Fossils Parti:! Rolf Ludvigsen ROM Royal Ontario Museum Life Sciences Miscellaneous Publications ^ *<\ & tft* o LIFE SCIENCES MISCELLANEOUS PUBLICATIONS ROYAL ONTARIO MUSEUM Roif Ludvigsen Fossils of Ontario Part 1: The Trilobites Publication date: 31 January 1979 ISBN 0-88854-221-6 ROYAL ONTARIO MUSEUM PUBLICATIONS IN LIFE SCIENCES The Royal Ontario Museum publishes three series in the Life Sciences: LIFE SCIENCES CONTRIBUTIONS, a numbered series of original scientific publications including mono- graphic works. life sciences occasional papers, a numbered series of original scientific publications, primarily short and usually of taxonomic significance. life sciences miscellaneous publications, an unnumbered series of publications of varied sub- ject matter and format. All manuscripts considered for publication are subject to the scrutiny and editorial policies of the Life Sciences Editorial Board, and to review by persons outside the museum staff who are authori- ties in the particular field involved. life sciences editorial board Chairman: a G EDMUND Editor: J H mcandrews Editor: r. D James rolf ludvigsen is a Research Associate of the Department of Invertebrate Palaeontology, Royal Ontario Museum, and Assistant Professor in the Department of Geology, University of Toronto. LIBRARY ROYAC ONTARIO MUSEiM Cover drawing: Arctinurus boltoni (Bigsby) © The Royal Ontario Museum, 1979 100 Queen's Park, Toronto, Canada M5S 2C6 PRINTED AND BOUND IN CANADA BY THE HUNTER ROSE COMPANY Contents Foreword 5 Acknowledgements 7 Introduction 9 Palaeozoic Geology of Ontario 18 Introduction to Trilobites 20 History of Trilobite Studies in Ontario 28 Types of Trilobites Represented in Ontario 31 Ordovician Trilobites 34 Strotactinus 34 Goniotelina 35 Gignopeltis 35 Basiliella 36 Thaleops 37 Nanillaenus 37 Bathyurus 37 Raymondites 37 Faiileana 39 Calyptaulax 40 /4 nataphrus 42 Isotelus 42 Ceraurus 42 Eomonorachus 42 Encrinuroides 45 Achatella 46 Bumastoides 46 "Calyptaulax" 46 Flexicalymeme 46 Paraharpes 48 Dolichoharpes 48 Cyphoproetus 50 Dimeropyge 50 Hypodicranotus 50 Cybeloides 50 Cryptolithus 50 Eobronteus 5 1 Ceraurinella 52 Sphaerocoryphe 52 Hemiarges 52 Amphilichas 52 Ceraurinus 54 Pseudogygites 55 Triarthrus 55 Silurian Trilobites 61 Acernaspis 61 Leonaspis 62 Dicranopeltis 63 Encrinurus 63 Dalmanites 65 Trimerus 65 Arctinuras 65 Calymene 65 Liocalymene 68 Scutellum 68 Ekwanoseutelluni 70 Cheirurus 70 Bumastus 70 Sphaerexochus 70 Devonian Trilobites 73 Terataspis 73 Arte hi ops is 75 Phacops 76 Acanthopyge 11 "Dechenella" 11 Mystrocephala 11 Coronura 78 Trypaulites 79 Greenops 80 Crassiproetus 82 Dechenella 84 Otarion 84 Dipleura 84 Proetus 84 Repositories of Illustrated Specimens 86 Glossary of Morphological Terms 87 Literature Cited 89 Foreword More than 100 years have passed since H.A. Nicholson, Professor of Natural History in the University of Toronto, published in 1874 and 1875 his two re- ports on the palaeontology of the province of Ontario. Since that time not only has there been a great increase in the volume of palaeontological research on Ontario, but increasingly, publication has been in diverse and sometimes difficult to obtain journals. The effects of this have been to make it difficult for the professional, as well as for the amateur, to obtain up-to-date information. This new series, Fossils of Ontario, seeks to remedy some of these problems by drawing together and synthesizing information on particular taxonomic groups as they occur in the rocks and sediments of Ontario. The authors of each contri- bution are experts in the particular taxonomic group or topics being considered and their synthesis is directed to the student, the collector, the professional pa- laeontologist, as well as to the interested person who wishes to be informed. P.H. von Bitter, Associate Curator-in-charge, Department of Invertebrate Palaeontology, Royal Ontario Museum. Associate Professor, Department of Geology, University of Toronto. Digitized by the Internet Archive in 2012 with funding from Royal Ontario Museum http://archive.org/details/fossilsofontario01bolt Acknowledgements I am grateful to the curators of the various institutions who responded promptly to my requests for particular trilobite specimens and especially to the staff of the Royal Ontario Museum and the Geological Survey of Canada who gave me free access to their trilobite collections. Richard Fortey of the British Museum (Nat- ural History) supplied the photographs of Isotelus platycephalus, Murray Cope- land of the gsc brought to my attention the cock-eyed specimen of Phacops rana, Allen Ormiston of Amoco Research helped in the identification of several Devonian trilobites, and Don Mikulic of Oregon State University did the same for Silurian trilobites. David Dillon executed the fine trilobite reconstructions seen on the cover and in the text, and Subhash Shanbhag drafted the figures. I am especially indebted to Brian O'Donovan for his expert photographic work and to Desmond Collins and Peter von Bitter of the ROM for their encouragement during the preparation of this book. The cost of photography was partially defrayed by the Department of Inver- tebrate Palaeontology of the Royal Ontario Museum. Finally, I thank Tom Bolton and Niles Eldredge for reading the manuscript. Introduction Within the layered Palaeozoic rocks of Ontario are preserved the remains of an extinct group of animals whose demise predated the appearance of the human animal by over 200 million years and whose name, along with that of the dino- saurs, has become synonymous with the term fossil. These creatures are trilo- bites, and their fossil record in Ontario is the subject of this book. Trilobite remains are often fascinating and aesthetically pleasing. Their pecu- liar shapes and striking ornamentation attract the interest of those who collect the strange, the unusual, and the beautiful; the minute perfection of their pet- rified outer skeletons delights those who seek natural beauty. However, trilo- bites