Paleozoic Life in the Seas

Total Page:16

File Type:pdf, Size:1020Kb

Paleozoic Life in the Seas Paleozoic Life in the Seas • Environmental variables to watch – Sea level – Positions of land and sea (continents & oceans) – Climate • Patterns of diversity • Mass extinctions • Cast of characters 1 The “Sepksoski Curve” From Sepkoski, Paleobiology, 1982 2 The Big 5 Mass Extinctions 3 4 From Alroy et al. PNAS (2001) 5 6 7 Cambrian Period 543 - 490 million years ago 8 Cambrian Trilobites 9 Archaeocyathids Cambrian seascape, painting by Zdenek Burian, ca. 1960 10 Ordovician Period 490 to 443 Million Years Ago 11 Ordovician Brachiopods Brachiopods, Ordovician, Ohio Ordovician Corals Rugose Tabulate www.humboldt.edu/~natmus/Exhibits/Life_time/Ordovician.web/55b.jpg 12 Maclurites at Crown Point, Lake Champlain, NY Leviceraurus Asaphus Ordovician Trilobites Isotelus 13 The largest known trilobite Isotelus rex, Late Ordovician, northern Manitoba Triarthrus, Ordovician, New York 14 Kentucky Ordovician Nautiloids Ohio Minnesota 15 Giant nautiloid Rayonnoceras solidiforme Mississippian, Fayetteville, ARK 16 Ordovician crinoids www.emc.maricopa.edu/faculty/ farabee/BIOBK/1ord04b.gif Ordovician vertebrates Harding Sandstone, Utah 17 www.karencarr.com/images/Gallery / gallery_ordovician.jpg Ordovician seascape Ordovician seascape www.pbs.org/wgbh/nova/link/images/ hist_img_03_ordo.jpg 18 Ordovician seascape http://www.ucmp.berkeley.edu/ordovician/ordovicsea.gif Ordovician seascape www.emc.maricopa.edu/faculty/farabee/BIOBK/1ord04b.gif 19 Silurian Period 443 to 417 Million Years Ago 20 Bumastus Arctinurus Silurian Trilobites Dalmanites Eurypterids (sea scorpions) 21 http://www.karencarr.com/images/Detail/detail_silurian.jpg 22 23 Silurian seascape Painting by Zdenek Burian Devonian Period 417 to 354 Million Years Ago 24 Devonian Brachiopods 25 Odontochile formosa Phacops rana Devonian Trilobites Dipleura dekayi Greenops Terataspis Devonian Rugose Corals 26 www.fallsoftheohio.org/virtualtour/images/FALLS4.JPG www.palaeos.com/Paleozoic/Devonian/ Images/dev16b.jpg Devonian seascapes www.emc.maricopa.edu/faculty/farabee/BIOBK/dev15b.gif “The Age of Fishes” Placoderms Acanthodians Sharks 27 “The Age of Fishes” Dunkleosteus 28 Carboniferous Period 354 to 290 Million Years Ago 29 Carboniferous Crinoids 30 Carboniferous Corals Rugose Tabulate Permian Period 290 to 248 Million Years Ago 31 Permian reef 32 33.
