DOCSLIB.ORG

The Phylogeny of the Ornithischian Dinosaurs

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Phylogeny of the Ornithischian Dinosaurs Journal of Systematic Palaeontology 6 (1): 1–40 Issued 22 February 2008 doi:10.1017/S1477201907002271 Printed in the United Kingdom C The Natural History Museum The phylogeny of the ornithischian dinosaurs RichardJ.Butler∗ Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, UK & Department of Palaeontology, The Natural History Museum, Cromwell Road, London, SW7 5BD, UK Paul Upchurch† Department of Earth Sciences, University College London, Gower Street, London, WC1E 6BT, UK David B. Norman‡ Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, UK SYNOPSIS Ornithischia is a familiar and diverse clade of dinosaurs whose global phylogeny has remained largely unaltered since early cladistic analyses in the mid 1980s. Current understanding of ornithischian evolution is hampered by a paucity of explicitly numerical phylogenetic analyses that consider the entire clade. As a result, it is difficult to assess the robustness of current phylogenetic hypotheses for Ornithischia and the effect that the addition of new taxa or characters is likely to have on the overall topology of the clade. The new phylogenetic analysis presented here incorporates a range of new basal taxa and charac- ters in an attempt to rigorously test global ornithischian phylogeny. Parsimony analysis is carried out with 46 taxa and 221 characters. Although the strict component consensus tree shows poor resolution in a number of areas, application of reduced consensus methods provides a well-resolved picture of ornithischian interrelationships. Surprisingly, Heterodontosauridae is placed as the most basal group of all well-known ornithischians, phylogenetically distant from a stem-defined Ornithopoda, creating a topology that is more congruent with the known ornithischian stratigraphical record. There is no evidence for a monophyletic ‘Fabrosauridae’, and Lesothosaurus (the best-known ‘fabrosaur’) occupies an unusual position as the most basal member of Thyreophora. Other relationships within Thyreophora remain largely stable. The primitive thyreophoran Scelidosaurus is the sister taxon of Eurypoda (stegosaurs and ankylosaurs), rather than a basal ankylosaur as implied by some previous studies. The taxonomic content of Ornithopoda differs significantly from previous analyses and basal relationships within the clade are weakly supported, requiring further investigation. ‘Hypsilopho- dontidae’ is paraphyletic, with some taxa (Agilisaurus, Hexinlusaurus, Othnielia) placed outside of Ornithopoda as non-cerapodans. Ceratopsia and Pachycephalosauria are monophyletic and are united as Marginocephalia; however, the stability of these clades is reduced by a number of poorly preserved basal taxa. This analysis reaffirms much of the currently accepted ornithischian topology. Nevertheless, in- stability in the position and content of several clades (notably Heterodontosauridae and Ornithopoda) indicates that considerable future work on ornithischian phylogeny is required and causes problems for several current phylogenetic definitions. KEY WORDS vertebrate palaeontology, Ornithischia, systematics, cladistics, Dinosauria Contents Introduction 1 Institutional abbreviations 2 Previous analyses of ornithischian phylogeny 2 Traditional classifications 2 Cladistic studies 3 Material and Methods 5 The aim of the analysis 5 Phylogenetic framework 5 Selection of ingroup taxa 5 ∗E-mail: [email protected]; †Email: [email protected]; ‡Email: [email protected] 2 R. J. Butler et al. Supraspecific taxa 5 Included species level taxa 7 Excluded species level taxa 11 Selection of outgroup taxa 11 Analyses 12 Search methods 12 Testing the support for relationships 12 Randomisation tests 12 Bremer support 12 Bootstrapping 14 Results 16 Ornithischian monophyly 16 Pisanosaurus mertii 17 Heterodontosauridae 17 ‘Fabrosaurids’ 18 Thyreophora 19 Basal neornithischians 19 Ornithopoda 20 Hypsilophodontidae 20 Marginocephalia 21 Ceratopsia 21 Pachycephalosauria 22 Conclusions 22 Stability, instability, and future directions in ornithischian phylogeny 22 Implications for phylogenetic taxonomy of Ornithischia 22 Acknowledgements 23 References 23 Appendix 1 – Specimens and references used for coding operational taxonomic units 29 Appendix 2 – Character list 30 Appendix 3 – Data matrix 35 Appendix 