are not merely interesting objects; they are also valuable in palaeobiologic contexts in that they constitute a critical record of a unique group of well- adapted and highly successful marine arthropods. This record has yielded a sur- prising amount of anatomical, evolutionary, ecological, zoogeographical, and even behavioural information about these extinct animals. Trilobites are among the most lifelike of fossils, and perhaps this is one expla- nation of their popular appeal. Little imagination is required to "revive" a trilo- bite. Many well-preserved, complete specimens appear to belie their great anti- quity; some almost seem ready to arch their bodies, peer about, and crawl forward as if to continue a journey that was interrupted in the Palaeozoic. The first step towards the appreciation and understanding of any natural ob- ject is identification. Recognition of a peculiar blob in a rock as a fossil offers limited information about its nature and significance. If, however, the identifica- tion of this blob can be extended from fossil to trilobite, to lichid trilobite, to Arctinurus, and finally to A. boltoni (Bigsby), then each step in identification in- creases the cumulative awareness of the significance of this relic of past life. Thus the blob becomes an item of scientific importance through the process of identification. The Palaeozoic rocks of Ontario contain more than 60 genera of trilobites and perhaps a few hundred species. These trilobites have been described and il- lustrated in various professional journals, government publications, and schol- arly monographs, but most of these are difficult to obtain and a few are more than a century old. The palaeontologic information included in these works is generally unavailable to the serious amateur collector, the natural historian, and the student of geology and palaeontology. This publication provides a reference for identifying Ontario trilobites through good illustrations and brief descriptions of each genus. I hope that the illustrations will whet the reader's interest to the extent that he or she will grab hammer and hand-lens and go forth to the outcrops, roadcuts, and quarries of Ontario in search of trilobites. To aid these expeditions, a brief introduction to the Palaeozoic geology of Ontario and a series of maps showing the distribution of Palaeozoic formations is included. Because some readers, particularly stu- dents of geology and palaeontology, will want to search out additional informa- tion about certain trilobites, I have included a fairly extensive list of references. Although the book has been written with the collector and the student in mind, it may also assist palaeontologists from other parts of Canada and from other countries who need a quick overview of the Ontario trilobite faunas. Naturally, I have selected the best-preserved and most complete of the On- tario trilobites for illustration, but when better specimens have been available from adjoining provinces and states, I have let the quality of the specimen take precedence over political boundaries. As a result, some of the "Ontario" trilo- bites in the illustrations were actually collected as far afield as Kentucky and Manitoba. Exceptionally preserved specimens of trilobites are becoming increasingly difficult to find in Ontario, but while one is waiting for that perfect trilobite to come into view, there are thousands of more ordinary but still interesting speci- mens of most species to be collected and studied. DEVONIAN SILURIAN ORDOVICIAN Fig. 1 Distribution of Ordovician, Silurian, and Devonian rocks in Ontario. SOUTHERN ONTARIO NORTHERN ONTARIO Lake Ontario - Lake Huron Hudson Bay James Bay k_ o "O > "O LU E Q h. *E _l C/) k. a> ? o k. o O) Q ■o (T F O k. a> 5 o — PORT LAMBTON KETTLE POINT TT TT HAMILTON SH.LS I I I I I I I I I I I I I I I I I DUNDEE I I I I I I I I I I I I I IT LUCAS AMHERSTBURGdol™™°ls I I M I I I I I I I I I I I BOIS BLANC R I ORISKANY ss MINI BASS ISLAND-BERTIE dol SALINA DOL.EVAP GUELPH ERAMOSAlS.DOL LOCKPORT DOL DECEW ROCHESTER IRONDEQUOIT I I I I I I I IT FOSSIL HILL REYNALES i_s NEAHGA DOL THOROLD TT GRIMSBY CABOT HEAD MANITOULIN WHIRLPOOL QUEENSTON KAGAWONG p0L GEORGIAN BAY LS.SH SLTST WHITBY .j_ COBOURG VERULAM BOBCAYGEON w GULL RIVER > SHADOW LAKE ss.sh i i i i i i i i i I CHAZYls.sh.ss OXFORD MARCH LONG RAPIDS I I I I I I I I ITT WILLIAMS ISLAND I I I I I I MURRAY ISLAND M MOOSE RIVER D0L evap KWATABOAHEGAN STOOPING RIVER SEXTANT ss KENOGAMI RIVER SLTST SH.SS ATTAWAPISKAT EKWAN RIVER SEVERN RIVER RED HEAD RAPIDS CHURCHILL RIVER BAD CACHE RAPIDS LS DOL EVAP SH SLTST SS LIMESTONE DOLOSTONE EVAPORITE SHALE SILTSTONE SANDSTONE Legend Fig. 2 Succession of Palaeozoic formations in southern and northern Ontario. Adapted from Win- der and Sanford (1972) and Sanford and Norris (1973). "3 c ex IS < d •c B o o 11 O -J 00 72 50 km Lake Huron LURIAN FORMATIONS J BASS ISLAND & BERTIE SAUNA GUELPH ERAMOSA AMABEL CATARACT & FOSSIL HILL NIAGARA FALLS Lake Erie Fig. 4 Silurian geology of southern Ontario. Adapted from Winder and Sanford (1972). 13 in cc O O > LLI Q z O o \- cr 1- -z. Z> CO 1— (J o Z Z Q_ o LU CO < _l 1- cc LU _l 1- 1— LU Q GO < ( ) cc LU X CQ 00 o LU < _) — > :> o Q_ ^ I Q _i < OQ r^ CD LO ^t CO CN ,- s\v o*£! ^ £ o ID *Q c^ CN CM CO DC C < 2 3 O a 00 lo LO o CD c CD OQ 74 6 o •6 e a o "3 0) c I s c o -a 00 7 Nvmmis nvioiaoquo 15 X E o < o U 43 00 16 Hudson Bay James Bay O < ORDOVICIAN-DEVONIAN FORMATIONS ^13 LONG RAPIDS 12 WILLIAMS ISLAND 11 MURRAY ISLAND 10 MOOSE RIVER 9 KWATABOAHEGAN 8 STOOPING RIVER *7 KENOGAMI RIVER 6 ATTAWAPISKAT 5 EKWAN RIVER J[ SEVERN RIVER ^3 RED HEAD RAPIDS | 2 CHURCHILL RIVER | 1 BAD CACHE RAPIDS Fig. 8 Ordovician, Silurian, and Devonian geology of the Hudson Bay area. Adapted from San- ford and Norris (1973). 