

Oodiscus

subgranulatus

56, 120

Serrodiscus

griswoldi

56, 120

Serrodiscus

latus

120

Serrodiscus

speciosus

56, 120

Serrodiscus

spinulosus

56, 120

Serrodiscus

subclovatus

56, 120

Stigmadiscus

gibbosus

56, 120

Stigmadiscus

stenontetopus

56, 120

Weymoutliia

nobilis

56, 120 56, 118

Redlichiida

Holmiidae

Elliptocephala

asaphoides

Corynexochida

Dolichometopidae

Athabaskiella

proba

1 IS

Bathyuriscidella

socialis

118

Bathyuriscus

eboracensis

56, 118

Bathyuriscus

fibriatus

118

Corynexochidcs

expansus

56, 118

Fordaspis

nana

55, 56, 118

Kootenia

fordi

55, 56, 120

Olenoides

stissingcnsis

120

Olenoides

stockportensis

56

Bumastoides

aplatus

120

Bumastoides

bellevillensis

121

Bumastoides

billingsi

66, 121

Dorypygidae

Illaenidae

Styginidae

I N D E X

H,

I B , C, D, K

IK, 2

Bumastoides

comes

62

Bumastoides

gardenensis

62, 121

Bumastoides

globosus

62, 121

3

Bumastoides

holei

75, 121

4, 5

Bumastoides

milleri

66, 121

6

Bumastoides

porrectus

7 1 , 75, 121

7

Bumastoides

trentonensis

7 1 , 121

Illaenus

arcturus

121

IUaenus

consimilis

122

Illaenus

crassicauda

62

Illaenus

latidorsata

71

Nanillaenus

americanus

75, 122

Nanillaenus

conradi

7 1 , 122

Nanillaenus

latiaxiatus

66, 122

Nanillaenus

punctatus

62, 122

Nanillaenus

raymondi

62, 122

10A

Thaleops

longispina

62, 122

10B

Thaleops

ovata

62, 66, 122

Bumastus

ioxus

89, 123

11

Eobronteus

lunatus

78, 123

12

Eobronteus

62

S 9

TRILOBITE ORDER

Lichida

INDEX FAMILY

GENUS

SPECIES

PAGE

Failleana

indeterminata

66, 123

13

Illaenoides

cf.

trilohita

89, 123

14, 15

Platillaenus

erastusi

62, 123

Platillaenus

limbatus

123

Scutellum

barrandi

123

ScuteUum

niagarensis

85, 123

Scutellum

pompilius

98, 123

Scutellum

rochesterense

88, 89, 123

26B

Scutellum

senescens

116, 123

17

Scutellum

tullius

112,123

IS

Scutellum

wardi

93, 124

Zacanthoididae

Prozacanthoides

eatoni

56, 124

Lichidae

Acanthopyge

consanquinea

98, 124, 125

Acanthopyge

contusa

107, 124, 125

Amphilichas

conifrons

75, 124

Amphilichas

cornutus

75, 124

Amphilichas

minganensis

62, 124 7 1 , 124

Amphilichas

trentonensis

Arctinurus

boltoni

1, 18, 89, 126

Autoloxolichas

inconsuetus

7 1 , 126

Ceratolichas

dracon

107, 125, 126

Ceratolichas

PLATE

16

19

20, 21

107, 125, 126

Dicranopeltis

fragosa

126

Dicranopeltis

nereus

27, 89, 126

22, 23

Echinolichas

eriopsis

107, 126

24

Echinolichas

hispidus

105, 107, 125,

Hemiarges

paulianus

69, 7 1 , 126

25

lichid

sp.

126

26A

Oinochoe

bigsbyi

98, 125, 126

Oinochoe

pustulosis

98, 127

27

Richterarges

ptyonurus

127

28

Terataspis

grandis

17, 105, 107,

29

126

127

Odontopleuridae

Trochurus

bulbosa

127

Trochurus

halli

89, 127

Trochurus

phlyctainoides

127

Apianurus

narrawayi

62, 127

Ceratocara

shawi

127

Ceratocephala

triacantheis

62, 128

Diacanthaspis

parvula

75, 128

Dicranurus

elegantus

Dicranurus

hamatus

128

Kettneraspis

callicera

105, 107, 128

Kettneraspis

sp.

128

36

Kettneraspis

tuberculata

6, 98, 128

35 37, 38

30, 31

32 33

Meadowtownella

trentonensis

75, 128

Odontopleura

cerelepta

80, 128

Odontopleura

sp.

128

Primaspis?

crosota

128

34

39

194

TRILOBITE

ORDER

FAMILY

GENUS

Phacopida

Acastidae

asteropygin

SPECIES

PAGE

PLATE

129

40

112,129

41

Astropyginae aff. Greenops Bellacartwrightia

Calymenidae

Cheiruridae

INDEX

49 calderonae

Bellacartwrightia

calliteles

129

Bellacartwrightia

jennae

112, 129, 130

42, 43

Bellacartwrightia

phyllocaudata

112, 129, 130

44

Bellacartwrightia

pleione

107, 130, 131

Bellacartwrightia

whiteleyi

112,131

45

Bellacartwrightia

sp.

112,131

46, 47, 48

Greenops

barber i

112, 130, 131

50

Greenops

boothi

130, 131

51

Greenops

grabaui

11, 112, 131

52, 53,54

Greenops

sp.

11, 131

55, 56

Kennacryphaeus

harrisae

112, 131

Calymene

camerata

132

Calymene

conradi

80, 132

Calymene

niagarensis

9, 89, 132

58, 59

Calymene

platys

105, 107, 132

60

Calymene

singularis

93, 132

hi

calymenid

sp.

8, 27, 132

62, 63

Diacalymene

rostrata

85, 132

Diacalymene

sp.

132 132

57

64, 65

Diacalymene

vogdesi

Flexicalymene

granulosa

80, 133

Flexicalymene

meeki

25, 80, 133

Flexicalymene

senaria

14, 6 9 , 7 1 , 7 5 ,

67, 68, 69,

123

70

Gravicalymene

magnotuberculata

7 1 , 133

71,72

Liocalymene

clintoni

89, 133

73

Liocalymene

cresapensis

133

Acanthoparypha

sp.

62, 134

Acanthoparypha

trentonensis

134

Ceraurinella

latipyge

62, 134

86C

Ceraurinella

scofieldi

66, 134

74

Ceraurinus

marginatus

80, 134

75

Ceraurinus

sp.

134

Cerauropeltis

ruedemanni

62, 134

84C to E

Ceraurus

montyensis

134

Ceraurus

pleurexanthemus

9, 12, 19, 20,

Ceraurus

125

79, 80

Cheirurus

sp. sp.

135

81

Deiphon

pisum

89, 135

84B

Forteyops

approximus

135

Gabriceraurus

dentatus

7 1 , 75, 135

Gabriceraurus

hudsoni

62, 135

Heliomera

akocephala

62, 135

Kawina

chazyensis

62, 135

Kawina

vulcanus

62, 135

Nieszkowskia

satyrus

62, 135

Sphaerexochus

parvus

62, 135

Sphaerocoryphe

goodnovi

62, 135

76, 77, 78

2 2 , 7 1 , 134

82, 83

86B

TRILOBITE ORDER

195

INDEX FAMILY

GENUS

major

78, 135

robusta

75, 135

85

136

91B

Corycephalus

pygmaeus

107, 136

regalis

105, 137, 138

Dalmanites

aspinosus

137

Dalmanites

bisigmatus

101, 137

Dalmanites

limulurus limulurus

18, 27, 89, 137

Dalmanites

limulurus lunatus

137

pleuroptyx sp.

4(1

91A

russelli

137

nasutus

98, 137, 138

Neoprobilium

tridens

98, 137, 138 137

Odontochile

micrurus

98, 137

Odontochile

phacoptyx

101, 139

odontochilid Phalangocephalus

sp.

139

dentatus

88, 89

137

Forillonaria

litchfieldensis

87

98, 137

Neoprobilium Odontochile

92 43

138, 139

Cybeloides

ella

Cybeloides

prima

139

86B

Encrinurus

cf. raybesti

85, 93, 139

95

Encrinurus

139

139

96

Erratencrinurus

vigilans

69, 7 1 , 139

94

Physemataspis

insularis

139

86D

Brogniartella

trentonensis

139

sp.

Dipleura

dekayi

11, 140

Homalouotus

major

17, 101, 140

Trimerus Phacopidae

sp.

Corycephalus

Dalmanites

Homalonotidae

PLATI

Sphacrocoryphe

Dalmanites

Encrinuridae

PAGE

Sphaerocoryphe Staurocephalus Dalmanitidae

SPECIES

delphinocephalus

89, 93, 140

Trimerus

vanuxemi

101, 140

Burtonops

cristatus

102, 105, 140,

97, 98 99

141, 143 Eldredgeops Eldredgeops Eldredgeops

crassituberculatus rana rana norwoodensis

112, 141

100

2, 5 , 3 4 , 112,

101, 11

142

103, 11

112, 142

Eophacops

trisulcatus

85, 144

Paciphacops

hudsoniscus

141, 143, 144

Paciphacops

clarkci

101, 141, 143,

Paciphacops

logani

98, 107, 141,

Paciphacops

logani subsp. A

Phacopina

anceps

144

Phacops?

clarksoni

105, 141, 143,

Phacops?

iowensis

105, 11

144 143, 144

107

141, 144

144 112, 142, 144

108

Viaphacops

bombifrons

9, 107, 142,

109

Pliomerops

canadensis

62, 145

143, 145 Pliomeridae

112, 11 114

Pterygometopidae

Achatella

achates

23, 75, 78, 145

113

196 ORDER

TRILOBITE FAMILY

GENUS

SPECIES

PAGE

Calyptaulax

annulata

62, 145

Calyptaulax

callicephalus

9, 7 1 , 75, 78,

INDEX

PLATE

116,117

145

Synphoriidae

Calyptaulax

eboraceous

7 1 , 75, 78, 145

Calyptaulax

spbebryx

7 1 , 146

Chasmops? Eomonorachus

convexus

7 1 , 146

119

Anchiopella

anchiops

102, 105, 136,

120

Anchiopella

sobrinus

105, 146

Coronura

aspectans

107, 146

121, 122

Coronura

helena

107, 146

127B

Coronura

myrmecophorus

17, 107, 138,

Odontocephalus

aegeria

107, 147

123

Odontocephalus

bifidus

107, 147

124

Odontocephalus

coronatus

107, 147

Odontocephalus

humboltensis

107, 147

Odontocephalus

selenurus

107, 147

125

Odontocephalus

sp.