Recommended publications
  • Exoskeletal Structures and Ultrastructures in Lower Devonian Dalmanitid Trilobites of the Prague Basin (Czech Republic)
    Exoskeletal structures and ultrastructures in Lower Devonian dalmanitid trilobites of the Prague Basin (Czech Republic) PETR BUDIL & FRANTIEK HÖRBINGER Our current studies of the exoskeletal structures and ultrastructures in Lower Devonian dalmanitid trilobites of the Prague Basin are briefly described and discussed. The interior of the exoskeleton in most specimens from the Prague Ba- sin is recrystallised and largely filled with very fine homogeneous sparitic cement. The ultrastructures sensu stricto, e.g., the lamination, layers forming the exoskeleton, and the fine pores or “Osmólska” cavities, are mostly imperceptible even at higher magnifications. However, ultrastructural relics were observed in some polished thin sections and exoskeletal fragments using electron microscopy. Larger structures, especially the eyes, the megapores penetrating the exoskeleton, and the surface sculptures (prosopon sensu Gill 1949), are relatively well preserved and show very fine details. The bio- logical significance of megapores is briefly discussed. Modification of the inner parts of the exoskeletons by diagenetic processes, obscuring most of the fine internal structures, is evident. • Key words: Trilobita, Dalmanitidae, exoskeleton microstructure. BUDIL,P.&HÖRBINGER, F. 2007. Exoskeletal structures and ultrastructures in Lower Devonian dalmanitid trilobites of the Prague Basin (Czech Republic). Bulletin of Geosciences 82(1), 27–36 (4 figures, 1 table). Czech Geological Survey, Prague. ISSN 1214-1119. Manuscript received January 17, 2007; accepted
    [Show full text]
  • University of Michigan University Library
    CONTRIBUTIONS FROM THE MUSEUM OF PALEONTOLOGY UNIVERSITY OF MICHIGAN VOL. XI NO.6, pp. 101-157 (12 pk., 1 map) MARCH25, 1953 TRILOBITES OF THE DEVONIAN TRAVERSE GROUP OF MICHIGAN BY ERWIN C. STUMM UNIVERSITY OF MICHIGAN PRESS ANN ARBOR CONTMBUTIONS FROM THE MUSEUM OF PALEONTOLOGY UNIVERSITY OF MICHIGAN MUSEUM OF PALEONTOLOGY Director: LEWIS B. KELLUM The series of contributions from the Museum of Paleontology is a medium for the publication of papers based chiefly upon the collections in the Museum. When the number of pages issued is sufficient to make a volume, a title page and a table of contents will be sent to libraries on the mailing list, and also to individuals upon request. Correspondence should be directed to the University of Michigan Press. A list of the separate papers in Volumes II-IX will be sent upon request. VOL. I. The Stratigraphy and Fauna of the Hackberry Stage of the Upper Devonian, by C. L. Fenton and M. A. Fenton. Pages xi+260. Cloth. $2.75. VOL. 11. Fourteen papers. Pages ix+240. Cloth. $3.00. Parts sold separately in paper covers. VOL. 111. Thirteen papers. Pages viii+275. Cloth. $3.50. Parts sold separately in paper covers. VOL. IV. Eighteen papers. Pages viiif295. Cloth. $3.50. Parts sold separately in paper covers, VOL. V. Twelve papers. Pages viii+318. Cloth. $3.50. Parts sold separately in paper covers. VOL. VI. Ten papers. Pages vii+336. Paper covers. $3.00. Parts sold separately. VOLS. VII-IX. Ten numbers each, sold separately. (Continued on inside back cover) VOL.
    [Show full text]
  • Sequence of Post-Moult Exoskeleton Hardening Preserved in a Trilobite Mass Moult Assemblage from the Lower Ordovician Fezouata Konservat-Lagerstätte, Morocco
    Editors' choice Sequence of post-moult exoskeleton hardening preserved in a trilobite mass moult assemblage from the Lower Ordovician Fezouata Konservat-Lagerstätte, Morocco HARRIET B. DRAGE, THIJS R.A. VANDENBROUCKE, PETER VAN ROY, and ALLISON C. DALEY Drage, H.B., Vandenbroucke, T.R.A., Van Roy, P., and Daley, A.C. 2019. Sequence of post-moult exoskeleton hardening preserved in a trilobite mass moult assemblage from the Lower Ordovician Fezouata Konservat-Lagerstätte, Morocco. Acta Palaeontologica Polonica 64 (2): 261–273. Euarthropods have a tough exoskeleton that provides crucial protection from predation and parasitism. However, this is restrictive to growth and must be periodically moulted. The moulting sequence is well-known from extant arthropods, consisting of: (i) the long inter-moult stage, in which no changes occur to the hardened exoskeleton; (ii) the pre-moult stage where the old exoskeleton is detached and the new one secreted; (iii) exuviation, when the old exoskeleton is moulted; and (iv) the post-moult stage during which the new exoskeleton starts as soft, thin, and partially compressed and gradually hardens to the robust exoskeleton of the inter-moult stage. Trilobite fossils typically consist of inter-moult carcasses or moulted exuviae, but specimens preserving the post-moult stage are rare. Here we describe nine specimens assigned to Symphysurus ebbestadi representing the first group of contemporaneous fossils collected that preserve all key stages of the moulting process in one taxon, including the post-moult stage. They were collected from a single lens in the Tremadocian part of the Fezouata Shale Formation, Morocco. Based on cephalic displacement and comparison to other trilobite moults, one specimen appears to represent a moulted exoskeleton.