17 Palaeozoic Geology of Ontario The sequence of Ordovician, Silurian, and Devonian formations in southern and northern Ontario is shown in Figure 2 and their outcrop patterns summa- rized in Figure 1 and Figures 3 to 8. The southern and northern areas of Palaeo- zoic outcrop are separated by a broad expanse of Precambrian igneous and me- tamorphic crystalline rocks on which occur scattered Palaeozoic outliers; the largest of these outliers is in the Lake Timiskaming area. Because even a brief discussion of the Palaeozoic stratigraphy of Ontario is not possible here, references are given below. GENERAL REFERENCES Palaeozoic stratigraphy Ontario Southern Ontario Hudson Bay area Ordovician stratigraphy Hudson Bay area Ottawa area Southern Ontario Silurian stratigraphy Southern Ontario Hamilton area Devonian stratigraphy Southern Ontario Hudson Bay area SPECIFIC REFERENCES Toronto-Hamilton area Brantford area London area Windsor-Sarnia area Lake Simcoe area Bruce Peninsula Manitoulin Island Lake Timiskaming Douglas (1970) Winder and Sanford (1972) Winder c/fl/. (1975) Hewitt (1972) Sanford and Norris (1973) Cumming(1975) Wilson (1946) Wilson etal. (1936) Liberty (1964) Bolton (1957) Segall(1972) Sanford (1968) Sanford and Norris (1975) Caley(1940) Caley(1941) Caley(1943) Sanford and Brady (1955) Liberty (1969) Liberty and Bolton (1971) Liberty and Shelden (1968) Bolton and Copeland (1972) 18 It is beyond the scope of this book to provide a detailed list of collecting localities in Ontario where specific trilobites may be obtained. Such a list would run into hundreds of entries. In any case, virtually all roadcuts, natural expo- sures, and quarries in the Palaeozoic rocks of Ontario are likely trilobite pros- pecting areas. Many guidebooks describe and locate collecting areas. The reader should consult Bolton (1957), Bolton and Copeland (1972), Liberty (1969), Liberty and Bolton (1971), Liberty and Shelden (1968), Segall (1972), Sta- uffer (1915), Stumm and Wright (1958), Wilson (1947), Winder et al. (1975), and Winder and Sanford (1972). 19 Introduction to Trilobites Trilobites appeared abruptly at the beginning of the Cambrian and radiated rapidly to a diversity peak in the Late Cambrian. Their numbers declined mark- edly through the Ordovician, had a period of stability that lasted from the Early Silurian to the Middle Devonian, then another rapid decline to a period of slow attrition in numbers from the Late Devonian, through the Carboniferous, to their extinction in the Late Permian. This extinction involved only a handful of genera, and is a relatively insignificant event in light of the previous history of the group (Fig. 9). About 1,500 genera of trilobites existed during the one-third of a billion year history of the group. The name trilobite refers to the longitudinal division of the body into an axial lobe and two pleural lobes. The body also shows a transverse division into a head region (cephalon), an articulating thorax, and a tail region (pygidium). The cephalon is generally crescentic in outline and comprises a central glabella out- lined by axial and preglabellar furrows and flanked by a pair of cheeks. The gla- bella is usually inflated and may be divided into transverse lobes by an occipital furrow and a number of lateral glabellar furrows. In sighted trilobites, a com- pound eye is situated on each of the cheeks. The posterolateral portions of the cephalon may be blunt corners or may bear genal spines. Narrow lines of weak- ness where the cephalon splits during moulting are called facial sutures and these divide the cheek into an inner fixed cheek and an outer free cheek. The su- tural pattern has been used as a classification criterion. These sutures may be opisthoparian (posterior part of suture cuts posterior margin of cephalon inside the genal angle; for example, Pseudogygites, Fig. 10), or proparian (posterior part of suture cuts lateral margin of cephalon in front of genal angle; for exam- ple, Ceraurinella, Fig. 11), or marginal (suture runs along margin of cephalon; for example, Paraharpes, Fig. 30a). On the ventral side of the cephalon, the recurved portion of the dorsal exo- skeleton or doublure, extends inwards for some distance. The doublure may be entire, or it may be traversed by a single median suture, or it may include a ros- tral plate outlined by sutures on all sides. Beneath the glabella occurs the hypos- tome; this plate is generally attached to the doublure with a sutural contact and appears to have covered the stomach and mouth regions of the trilobite. The thorax consists of a number of bandlike segments between which articu- lation occurred. The distal portions of the thoracic segments may terminate in spines or may be faceted so that they can nest closely upon enrollment. The pygidium consists of a single plate of fused segments that covers the pos- 20 IU CO U_ UJ ° £ CO Z UJ O co£D o in < UJ PERIODS u- UJ _i Oh z UJ > UJ UJ u. o z U- ./ 4*^s8^^ ' •*•■•• •/ . - ■ *' .'$ ****** -2 - •'^■^l ^«r*r '•, ff~"*-~. s -^ - n V - 'l|':il|X Fig. 12 Dorsal (left) and ventral (right) views of two pyritized specimens of Triarthrus eatoni (Hall) showing the hard part morphology and the appendages. Approximately X 2.5. The speci- mens are from the Utica Shale (Upper Ordovician), near Rome, New York State and were collected and prepared by C.E. Beecher during the 1890s. The photographs are by Prof. Levi-Setti of the University of Chicago who captured the fine detail and contrast by im- mersing the specimens in xylene. Reprinted from Trilobiies: a photographic alias by R. Levi-Setti (1975, pis. 7 and 9) with permission of the University of Chicago Press. merely represent moults of a living trilobite. Therefore, a single trilobite may leave as many complete fossils as it had moult stages. The moult remains were generally scattered across the sea floor by currents. Occasionally, moult remains occur in the same configuration as the trilobite left them: a good example of this from the shales of the lower Whitby Formation at Craigleith is shown in Figure 14. If we compare the disposition of the moulted elements of Pseudogvgites latimarginatus (Fig. 14b) with a dead individual of the same species (Fig. 