147

126

Schoharia

emarginata

105, 147

Schoharia

sp.

148

Synphoria

concinnus

105, 107, 148

Synphoria

sopita

Synphoria

stemmata

compacta

101, 148

Synphoria

stemmata

stemmata

101, 138, 148

Synphoroides

dolphi

148

Trypaulites

calypso

138, 148

Trypaulites

erinus

105, 107, 148

Trypaulites

macrops

107, 148

Cyphaspis

sp.

112, 149

Harpidella

craspedota

149

H a rpi delta

sp.

149

131

Harpidella

spinafrons

112, 149

129,130

7 1 , 146

118

146

147

Proetida

Aulacopleuridae

101, 148

Harpidella

stephanophora

107, 149

Maurotarion

minuscula

102, 105, 107,

Maurotarion

sp.

Otarion?

coelebs

149

Otarion?

diadema

107, 149

Otarion?

hudsonicum

80, 149

Otarion?

hybrida

107, 149

Otarion?

laevis

116, 149

Otarion?

matutinurn

78, 149

Otarion?

spinicaudatum

62, 149

Acidiphorus

whittingtoni

6 1 , 150

Bathyurellus

platypus

6 1 , 150

Bathyuropsis

schucherti

71

Bathyurus

cf. B. angelina

150

Bathyurus

extans

150

Bathyurus

johnsoni

66, 150

127A

128

149

Bathyuridae

132

133

TRILOBITE ORDER

197

INDEX FAMILY

Brachymetopidae

GENUS

SPECIES

PAGE 61

Bathyurus

perkinsi

Bathyurus

taurifrons

150

Benthamaspis

striata

6 1 , 150

Bolhocephalus

seelyi

Grinnellaspis

cf. G.

Raymondites

ingalli

7 1 , 150

Raymondites

longispinus

66, 150

PLATE

6 1 , 150 marginiata

6 1 , 150

Raymondites

spiniger

66, 150

Strigigenalis

cassinensis

6 1 , 151

Strigigenalis Uromystrum

caudatus brevispinum

6 1 , 151

Uromystrum

minor

62, 151

Australosutera

gemmaea

107, 112, 151

Cordania

becraftensis

101, 151

62, 151 134

Cordania

cyclurus

98, 151

Mystrocephala

arenicolus

105, 151

Mystrocephala

ornata

151

Mystrocephala

baccata

112,151

Mystrocephala

varicella

107, 151

Radnoria

sp.

151

Dimeropygidae

Dimeropyge

clintonensis

62, 151

Proetidae

Basidechenella

hesionea

105, 152, 153

Coniproetus

angustifrons

105, 152, 153

Coniproetus

conradi

105, 152, 153

Coniproetus

folliceps

107, 152, 154

Cornuproetus

beecheri

78, 80, 152,

Crassiproetus

brevispinus

107, 152, 154

Crassiproetus

crassimarginatus

107, 152, 154

Crassiproetus

neoturgitus

107, 154, 155

Crassiproetus

schohariensis

101, 153, 155

Crassiproetus

stummi

107, 153, 155

Cyphoproetus

wilsonae

7 1 , 155

Dechenella

haldemani

112, 154, 155

138

Decoroproetus

corycoeus

89, 155

139, 140

135

136

153

Gerastos

protuberans

153, 155

Hedstroemia

pachydermata

153, 155

Mannopyge

halli

107, 154, 155

Monodechenella

macrocephala

9, 112, 154, 155

Proetus

artiaxis

93, 153, 156

Proetus

clelandi

62, 153, 156

Proetus

hesione

153

Proetus

jejunus

112, 154, 156

Proetus

marginalis

154,156

Proetus

microgemma

154, 156

Proetus

parviusculus

153, 156

Proetus

spurlocki

80, 153, 156

Proetus

tenuisulcatus

93, 153, 156

Proetus

undulostriatulus

153, 156

proetid

sp.

156

Pseudodechenella

arkonensis

112, 154, 156

Pseudodechenella

canaliculata

107, 153, 157

137

141

142

TRILOBITE

198 ORDER

FAMILY

INDEX

GENUS

SPECIES

PAGE

PLATE

Pseudodechenella

clara

107, 154, 157

143

Pseudodechenella

rowi

112, 154, 157

144, 145 146, 147

Asaphida

Asaphidae

Basilicus

romingeri

157

Basilicas

ulrichi

66, 157 66, 157

Basilicus

vetustus

Basilicus

whittingtoni

17, 62, 158

Basiliella

barrandi

66, 158

Belle font ia

gyracanthus

6 1 , 158

Ectenaspis?

homalonotoides

66, 158

Homotelus

stegops

80, 158

Hyboaspis

depressa

62, 158

Isoteloidcs

angusticaudus

62, 158

Isoteloides

canalis

6 1 , 6 2 , 158

Isoteloides

peri

6 1 , 158

Isoteloides

whitfieldi

61

lsotelus

annectans

159

Isotelus

beta

62

lsotelus

giganteus

17, 62, 159

Isotelus

g'gas

148

149

1, 12, 14, 17,

150, 151,

2 3 , 7 1 , 7 5 , 159

152, 153

Isotelus

harrisi

62, 159

Isotelus

jacobus

7 1 , 159

Isotelus

latus

7 1 , 159

Isotelus

maximus

9, 17, 78, 159

Isotelus

platycephalus

1, 159

154, 155, 156, 157

Isotelus

pulaskiensis

80, 160

Isotelus

simplex

66, 160

Isotelus

walcotti

3, 75, 160

Niloides

perkinsi

62, 160

Pseudogygites

latimarginatus

80, 160

Vogdesia

bear si

62, 160

Vogdesia

obtusus

62, 160

Idahoiidae

Saratogia

calcifera

5 1 , 160

Pterocephaliidae

Cameraspis

convexa

5 1 , 160

Cameraspis

sp.

160

Conaspis

whitehallensis

160

Idiomesus Kiethiella

spdepressa

5 1 , 161

Lonchodoinas

chaziensis

62, 161

Lonchodonias

halli

62, 161

Lonchodoinas

hastatus

78, 161

Apatokephaloides

sp.

161

Hypodicranotus

striatulus

23, 75, 161

Remopleurides

canadensis

62, 161

Reniopleuridcs

linguatus

78, 161

Remopleurides

tumidus

78, 161

Richardsonella

sp.

101

Roberviella

brevilingua

6 1 , 161

Ptychaspididac

Raphiophoridae

Remopleurididae

158 159

175B

161

160, 161, 162

TRILOBITE ORDER

199

INDEX FAMILY Saukiidae

Symphysurinidae Trinucleidae

GENUS

SPECIES

PAGE 5 1 , 162

Hoytaspis

speciosa

Prosaukia

briarcliffensis

162

Prosaukia

hartti

5 1 , 162

Prosaukia

tribulis

5 1 , 162

Symphysurina

convexa

6 1 , 162

Symphysurina

woosteri

6 1 , 162

Cryptolithus

bchulus

20, 23, 28,

PLATE

175A

163

78, 80, 162 Cryptolithus

loretlensis

11,28, 6 9 , 7 1 ,

164, 165

162

Ptychopariida

Conocoryphidae Dokimocephalidae l-.lviniidae

Glaphuridae Harpidae

Cryptolithus

tcsseUatus

28, 69, 7 1 , 163

Trctaspis

diademata

78, 163

Tretaspis

reticulata

78, 163

Atops

trilineatus

55, 163

Conocoryphe

verrucosa

163

Sulcocephalus

saratogensis

163

166, 167

Calocephalites

minimus

5 1 , 163

Dellea

landingi

5 1 , 163

Ih-llca

saratogensis

5 1 , 164

1 )rabia

curtoccipita

5 1 , 164

Drabia

menusa

5 1 , 164

Elvinia

granulata

5 1 , 164

Glaphurina

lamottensis

62, 165

168B

Glaphurus

pustulosus

62, 165

168 A

Dolichoharpes

sp.

62, 165

Eoharpes

pustulosus

66, 165

Hibbertia

ottawaensis

165

Hibbcrtia

sp.

62, 165

167C

Hibbertia

valcourensis

62, 165

169A, B

Scotoharpes

cassiuensis

6 1 , 165

169D

Hystricurus

conicus

6 1 , 165

Hystricurus

crotalifrons

6 1 , 165

Hystricurus

ellipticus

6 1 , 165

Hystricurus

oculilunatus

6 1 , 166

Kingstoniidae

Kingstonia

seelyi

166

Komaspididae

Carrickia

setoni

62, 166

Lonchocephalidae

Lonchocephalus

sp.