    [Show full text]
  • Moscow Formation) in Erie County , Ny
    BIOSTRATIGRAPHY AND PALEOECOLO GY OF THE WINDOM SHALE MEMBER (MOSCOW FORMATION) IN ERIE COUNTY , NY. Carlton E. Brett) State University of New York at Buffalo INTRODUCTION The exposures of Hamilton strata along Lake Erie shore and in various creek beds in Erie County south of Buffalo a r e among the best- known and most thoroughly- studied Middle Devonian fossiliferous sequences in the world. The monumental studies of James Hall and A. W. Grabau (1898, 1899) provided a solid back­ ground for numerous later studies . Yet , in over a century of study, many biostratigraphic and paleoecological problems remain unlnvestigated . Recently , an exceptionally large and complete section of the Windom Shale (Moscow Formation) has been exposed 1n the shale quarries of Penn Dixie Cement Co . near Bayview , N. Y, This outcrop provides an excellent opportunity for detailed study of the fossil horizons of this upper Hamilton unit . Discovery of several new and little- known horizons at this quarry have led to the present restudy of biostratigraphy of the Windom in Erie County . STRATIGRAPHY From its type locality at Smokes Creek near Windom , Erie County N. Y., the Windom Member can be traced eastward nearly 200 miles to the vicinity of Skaneateles Lake (see Rickard, 1964) where the unit becomes sandy and grades into the Cooperstown shales and sandstones . Over mos t of this interval the Windom is a grey , calcareous shale . It is fossiliferous throughout most of its thickness and contains a characteristic IIMoscow Facies" suite fossils. In Erie County the Windom ranges from 9 to 50 ft . in thickness and is composed dominantly of soft, fissile medium- gray shale with thin bands of fossiliferous limestone .
    [Show full text]
  • Instituto De Geociências Revisão Sistemática E
    UNIVERSIDADE DE SÃO PAULO INSTITUTO DE GEOCIÊNCIAS REVISÃO SISTEMÁTICA E PALEOBIOGEOGRÁFICA DE TRILOBITAS PHACOPIDA (HOMALONOTIDAE E CALMONIIDAE) DO DEVONIANO DAS BACIAS DO PARNAÍBA E AMAZONAS, BRASIL Felipe van Enck Meira Tese apresentada ao Programa de Pós- Graduação em Geoquímica e Geotectônica do Instituto de Geociências da Universidade de São Paulo, como parte dos requisitos para a obtenção do título de doutor. Orientadora: Prof. Dra. Juliana de Moraes Leme TESE DE DOUTORAMENTO Programa de Pós-graduação em Geoquímica e Geotectônica São Paulo 2016 “Kites rise highest against the wind - not with it.” - Winston Churchill Agradecimentos Agradeço a Deus, por sempre iluminar o caminho durante esses anos de altos e baixos do Doutorado. Agradeço a Ele também por enviar dois verdadeiros anjos da guarda à minha vida – minha esposa Angela Faleiros van Enck Meira e meu filho, Thomas Faleiros van Enck Meira. Agradeço a meus pais, José Carlos e Sylvia, e à minha irmã, Patrícia, pelo apoio durante a jornada, ainda que à distância, por vezes. Sou grato aos meus sogros, Jair e Lucia, que sempre foram como verdadeiros pais e conselheiros. À FAPESP (Processo n° 2012/07075-3), pelo suporte financeiro, sem o qual o Doutorado não seria viável. À minha orientadora, Drª. Juliana de Moraes Leme, pela orientação, discussões e esclarecimentos pertinentes ao projeto. Ao Doutorando Fabio Carbonaro e ao Dr. Renato Ghilardi (UNESP-Bauru), pela parceria e por discussões importantes na realização do trabalho. À Drª. Niède Guidon (FUMDHAM), pelo empréstimo de fósseis da região de São João Vermelho (Piauí), estudados aqui. Sou grato às seguintes pessoas, por permitirem meu acesso às instituições para visita de acervos, e por sua disponibilidade, atenção e ajuda durante minha permanência: Bushra Hussaini (AMNH), Flávia Alessandra Figueiredo, Mônica de Medina Coeli, Dr.