14a), we can reconstruct the behaviour of the moulting trilobite in a series of dia- grams (Fig. 14c). One of the fascinating aspects of trilobites is the presence in many species of well-developed paired eyes; and because this visual system is the earliest about which information is available, it attracts considerable attention. The optical medium was precisely oriented crystals of calcium carbonate and, as such, the trilobite eyes are unique in the animal kingdom. Excellent accounts of trilobite eyes and vision are given by Towe (1973), Clarkson (1975), Clarkson and Levi- 24 Fig. 13 Life history of a trilobite, Shumardia pusilla (Sars), showing the division into the larval stage (protaspid, a), the juvenile stage (meraspid, b-g), and the adult stage (holaspid, h and I). Note the increase in the number of thoracic segments through the meraspid stage from 0 to 5. The holaspid stage is defined as when the full number of thoracic segments is reached — in this case, 6. Redrawn from Stubblefield ( 1926). Setti (1975), and Levi-Setti (1976). Two types of trilobite eye have been denned: the holochroal eye (Figs. 2 Id, 24e) consists of a visual surface of numerous, small, densely packed lenses covered by a single continuous cornea. The schizo- chroal eye (Figs. 24b, 56, 57b) consists of a visual surface of large separated lenses, each of which is covered by a single cornea. The holochroal eye is, by far, the most common trilobite eye and occurs in all groups except the phaco- pids and dalmanitids which have schizochroal eyes. Most sighted trilobites appear to have been benthic (bottom dwelling) ani- mals that lived in generally shallow and well-lit marine waters. Many, particu- larly those with large eyes and ornamented exoskeletons, were probably epifaunal (lived on the sediment or furrowed through the top few millimetres of sediment). In such settings, trilobites could have been filter feeders, detritus feeders, scavengers, or even predators. Others, particularly those large smooth forms with broad axes such as Bumastoides, Bumastus, Anataphrus, and Dipleura, were probably semi-infaunal (lived partially submerged in the sedi- ment) and were either detritus or filter feeders. Trilobites with reduced pleural portions and downwardly directed eyes may have been nektic (swimmers) or planktic (floaters). Blind trilobites could have been deep burrowers or could have lived in habitats below the photic zone. Undoubtedly the best and most authoritative source book on trilobites is the Treatise (Moore, 1959). This volume summarizes available knowledge on trilo- bites and includes diagnoses and illustrations of most genera described up to 20 years ago. Information about trilobites and other fossils may be found in intro- ductory palaeontology textbooks such as Moore et al. (1952), and Black (1970) and in nontechnical books such as MacFall and Wollin (1972). Finally, Trilobites: a photographic atlas by R. Levi-Setti (1975) is highly recommended as a superbly illustrated and well-written passport into the world of trilobites. 25 Fig. 14 How the trilobite Pseudogygites moulted. a A dead individual (sutures essentially closed, hypostome in place). ROM 35029, X 2.5. b The moult remains left by the trilobite, ROM 30015. X 1.8. c A moult scenario. The trilobite severed the connection between the thorax and cephalon by anchoring one genal spine in the mud and backing up. This caused the cephalon to rotate back over the front part of the thorax. With its head, the trilobite then nudged the cranidium free from the remaining cephalon and crawled obliquely forward through the gap left by the split facial suture. As the trilobite moved forward it pushed the cranidium while the conjoined thorax and pygidium became caught against the cephalon and slid off the back of the trilobite. Finally, when it was almost free of its moult remains, the trilobite dislodged and overturned the hypostome with its thrashing legs. 26 o Hamilton Dundee > Lucas LU Amherstburg Q Bois Blanc —r Guelph ^ Eromosa — Amabel cc Rochester Fossil Hill TZ Cataract < Georgian Bay o o o o o o Whitby 0 0 0 q o o — Cobourg ooooo o ogooooo ^Verulam oooooggooooogoooooooooo O Bobcaygeon 00 ggooggoggo „ Gul I River oooooooooo O Oxford o o o Fig. 15 Stratigraphic occurrences of Ordovician, Silurian, and Devonian trilobite genera in south- ern Ontario. 27 History of Trilobite Studies in Ontario In 1820, Dr. John J. Bigsby (Fig. 16a), at that time the British representative to the Boundary Commission between British North America and the United States, collected fossils from limestones exposed on St. Joseph Island in Lake Huron. Among the fossils were several trilobite specimens and, on his return to England, Bigsby gave them to Charles Stokes. In an appendix to Bigsby's paper on the geography and geology of Lake Huron published in 1824, Stokes illus- trated and briefly commented on this trilobite and gave it a name — Asaphus platycephalus. This was the first trilobite from the area now included in Ontario to receive a name, and was also the first trilobite from North America to be de- scribed. In addition, Stokes' note was the first published identification of the plate that covers the mouth region in trilobites, the hypostome. The original il- lustrations of this trilobite, now identified as Isotelus platycephalus (Stokes), are shown in Figure 17 along with photographs of the specimen in its present state. Little further work was done on Ontario trilobites until 1856 when Sir Wil- liam Logan appointed Elkanah Billings (Fig. 16b) palaeontologist to the Geo- logical Survey of Canada. Billings developed a deep interest in natural history and fossils while pursuing twin careers in law and as the editor of the Bytown Citizen. He also founded and served as the editor and chief contributor to a scientific journal called The Canadian Naturalist and Geologist. After 1856 Bill- ings started the massive task of arranging, identifying, and classifying the fossils collected by members of the Survey from