166

Marjumiidae

Modocia

punctata

166

Menomoniidae

Bolaspidclla

fisheri

56, 166

Olenidae

Triarthrus

beckii

7 1 , 76, 166

170

Triarthrus

eatoni

14, 19, 20, 22,

171, 172

Hystricuridae

23, 78, 80, 166

Plethopeltidae

Ptychopariidae

Uncertain

Triarthrus

ghiber

80, 167

Triarthrus

spinosus

80, 167

Plethoinetopus

knopfi

167

Plethopeltis

granulosa

5 1 , 167

Plethopeltis

saratogensis

5 1 , 167

Ptychoparia

minuta

167

Ptychoparia

matheri

167

Shumardiidae

Shumardia

pusilla

6 1 , 167

Solenopleuridae

Rimouskia

typica

56, 167

Uncertain

Clelandia

parabola

167

173, 174

175C

Index

Abrasion, corrosion, and encrustation, 37

Cabot Head Shales, 83

Daedalus,

Caladonian Orogeny, 83, 100

Dawes Sandstone, 86

85

Cambrian allochthon, 51-56

Day Point F o r m a t i o n , 62

Cambrian autochthon, 4 9 - 5 1

death, 32

Agnostida, 117

Cambrian Period, 46-56

Death, decay and disarticulation, 32, 35

Agnostina, 117

C a m b r i a n stratigraphic charts, 52,

Acadian Orogeny, 49, 97, 99, 100, 105, 107, 110, 112, 115, 116

Alden pyrite beds, 111

55

1 )e( lew Formation, 90 Decker F o r m a t i o n , 95

Algonquin A r c h , 85, 86

Camillus F o r m a t i o n , 109

Alsen Formation, 99, 100, 101

Canajoharie A r c h , 69

Deep Run Member, 111

Ammonoosuc island arc, 6 1 , 62

Canajoharie Shale, 76

Deer River Shale, 76, 78

Amsterdam Formation, 68, 70

Cardiff F o r m a t i o n , 109

D e l p h i Station Member, 110

apodemes, 12

Carlisle Center Sandstone, 102

Denley F o r m a t i o n , 70, 7 1 , 72, 73, 74

appendages, 17, 19, 20

Catskill facies, 115

D e n m a r k F o r m a t i o n , 71

Arthrophycus,

Cedar Valley Limestone, 112

Devonian Period, 95-116

articulated remains, 33-35

cephalic border, 8

Devonian stratigraphic charts, 96, 97, 103,

Asaphida, 157

cephalic spine, 6

Ashokan Formation, 110

cephalic sutures, 9

Austin Glen Formation, 55, 64, 66, 81

cephalon, 5, 8

Dolgeville F o r m a t i o n , 76, 77, 78

Avalonia, 49, 100, 116

Centerfield Member, 110

doublure, 12

axial lobe, 5

Chazy G r o u p , 59, 62, 63

85

Chazy stratigraphic chart, 63

Deep K i l l F o r m a t i o n , 55, 61

108, 115 disarticulation, 34

Early Devonian, 96

Bald H i l l bentonite, 100

C h e m u n g facies, 115

Early Silurian, 83-85

Baltica, 49, 83

Chenango Member, 110

Eastern Trenton equivalents and Utica

basis, 19, 20

Cherokee U n c o n f o r m i t y , 80, 8 1 , 83,

Beaver Dam Shale, 102

84

Shale, 76-78 Edgecliff Member, 105

Becraft Limestone, 99, 100, 101

Cherry Valley Limestone, 109

eggs, 13

Beecher's Trilobite Bed, 17, 28, 40, 78

Chestnut Street bed, 107

endites, 19, 21

Beekmantown G r o u p , 57, 61

Chittenango Shale Member, 60

Eodiscina, 118

Bertie G r o u p , 83, 95

City Brook bed, 71

Eramosa F o r m a t i o n , 93

b i o h e r m , 62, 88, 90, 9 1 , 92, 105

cladistics, 30-31

l.sopus Formation, 101, 102

biostratinomy, 32

C l i n t o n G r o u p , 83, 84, 85

e v o l u t i o n , 30

Black River G r o u p , 59, 64, 67

C l i n t o n i r o n ores, 85

exites, 19

Bloomsburg Formation, 94

Cobleskill Limestone, 95

exoskeleton, 4 - 6

Bois Blanc Formation, 102

Coeymans Member, 96, 98, 101

exoskeletons w i t h attached fauna, 18

brachial appendage, 19, 20

Cole H i l l tongue, 110

eyes, 7

Bridgewater Member, 109

C o l u m b u s Limestone, 105

Bridport Member, 61

Corynexochida, 118

Findley A r c h , 85

Brown's Creek bed, 4 1 , 111

cranidium, 7

fixed cheek, 8

Browns Pond f o r m a t i o n , 53, 55

Creek phase (Tippecanoe Supersequence),

Flat Creek F o r m a t i o n , 76

Burgess Shale, 17

62, 64, 68

Fonda Member, 60

Burleigh H i l l Member, 89

C r o w n Point F o r m a t i o n , 62

Fort Cassin F o r m a t i o n , 60, 61

Butternut Member, 110

Cruziana,

fossil diagenesis, 32, 37-40

102

201

202 Fragmentation, and biased preservation, 36-37

INDEX Irondequoit Limestone, 87, 88, 91

m o l t i n g , 14, 15

Ivy Point Member, 111

Moorehouse Member, 105

Frankfort F o r m a t i o n , 78, 80, 81

Moscow F o r m a t i o n , 111

free cheek, 8

Jamesville Member, 98

M o t t v i l l e Member, 110

Frontenac A r c h , 57

Jaycox Member, 111

M o u n t M a r i o n Formation, 106, 109

Galway Formation, 51

Jeffersonville Limestone, 105

M o u n t M e r i n o Formation, 55, 63

Joshua Coral bed, 111

Moyer Creek Member, 78 M u r d e r Creek Beds, 42

Gasport F o r m a t i o n , 90, 92

muscles, 22

genal angle, 10

Kalkberg F o r m a t i o n , 96, 98, 101

genal spine, 6

Kashong Member, 111

Genesee Formation, 115

Kaskaskia Supersequence, 100

Napanee F o r m a t i o n , 67, 68, 70

Geneseo Shale, 112, 114, 115

Keefer F o r m a t i o n , 89

Nassau F o r m a t i o n , 53

glabella, 7

Keyser F o r m a t i o n , 95

Neahga Shale, 85

glabellar furrows, 8

Kings Falls Limestone, 69, 70

Nedrow Member, 104, 105

glabellar lobes, 8

K i r k l a n d F o r m a t i o n , 89

neotype, 3

Glens Falls Limestone, 69

Knox U n c o n f o r m i t y , 57, 60, 6 1 , 62, 63, 64

New Scotland Limestone, 98, 101

Glenerie Limestone, 101

Kodak Sandstone, 84, 85

Niagara Gorge, 88

gnathobases, 19

Lagerstatten, 17, 4 0 - 4 2

N o r m a n s k i l l G r o u p , 63

Glenmark Shale, 90

nodes, 6

Goat Island F o r m a t i o n , 90

lappets, 10

gonatoparion cephalic suture, 9

Late Devonian strata, 115-116

Oak Orchard Member, 93

Gondwana, 96, 100

Late Early Devonian, 96-100

Oatka Creek Shale, 109

Granville Shale, 53

Late O r d o v i c i a n , 78-81

o b r u t i o n , 34

"Grabau Trilobite Beds", 111

Late Silurian, 93-95

Ogdensburg Formation, 60

Grenville Orogeny, 43

Laurentia, 45, 49, 56, 6 1 , 100, 116

Olney Member, 98

Grenville rocks, 45, 46, 47, 48

Ledyard Member, 110, 111

Onondaga G r o u p , 102, 103, 105, 106

Grimsby F o r m a t i o n , 83

Leicester Pyrite, 112

Onondaga Indian Nations Ash, 105

Gull River F o r m a t i o n , 64

LeRoy bed, 109

Ontogeny, 13-17

gut, 22

Levanna Shale, 110

opisthoparion cephalic suture, 19

Lewiston Member, 89

Ordovician allochthonous rocks, 61

Halihan H i l l beds, 109

Lichida, 124

Ordovician Period, 56-81

H a m i l t o n G r o u p , 107, 108

life-mode, 21-30

Ordovician stratigraphic chart, 57

Hannacroix Member, 98

Little Falls F o r m a t i o n , 50, 51

Oriskany Sandstone, 101

Hasenclever Member, 78

Lockport G r o u p , 83, 90-93

Oswego F o r m a t i o n , 78, 79, 80

Hatch H i l l F o r m a t i o n , 55, 56, 61

Lorraine G r o u p , 78

Otisco Shale, 111

heart, 22

Lowville F o r m a t i o n , 64, 65

Otsquago F o r m a t i o n , 86

Helderberg G r o u p , 96

Ludlowville F o r m a t i o n , 108, 110, 113

hepatopancreatic organ, 22

Palatine Bridge Member, 60

Herkimer F o r m a t i o n , 87, 89

Mackenzie F o r m a t i o n , 93

H i g h Falls Ash, 73, 74

M a n i t o u l i n Dolostone, 83

Paleozoic stratigraphic charts, 44, 45

Hillier Limestone, 75, 79

Manlius F o r m a t i o n , 96, 101

palpebral lobe, 5, 7

holaspid, 13, 14

M a n o r k i l l F o r m a t i o n , 110

Pamelia F o r m a t i o n , 64

holochroal eye, 7, 9

M a p l e w o o d Shale, 84, 85

paratype, 3

holotype, 3

Marcellus F o r m a t i o n , 105, 109

Pecksport Shale, 109

House Creek F o r m a t i o n , 64

Medina G r o u p (Sandstone), 82, 83, 84, 85

Penfield Formation, 90

Hoyt Formation, 5 1 , 54

Menteth Limestone, 111, 113

Penn Dixie Quarry, 42

hypostome, 12

meraspid, 13, 14

perforations, 11

hypotype, 3

M i d d l e and Upper Trenton G r o u p , 71-76

Phacopida, 128

M i d d l e Granville Shale, 55

phaselus, 13

Iapetus Ocean (Protoatlantic), 46, 49, 61

M i d d l e Devonian, 105-114

Phytopsis, 64, 65, 69

I l i o n F o r m a t i o n , 90, 93

M i d d l e O r d o v i c i a n , 62-78

pits, 11

Indian Castle F o r m a t i o n , 76, 77

M i d d l e Ordovician allochthonous rocks,

plastotype, 3

Indian River F o r m a t i o n , 55, 6 1 , 63, 78 internal anatomy, 2 1 , 22

62-64 M i d d l e Silurian, 85-93

Paleozoic geology, 43-116

Plattekill F o r m a t i o n , 110 pleural lobes, 5

INDEX

203

podomeres, 19, 21

schizochroal eye, 7, 9

Tribes H i l l F o r m a t i o n , 57, 60

Poland Member, 7 1 , 72, 73

Schodack Limestone, 55

trilobite injury, 18, 26, 27

Pompey Member, 110

Schoharie F o r m a t i o n , 102

trilobite Lagerstatten in New York, 17,

Pools Brook Member, 98

Schoharie G r i t , 102

Port Ewen Formation, 99, 100, 101

Selinsgrove F o r m a t i o n , 107

Trilobite M o u n t a i n , 100

Port Jervis Formation, 100

setae, 19

trilobite names, 2

Portage facies, 115

Shadow Lake F o r m a t i o n , 64

trilobite preservation, 34

Potsdam Sandstone, 50, 51,53

Shawangunk, 85

trilobite shape, 23

40

Poulteney Formation, 61

Silurian Period, 81-95

trilobite size, 17

Power Glen Shale, 83, 84

Silurian stratigraphic chart, 82

Tristates G r o u p , 96, 101-106

Prasopora, 7 1 , 76

S k u n n e m u n k Outlier, 100, 101

Trocholites,

preglabellar field, 10

Sloss Supersequences, 62

Truthville Shale, 53, 55

71

Prelude to the Paleozoic, 43-46

Smoke Creek beds, 42

Tully Limestone, 112, 114

Proetida, 148

Snake H i l l F o r m a t i o n , 70, 76

Tuscarora F o r m a t i o n , 80, 83, 85

proparion cephalic suture, 9

Sodus Shale F o r m a t i o n , 85

Tutelo Phase (Tippecanoe Supersequence),

protaspid, 13, 14

soft body parts, 17

Ptychopariida, 163

soft tissue decay, 33

83, 96

Pulaski Member, 76, 79, 80

Solsville Sandstone, 109

pustules, 6

Sonyea G r o u p , 116

U n i o n Springs F o r m a t i o n , 106, 107, 109 Upper C l i n t o n G r o u p , 86-90