4 – Tree descriptions 40 Introduction tebrate faunas are dominated by saurischians (Weishampel et al. 2004b). Ornithischians became much more abundant during the Late Jurassic and Early Cretaceous and ornith- The clade Ornithischia represents a major grouping within ischian diversity peaked during the Campanian stage of the Dinosauria, the most familiar and widely popularised of Late Cretaceous. Late Triassic–Early Jurassic ornithischians all extinct organisms. An ornithischian, Iguanodon Mantell, were generally small-bodied (1–2 m in length) bipedal curs- 1825, was the second dinosaur genus to be named, while ors (e.g. Lesothosaurus diagnosticus: Thulborn 1972; Sereno of the three taxa explicitly included within Dinosauria by 1991a), but during the rest of the Mesozoic they diversified Owen (1842), two (Iguanodon and Hylaeosaurus) were later into a considerable range of morphologies and sizes, with recognised as ornithischians. Since these early discoveries, a many groups reverting to quadrupedality. The vast majority large number of genera and species of ornithischians have of ornithischians are believed to have been herbivorous, al- been named: a recent review (Weishampel et al. 2004a) though some basal forms have been interpreted as potentially recognised over 180 valid genera. The earliest ornithischi- omnivorous (Barrett 2000). ans are known from the Carnian stage of the Late Trias- One major problem in understanding ornithischian sic (Casamiquela 1967) and the clade disappeared in the evolution is that, to date, there are few published numer- mass extinctions at the end of the Cretaceous. During this ical phylogenetic analyses dedicated solely to Ornithischia time ornithischians achieved a global distribution and are (Weishampel 2004). It is difficult, therefore, to assess the re- now known from every continent, including Antarctica (e.g. lative phylogenetic support for ornithischian clades, to look Hooker et al. 1991; Weishampel et al. 2004b). at the effects upon phylogenetic results of adding or deleting Ornithischians appear to have been extremely scarce taxa or characters, or to test alternative hypotheses of taxon during the Late Triassic (Sereno 1997) and remained un- or character evolution. Here, we present a new phylogen- common (although apparently more diverse) during the Early etic analysis of Ornithischia, as part of an on-going study of and Middle Jurassic; during this time interval terrestrial ver- ornithischian phylogeny. Phylogeny of ornithischian dinosaurs 3 Institutional abbreviations ZDM = Zigong Dinosaur Museum, Dashanpu, People’s Republic of China BMNH = Natural History Museum, London, UK ZPAL = Institute of Paleobiology of the Polish BRSMG = Bristol City Museum and Art Gallery, Bris- Academy of Sciences, Warsaw, Poland. tol, UK BP = Bernard Price Institute for Palaeontological Research, Johannesburg, South Africa BYU = Earth Science Museum, Brigham Young Previous analyses of University, Provo, Utah, USA ornithischian phylogeny CAMSM = Sedgwick Museum, University of Cam- bridge, Cambridge, UK Traditional classifications CEUM = Prehistoric Museum, College of Eastern Utah, Price, Utah, USA Although material from the clade began to be described and CV = Chongqing Natural History Museum, named in the early 19th century (Mantell 1822, 1825, 1833), Chongqing, People’s Republic of China the recognition that ornithischians formed a grouping dis- GCC = Museum of the Chendgu University of tinct from other reptiles (including other dinosaurs) was not Technology (formerly Chendgu College of reached until the work of Seeley (1887). Seeley was the first Geology), Chengdu, People’s Republic of to identify and articulate a fundamental morphological dicho- China tomy within the then described dinosaurian taxa. He recog- GI = Geological Institute, Ulaanbaatar, Mongo- nised two orders, distinguished mainly on the basis of pelvic lia anatomy, that he named Ornithischia and Saurischia. Major GSM = Geological Survey Museum, Keyworth, subdivisions of Seeley’s Ornithischia (Stegosauria, Ornitho- UK poda, Ceratopsia) were identified by Marsh (1877a, 1881, GZG = Geowissenschaftliches Zentrum der Uni- 1890) and Marsh (1894) later grouped these subdivisions versitat¨ Gottingen,¨ Gottingen,¨ Germany together as the order Predentata, generally considered syn- IGCAGS = Institute of Geology, Chinese Academy onymous with Ornithischia. of Sciences, Beijing, People’s