all parts of Upper and Lower Canada. These fossils, including trilobites, were described in a long series of papers pub- lished during the next 20 years. Billings' authoritative initiation of Canadian Pa- laeozoic palaeontology is perhaps best displayed in his contribution to Logan's monumental Geology of Canada published in 1863 and in his Palaeozoic Fossils published in 1865. Elkanah Billings died in 1876 and is buried in Toronto. Contemporaries of Billings also involved in the study of Ontario trilobites in- clude James Hall, State Palaeontologist of New York, whose work on Silurian and Devonian trilobites extended into Ontario, and E.J. Chapman, Professor of Mineralogy and Geology at the University of Toronto. Chapman published an obsolete classification of trilobites in 1890. The next major personage in Ontario trilobite studies was Percy E. Raymond (Fig. 16c) who was Chief Palaeontologist to the Geological Survey of Canada from 1910 to 1912. Raymond's particular forte was Ordovician trilobites and he produced a large number of papers on trilobites of the Trenton and Black River Groups in southern Ontario. 28 The only comprehensive work on trilobites of a specific region in Ontario was that of Alice E. Wilson (Fig. 16d) in 1947. This book was on Middle Ordovician trilobites of the Ottawa area. It formed part of an extensive series of mono- graphs on the Ordovician invertebrate fossils of the region published between 1945 and 1961. More recently other investigators have contributed towards an understanding of Ontario trilobites: G.W. Sinclair of the Geological Survey of Canada on Or- dovician trilobites, E.C. Stumm of the University of Michigan on Devonian tri- lobites, and H.B. Whittington of Harvard University on Ordovician, Silurian, and Devonian trilobites. Their contributions are in the reference list. aw Fig. 16 Students of Ontario trilobites. a John J. Bigsby, 1792-1881 B Elkanah Billings, 1820-1876 c Percy E. Raymond, 1879-1952 D Alice E. Wilson, 1881-1964 29 Fig. 17 Isolelus platvcephalus (Stokes) — the first Ontario trilobite to be described. The specimen was collected in 1820 by Dr. J.J. Bigsby on St. Joseph Island. a.b The illustration of Asaphus platvcephala published by Charles Stokes (in Bigsby, 1824). Dorsal and ventral views of cephalon. x .65. CD The specimen as it appears now, bm 182, X .65. 30 Types of Trilobites Represented in Ontario I will not provide a formal classification of trilobites; the reader is referred to the Treatise (Moore, 1959) and to Bergstrom (1973) for two differing interpreta- tions of trilobite classification. I will merely present outline drawings of a typical member of each of 21 informal groupings of genera that occur in Ontario (Fig. 18), indicate (in brackets) the corresponding classification according to the Treatise, and list the Ontario genera that belong in each. Olenid trilobites (Family Olenidae) Triarthrus Asaphid trilobites (Family Asaphidae) Isotelus, Basiliella, Anataphrus, Pseudogygites Remopleuridid trilobites (Family Remopleurididae) Hypodicranotus Illaenid trilobites (Family Illaenidae) Failleana, Nanillaenus, Thaleops, Bumastoides, Bumastus Scutelluid trilobites (Family Thysanopeltidae) Eobronteus, Scutellum, Ekwanoscutellum Bathyurid trilobites (Superfamily Bathyuracea) Bathyurus, Raymondites, Goniotelina, Gignopeltis Dimeropygid trilobites (Family Dimeropygidae) Dimeropyge Proetid trilobites (Family Proetidae) Crassiproetus, Proetus, Cyphoproetus, Dechenella, "Dechenella" Otarionid trilobites (Family Otarionidae) Otarion Brachymetopid trilobites (Family Brachymetopidae) Mystrocephala Harpid trilobites (Family Harpidae) Paraharpes, Dolichoharpes Trinucleid trilobites (Family Trinucleidae) Cryptolithus Cheirurid trilobites (Family Cheiruridae) Ceraurus, Ceraurinus, Ceraurinella, Sphaerocoryphe, Cheirurus, Sphaerexochus Pliomerid trilobites (Family Pliomeridae) Strotactinus 31 Fig. 18 Types of trilobites represented in Ontario. Mainly culled from Moore ( 1959). Not to sea a Olenid (Olenus illustrated) B Asaphid (Plectasaphus) C Remopleundid (Remopkurides) D lllaenid (Bumastus) E Scutelluid (Scutellum) F Bathyund (Balhyurus) G Dimeropygid (Dimeropyge) H Proetid (Dechenellci) t Otarionid (Otarion) j Brachymetopid (Brachymetopus) K Harpid (Harpes) l Tnnucleid (Cryptolithus) M Cheirurid (Ceraurinella) N ?\iomer\d (Pliomerops) o Encrinurid(£nm>iM/-itf) p Calymenid (Calymene) q Homalonotid (Dipleura) r Phacopid {Reedops) s Dalmanitid (Dalmanites) T Lichid (Arctinurus) U Odontopleurid (Odontopleura) Encrinurid trilobites (Family Encrinuridae) Encrinurus, Encrinuroides, Cybeloides Calymenid trilobites (Subfamily Calymeninae) Flexicalymene, Liocalymene, Calvmene Homalonotid trilobites (Subfamily Homalonotinae) Trimerus, Dipleura Phacopid trilobites (Superfamily Phacopacea) Acernaspis, Phacops Dalmanitid trilobites (Superfamily Dalmanitacea) Calyptaulax, Eomonorachus, "Calyptaulax", Achatella, Dalmanites, Anchiopsis, Greenops, Trypaulites, Coronura Lichid trilobites (Order Lichida) Hemiarges, Amphilichas, Dicranopeltis, Terataspis, Arctinurus, Acanthopyge Odontopleurid trilobites (Order Odontopleurida) Leonaspis 33 Ordovician Trilobites Figs. 19 to 39 At least 34 genera of trilobites are found in Ordovician rocks of southern On- tario (Fig. 15). Trilobites are rare in the Lower Ordovician dolostones of the Ot- tawa area where only a few specimens are known. They are more diverse and abundant in the Black River Group, but are often difficult to collect because of the preponderance of tough, fine-grained limestones. Fossiliferous limestones of the Trenton Group have yielded abundant and well-preserved specimens and trilobites reach a diversity peak with 23 genera in the limestones and shales of the Verulam Formation. Even here, trilobites are not among the more conspicu- ous faunal elements. Of the 330 species of fossils recorded from the Verulam Formation (Liberty, 1969) in the Lake Simcoe area only 31 are trilobites. The only stratigraphic interval in Ontario in