pygidial spine, 6

Stafford Member, 110

Upper O r d o v i c i a n Oswego and Queenston

p y g i d i u m , 5, 7, 10

Staghorn Point, 111

pyritization, 9, 2 1 , 37, 38, 39

Steuben F o r m a t i o n , 75, 78

Queenston Formation, 78, 80, 84

stomach, 22

Valcour F o r m a t i o n , 62

Stony H o l l o w Member, 109

Valley Brook Shale, 76

stromatolites, 5 1 , 54, 94, 112

ventral anatomy, 12, 28

Rathbun Member, 69, 71

Sugar River F o r m a t i o n , 69

Vernon F o r m a t i o n , 94

Ravenna Member, 98

syntype, 3

volcanic island arc, 56

Redlichiida, 118

Syracuse F o r m a t i o n , 95

formations, 80 Utica Shale G r o u p , 76, 78

Stockbridge Member, 60

Rafinesquina,

75

Walcott-Rust Q u a r r y beds, 17, 4 1 , 74,

Retsof beds, 111 Richmond Group, 80

Taconic allocthon, 6 1 , 62, 68

Rickard H i l l Member, 102

Taconic Orogeny, 53, 56, 6 1 , 76, 82

Wallbridge U n c o n f o r m i t y , 101, 102, 104

75

Rochdale Formation, 61

taphofacies, 40

Wanakah Member, 111

Rochester Shale, 4 1 , 87, 88, 89, 91

terminal spine, 10

Ward Siltstone Member, 61

Rockway Formation, 86, 91

Tetradium, 64, 69

Watertown F o r m a t i o n , 64, 66, 67, 68

Rodinia, 43, 48

Thatcher Member, 96

West Falls G r o u p , 115

Rondout Group, 8 1 , 8 3 , 9 5

Theresa Dolostone, 5 1 , 60

Westmoreland, 86

Rose H i l l Shale, 86

thoracic segments, 10

Whetstone G u l f Member, 78

Rusophycus, 83, 85, 89

thoracic spines, 6

W h i r l p o o l Sandstone, 83, 84

Russia Member, 7 1 , 72, 74

thorax, 5

Whitehall F o r m a t i o n , 54, 60

Rust Formation, 72, 73, 74, 78

T h o r o l d Sandstone, 85

W i l l i a m s o n F o r m a t i o n , 90

Rysedorph H i l l conglomerate, 76

Tichenor Member, 111, 113

W i l l i a m s o n - W i l l o w v a l e shales, 86

Tioga bentonite, 105

W i n d o m Member, 112, 113, 114

Tippecanoe Supersequence, 62, 64, 68, 83,

W i n c h e l l Creek Member, 60

Salina Group, 83, 93, 94 Salinic Orogeny, 83, 94

96

Wintergreen Flat beds, 76

Sauk Supersequence, 49, 60, 62

Tonoloway F o r m a t i o n , 95

Wolcott F o r m a t i o n , 86

Sauk Unconformity, 61

trace fossils, 24, 25

W o l f H o l l o w Member, 60

Sauquoit Shale, 8 1 , 86

Transport and reorientation, 35-36

Schenectady Formation, 78, 79, 80

Trenton G r o u p , 68, 70

Zoophycos,

102

Plates T h e specimens on the following pages were p h o t o g r a p h e d and reproduced with the permission of their owners. T h e scale bars are 1 cm except where n o t e d .

ORDER A G N O S T I D A

Suborder Eodiscina

PLATE 1. Eodiscid trilobites from the Early Cambrian allochthonous rocks of New York. A. Acimetopus bilobatus cephalon from Columbia County. NYSM 17020. B. Serrodiscus speciosus from Columbia County. USNM 156592. Articulated specimens are rare in these rocks. C. Serrodiscus speciosus cephalon from Rensselaer County. NYSM 17018. D. Serrodiscus speciosus pygidium from Rensselaer County. NYSM 17019. E. Bolboparia superba cephalon from Columbia County. USNM 145998 (holotype). F. Bolboparia elongata pygidium from Columbia County. USNM 146002b (paratype). G. Calodiscus reticulatus cephalon from Columbia County. USNM 146006 (holotype). H. Acidiscus hexacanthus cephalon from Columbia County. USNM 145989 (holotype). I. Acidiscus hexacanthus pygidium from Columbia County. USNM 156574. J. Litometopus longispinus cephalon from Columbia County. USNM 146012. K. Cephala of Serrodiscus speciosus and Elliptocephala asaphoides from Rensselaer County. NYSM 17021.

ORDER R E D L I C H I I D A

Family Holmiidae

PLATE 2. Elliptocephala asaphoides from the Lower Cambrian Schodack Formation in Washington County. The cephalon is 100mm wide. Articulated specimens of this trilobite are very rare. USNM 18350.

ORDER C O R Y N E X O C H I D A

Family lllaenidae

PLATE 3. Bumastoides globosus from the Middle Ordovician Chazy Group, Valcour Formation, Valcour Island, Clinton County. The trilobite is 21 mm long. NYSM 12481.

PLATE 4. Bumastoides holei from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry, Herkimer County. The trilobite is 26 mm long. MCZ 3756.

PLATE 5. Bumastoides holei from the Middle Ordovician Rust Formation, Trenton Group Walcott-Rust Quarry, Herkimer County. The trilobite is 37mm long. MCZ 115909.

PLATE 6. Bumastoides milleri from the Middle Ordovician Trenton Group in Watertown, Jefferson County. The specimen is 25mm long. PRI 49621.

PLATE 7. Bumastoides porrectus from the Middle Ordovician Rust Formation of the Trenton Group, WalcottRust Quarry, Herkimer County. The trilobite is 23mm long. MCZ 101147.

PLATE 8. Nanillaenus americanus from the Middle Ordovician Rust Formation of the Trenton Group at the Walcott-Rust Quarry, Herkimer County. The trilobite is 20mm long. MCZ 707.

PLATE 9. Nanillaenus latiaxiatus from the Middle Ordovician in the Bowmanville Quarry, Ontario. This trilobite is reported in New York. The trilobite is 36mm long. In the collection of William Pinch.

PLATE 10. Illaenids from the Middle Ordovician Chazy Group. A. Nanillaenus ? raymondifrom the Day Point Formation, Valcour, Clinton County. NYSM 12491 (holotype). B. Thaleops longispina from the Crown Point Formation, Essex County. NYSM 12922 (holotype).

ORDER C O R Y N E X O C H I D A

Family Styginidae

PLATE 11. Bumastus ioxus from the Lower Silurian Rochester Shale in a commercial quarry near Middleport, Orleans County. The trilobite is 91 mm long. In the collection of Kent Smith.

PLATE 12. Eobronteus lunatus from the Middle Ordovician Snake Hill Shale, Snake Hill, Saratoga, Saratoga County. The trilobite is 45 mm long. NYSM 17001.

PLATE 13. Failleana indeterminata from the Middle Ordovician Black River Group limestones at Buck's Quarry, Poland, Herkimer County. The trilobite is somewhat disarticulated. MCZ 104928 (holotype).

PLATE 14. Illaenoides cf. /. trilobita from the Lower Silurian Rochester Shale in a commercial quarry near Middleport, Orleans County. The trilobite is 45 mm long. In the collection of Kent Smith.

PLATE 15. Illaenoides cf. /. trilobita and Dalmanites limulurus from the Lower Silurian Rochester Shale in a commercial quarry near Middleport, Orleans County. The Illaenoides species is 51 mm long. In the collection of Kent Smith.

PLATE 16. Scutellum niagarensis from drift block of the Lower Silurian Reynales Limestone in Clarendon, Orleans County. The cephalon is 17 mm long and the pygidium is 22mm long. NYSM 17023 (cephalon) and NYSM 17024 (pygidium).

PLATE 17. Scutellum senescens from the Upper Devonian Chemung beds near Avoca, Chemung County. Trilobites are rare in the Upper Devonian in New York. The specimen is about 63 mm long. NYSM 4152 (hypotype).

PLATE 18. Scutellum tullius from the Middle Devonian Tully Limestone at Borodino, Cayuga County. The illustrated cephala in A are 12 and 8mm long. PRI 49622. B. Associated pygidium of the same species. C. Reconstruction of the trilobite by Professor Wells, formerly at Cornell University.

ORDER LICHIDA

Family Lichidae

PLATE 19. Amphilichas cornutus from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry, Herkimer County. The trilobite was damaged probably during attempts to prepare it. The specimen is 36mm long. NYSM 4533 (holotype).

PLATE 20. Arctinurus boltonifrom the Lower Silurian Rochester Shale at Middleport, Niagara County. This specimen shows attached brachiopods. The trilobite is 150mm long. USNM 499453.

PLATE 21. Arctinurus boltoni from the Lower Silurian Rochester Shale in a commercial quarry near Middleport in Orleans County. This specimen shows healed damage, perhaps from a predator. The trilobite is 127 mm long. PRI 42095.