    [Show full text]
  • 001-012 Primeras Páginas
    PUBLICACIONES DEL INSTITUTO GEOLÓGICO Y MINERO DE ESPAÑA Serie: CUADERNOS DEL MUSEO GEOMINERO. Nº 9 ADVANCES IN TRILOBITE RESEARCH ADVANCES IN TRILOBITE RESEARCH IN ADVANCES ADVANCES IN TRILOBITE RESEARCH IN ADVANCES planeta tierra Editors: I. Rábano, R. Gozalo and Ciencias de la Tierra para la Sociedad D. García-Bellido 9 788478 407590 MINISTERIO MINISTERIO DE CIENCIA DE CIENCIA E INNOVACIÓN E INNOVACIÓN ADVANCES IN TRILOBITE RESEARCH Editors: I. Rábano, R. Gozalo and D. García-Bellido Instituto Geológico y Minero de España Madrid, 2008 Serie: CUADERNOS DEL MUSEO GEOMINERO, Nº 9 INTERNATIONAL TRILOBITE CONFERENCE (4. 2008. Toledo) Advances in trilobite research: Fourth International Trilobite Conference, Toledo, June,16-24, 2008 / I. Rábano, R. Gozalo and D. García-Bellido, eds.- Madrid: Instituto Geológico y Minero de España, 2008. 448 pgs; ils; 24 cm .- (Cuadernos del Museo Geominero; 9) ISBN 978-84-7840-759-0 1. Fauna trilobites. 2. Congreso. I. Instituto Geológico y Minero de España, ed. II. Rábano,I., ed. III Gozalo, R., ed. IV. García-Bellido, D., ed. 562 All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system now known or to be invented, without permission in writing from the publisher. References to this volume: It is suggested that either of the following alternatives should be used for future bibliographic references to the whole or part of this volume: Rábano, I., Gozalo, R. and García-Bellido, D. (eds.) 2008. Advances in trilobite research. Cuadernos del Museo Geominero, 9.
    [Show full text]
  • Type and Figured Fossils in the Worthen Collection at the Illinois
    s Cq&JI ^XXKUJtJLI 14oGS: CIR 524 c, 2 TYPE AND FIGURED FOSSILS IN THE WORTHEN COLLECTION AT THE ILLINOIS STATE GEOLOGICAL SURVEY Lois S. Kent GEOLOGICAL ILLINOIS Illinois Department of Energy and Natural Resources, STATE GEOLOGICAL SURVEY DIVISION CIRCULAR 524 1982 COVER: This portrait of Amos Henry Worthen is from a print presented to me by Worthen's great-grandson, Arthur C. Brookley, Jr., at the time he visited the Illinois State Geological Survey in the late 1950s or early 1960s. The picture is the same as that published in connection with the memorial to Worthen in the appendix to Vol. 8 of the Geological Survey of Illinois, 1890. -LSK Kent, Lois S., Type and figured fossils in the Worthen Collection at the Illinois State Geological Survey. — Champaign, III. : Illinois State Geological Survey, 1982. - 65 p. ; 28 cm. (Circular / Illinois State Geological Survey ; 524) 1. Paleontology. 2. Catalogs and collections. 3. Worthen Collection. I. Title. II. Series. Editor: Mary Clockner Cover: Sandra Stecyk Printed by the authority of the State of Illinois/1982/2500 II I IHOI'.MAII '.I 'II Of.ir.AI MIHVI y '> 300 1 00003 5216 TYPE AND FIGURED FOSSILS IN THE WORTHEN COLLECTION AT THE ILLINOIS STATE GEOLOGICAL SURVEY Lois S. Kent | CIRCULAR 524 1982 ILLINOIS STATE GEOLOGICAL SURVEY Robert E. Bergstrom, Acting Chief Natural Resources Building, 615 East Peabody Drive, Champaign, IL 61820 TYPE AND FIGURED FOSSILS IN THE WORTHEN COLLECTION AT THE ILLINOIS STATE GEOLOGICAL SURVEY CONTENTS Acknowledgments 2 Introduction 2 Organization of the catalog 7 Notes 8 References 8 Fossil catalog 13 ABSTRACT This catalog lists all type and figured specimens of fossils in the part of the "Worthen Collection" now housed at the Illinois State Geological Survey in Champaign, Illinois.