which trilobites occur on virtually every piece of rock and consistently outnumber all other fossils is the lower part of the Whitby Formation. Here, dark brown bituminous shales contain massed speci- mens of Pseudogygites and Triarthrus. Only a few poorly preserved trilobites oc- cur in the younger Ordovician formations in southern Ontario. The very large specimens of Isotelus in the Georgian Bay Formation are rare exceptions. Trilobites have not been described from the Ordovician limestones of the Hudson Bay area and only a few genera are recorded, including Ceraurinus and Isotelus in the Bad Cache Rapids Group and the same genera plus Nanillaenus, Encrinuroides, Calyptaulax, and Bumastoides in the overlying Churchill River Group. Strotactinus Bradley Fig. 19a, b Strotactinus is one of the few trilobites that occurs in the Lower Ordovician dolostones of the Ottawa area. It has a convex cranidium and a rectangular gla- bella with three pairs of straight lateral furrows; the specimen illustrated in Fig- ure 19a is an internal mould and only two pairs of lateral furrows are evident. The anterior border of the cranidium is high and roll-like and the eyes are lo- cated far out on the cheeks opposite the second glabellar lobe. The pygidium consists of a broad segmented axis flanked by five pairs of downwardly curving tubular ribs that terminate as short pointed spines. species Strotactinus salteri (Billings) — Oxford Formation, Ottawa area. references Billings ( 1865), Bradley (1925) 34 Goniotelina Whittington and Ross Fig. 19c,d This early bathyurid trilobite has an inflated and parallel-sided glabella lacking furrows and large palpebral lobes with distinct curving palpebral furrows. The triangular pygidium has a well-defined axis bearing four furrows, concave bor- ders, and a terminal spine. The surface of the cranidium and pygidium is sparsely granulate. species Goniotelina subrectus (Bradley) — Oxford Formation, Ottawa area. reference Whittington (1953) Gignopeltis Raymond Fig. 19e Only a few pygidia of this genus are known and it is difficult to decide how it should be classified. The pygidium of Gignopeltis is sub-semicircular in outline, evenly inflated in cross-section, and lacks a border. The axis is outlined by shal- Fig. 19 Strotactinus Goniotelina Gignopeltis Strotactinus salten ( Billings) a Cranidium, X 4.6, gsc 7834, Oxford Fm., Oxford Township. B Pygidium, X 3.5, Gsc 515, Oxford Fm., Oxford Township. Goniotelina subrectus (Bradley) c Pygidium, X 3.2, ROM 19a cal, Oxford Fm., Marlborough Township. D Cranidium, X 2.6, ROM 19b cal, Oxford Fm., Marlborough Township. Gignopeltis conve.xus (Billings) E Pygidium, X 3.2, ROM 18 cal, Oxford Fm.. Marlborough Township. 35 low furrows and the pleural lobe is crossed by four faint furrows. Such a pygi- dium is not unlike those of some bathyurid trilobites. species Gignopeltis rarus (Billings) and Gignopeltis eonvexus (Billings) — Oxford Formation, Ottawa area. references Billings ( 1 865), Raymond ( 1 924) Basiliella Kobayashi Fig. 20a,b Basiliella is an asaphid trilobite characterized by the markedly divergent course of the facial suture in front of the large eyes, the very long and broad genal spines, and the strongly ribbed pygidium. Like many other asaphid genera, Basiliella has a forked hypostome. Fig. 20 Basiliella Thaleops Nanillaenus Basiliella barrandei (Hall) A Reconstruction, X .9. B Pygidium, X 2.1, rom 18695, Black River Gp., Ottawa. Thaleops ovata Conrad C Exoskeleton, X 1.6, GS( 1321, Black River Gp., Ottawa. Nanillaenus latiaxiatus (Raymond and Narraway) D Cranidium, X 1.7, rom 18754a, Black River Gp., Ottawa. E Thorax and pygidium, X 1.7, rom 18754b, Black River Gp.. Ottawa. 36 species Basiliella barrandei (Hall) — Black River Group, southern Ontario and Ottawa area. reference Raymond ( 1916) Thaleops Conrad Fig. 20c This illaenid trilobite has an axis defined by deep furrows. These axial furrows are nearly obsolescent on the posterior part of the pygidium and the anterior part of the cephalon. The eyes of Thaleops are elevated and the genal spines are fairly long and hooked inwardly. species Thaleops ovata Conrad — upper Black River and Trenton Groups, southern Ontario and Ottawa area. references Wilson ( 1 947), Jaanusson ( 1 954) Nanillaenus Jaanusson Fig. 20d,e Nanillaenus is rather similar to Thaleops; the principal difference is the presence of shallower axial furrows, less elevated eyes, and shorter genal spines. species Nanillaenus conradi (Billings), Nanillaenus latiaxiatus (Raymond and Narraway), Nanillaenus angusticollis (Billings), Nanillaenus americanus (Billings) — upper Black River and Trenton Groups, southern Ontario and Ottawa area. references Billings (1865), Sinclair (1947), Wilson (1947), Jaanusson (1954), Chatterton and Ludvigsen (1976) Bathyurus Billings Fig. 21 Bathyurus has a large inflated glabella with two pairs of faint lateral glabellar furrows. The palpebral lobes are large and semicircular; the genal spines are moderately long and tapering. The pygidium is triangular and has four inter- pleural furrows. The square hypostome is diagnostic, as is the pecular rostral plate. This plate has not yet been recognized on specimens from Ontario, but silicified material from the Northwest Territories shows it to perfection (Fig. 21e). Bathyurus is moderately common in the fine-grained limestones of the Black River Group in southern Ontario. It probably lived partially submerged in the carbonate mud with only the eyes protruding and appears to have prefer- red a shallow marine environment. species Bathyurus superbus Raymond, Bathyurus acutus Raymond, Bathyurus extans (Hall) — Black River Group, southern Ontario and Ottawa area. references Wilson (1947), Whittington (1953), Ludvigsen (1978) Raymondites Sinclair Fig. 22 This bathyurid trilobite is in many respects similar to Bathyurus and was proba- bly a descendant of that genus. Compared with Bathyurus, Raymondites has a narrower glabella, a broader border on the cephalon, and palpebral lobes that are located further back on the cranidium. In addition, the glabella is covered by coarse tubercles. The most striking feature of the Ontario species of Raymondites is the presence of a pair of long curving median spines — one on the occipital ring and one on the pygidium. The name Raymondites is in honour of an early student of Ontario trilobites, P.E. Raymond (Fig. 16c). species Raymondites spiniger (Hall) — Black River Group and Bobcaygeon and 37 11 "'- •«$$< Fig. 2 1 Bathyurus Bathyurus superbus Raymond a Exoskeleton, X 1. rom 18788. Black River Gp., Ottawa. b Hypostome. X 1.7. rom 32374, Black River Gp., Ottawa. Bathvurus extans (Hall) CD Exoskeleton, x 2 and x 3.5, lisnm 306, Lowville Fm„ Great Bend, New York. Bathyurus sp. K Hypostome and attached rostral plate, X 8.2, gsc 40431, Esbataottine Fm„ South Nahanni River area. District of Mackenzie. 