PLATE 22. Dicranopeltis nereus from the Lower Silurian Rochester Shale in a commercial quarry near Middleport in Orleans County. This trilobite is uncommon and good specimens are rare. The trilobite is 70mm long. In the Kent Smith collection.

PLATE 23. Dicranopeltis nereus from the Lower Silurian Rochester Shale in a commercial quarry near Middleport in Orleans County. This specimen shows considerable damage, perhaps by a predator. The trilobite is 59 mm long. PRI 49623.

PLATE 24. Echinolichas eriopsis from the Lower Devonian of eastern New York. NYSM 4537 (type).

PLATE 25. Hemiarges paulianus from the Middle Ordovician Bobcaygeon Formation at the Carden Quarry, Lake Simcoe area, Ontario. This small lichid is fairly common in the Kings Falls Limestone of the lower Trenton Group. The trilobite is 14 mm long. PRI 49637.

PLATE 26. A. A lichid species from the Middle Devonian Onondaga Limestone, Cheektawaga Quarry, Erie County. The pygidium is 30mm long. In the collection of Lee Tutt. B. Scutellum rochesterense (family Styginidae) from the Lower Silurian Irondequoit Limestone; exact locality is unknown. This cranidium is associated with closely packed pygidia and cranidia of Bumastus ioxus, a situation characteristic of bioherms in the Irondequoit. NYSM 17016.

PLATE 27. Cranidium of Oinochoe pustulosus from the Lower Devonian New Scotland Limestone in eastern New York. NYSM 17002.

PLATE 28. Richterarges ptyonurus from the Upper Silurian Cobleskill Limestone in Schoharie County. The figured cranidium is 7 mm long and the pygidium is 10 mm wide. NYSM 4555.

PLATE 29. Terataspis grandis from the Middle Devonian Williamsville Quarry, Erie County, in the Onondaga Limestone. This very large genal spine came from a trilobite about 580mm (23 inches) long. PRI 49638. The reconstruction drawing in the upper corner shows where this genal spine was on the trilobite and gives some idea of the scale of the complete specimen. The specimen of Eldredgeops milleri from the Middle Devonian of Arkona, Ontario, Canada, is also included for scale. The Eldredgeops is 42mm long. PRI 49639.

PLATE 30. Trochurus halli from the Lower Silurian Rochester Shale at Brockport, Monroe County. This specimen, which is missing the cranidium, is a molt 30mm long. In the collection of Paul Krohn.

PLATE 31. Trochurus hallifrom the Lower Silurian Rochester Shale in an unnamed creek in the Sodus area, Wayne County. This cranidium gives some idea of what the trilobite from Plate 30 must have looked like whole. The cranidium is 28mm wide. In the collection of Gerald Kloc.

ORDER LICHIDA

Family Odontopleuridae

PLATE 32. Diacanthaspis parvula from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry, Herkimer County. This is a rare trilobite in New York, perhaps because of its small size. The specimen is 8mm long. MCZ 4372.

PLATE 33. Dicranurus elegantus from the Lower Devonian Haragan Formation in Oklahoma. This specimen is illustrated to give an idea of how the Dicranurus hamatus from the Lower Devonian of New York looked like as an articulated trilobite. The illustrated specimen is 38mm long. In the collection of Gerald Kloc.

PLATE 34. Kettneraspis callicera from the Middle Devonian Onondaga Limestone at the Benchmark Quarry, Oak Corners, Ontario County. The specimen is 26mm wide. In the collection of Gerald Kloc.

PLATE 35. Kettneraspis tuberculata from the Lower Devonian New Scotland Limestone of the Helderberg Group. The specimen is 28mm long and is found in the Blue Circle Quarry, Ravenna, Albany County. In the collection of Gerald Kloc.

PLATE 36. Kettneraspis?species, with a free cheek obviously quite different from that in the odontopleurid in Plate 35. This species is also found in the Lower Devonian New Scotland Limestone, Helderberg Group, at the Blue Circle Quarry, Ravenna, Albany County. The specimen is 18 mm across at the widest point. In the collection of Gerald Kloc.

PLATE 37. Meadowtownella trentonensis from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry, Herkimer County. This is a fairly common trilobite in the quarry but is not often reported from other Trenton rocks, possibly owing to its small size. The specimen is 12mm long and shows the ventral exoskeletal anatomy. MCZ 111717.

PLATE 38. Meadowtownella trentonensis from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry, Herkimer County. A dorsal view of the same trilobite in Plate 37. MCZ.

PLATE 39. Miraspis crosota from the Upper Ordovician Frankfort Member of the Lorraine Group at Rome, Oneida County. The glabella of this partial specimen is 1 mm long. USNM 23600.

ORDER P H A C O P I D A

Family Acastidae

PLATE 40. An unidentified asteropygin from the upper Middle Devonian, Tully Limestone in Groves Creek off Cayuga Lake, Seneca County. The trilobite is 26 mm long. In the collection of Gerald Kloc.

PLATE 41. Disarticulated specimen of Bellacartwrightia calderonae from the Middle Devonian Windom Shale, Hamilton Group, Kashong Glen, Ontario County. AMNH 45273 (holotype).

PLATE 42. Bellacartwrightia jennyae from the Middle Devonian Centerfield Limestone, Hamilton Group, at Brown's Creek, Livingston County. The specimen is 38mm long. AMNH 45310 (paratype).

PLATE 43. Bellacartwrightia jennyae and Harpidella craspedota from the Middle Devonian Centerfield Limestone, Hamilton Group, at Centerfield, Ontario County. The largest Bellacartwrightia is 40mm long. NYSM 4235.

PLATE 44. Bellacartwrightia phyllocaudata from the Middle Devonian Deep Run Member, Hamilton Group, near Geneseo, Livingston County. The specimen is 34mm long. AMNH 45230 (holotype).

PLATE 45. Bellacartwrightia whiteleyi from the Middle Devonian Wanakah Member, Hamilton Group, Darien, Genesee County. The trilobite is 25 mm long. AMNH 45314 (paratype).

PLATE 46. Bellacartwrightia species from the upper Middle Devonian, Tully Limestone in Madison County. USNM 89959.

PLATE 47. Bellacartwrightia species from the Middle Devonian Windom Shale, Hamilton Group, on the Geneseo College campus, Geneseo, Livingston County. The ventral exoskeletal features of the Bellacartwrightia are shown. The specimen is 41 mm long. In the collection of James Scatterday.

PLATE 48. Bellacartwrightia species from the Middle Devonian Windom Shale, Hamilton Group, at the PennDixie Quarry, Hamburg, Erie County. The specimen is 40mm long. In the collection of Gregory Jennings.

PLATE 49. Astropyginae aff. Greenops from the Middle Devonian Pompey Member, Hamilton Group, at Rockefeller Road, Cayuga County. The specimen is 15 mm long. In the collection of Gerald Kloc.

PLATE 50. Greenops barberi from the Middle Devonian Windom Member, Hamilton Group, Buffalo Creek, Erie County. The specimen is 21 mm long. AMNH 45277 (paratype).

PLATE 51. Greenops boothi from the Middle Devonian Frame Member, Mahantango Formation, Huntington, Pennsylvania. This is the area where the original Green specimen came from and is the type area for the genus. The specimen is coiled. The cephalon is 24mm wide. YPM 35807 (neotype).

PLATE 52. Greenops grabaui from the Middle Devonian Wanakah Member, Hamilton Group, Erie County. In the collection of Fred Barber.

PLATE 53. Greenops grabauifrom the Middle Devonian Wanakah Member, Hamilton Group, Lake Erie shore, Erie County. This meraspid is 10mm long. In the collection of Kym Pocius.

PLATE 54. Greenops grabaui from the Middle Devonian Wanakah Member, Hamilton Group, Darien, Genesee County. The specimen is 24mm long. PRI 49640.

PLATE 55. Greenops species from the Middle Devonian, upper Windom Member, Hamilton Group, Groves Creek, Seneca County. The specimen is 30mm long. In the collection of Gerald Kloc.

PLATE 56. Greenops species from the Middle Devonian Kashong Shale, Hamilton Group. The specimen is 24mm long. In the collection of Gerald Kloc.

ORDER PHACOPIDA

Family Calymenidae

PLATE 57. Calymene camerata from the Upper Silurian Cobleskill Limestone at Jerusalem Hill, Herkimer County. This calymenid is distinguished by the inward curve of the anterior cheek toward the glabella. PRI 49624.

PLATE 58. Calymene niagarensis from the Lower Silurian Rochester Shale near Middleport, Orleans County. The specimen is 36mm long. NYSM 16795.

PLATE 59. Calymene niagarensis from the Lower Silurian Rochester Shale near Middleport, Orleans County. The plate is an exceptional cluster of trilobites. The largest is 34 mm long. In the collection of Gregory Jennings.

PLATE 60. Calymene platys from the Middle Devonian Onondaga Limestone in Hagersville, Ontario, Canada. This species is reported from New York. The specimen is 95 mm long. USNM 380869.

PLATE 6 1 . Calymene singularis from the Upper Silurian Oak Orchard Member of the Lockport Group. The figured cephalon is 20mm long. USNM 488139 (paratype).

PLATE 62. Calymene species from the Lower Silurian Rochester Shale on an unnamed creek near Sodus, Wayne County. The specimen is 28 mm long. In the collection of Sam Insalaco.

PLATE 63. Calymenid from the Upper Ordovician Pulaski Member, Lorraine Group, at Burke Creek, Oneida County. The latex pull figured here is very pustulose. PRI 49641.

PLATE 64. Diacalymene species from the Lower Silurian Rochester Shale at Densmore Creek, Rochester, Monroe County. The specimen, though incomplete, is strikingly different from the Rochester Shale calymenids found to the west of Rochester. The specimen is 60 mm long. NYSM 16799.

PLATE 65. Diacalymene species from the Lower Silurian Rochester Shale in Wayne County. This trilobite is different, primarily in the anterior of the cephalon, from the Diacalymene specimen in Plate 64. The specimen is 45 mm long. NYSM 16793.

PLATE 66. Flexicalymene meek/from the Upper Ordovician shales at Cincinnati, Ohio. This specimen is figured because Upper Ordovician calymenids in New York have been identified as this species. The trilobite is 55mm long. PRI 49642.