    [Show full text]
  • Injuries and Molting Interference in a Trilobite from the Cambrian (Furongian) of South China
    Injuries and molting interference in a trilobite from the Cambrian (Furongian) of South China Ruiwen Zong State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China ABSTRACT An injured Shergoldia laevigata Zhu, Hughes & Peng, 2007 (Trilobita, Asaphida) was collected from the Furongian of Guangxi, South China. The injuries occurred in the left thoracic pleurae possessing two marked V-shaped gaps. It led to substantial transverse shortening of the left pleural segments, with barely perceptible traces of healing. This malformation is interpreted as a sub-lethal attack from an unknown predator. The morphology of injuries and the spatial and temporal distribution of predators indicated that the predatory structure might have been the spines on the ganathobase or ganathobase-like structure of a larger arthropod. There were overlapped segments located in the front of the injuries, and slightly dislocated thoracic segments on the left part of the thorax, suggesting that the trilobite had experienced difficulties during molting. The freshly molted trilobite had dragged forward the old exuvia causing the irregular arrangement of segments. This unusual trilobite specimen indicates that the injuries interfered with molting. Subjects Animal Behavior, Evolutionary Studies, Paleontology Keywords Sub-lethal attack, Shergoldia, Predator-prey interactions, Sandu formation, Guangxi INTRODUCTION Submitted 24 November 2020 Accepted 11 March 2021 Numerous trilobite exoskeleton deformities have been documented, including abnormal Published 7 April 2021 healing, hyperplasia, deformation, and missing or fractured segments. The causes of these Corresponding author deformities are usually thought to be injuries, developmental disorders, and diseases Ruiwen Zong, [email protected] (Owen, 1985; Babcock, 1993; Pates et al., 2017; Bicknell & Pates, 2020).
    [Show full text]
  • 2Nd International Trilobite Conference (Brock University, St. Catharines, Ontario, August 22-24, 1997) ABSTRACTS
    2nd International Trilobite Conference (Brock University, St. Catharines, Ontario, August 22-24, 1997) ABSTRACTS. Characters and Parsimony. Jonathan M. Adrain, Department of Palaeontology, The Natural History Museum, London SW7 5BD, United King- dom; Gregory D. Edgecombe, Centre for Evolutionary Research, Australian Museum, 6 College Street, Sydney South, New South Wales 2000, Australia Character analysis is the single most important element of any phylogenetic study. Characters are simply criteria for comparing homologous organismic parts between taxa. Homology of organismic parts in any phylogenetic study is an a priori assumption, founded upon topological similarity through some or all stages of ontogeny. Once homolo- gies have been suggested, characters are invented by specifying bases of comparison of organismic parts from taxon to taxon within the study group. Ideally, all variation in a single homology occurring within the study group should be accounted for. Comparisons are between attributes of homologous parts, (e.g., simple presence, size of some- thing, number of something), and these attributes are referred to as character states. Study taxa are assigned member- ship in one (or more, in the case of polymorphisms) character-state for each character in the analysis. A single char- acter now implies discrete groupings of taxa, but this in itself does not constitute a phylogeny. In order to suggest or convey phylogenetic information, the historical status of each character-state, and of the the group of taxa it sug- gests, must be evaluated. That is, in the case of any two states belonging to the same character, we need to discover whether one state is primitive (broadly speaking, ancestral) or derived (representative of an evolutionary innovation) relative to the other.
    [Show full text]
  • The Bulletin of Zoological Nomenclature. Vol 12, Part 3
    VOLUME 12. Part 3 26if/i June, 1956 pp. 65—96 ; 1 pi. THE BULLETIN OF ZOOLOGICAL NOMENCLATURE The Official Organ of THE INTERNATIONAL COMMISSION ON ZOOLOGICAL NOMENCLATURE Edited by FRANCIS HEMMING, C.M.G., C.B.E. Secretary to the International Commission on Zoological Nomenclature Contents: Notices prescribed by the International Congress of Zoology : Page Date of commencement by the International Commission on Zoo¬ logical Nomenclature of voting on applications published in the Bulletin of Zoological Nomenclature .. .. .. .. .. 65 Notice of the possible use by the International Commission on Zoo¬ logical Nomenclature of its Plenary Powers in certain cases .. 65 (continued outside back wrapper) LONDON: Printed by Order of the International Trust for Zoological Nomenclature and Sold on behalf of the International Commission on Zoological Nomenclature by the International Trust at its Publication Office, 41, Queen's Gate, London, S.W.7 1956 Price Nineteen Shillings IAll rights reserved) Original from and digitized by National University of Singapore Libraries INTERNATIONAL COMMISSION ON ZOOLOGICAL NOMENCLATURE A. The Officers of the Commission Honorary Life President: Dr. Karl Jordan (British Museum (Natural History), Zoological Museum, Tring, Herts, England) President: Professor James Chester Bradley (Cornell University, Ithaca, N.Y., U.S.A.) (12th August 1953) Vice-President: Senhor Dr. Afranio do Amaral (Sao Paulo, Brazil) (12th August 1953) Secretary : Mr. Francis Hemming (London, England) (27th July 1948) B. The Members of the Commission (Arranged in order of precedence by reference to date of election or of most recent re-election, as prescribed by the International Congress of Zoology) Professor H. Boschma (Rijksmuseum van Natuurlijke Historie, Leiden, The Netherlands) (1st January 1947) Senor Dr.