38 Fig. 22 Raymondites Raymondites spiniger (Hall) a Reconstruction, X 1.7. b Cranidium, X 1.5, osc 4318, Bobcaygeon Fm., Kirkfield Quarry, Kirkfield. c Pygidium. X 3.5, ROM 35353, Verulam Fm., Moira River, Belleville. Verulam Formations, southern Ontario. Other species are Raymondites bandifer Sinclair and R. trispinosus (Wilson). references Sinclair (1944), Wilson (1947), Whittington (1953) Failleana Chatterton and Ludvigsen Fig. 23 Failleana is a large, smooth and slightly inflated illaenid trilobite that is occa- sionally found in the limestones of the upper Black River and Trenton Groups of southern Ontario. It is virtually devoid of furrows except for shallow axial furrows on the cephalon. It is thus sometimes difficult to recognize isolated cra- nidia and pygidia of this genus as belonging to a trilobite. species Failleana indeterminata (Walcott) — upper Black River and Trenton Groups, southern Ontario and Ottawa area. references Raymond (1916), Wilson (1947), Chatterton and Ludvigsen (1976) 39 Fig. 23 Failleana Failleana indeterminate (Walcott) a Exoskeleton, X 1, GSC 331. Cobourg Fm, Ottawa. B Reconstruction. X I. Calyptaulax Cooper Fig. 24a,b Calyptaulax (or Calliops as it has often been called) is one of the more com- monly encountered trilobites in the Ordovician limestones of Ontario. This dal- manitid trilobite is characterized by a bulbous glabella with three pairs of straight lateral furrows, large crescent-shaped palpebral lobes with deep palpe- bral furrows, and blunt genal angles. The glabella is covered by large granules. The pygidium is triangular with a well-defined axis and is strongly ribbed. The aggregate eyes of Calyptaulax are large and strongly curved in a horizontal plane. Each eye is comprised of about 130 small domelike lenses which are dis- tinctly separated from each other and arranged in vertical rows. Each lens is covered by a discrete cornea and is oriented slightly differently than its neigh- bour. This permits the accumulation of visual information from a wide horizon- tal field — in fact, from all directions except immediately in front of and behind the trilobite. Levi-Setti (1976) gave a concise account of trilobite eyes and trilo- bite vision, including discussion of genera very similar to Calyptaulax. species Calyptaulax callicephalus (Hall) — at almost every locality of the upper Black River and Trenton Groups, southern Ontario and Ottawa area. references Delo (1940), Cooper (1953), Shaw (1968, 1974), Chatterton and Ludvigsen (1976) 40 mS 1 Fig. 24 Calyptaulax Isotelus Anataphrus Calyptaulax callicephalus (Hall) a Exoskeleton. X 3, ROM 35167, Verulam Fm., Gamebridge. Calyptaulax callirachis (Cooper) B Silicified cephalon. X 9.5, esc 40438, Esbataottine Fm., South Nahanni River area. District of Mackenzie. Isotelus gigas DeKay c Enrolled specimen, X 2.6. ROM 35367, Verulam Fm., Lakefield Quarry, Lakefield. D Hypostome. X 1.7, ROM 35368, Verulam Fm., Lakefield Quarry. Lakefield. Anataphrus sinclairi (Wilson) e Cephalon, x 3.5. osc 13252, Black River Gp., Ottawa. Anataphrus Whittington Fig. 24e Anataphrus means "without furrows" and this asaphid trilobite is aptly named. The absence of axial, glabellar, and border furrows lends a globose aspect to this trilobite and distinguishes it from the related genus Isotelus. species Anataphrus sinclairi (Wilson) — Black River Group, Ottawa area. references Wilson (1947), Whittington (1954) Isotelus DeKay Figs. 17, 24c,D, 25 This asaphid trilobite is, without question, the most frequently encountered tri- lobite in Ordovician rocks of Ontario. Species of Isotelus occur in a wide variety of rock types, including limestones, shales, and siltstones, and often attain im- pressive dimensions. The specimen illustrated in Figure 25 measures almost 30 cm in length and larger specimens have been found. Isotelus has a smooth trian- gular cephalon with flattened borders and shallow axial furrows. The eyes are prominent and slightly elevated. The axial furrows are distinct on the thorax, but very faint on the triangular pygidium. The distinctive hypostome is rectan- gular in outline and is deeply notched posteriorly. In front of the hypostome oc- curs a broad and flat doublure that is covered with fine ledgelike lines that par- allel the margin of the cephalon. species A large number of species of Isotelus have been reported from Ontario; among them Isotelus gigas DeKay, Isotelus platycephalus (Stokes), Isotelus maximus Locke, Isotelus iowensis (Owen), Isotelus ottawaensis Wilson, and Isotelus latus Raymond. references Raymond ( 1 92 1 ), Wilson ( 1 947), Darby and Stumm ( 1 965), Chat- terton and Ludvigsen (1976) Ceraurus Green Fig. 26a-d It is a rare Ordovician limestone outcrop in Ontario that does not yield this dis- tinctive and often large cheirurid trilobite. Ceraurus has an inflated and forwardly expanding glabella with three pairs of deep lateral furrows. The eyes are generally located far out on the cheek and the genal angles are extended into a pair of long and curving genal spines. The cephalon is covered by tubercles of varying sizes. The semicircular pygidium is enhanced in size by