Republic of Nopcsa (1915) proposed a subdivision within Ornithis- China chia, between the bipedal, unarmoured forms (ornithopods) IVPP = Institute of Vertebrate Paleontology and and a new suborder that he named Thyreophora (compris- Paleoanthropology, Bejing ing ankylosaurs, stegosaurs and ceratopsians). The group- MCZ = Museum of Comparative Zoology, Harvard, ing Thyreophora was often ignored by later workers, but USA the name was revived by Norman (1984) and Sereno (1984, MB = Museum fur¨ Naturkunde, Berlin, Germany 1986), although its current usage (for a clade consisting of MCF-PVPH = Museo Carmen Funes, Paleontolog´ıa de all armoured ornithischians) differs somewhat from that pro- Vertebrados Plaza Huincul, Argentina posed by Nopcsa (i.e. in current usage ceratopsians are not MNA
Load more

Recommended publications
  • Journal of Paleontology
    Journal of Paleontology http://journals.cambridge.org/JPA Additional services for Journal of Paleontology: Email alerts: Click here Subscriptions: Click here Commercial reprints: Click here Terms of use : Click here New heterodontosaurid remains from the Cañadón Asfalto Formation: cursoriality and the functional importance of the pes in small heterodontosaurids Marcos G. Becerra, Diego Pol, Oliver W.M. Rauhut and Ignacio A. Cerda Journal of Paleontology / Volume 90 / Issue 03 / May 2016, pp 555 - 577 DOI: 10.1017/jpa.2016.24, Published online: 27 June 2016 Link to this article: http://journals.cambridge.org/abstract_S002233601600024X How to cite this article: Marcos G. Becerra, Diego Pol, Oliver W.M. Rauhut and Ignacio A. Cerda (2016). New heterodontosaurid remains from the Cañadón Asfalto Formation: cursoriality and the functional importance of the pes in small heterodontosaurids. Journal of Paleontology, 90, pp 555-577 doi:10.1017/jpa.2016.24 Request Permissions : Click here Downloaded from http://journals.cambridge.org/JPA, IP address: 190.172.49.57 on 16 Aug 2016 Journal of Paleontology, 90(3), 2016, p. 555–577 Copyright © 2016, The Paleontological Society 0022-3360/16/0088-0906 doi: 10.1017/jpa.2016.24 New heterodontosaurid remains from the Cañadón Asfalto Formation: cursoriality and the functional importance of the pes in small heterodontosaurids Marcos G. Becerra,1 Diego Pol,1 Oliver W.M. Rauhut,2 and Ignacio A. Cerda3 1CONICET- Museo Palaeontológico Egidio Feruglio, Fontana 140, Trelew, Chubut 9100, Argentina 〈[email protected]〉; 〈[email protected]〉 2SNSB, Bayerische Staatssammlung für Paläontologie und Geologie and Department of Earth and Environmental Sciences, LMU München, Richard-Wagner-Str.
    [Show full text]
  • A Neoceratopsian Dinosaur from the Early Cretaceous of Mongolia And
    ARTICLE https://doi.org/10.1038/s42003-020-01222-7 OPEN A neoceratopsian dinosaur from the early Cretaceous of Mongolia and the early evolution of ceratopsia ✉ Congyu Yu 1 , Albert Prieto-Marquez2, Tsogtbaatar Chinzorig 3,4, Zorigt Badamkhatan4,5 & Mark Norell1 1234567890():,; Ceratopsia is a diverse dinosaur clade from the Middle Jurassic to Late Cretaceous with early diversification in East Asia. However, the phylogeny of basal ceratopsians remains unclear. Here we report a new basal neoceratopsian dinosaur Beg tse based on a partial skull from Baruunbayan, Ömnögovi aimag, Mongolia. Beg is diagnosed by a unique combination of primitive and derived characters including a primitively deep premaxilla with four pre- maxillary teeth, a trapezoidal antorbital fossa with a poorly delineated anterior margin, very short dentary with an expanded and shallow groove on lateral surface, the derived presence of a robust jugal having a foramen on its anteromedial surface, and five equally spaced tubercles on the lateral ridge of the surangular. This is to our knowledge the earliest known occurrence of basal neoceratopsian in Mongolia, where this group was previously only known from Late Cretaceous strata. Phylogenetic analysis indicates that it is sister to all other neoceratopsian dinosaurs. 1 Division of Vertebrate Paleontology, American Museum of Natural History, New York 10024, USA. 2 Institut Català de Paleontologia Miquel Crusafont, ICTA-ICP, Edifici Z, c/de les Columnes s/n Campus de la Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès Sabadell, Barcelona, Spain. 3 Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695, USA. 4 Institute of Paleontology, Mongolian Academy of Sciences, ✉ Ulaanbaatar 15160, Mongolia.