    [Show full text]
  • Introduction to the Trilobites: Morphology, Ecology, Macroevolution and More by Michelle M
    Introduction to the Trilobites: Morphology, Ecology, Macroevolution and More By Michelle M. Casey1, Perry Kennard2, and Bruce S. Lieberman1, 3 1Biodiversity Institute, University of Kansas, Lawrence, KS, 66045, 2Earth Science Teacher, Southwest Middle School, USD497, and 3Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66045 Middle level laboratory exercise for Earth or General Science; supported provided by National Science Foundation (NSF) grants DEB-1256993 and EF-1206757. Learning Goals and Pedagogy This lab is designed for middle level General Science or Earth Science classes. The learning goals for this lab are the following: 1) to familiarize students with the anatomy and terminology relating to trilobites; 2) to give students experience identifying morphologic structures on real fossil specimens 3) to highlight major events or trends in the evolutionary history and ecology of the Trilobita; and 4) to expose students to the study of macroevolution in the fossil record using trilobites as a case study. Introduction to the Trilobites The Trilobites are an extinct subphylum of the Arthropoda (the most diverse phylum on earth with nearly a million species described). Arthropoda also contains all fossil and living crustaceans, spiders, and insects as well as several other extinct groups. The trilobites were an extremely important and diverse type of marine invertebrates that lived during the Paleozoic Era. They only lived in the oceans but occurred in all types of marine environments, and ranged in size from less than a centimeter to almost a meter across. They were once one of the most successful of all animal groups and in certain fossil deposits, especially in the Cambrian, Ordovician, and Devonian periods, they are extremely abundant.
    [Show full text]
  • The Evolution of Trilobite Body Patterning
    ANRV309-EA35-14 ARI 20 March 2007 15:54 The Evolution of Trilobite Body Patterning Nigel C. Hughes Department of Earth Sciences, University of California, Riverside, California 92521; email: [email protected] Annu. Rev. Earth Planet. Sci. 2007. 35:401–34 Key Words First published online as a Review in Advance on Trilobita, trilobitomorph, segmentation, Cambrian, Ordovician, January 29, 2007 diversification, body plan The Annual Review of Earth and Planetary Sciences is online at earth.annualreviews.org Abstract This article’s doi: The good fossil record of trilobite exoskeletal anatomy and on- 10.1146/annurev.earth.35.031306.140258 togeny, coupled with information on their nonbiomineralized tis- Copyright c 2007 by Annual Reviews. sues, permits analysis of how the trilobite body was organized and All rights reserved developed, and the various evolutionary modifications of such pat- 0084-6597/07/0530-0401$20.00 terning within the group. In several respects trilobite development and form appears comparable with that which may have charac- terized the ancestor of most or all euarthropods, giving studies of trilobite body organization special relevance in the light of recent advances in the understanding of arthropod evolution and devel- opment. The Cambrian diversification of trilobites displayed mod- Annu. Rev. Earth Planet. Sci. 2007.35:401-434. Downloaded from arjournals.annualreviews.org ifications in the patterning of the trunk region comparable with by UNIVERSITY OF CALIFORNIA - RIVERSIDE LIBRARY on 05/02/07. For personal use only. those seen among the closest relatives of Trilobita. In contrast, the Ordovician diversification of trilobites, although contributing greatly to the overall diversity within the clade, did so within a nar- rower range of trunk conditions.
    [Show full text]