a pair of long curving first spines, behind which may occur another two pairs of small spines. The hypostome is oval in outline and has an inflated central portion and a rolled border. species Ceraurus pleurexanthemus Green, Ceraurus dentatus Raymond and Barton, Ceraurus bispinosus Raymond and Barton — upper Black River and Trenton Groups, southern Ontario and Ottawa area. references Raymond and Barton (1913), Raymond (1921), Wilson (1947), Cooper ( 1953), Evitt ( 1953), Lane (1971) Eomonorachus Delo Fig. 26e Eomonorachus is similar to Calyptaulax, but differs from that dalmanitid trilo- bite by possessing smaller palpebral lobes which are located closer to the axial furrows, long genal spines, and sparser granulate ornament on the diamond- shaped glabella. In addition, the triangular pygidium has an axis that extends 42 Fig. 25 hotelus Isotelus maximus Locke Large specimen, x .65, ROM 189, Georgian Bay Fm., Don Valley Brickyards, Toronto. 43 Fig. 26 Ceraurus Eomonoraehus Ceraurus sp. a Hypostome, X 2.3. ROM 35363, Verulam Fm., Moira River, Belleville. B Pygidium, X 1.3, ROM 35364, Bobcaygeon Fm., Kirkfield Quarry. Kirkfield. Ceraurus dentatus Raymond and Barton c Exoskeleton, x 1.9, osc 1769, Verulam Fm., Belleville. Ceraurus pleurexanthemus Green D Crushed specimen and pygidium. X 1.7. ROM 35366. Verulam Fm.. Moira River. Belle- ville. Eomonoraehus iniermedius (Walcott) E Exoskeleton, x 1.7, esc 57761, Trenton Gp., Goat Island. nearly to the tip of the pygidium and the ribs on the flanks of the pygidium are unfurrowed. Eomonorachus is a rather uncommon trilobite in Ontario. species Eomonorachus intermedins (Walcott) — Trenton Group, Goat Island. REFERENCE Delo(1940) Encrinuroides Reed Fig. 27 Encrinuroides is one of the more common trilobites in the Bobcaygeon and Ver- ulam Formations of southern Ontario. It is readily distinguished by its nearly parallel-sided glabella which is covered by large blunt tubercles. These tubercles largely obscure three short lateral glabellar furrows. The front portion of the glabella has a short longitudinal furrow. The Ontario species of Encrinuroides bears long curving genal spines and a single median axial spine on the seventh and ninth thoracic segment and paired spines on the pleural lobe of the eighth. The pygidium is triangular and has numerous axial rings and 10 ribs that curve downward and backward and terminate as short blunt spines. species Encrinuroides vigilans (Hall) — Bobcaygeon and Verulam Formations, southern Ontario. This species masqueraded under a number of names, includ- ing Encrinurus trentonensis Walcott and Encrinurus cybeleformis Raymond. reference Evitt and Tripp (1977) , ■■:-:■ V:- '•;¥• '^) ^I^A Fig. 27 Encrinuroides Encrinuroides vigilans (Hall) a Exoskeleton. X 5.2, amnh 36070. Trenton Gp„ Middleville. New York. b Cranidium, X 3.9, ROM 35357, Verulam Fm„ Moira River. Belleville. c Pygidium, X 3.9, ROM 35358, Verulam Fm., Moira River, Belleville. 45 Achatella Delo Fig. 28a.b Achatella is a rather uncommon dalmanitid trilobite in the Verulam Formation. The cephalon is lowly vaulted, crescentic in outline, and has a pair of long slim genal spines. The sparsely tuberculate glabella expands markedly forward and has three pairs of straight lateral glabellar furrows. The palpebral lobes are small and nearly vertical and the visual surface of the eye is high and triangular. species Achatella achates (Billings) — Verulam and Cobourg Formations, southern Ontario and Ottawa area. references Delo ( 1 940), Sinclair ( 1 944), Wilson ( 1 947 ) Bumastoides Whittington Fig. 28c,D This illaenid trilobite is generally represented by discrete cranidia and pygidia; both are distressingly nondescript in their oval outline, inflation, and lack of or- namentation or distinct furrows. Internal moulds of the cranidium, however, show shallow axial furrows which terminate in crescent-shaped depressions ("lunettes"). The complete trilobite is elliptical in outline, smooth, and lacks projections of any kind. Bumastoides was probably a burrowing trilobite. species Bumastoides billingsi (Raymond and Narraway) and Bumastoides mill- eri (Billings) — upper Black River and Trenton Groups, southern Ontario and Ottawa area. references Raymond and Narraway (1906), Wilson (1947), Whittington (1954), Chatterton and Ludvigsen (1976) "Calyptaulax " Fig. 28e,f Species of this genus have hitherto been assigned to Calyptaulax, but well-pre- served specimens from the Verulam Formation suggest that they belong to a new unnamed genus. "Calyptaulax" differs from Calyptaulax in having a larger anterior portion of the glabella, eyes situated further away from the axial fur- rows, long tapering genal spines, and a narrower and higher pygidium. species "Calyptaulax" lincolnensis (Branson) — Bobcaygeon and Verulam For- mations, southern Ontario. Other species, such as Calliops alatus Okulitch, Calyptaulax ottawanus Okulitch, and Calyptaulax calderi Wilson probably be- long in "Calyptaulax". references Delo (1940), Wilson (1947) Flexicalymene Shirley Figs. 29, 45a,b Flexicalymene is one of the more abundant trilobites in Ordovician strata of Ontario, probably second only to Isotelus. The name refers to the common oc- currence of this trilobite as enrolled specimens, but such preservation is not uni- que to this trilobite. Flexicalymene is characterized by a moderately convex gla- bella of parabolic outline and a broad trough-shaped preglabellar furrow. Three pairs of lateral glabellar lobes decrease in size towards the front. The pygidium has a broad axis and lacks a border. The elongate hypostome bears a pair of pointed posterior projections. The entire exoskeleton is finely granulate. A sin- gle species occurs in Silurian rocks of southern Ontario. species Flexicalymene senaria (Conrad) — Trenton Group, Flexicalymene granulosa (Foerste) — Georgian Bay Formation, Flexicalymene celebra (Raymond) — Amabel Formation, southern Ontario. 46 *r' ■ ' 1 *^'"7 ^^ -Int*0, M H i«# "^ ' *?*pL . .■W^WJ^Bj m r '" -,*$£, A l