    [Show full text]
  • Eubrontes and Anomoepus Track
    Sullivan, R.M. and Lucas, S.G., eds., 2016, Fossil Record 5. New Mexico Museum of Natural History and Science Bulletin 74. 345 EUBRONTES AND ANOMOEPUS TRACK ASSEMBLAGES FROM THE MIDDLE JURASSIC XIASHAXIMIAO FORMATION OF ZIZHONG COUNTY, SICHUAN, CHINA: REVIEW, ICHNOTAXONOMY AND NOTES ON PRESERVED TAIL TRACES LIDA XING1, MARTIN G. LOCKLEY2, GUANGZHAO PENG3, YONG YE3, JIANPING ZHANG1, MASAKI MATSUKAWA4, HENDRIK KLEIN5, RICHARD T. MCCREA6 and W. SCOTT PERSONS IV7 1School of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China; -email: [email protected]; 2Dinosaur Trackers Research Group, University of Colorado Denver, P.O. Box 173364, Denver, CO 80217; 3 Zigong Dinosaur Museum, Zigong 643013, Sichuan, China; 4 Department of Environmental Sciences, Tokyo Gakugei University, Koganei, Tokyo 184-8501, Japan; 5 Saurierwelt Paläontologisches Museum Alte Richt 7, D-92318 Neumarkt, Germany; 6 Peace Region Palaeontology Research Centre, Box 1540, Tumbler Ridge, British Columbia V0C 2W0, Canada; 7 Department of Biological Sciences, University of Alberta 11455 Saskatchewan Drive, Edmonton, Alberta T6G 2E9, Canada Abstract—The Nianpanshan dinosaur tracksite, first studied in the 1980s, was designated as the type locality of the monospecific ichnogenus Jinlijingpus, and the source of another tridactyl track, Chuanchengpus, both presumably of theropod affinity. After the site was mapped in 2001, these two ichnotaxa were considered synonyms of Eubrontes and Anomoepus, respectively, the latter designation being the first identification of this ichnogenus in China. The assemblage indicates a typical Jurassic ichnofauna. The present study reinvestigates the site in the light of the purported new ichnospecies Chuanchengpus shenglingensis that was introduced in 2012. After re- evaluation of the morphological and extramorphological features, C.
    [Show full text]
  • And the Origin and Evolution of the Ankylosaur Pelvis
    Pelvis of Gargoyleosaurus (Dinosauria: Ankylosauria) and the Origin and Evolution of the Ankylosaur Pelvis Kenneth Carpenter1,2*, Tony DiCroce3, Billy Kinneer3, Robert Simon4 1 Prehistoric Museum, Utah State University – Eastern, Price, Utah, United States of America, 2 Geology Section, University of Colorado Museum, Boulder, Colorado, United States of America, 3 Denver Museum of Nature and Science, Denver, Colorado, United States of America, 4 Dinosaur Safaris Inc., Ashland, Virginia, United States of America Abstract Discovery of a pelvis attributed to the Late Jurassic armor-plated dinosaur Gargoyleosaurus sheds new light on the origin of the peculiar non-vertical, broad, flaring pelvis of ankylosaurs. It further substantiates separation of the two ankylosaurs from the Morrison Formation of the western United States, Gargoyleosaurus and Mymoorapelta. Although horizontally oriented and lacking the medial curve of the preacetabular process seen in Mymoorapelta, the new ilium shows little of the lateral flaring seen in the pelvis of Cretaceous ankylosaurs. Comparison with the basal thyreophoran Scelidosaurus demonstrates that the ilium in ankylosaurs did not develop entirely by lateral rotation as is commonly believed. Rather, the preacetabular process rotated medially and ventrally and the postacetabular process rotated in opposition, i.e., lateral and ventrally. Thus, the dorsal surfaces of the preacetabular and postacetabular processes are not homologous. In contrast, a series of juvenile Stegosaurus ilia show that the postacetabular process rotated dorsally ontogenetically. Thus, the pelvis of the two major types of Thyreophora most likely developed independently. Examination of other ornithischians show that a non-vertical ilium had developed independently in several different lineages, including ceratopsids, pachycephalosaurs, and iguanodonts.