PLATE 67. Flexicalymene senaria from the Middle Ordovician limestones at Middleville, Herkimer County. The original type for this species is lost, and this specimen, figured by Hall, was chosen as the neotype. The specimen is 24.5mm long. AMNH 29474 (neotype).

PLATE 68. Flexicalymene senaria from the Middle Ordovician Poland Member of the Trenton Group at Trenton Falls, Herkimer County. This specimen is characteristic of the middle and lower Trenton F. senaria. The trilobite is 43mm long. In the collection of Gerald Kloc.

PLATE 69. Flexicalymene cf. F senaria from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry. This trilobite is somewhat different from many F. senaria specimens in that it is more pustulose and has a spinelike, acute genal angle. The specimen is 28mm long. MCZ 111710.

PLATE 70. Flexicalymene senaria from the Middle Ordovician Hillier Member of the uppermost Trenton Group in a quarry off Rte. 3 in Jefferson County. The trilobite is flattened because it was on a bedding plane, but it is apparently much less pustulose than the trilobite in Plate 69. The specimen is 28mm long. PRI 49643.

PLATE 71. Gravicalymene magnotuberculata from the Middle Ordovician Sugar River Formation, Trenton Group, North Creek, Herkimer County. Note the very differently shaped glabella compared to the one in F. senaria in Plate 70. The trilobite is 45 mm long. PRI 49644.

PLATE 72. Gravicalymene magnotuberculata from the Middle Ordovician Sugar River Formation, Trenton Group, on Allen Road, Fulton County. The ventral exoskeletal anatomy of this trilobite is shown. This is a molt as there is no sign of the hypostome. The specimen is 40mm long. PRI 49645.

PLATE 73. Liocalymene clintoni from the Lower Silurian Clinton Group, Clinton, Oneida County. Most of the Liocalymene specimens one sees are internal molds like this one. The specimen is 26mm long. PRI 49625.

ORDER PHACOPIDA

Family Cheiruridae

PLATE 74. Ceraurinella cf. C. scofieldi from the Middle Ordovician Watertown Member, Black River Group, Buck's Quarry, Poland, Herkimer County. This trilobite is usually found in the equivalent rocks in the Midwest. The cranidium is 12.5mm wide. MCZ 13.

PLATE 75. Ceraurinus marginatus from the Middle Ordovician Lindsay Formation, Trenton Group, Colborne Quarry, Colborne, Ontario, Canada. This trilobite is known from New York but is uncommon. In the collection of Kevin Brett.

PLATE 76. Ceraurus pleurexanthemus from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry, Herkimer County. This specimen is 35mm long. MCZ 111708.

PLATE 77. Ceraurus pleurexanthemus from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry, Herkimer County. This specimen shows the ventral exoskeletal anatomy. It is 29mm long. MCZ 111715.

PLATE 78. Ceraurus pleurexanthemus from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry, Herkimer County. This specimen from inside a limestone shows a ferruginous trace along the axis, which is interpreted to be a trace of the gut. MCZ 111716.

PLATE 79. Ceraurus species from interface of the Middle and Upper Ordovician at a flooding surface between the Hillier Member of the Trenton Group and the Utica Shale on Gulf Stream, Rodman, Jefferson County. This trilobite shows differences from the more common C. pleurexanthemus. The specimen is 13mm long. NYSM 17000.

PLATE 80. Ceraurus species from the Middle Ordovician Trenton Group in a Quarry near Watertown, Jefferson County. Although similar to the specimen in Plate 79, there are differences from C. pleurexanthemus. The trilobite is 35 mm long. In the collection of Gerald Kloc.

PLATE 81. Cheirurus cf. C. niagarensis from the Lower Silurian Irondequoit Limestone in Monroe County. The cephalothorax is USNM 489751, and the pygidium, which is 23mm wide. NYSM 17022.

PLATE 82. Gabriceraurus dentatus from the Middle Ordovician Kings Falls Limestone, Trenton Group, Ingham Mills, Fulton County. This fairly three-dimensional specimen is 70mm long. In the collection of Gerald Kloc.

PLATE 83. Gabriceraurus dentatus from the Middle Ordovician Lindsay Formation, Trenton Group, Colborne Quarry, Colborne, Ontario, Canada. This specimen is 69mm long. In the collection of Kevin Brett.

PLATE 84. Cheirurids from New York for which articulated specimens are not known. A. Gabriceraurus hudsoni from the Middle Ordovician Chazy Group, Valcour Island, Clinton County. YPM 23296. B. Deiphon species from the Lower Silurian, possibly at Lockport, Niagara County. The figured glabella is 10mm wide. PRI 49626. C-E. Cerauropeltis ruedemanni from the Chazy Group limestones near Chazy, Clinton County. C. MCZ 7701. D. MCZ 1612. E. NYSM 9692 (holotype). The negatives for A and C-E were supplied by Dr. Fredrick Shaw, Lehmann University.

PLATE 85. Sphaerocoryphe robusta from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry, Herkimer County. This small but interesting trilobite generally is rarely found, but a fair number were found at the Walcott-Rust Quarry, probably because of the area quarried. This specimen is 13mm long. MCZ 110901.

PLATE 86. Silicified trilobites from the Middle Ordovician Chazy Group in Clinton County. A. The cephalon (NYSM 12404) and two views of the pygidium (NYSM 12402) of Sphaerocoryphe goodnovi from Chazy. B. The cranidium (NYSM 12317), free cheek (NYSM 12325), and pygidium (NYSM 12318) of Cybeloides prima from the Crown Point Formation, Valcour Island. C. The cranidium (NYSM 12442) and pygidium (NYSM 12450) of Ceraurinella latipyga from the Crown Point Formation, Valcour Island. D. Two views of the cranidium (NYSM 12331) and one of the pygidium (NYSM 12330) of Physemataspis insularis from the Crown Point Formation, Valcour Island. The negatives for all these pictures were supplied by Dr. Fred Shaw, Lehmann University.

ORDER P H A C O P I D A

Family Dalmanitidae

PLATE 87. Dalmanites aspinosus from the Silurian Keyser Formation in Flintstone Maryland. This trilobite is also reported in New York. The pygidium is 30mm long. In the collection of Gerald Kloc.

PLATE 88. Dalmanites limulurus from the Lower Silurian Rochester Shale in Brockport, Monroe County. The actual specimen is stained red by iron minerals. It is 60mm long. In the collection of Gerald Kloc.

PLATE 89. Four specimens of Dalmanites limulurus from the Lower Silurian Rochester Shale in a commercial quarry near Middleport. Orleans County. In the collection of Kent Smith.

PLATE 90. Dalmanites pleuroptyx from the Lower Devonian Helderberg Group at Slingerlands near Clarksville, Albany County. The specimen is 60mm long. NYSM 17003.

PLATE 91. A. Dalmanites species from the Upper Silurian Lockport Group on an unnamed creek near Sodus, Wayne County. This unusual cephalon is 21 mm wide. In the collection of Gerald Kloc. B. Staurocephalus species from the Lower Silurian Rochester Shale on an unnamed creek near Sodus, Wayne County. This trilobite is rare, possibly due to the small size of the sclerites. In the collection of Gerald Kloc.

PLATE 92. Pygidium of Odontochile micrurus from the Lower Devonian at a Jerusalem Hill quarry on Albany Road, Herkimer County. PRI 49627.

PLATE 93. A cephalon and pygidium from an odontochilid from the Lower Devonian, upper Manlius Limestone, Helderberg Group, Cobleskill, Schoharie County. The cephalon is 16mm long and the pygidium is 18mm long. Both in the collection of Gerald Kloc.

ORDER PHACOPIDA

Family Encrinuridae

PLATE 94. Erratencrinurus vigilans from the Middle Ordovician at the Brechin Quarry, Brechin, Ontario. This trilobite is known from the lower Trenton Group in New York, but this is a particularly good specimen. This specimen is 14mm long. RMSC 2001.46.1.

PLATE 95. Encrinurus cf. £ raybesti from the Lower Silurian Reynales Limestone at Reynolds Basin, Orleans County. This specimen is 31 mm long. PRI 49628.

PLATE 96. A cranidium, free cheek, and pygidium of an unidentified Encrinurus species from the Upper Silurian Lockport Group in Wayne County. The figured glabella is 7 mm long. All in the collection of Gerald Kloc.

PLATE 97. Dipleura dekayi from the Kashong Shale, Hamilton Group, Livingston County. The trilobite shows healed damage to the lower right thorax, possibly due to a predator. This large trilobite is 115mm long. In the collection of Fred Barber.

PLATE 98. Dipleura dekayi from the Middle Devonian Hamilton Group, Interlaken Beach, Seneca County. This large specimen has some exoskeleton broken on the posterior thorax. The broken edges show clearly that the apparent pits on the dorsal surface actually go all the way through the exoskeleton and are holes. The cephalon is 119mm wide. PRI 49629.

PLATE 99. A Trimerus delphinocephalus and a Dalmanites limulurus together on one slab from the Lower Silurian Rochester Shale at a commercial quarry near Middleport, Orleans County. The large T. delphinocephalus is 172mm long, and D. limulurus is 60mm long. In the collection of Kent Smith.

ORDER PHACOPIDA

Family Phacopidae

PLATE 100. Eldredgeops crassituberculata from the Middle Devonian Silica Formation, Silica, Ohio. This trilobite is well known in the Midwest where this specimen was found. It is also reported from New York but is considered uncommon. This specimen is 47 mm long. PRI 49646.

PLATE 101. Eldredgeops rana from the Middle Devonian Hamilton Group in Seneca, Ontario County. This specimen has both the part and the counterpart, with the mold to the upper left. NYSM 4645 (holotype).

PLATE 102. Eldredgeops rana from the Middle Devonian Windom Member, Hamilton Group, Penn-Dixie Quarry, Hamburg, Erie County. This site is noted for the occasional finding of clusters of trilobites such as this. The Eldredgeops specimens in this cluster are relatively small, as are most of them from this site. USNM 403874.

PLATE 103. Eldredgeops rana from the Middle Devonian Wanakah Member, Hamilton Group, Darien, Genesee County. This specimen exhibits color markings in non-random patterns on the dorsal exoskeleton. These markings have been interpreted as the positions of internal muscle attachment. PRI 49647.