    [Show full text]
  • New Heterodontosaurid Remains from the Cañadón Asfalto Formation: Cursoriality and the Functional Importance of the Pes in Small Heterodontosaurids
    Journal of Paleontology, 90(3), 2016, p. 555–577 Copyright © 2016, The Paleontological Society 0022-3360/16/0088-0906 doi: 10.1017/jpa.2016.24 New heterodontosaurid remains from the Cañadón Asfalto Formation: cursoriality and the functional importance of the pes in small heterodontosaurids Marcos G. Becerra,1 Diego Pol,1 Oliver W.M. Rauhut,2 and Ignacio A. Cerda3 1CONICET- Museo Palaeontológico Egidio Feruglio, Fontana 140, Trelew, Chubut 9100, Argentina 〈[email protected]〉; 〈[email protected]〉 2SNSB, Bayerische Staatssammlung für Paläontologie und Geologie and Department of Earth and Environmental Sciences, LMU München, Richard-Wagner-Str. 10, Munich 80333, Germany 〈[email protected]〉 3CONICET- Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro, Museo Carlos Ameghino, Belgrano 1700, Paraje Pichi Ruca (predio Marabunta), Cipolletti, Río Negro, Argentina 〈[email protected]〉 Abstract.—New ornithischian remains reported here (MPEF-PV 3826) include two complete metatarsi with associated phalanges and caudal vertebrae, from the late Toarcian levels of the Cañadón Asfalto Formation. We conclude that these fossil remains represent a bipedal heterodontosaurid but lack diagnostic characters to identify them at the species level, although they probably represent remains of Manidens condorensis, known from the same locality. Histological features suggest a subadult ontogenetic stage for the individual. A cluster analysis based on pedal measurements identifies similarities of this specimen with heterodontosaurid taxa and the inclusion of the new material in a phylogenetic analysis with expanded character sampling on pedal remains confirms the described specimen as a heterodontosaurid. Finally, uncommon features of the digits (length proportions among nonungual phalanges of digit III, and claw features) are also quantitatively compared to several ornithischians, theropods, and birds, suggesting that this may represent a bipedal cursorial heterodontosaurid with gracile and grasping feet and long digits.
    [Show full text]
  • The Origin and Early Evolution of Dinosaurs
    Biol. Rev. (2010), 85, pp. 55–110. 55 doi:10.1111/j.1469-185X.2009.00094.x The origin and early evolution of dinosaurs Max C. Langer1∗,MartinD.Ezcurra2, Jonathas S. Bittencourt1 and Fernando E. Novas2,3 1Departamento de Biologia, FFCLRP, Universidade de S˜ao Paulo; Av. Bandeirantes 3900, Ribeir˜ao Preto-SP, Brazil 2Laboratorio de Anatomia Comparada y Evoluci´on de los Vertebrados, Museo Argentino de Ciencias Naturales ‘‘Bernardino Rivadavia’’, Avda. Angel Gallardo 470, Cdad. de Buenos Aires, Argentina 3CONICET (Consejo Nacional de Investigaciones Cient´ıficas y T´ecnicas); Avda. Rivadavia 1917 - Cdad. de Buenos Aires, Argentina (Received 28 November 2008; revised 09 July 2009; accepted 14 July 2009) ABSTRACT The oldest unequivocal records of Dinosauria were unearthed from Late Triassic rocks (approximately 230 Ma) accumulated over extensional rift basins in southwestern Pangea. The better known of these are Herrerasaurus ischigualastensis, Pisanosaurus mertii, Eoraptor lunensis,andPanphagia protos from the Ischigualasto Formation, Argentina, and Staurikosaurus pricei and Saturnalia tupiniquim from the Santa Maria Formation, Brazil. No uncontroversial dinosaur body fossils are known from older strata, but the Middle Triassic origin of the lineage may be inferred from both the footprint record and its sister-group relation to Ladinian basal dinosauromorphs. These include the typical Marasuchus lilloensis, more basal forms such as Lagerpeton and Dromomeron, as well as silesaurids: a possibly monophyletic group composed of Mid-Late Triassic forms that may represent immediate sister taxa to dinosaurs. The first phylogenetic definition to fit the current understanding of Dinosauria as a node-based taxon solely composed of mutually exclusive Saurischia and Ornithischia was given as ‘‘all descendants of the most recent common ancestor of birds and Triceratops’’.
    [Show full text]
  • At Carowinds
    at Carowinds EDUCATOR’S GUIDE CLASSROOM LESSON PLANS & FIELD TRIP ACTIVITIES Table of Contents at Carowinds Introduction The Field Trip ................................... 2 The Educator’s Guide ....................... 3 Field Trip Activity .................................. 4 Lesson Plans Lesson 1: Form and Function ........... 6 Lesson 2: Dinosaur Detectives ....... 10 Lesson 3: Mesozoic Math .............. 14 Lesson 4: Fossil Stories.................. 22 Games & Puzzles Crossword Puzzles ......................... 29 Logic Puzzles ................................. 32 Word Searches ............................... 37 Answer Keys ...................................... 39 Additional Resources © 2012 Dinosaurs Unearthed Recommended Reading ................. 44 All rights reserved. Except for educational fair use, no portion of this guide may be reproduced, stored in a retrieval system, or transmitted in any form or by any Dinosaur Data ................................ 45 means—electronic, mechanical, photocopy, recording, or any other without Discovering Dinosaurs .................... 52 explicit prior permission from Dinosaurs Unearthed. Multiple copies may only be made by or for the teacher for class use. Glossary .............................................. 54 Content co-created by TurnKey Education, Inc. and Dinosaurs Unearthed, 2012 Standards www.turnkeyeducation.net www.dinosaursunearthed.com Curriculum Standards .................... 59 Introduction The Field Trip From the time of the first exhibition unveiled in 1854 at the Crystal
    [Show full text]
  • A Phylogenetic Analysis of the Basal Ornithischia (Reptilia, Dinosauria)
    A PHYLOGENETIC ANALYSIS OF THE BASAL ORNITHISCHIA (REPTILIA, DINOSAURIA) Marc Richard Spencer A Thesis Submitted to the Graduate College of Bowling Green State University in partial fulfillment of the requirements of the degree of MASTER OF SCIENCE December 2007 Committee: Margaret M. Yacobucci, Advisor Don C. Steinker Daniel M. Pavuk © 2007 Marc Richard Spencer All Rights Reserved iii ABSTRACT Margaret M. Yacobucci, Advisor The placement of Lesothosaurus diagnosticus and the Heterodontosauridae within the Ornithischia has been problematic. Historically, Lesothosaurus has been regarded as a basal ornithischian dinosaur, the sister taxon to the Genasauria. Recent phylogenetic analyses, however, have placed Lesothosaurus as a more derived ornithischian within the Genasauria. The Fabrosauridae, of which Lesothosaurus was considered a member, has never been phylogenetically corroborated and has been considered a paraphyletic assemblage. Prior to recent phylogenetic analyses, the problematic Heterodontosauridae was placed within the Ornithopoda as the sister taxon to the Euornithopoda. The heterodontosaurids have also been considered as the basal member of the Cerapoda (Ornithopoda + Marginocephalia), the sister taxon to the Marginocephalia, and as the sister taxon to the Genasauria. To reevaluate the placement of these taxa, along with other basal ornithischians and more derived subclades, a phylogenetic analysis of 19 taxonomic units, including two outgroup taxa, was performed. Analysis of 97 characters and their associated character states culled, modified, and/or rescored from published literature based on published descriptions, produced four most parsimonious trees. Consistency and retention indices were calculated and a bootstrap analysis was performed to determine the relative support for the resultant phylogeny. The Ornithischia was recovered with Pisanosaurus as its basalmost member.