PLATE 104. Eldredgeops rana from the Middle Devonian Wanakah Member, Hamilton Group, Darien, Genesee County. A good view of the dorsal exoskeleton. The specimen is 22mm long. PRI 49648.

PLATE 105. Eophacops? trisulcatus from the Lower Silurian Williamson Member of the Clinton Group at Densmore Creek, Rochester, Monroe County. The preservation of exoskeletal material is poor in these rocks. USNM 79137.

PLATE 106. Eophacops? trisulcatus from the Lower Silurian Sodus Shale Member of the Clinton Group at the Genesee Gorge, Rochester, Monroe County. This is a latex mold from a not-too-good mold in shale. It does show a little more detail than Plate 105. NYSM 17041.

PLATE 107. Paciphacops loganifrom the Lower Devonian New Scotland Member of the Helderberg Group at a roadcut on Interstate 88 in Schoharie County. The specimen is 41 mm long. PRI 49649.

PLATE 108. Phacops? iowensis from the Middle Devonian Taunton Beds of the Windom Member, Hamilton Group, Livingston County. This trilobite has only been reported from the upper Windom in New York. In the collection of Steve Pavelsky.

PLATE 109. Viaphacops bombifrons from the Middle Devonian Moorehouse Member of the Onondaga Limestone in the Honeyoe Falls Quarry, Monroe County. The specimen is 24 mm wide. In the collection of Gerald Kloc.

PLATE 110. A composite plate showing the characteristics of the eyes of seven phacopid trilobites found in New York.

PLATE 111. A composite plate showing some dorsal characteristics of New York phacopids. The combination of eye structure and dorsal cephalic structure are often diagnostic to species.

ORDER PHACOPIDA

Family Pliomeridae

PLATE 112. Pliomerops canadensis from the Middle Ordovician Chazy limestones in Clinton County. Articulated trilobites are rare in the Chazy because of the high-energy conditions of these limestones. MCZ 6920.

PLATE 113. A side view of the specimen in Plate 112.

PLATE 114. Pliomerops canadensis from a reworked Chazy limestone block in the Middle Ordovician Snake Hill Shale. This pygidium shows an unusual displacement of one of the axial rings, perhaps a healed injury. In the collection of Gerald Kloc.

ORDER P H A C O P I D A

Family Pterygometopidae

PLATE 115. Achatella achates from the Middle Ordovician Trenton rocks at Trenton Falls, Herkimer County. This specimen is 21 mm long. PRI 49630.

PLATE 116. Calyptaulax callicephalus from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry, Herkimer County. This specimen is 28mm long. MCZ 111712.

PLATE 117. Calyptaulax callicephalus from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry, Herkimer County. This specimen shows the ventral exoskeletal anatomy of the trilobite. The specimen is 22mm long. MCZ 111713.

PLATE 118. Chasmops? bebryx from the Middle Ordovician Trenton Group at Jacksonburg, Herkimer County. This trilobite was used by Billings (1863) to illustrate the species, although he was naming a Canadian specimen. It is 39mm long. PRI 49631 (type).

PLATE 119. Eomonorachus convexus from the Middle Ordovician Glens Falls Limestone, Trenton Group, Amsterdam, Montgomery County. The holotype is reported from Trenton Falls, but it is a very uncommon trilobite in the Trenton rocks. PR I 49632.

ORDER P H A C O P I D A

Family Synphoriidae

PLATE 120. Cephalon of Anchiopella anchiops from the Lower Devonian Helderberg Group. NYSM 4262.

PLATE 121. Coronura aspectans from the Middle Devonian Onondaga Limestone at LeRoy, Genesee County. This latex cast of the external mold, or counterpart, is in better condition than the internal mold of the trilobite. The trilobite is 145mm long. NYSM 4316 (hypotype).

PLATE 122. Coronura aspectans from the Middle Devonian Moorehouse Member of the Onondaga Limestone at LeRoy, Genesee County. As one can see from the 1-cm scale bars, the cephalon and pygidium are very different sizes. Both in the collection of Gerald Kloc.

PLATE 123. Odontocephalus aegeria from the Middle Devonian Needmore Shale at Cumberland, Maryland. This same species is reported in New York. The plate is two views of the same specimen, as it is semicoiled. The trilobite is 30mm long. In the collection of Gerald Kloc.

PLATE 124. Odontocephalus bifidus from the Middle Devonian Moorehouse Member of the Onondaga Limestone at the LeRoy Quarry, LeRoy, Genesee County. The specimen is 85mm long. In the collection of Gerald Kloc.

PLATE 125. Odontocephalus selenurus from the Middle Devonian Moorehouse Member of the Onondaga Limestone at the Seneca Stone Quarry, Seneca, Seneca County. The trilobite is 41 mm long. In the collection of Gerald Kloc.

PLATE 126. Odontocephalus species from the Middle Devonian Moorehouse Member of the Onondaga Limestone in the LeRoy Quarry, LeRoy, Genesee County. There are enough differences in these specimens from the other Odontocephalus species to question whether these are of known species. The cephalon is 25mm wide. In the collection of Gerald Kloc.

PLATE 127. A. Trypaulites erinus found in a loose block, possibly Lower Devonian Bois Blanc Limestone, at Mumford, Monroe County. This pygidium is 17mm wide. B. Coronura helena from the Middle Devonian Moorehouse Member of the Onondaga Limestone. The pygidium was found in a construction excavation at Clarence, Erie County. Both in the collection of Gerald Kloc.

ORDER P R O E T I D A

Family Aulacopleuridae

PLATE 128. Harpidella craspedota from the Middle Devonian Centerfield Limestone, Hamilton Group, Browns Creek, York, Livingston County. These are small trilobites, about 15 mm long. NYSM 16798.

PLATE 129. Harpidella spinafrons from the late Middle Devonian, Tully Limestone at Moravia, Cayuga County. This specimen is 16mm long. USNM 89980.

PLATE 130. Harpidella spinafrons from the late Middle Devonian, Tully Limestone on West Brook, Sherburne, Chenango County. The original is an external mold and this is a gutta-percha cast. The longest dimension is 8 mm. USNM 516589.

PLATE 131. Harpidella species from the Middle Devonian Onondaga Limestone in the Honeoye Falls Quarry, Honeoye Falls, Monroe County. This is a previously unreported species. RMSC 2001.48.1.

PLATE 132. Maurotarion species from the Upper Silurian Lockport Group on an unnamed creek near Sodus, Wayne County. The cranidia are 5mm wide. In the collection of Gerald Kloc.

ORDER P R O E T I D A

Family Bathyuridae

PLATE 133. Bathyurus exfansfrom the Middle Ordovician Black River Group, Black River, Great Bend, Jefferson County. This specimen is 23mm long. USNM 92844.

ORDER P R O E T I D A

Family Brachymetopidae

PLATE 134. Australosutura gemmaea from the Middle Devonian Windom Member on Fall Brook, Geneseo, Livingston County. This trilobite is rare in articulated form. The specimen is 12mm long. In the collection of James Scatterday.

PLATE 135. Radnoria species from the Lower Silurian Rochester Shale. This small trilobite is usually found associated with bryozoan colonies. The specimen is 14mm long. NYSM 16792.

ORDER P R O E T I D A

Family Proetidae

PLATE 136. Coniproetus folliceps from the Middle Devonian Onondaga Limestone at LeRoy, Genesee County. This specimen is 48mm long. NYSM 4722 (lectotype).

PLATE 137. Cyphoproetus? cf. C. wilsonae from the Middle Ordovician, lower Trenton exposures at Sacketts Harbor, Jefferson County. This rare trilobite is 11.5 mm long. PR I 49633.

PLATE 138. Dechenella haldemani from the Middle Devonian Union Springs Member in Cherry Valley, Otsego County. NYSM 6489.

PLATE 139. Decoroproetus corycoeus from the Lower Silurian Rochester Shale at Brockport, Monroe County. This uncommon trilobite is 29mm long. In the collection of Tod Clements.

PLATE 140. The same specimen as in Plate 139, showing the associated ophiuroid (brittle star).

PLATE 141. Monodechenella macrocephala from the Middle Devonian Centerfield Limestone at Browns Creek, York, Livingston County. This trilobite is often found curved upward in these beds, and the two views give a good perspective on this preservation. The specimen is 29mm long. In the collection of Douglas DeRosear.

PLATE 142. Proetid from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry, Herkimer County. Proetids are very uncommon in the New York Trenton. This specimen is 11 mm long. MCZ 111714.

PLATE 143. Pseudodechenella clara from the Middle Devonian Moorehouse Member of the Onondaga Limestone, Honeoye Falls Quarry, Honeoye, Monroe County. This is a nice specimen of an uncommon trilobite. It is 31 mm long. RMSC 2001.47.1.

PLATE 144. Pseudodechenella row/from the Middle Devonian Windom Member, Hamilton Group, PennDixie Quarry, Hamburg, Erie County. Shown are two specimens with the molt remains of a third. The largest trilobite is 31 mm long. In the collection of Gregory Jennings.

PLATE 145. Pseudodechenella rowi along with Bellacartwrightia whiteleyi from the Middle Devonian Wanakah Member, Hamilton Group, Darien, Genesee County. In addition to these trilobites, one can see the pygidium of Eldredgeops rana, which shows the richness of these beds. PRI 49634.

PLATE 146. Pseudodechenella raw; from the Middle Devonian Centerfield Limestone, Hamilton Group, Bethany, Genesee County. Although this is not a close cluster, it does record an association of these trilobites before the burial event. The widest cephalon is 24 mm. In the collection of Gerald Kloc.

PLATE 147. Pseudodechenella rowi'from the upper Middle Devonian, Tully Limestone at Moravia, Cayuga County. This trilobite is recorded over a long time range in the Middle Devonian, ending with the Tully. The largest specimen is 34mm long. USNM 26767.

ORDER ASAPH I DA

Family Asaphidae

PLATE 148. ? Ectenaspis homalonotoides from the Middle Ordovician Bobcaygeon Formation, Trenton Group, in the Brechin Quarry, Brechin, Ontario, Canada. This trilobite is reported in New York but is very uncommon. In the collection of Kevin Brett.

PLATE 149. Isoteloides canalis from the Lower Ordovician Fort Cassin Formation, Crown Point, Essex County. Isoteloides canalis is the most common trilobite in these rocks, but articulated material is rare. CM 1433. The negative for this plate was supplied by Dr. Stephen Westrop, Oklahoma State Museum.

PLATE 150. Isotelus gigas from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry, Herkimer County. This specimen was elected as the neotype, as the original type is lost. Isotelus gigas is characterized by the small pits abundant on the cephalon. This trilobite is 52mm long. MCZ 100938 (neotype).

PLATE 151. Isotelus gigas from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry, Herkimer County. This large specimen is more characteristic of the large cephalic parts and pygidia common in the Trenton rocks. The trilobite is 122mm long. MCZ 311.

PLATE 152. Isotelus gigas from the Middle Ordovician Rust Formation, Trenton Group, at Trenton Falls, Herkimer County. Many /. gigas specimens found in museums came from one bed at Trenton Falls. This is an unusual cluster from this area. USNM 139617.

PLATE 153. Isotelus cf. /. gigas from the Middle Ordovician Grandine Member of the Neuville Formation in a quarry in Quebec City, Quebec, Canada. This is a view of the ventral exoskeletal anatomy. In the collection of Kevin Brett.

PLATE 154. Isotelus maximus from the Upper Ordovician Fort Ancient Member of the Waynesville Formation at Mount Orab, Ohio. Isotelus maximus is reported from the Upper Ordovician of New York, but this needs confirmation. This specimen is 34mm long. PRI 49650.

PLATE 155. Isotelus maximus from the Upper Ordovician at Cincinnati, Ohio. This is a ventral view of a heavily pyritized exoskeleton. The specimen is 87mm long. PRI 49651.

PLATE 156. A closer view of the pygidium from the trilobite in Plate 155. One can make out evidence of pyritized appendages on the left.

PLATE 157. Isotelus maximus from the Upper Ordovician at Cincinnati, Ohio. This molt assemblage shows the turnover of the cranidium from the molting process. The specimen is 55mm long. PRI 49652.

PLATE 158. Isotelus walcotti from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry, Herkimer County. This trilobite is only reported from the Rust Formation in the immediate Trenton Falls vicinity. Although the illustrated specimen is small, one has been found at the Walcott-Rust Quarry measuring 120mm across the width of the cephalon. The specimen is 32mm long. USNM 61261a (holotype).

PLATE 159. Pseudogygites latimarginatus from the Middle/Upper Ordovician Utica Shale at Alder Creek, Oneida County. This trilobite is only found in New York in the uppermost Trenton, Hillier Member, and the Middle/Upper Ordovician transition shales. It is common in the Collingwood Shale in Ontario, Canada. This specimen is 82mm long. NYSM 17005.

ORDER ASAPHIDA

Family Remopleurididae

PLATE 160. Hypodicranotus striatulus from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry, Herkimer County. This specimen prepared from inside a limestone layer shows the streamlining, suggesting that the species is free swimming. The tiny granules on the surface are not "dirt" but silica sand granules that could not be removed without causing damage. The specimen is 26mm long. MCZ 115910.

PLATE 161. Hypodicranotus striatulus from the Middle Ordovician Rust Formation, Trenton Group, Walcott-Rust Quarry, Herkimer County. This specimen was found inside limestone and reveals the remarkable hypostome, which is almost the full length of the thorax. The specimen is 26mm long. In the collection of Thomas Whiteley.

PLATE 162. Hypodicranotus striatulus from the Middle Ordovician Trenton Group at Trenton Falls, Herkimer County. This specimen from a bedding plain shows the unusual, split genal spine and the very small pygidium. PRI 49635.

ORDER ASAPHIDA Family Trinucleidae PLATE 163. Cryptolithus bellulus from the Upper Ordovician Whetstone Gulf Shale, Lorraine Group, on Burke Creek, Oneida County. The original exoskeletal material is not well preserved in these shales, but there are good external molds. This specimen does not have the long genal spine characteristic of Cryptolithus, which indicates it is a molt. Cryptolithus molted by losing the lower lamella of the ventral cephalon and exiting the exoskeleton by crawling forward. This is a latex cast from such a mold. The specimen is 8 mm long. PRI 49654.

PLATE 164. Cryptolithus lorettensis from the Middle Ordovician Sugar River Formation, Trenton Group, at Mill Creek off Rte. 3, Jefferson County. This cephalon shows the reticulation on the glabella reported for this species. The occipital spine is also nicely preserved. NYSM 17006.

PLATE 165. Cryptolithus lorettensis from the Middle Ordovician Sugar River Formation, Trenton Group, at Ingham Mills, Fulton County. Articulated specimens of the Middle Ordovician Cryptolithus are very rare, as these trilobites lived in fairly high-energy conditions and the thorax is very fragile. The specimen is a molt and is 19mm long. NYSM 17007.

PLATE 166. Cryptolithus tessellatus from the Middle Ordovician Sugar River Formation, Trenton Group, Cold Brook, Herkimer County. Although the cephala of this trilobite may be found in large numbers in beds of the Sugar River Formation, articulated specimens are rare. This trilobite is 15mm long. MCZ 921.

PLATE 167. Cryptolithus tessellatus from the Middle Ordovician Sugar River Formation, Trenton Group, at Trenton Falls, Oneida County. This plate shows the pit structure on the cephalic brim, which differentiates the Cryptolithus species. Cryptolithus tessellatus has three rows of pit immediately anterior to the cheek area. PRI 49636.

ORDER PTYCHOPARIIDA Family Glaphuridae PLATE 168. Glaphurids from the Middle Ordovician Chazy Group. A. Glaphurus pustulosus from near Chazy, Clinton County. CM 1274. B. Glaphurina lamottensis from Isle La Motte, Vermont. This trilobite is also found in the New York Chazy. In the collection of the University of Vermont Museum, specimen 2-63. The negatives for this plate were supplied by Dr. Fredrick Shaw, Lehmann University.

ORDER P T Y C H O P A R I I D A

Family Harpidae

PLATE 169. Trilobite from the family Harpidae. A. Hibbertia valcourensis from the Middle Ordovician Day Point Formation, Chazy Group, at Day Point, Clinton County. This is a rubber cast of the original external mold of the trilobite. NYSM 12293 (holotype). B. Hibbertia valcourensis from the Middle Ordovician Day Point Formation, Chazy Group, at Day Point, Clinton County. This is a rubber cast of the original external mold of the trilobite. NYSM 12292. C. Hibbertia ottawaensis from the Middle Ordovician of Canada. This trilobite is also found in New York. The figured specimen is a metal cast of the original. GSC 329 (holotype). D. Scotoharpes cassinensis from the Lower Ordovician Fort Cassin Formation, Fort Cassin Point, Vermont. This trilobite is believed to occur in New York. USNM 35817 (holotype). The negatives for A-C were supplied by Dr. Fredrick Shaw, Lehmann University. The negative for D was supplied by Dr. Stephen Westrop, Oklahoma State Museum.

ORDER P T Y C H O P A R I I D A

Family Olenidae

PLATE 170. Triarthrus beckii from the Middle Ordovician Utica Shale at Dolgeville, Herkimer County. This specimen shows the yoked, connected, free cheeks of this trilobite. They are slightly displaced here. In the collection of Fred Wessman.

PLATE 171. Triarthrus cf. T. eatonifrom the Upper Ordovician Whetstone Gulf Member, Lorraine Group, on Burke Creek, Oneida County. This specimen is unusual in that there are no axial nodes on the anterior thoracic segments. The specimen is 21 mm long. PRI 49655.

PLATE 172. Tharthrus eatoni from the Upper Ordovician Frankfort Member, Lorraine Group, on Six Mile Creek north of Rome, Oneida County. This specimen is from the world renowned Beecher Trilobite Bed, which is the most prolific known source of trilobites with appendage information. This trilobite is 40mm long. YPM 228.

PLATE 173. Triarthrus spinosus from the Upper Ordovician Utica Shale on Nine Mile Creek, Oneida County. This is a rare trilobite in New York but is often found in Canada. The width across the posterior aspect of the cephalon is 15mm. USNM 96235 (holotype).

PLATE 174. Triarthrus spinosus from the Upper Ordovician at Ottawa, Ontario, Canada. This specimen shows the characteristic genal spines and thoracic spines of the species. The trilobite is 15mm long. In the collection of Kevin Brett.

ORDERS ASAPHIDA A N D PTYCHOPARIIDA

Families Saukiidae, Idahoiidae, Plethopeltidae

PLATE 175. Trilobites from the Middle Cambrian limestones of New York. A. Prosaukia hartti from the Hoyt Limestone, Greenfield railroad cut, Saratoga County. NYSM 14079. B. Saratogia calcifera from the Hoyt Limestone in the Hoyt Quarry at Lester Park, Saratoga County. NYSM 14081. C. Plethopeltis saratogensis from the Briarcliff Dolostone at Poughkeepsie, Dutchess County. NYSM 14147. The negatives for A and B were supplied by Dr. Stephen Westrop, Oklahoma State Museum.

"Paleontologists both young and old will enjoy

"Thomas E. Whiteley is a research chemist re-

this book. Trilobites of New York is a wonderfully

tired from the photographic industry, Gerald J.

illustrated book that all fossil collectors will rel-

Kloc is a nationally known preparator of fossils,

ish. The authors combine a thorough review of

and Carlton E. Brett is a professor of geology

the natural history of trilobites with taxonomic

who has looked at almost every outcrop of sedi-

descriptions, photographs, and occurrence data.

mentary rock in New York State; together they

The photography is superb, and the plates will

have produced a book that should be a broad

be the envy of many paleontologists."

path for other amateurs and professionals to follow. Trilobites of New York has the charm of an

— T i m White, Senior Collection Manager,

artistic portfolio and the fullness of the rigors of

Division of Invertebrate Paleontology, Peabody

systematic stratigraphy and paleontology. This

Museum of Natural History, Yale University

book will be used extensively by the teachers of New York, it will be eagerly sought after by amateur collectors, and for good reason will be used by college professors teaching paleontology to undergraduates around the world." —Fred Collier, Curatorial Associate in the Department of Invertebrate Paleontology, Museum of Comparative Zoology, Harvard University

Published in cooperation with the Paleontological Research Institution, Ithaca, New York A Comstock Book

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