    [Show full text]
  • A Re-Evaluation of the Enigmatic Dinosauriform Caseosaurus Crosbyensis from the Late Triassic of Texas, USA and Its Implications for Early Dinosaur Evolution
    A re-evaluation of the enigmatic dinosauriform Caseosaurus crosbyensis from the Late Triassic of Texas, USA and its implications for early dinosaur evolution MATTHEW G. BARON and MEGAN E. WILLIAMS Baron, M.G. and Williams, M.E. 2018. A re-evaluation of the enigmatic dinosauriform Caseosaurus crosbyensis from the Late Triassic of Texas, USA and its implications for early dinosaur evolution. Acta Palaeontologica Polonica 63 (1): 129–145. The holotype specimen of the Late Triassic dinosauriform Caseosaurus crosbyensis is redescribed and evaluated phylogenetically for the first time, providing new anatomical information and data on the earliest dinosaurs and their evolution within the dinosauromorph lineage. Historically, Caseosaurus crosbyensis has been considered to represent an early saurischian dinosaur, and often a herrerasaur. More recent work on Triassic dinosaurs has cast doubt over its supposed dinosaurian affinities and uncertainty about particular features in the holotype and only known specimen has led to the species being regarded as a dinosauriform of indeterminate position. Here, we present a new diagnosis for Caseosaurus crosbyensis and refer additional material to the taxon—a partial right ilium from Snyder Quarry. Our com- parisons and phylogenetic analyses suggest that Caseosaurus crosbyensis belongs in a clade with herrerasaurs and that this clade is the sister taxon of Dinosauria, rather than positioned within it. This result, along with other recent analyses of early dinosaurs, pulls apart what remains of the “traditional” group of dinosaurs collectively termed saurischians into a polyphyletic assemblage and implies that Dinosauria should be regarded as composed exclusively of Ornithoscelida (Ornithischia + Theropoda) and Sauropodomorpha. In addition, our analysis recovers the enigmatic European taxon Saltopus elginensis among herrerasaurs for the first time.
    [Show full text]
  • Phylogeny and Biogeography of Iguanodontian Dinosaurs, with Implications from Ontogeny and an Examination of the Function of the Fused Carpal-Digit I Complex
    Phylogeny and Biogeography of Iguanodontian Dinosaurs, with Implications from Ontogeny and an Examination of the Function of the Fused Carpal-Digit I Complex By Karen E. Poole B.A. in Geology, May 2004, University of Pennsylvania M.A. in Earth and Planetary Sciences, August 2008, Washington University in St. Louis A Dissertation submitted to The Faculty of The Columbian College of Arts and Sciences of The George Washington University in partial fulfillment of the requirements for the degree of Doctor of Philosophy August 31, 2015 Dissertation Directed by Catherine Forster Professor of Biology The Columbian College of Arts and Sciences of The George Washington University certifies that Karen Poole has passed the Final Examination for the degree of Doctor of Philosophy as of August 10th, 2015. This is the final and approved form of the dissertation. Phylogeny and Biogeography of Iguanodontian Dinosaurs, with Implications from Ontogeny and an Examination of the Function of the Fused Carpal-Digit I Complex Karen E. Poole Dissertation Research Committee: Catherine A. Forster, Professor of Biology, Dissertation Director James M. Clark, Ronald Weintraub Professor of Biology, Committee Member R. Alexander Pyron, Robert F. Griggs Assistant Professor of Biology, Committee Member ii © Copyright 2015 by Karen Poole All rights reserved iii Dedication To Joseph Theis, for his unending support, and for always reminding me what matters most in life. To my parents, who have always encouraged me to pursue my dreams, even those they didn’t understand. iv Acknowledgements First, a heartfelt thank you is due to my advisor, Cathy Forster, for giving me free reign in this dissertation, but always providing valuable commentary on any piece of writing I sent her, no matter how messy.
    [Show full text]
  • A Revision of the Upper Triassic Ornithischian Dinosaur Revueltosaurus, with a Description of a New Species
    Heckert, A.B" and Lucas, S.O., eds., 2002, Upper Triassic Stratigraphy and Paleontology. New Mexico Museum of Natural History & Science Bulletin No.2 J. 253 A REVISION OF THE UPPER TRIASSIC ORNITHISCHIAN DINOSAUR REVUELTOSAURUS, WITH A DESCRIPTION OF A NEW SPECIES ANDREW B. HECKERT New Mexico Museum of Natural History, 1801 Mountain Road NW, Albuquerque, NM 87104-1375 Abstract-Ornithischian dinosaur body fossils are extremely rare in Triassic rocks worldwide, and to date the majority of such fossils consist of isolated teeth. Revueltosaurus is the most common Upper Triassic ornithischian dinosaur and is known from Chinle Group strata in New Mexico and Arizona. Historically, all large (>1 cm tall) and many small ornithischian dinosaur teeth from the Chinle have been referred to the type species, Revueltosaurus callenderi Hunt. A careful re-examination of the type and referred material of Revueltosaurus callenderi reveals that: (1) R. callenderi is a valid taxon, in spite of cladistic arguments to the contrary; (2) many teeth previously referred to R. callenderi, particularly from the Placerias quarry, instead represent other, more basal, ornithischians; and (3) teeth from the vicinity of St. Johns, Arizona, and Lamy, New Mexico previously referred to R. callenderi pertain to a new spe­ cies, named Revueltosaurus hunti here. R. hunti is more derived than R. callenderi and is one of the most derived Triassic ornithischians. However, detailed biostratigraphy indicates that R. hunti is older (Adamanian: latest Carnian) than R. callenderi (Revueltian: early-mid Norian). Both taxa have great potential as index taxa of their respective faunachrons and support existing biochronologies based on other tetrapods, megafossil plants, palynostratigraphy, and lithostratigraphy.
    [Show full text]
  • Síntesis Del Registro Fósil De Dinosaurios Tireóforos En Gondwana
    ISSN 2469-0228 www.peapaleontologica.org.ar SÍNTESIS DEL REGISTRO FÓSIL DE DINOSAURIOS TIREÓFOROS EN GONDWANA XABIER PEREDA-SUBERBIOLA 1 IGNACIO DÍAZ-MARTÍNEZ 2 LEONARDO SALGADO 2 SILVINA DE VALAIS 2 1Universidad del País Vasco/Euskal Herriko Unibertsitatea, Facultad de Ciencia y Tecnología, Departamento de Estratigrafía y Paleontología, Apartado 644, 48080 Bilbao, España. 2CONICET - Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro, Av. General Roca 1242, 8332 General Roca, Río Negro, Ar gentina. Recibido: 21 de Julio 2015 - Aceptado: 26 de Agosto de 2015 Para citar este artículo: Xabier Pereda-Suberbiola, Ignacio Díaz-Martínez, Leonardo Salgado y Silvina De Valais (2015). Síntesis del registro fósil de dinosaurios tireóforos en Gondwana . En: M. Fernández y Y. Herrera (Eds.) Reptiles Extintos - Volumen en Homenaje a Zulma Gasparini . Publicación Electrónica de la Asociación Paleon - tológica Argentina 15(1): 90–107. Link a este artículo: http://dx.doi.org/ 10.5710/PEAPA.21.07.2015.101 DESPLAZARSE HACIA ABAJO PARA ACCEDER AL ARTÍCULO Asociación Paleontológica Argentina Maipú 645 1º piso, C1006ACG, Buenos Aires República Argentina Tel/Fax (54-11) 4326-7563 Web: www.apaleontologica.org.ar Otros artículos en Publicación Electrónica de la APA 15(1): de la Fuente & Sterli Paulina Carabajal Pol & Leardi ESTADO DEL CONOCIMIENTO DE GUIA PARA EL ESTUDIO DE LA DIVERSITY PATTERNS OF LAS TORTUGAS EXTINTAS DEL NEUROANATOMÍA DE DINOSAURIOS NOTOSUCHIA (CROCODYLIFORMES, TERRITORIO ARGENTINO: UNA SAURISCHIA, CON ENFASIS EN MESOEUCROCODYLIA) DURING PERSPECTIVA HISTÓRICA. FORMAS SUDAMERICANAS. THE CRETACEOUS OF GONDWANA. Año 2015 - Volumen 15(1): 90-107 VOLUMEN TEMÁTICO ISSN 2469-0228 SÍNTESIS DEL REGISTRO FÓSIL DE DINOSAURIOS TIREÓFOROS EN GONDWANA XABIER PEREDA-SUBERBIOLA 1, IGNACIO DÍAZ-MARTÍNEZ 2, LEONARDO SALGADO 2 Y SILVINA DE VALAIS 2 1Universidad del País Vasco/Euskal Herriko Unibertsitatea, Facultad de Ciencia y Tecnología, Departamento de Estratigrafía y Paleontología, Apartado 644, 48080 Bilbao, España.
    [Show full text]