DOCSLIB.ORG

Early Ornithischian Dinosaurs: the Triassic Record

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Early Ornithischian Dinosaurs: the Triassic Record Historical Biology An International Journal of Paleobiology ISSN: 0891-2963 (Print) 1029-2381 (Online) Journal homepage: https://www.tandfonline.com/loi/ghbi20 Early ornithischian dinosaurs: the Triassic record Randall B. Irmis , William G. Parker , Sterling J. Nesbitt & Jun Liu To cite this article: Randall B. Irmis , William G. Parker , Sterling J. Nesbitt & Jun Liu (2007) Early ornithischian dinosaurs: the Triassic record, Historical Biology, 19:1, 3-22, DOI: 10.1080/08912960600719988 To link to this article: https://doi.org/10.1080/08912960600719988 Published online: 10 Oct 2011. Submit your article to this journal Article views: 291 View related articles Citing articles: 70 View citing articles Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=ghbi20 Historical Biology, 2007; 19(1): 3–22 Early ornithischian dinosaurs: the Triassic record RANDALL B. IRMIS1, WILLIAM G. PARKER2, STERLING J. NESBITT3,4, & JUN LIU3,4 1Museum of Paleontology and Department of Integrative Biology, University of California, 1101 Valley Life Sciences Building, Berkeley, CA, 94720-4780, USA, 2Division of Resource Management, Petrified Forest National Park, P.O. Box 2217, Petrified Forest, AZ, 86028, USA, 3Lamont–Doherty Earth Observatory, Columbia University, 61 Route 9W, Palisades, NY, 10964, USA, and 4Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY, 10024, USA Abstract Ornithischian dinosaurs are one of the most taxonomically diverse dinosaur clades during the Mesozoic, yet their origin and early diversification remain virtually unknown. In recent years, several new Triassic ornithischian taxa have been proposed, mostly based upon isolated teeth. New discoveries of skeletal material of some of these tooth taxa indicate that these teeth can no longer be assigned to the Ornithischia using unambiguous synapomorphies. The Triassic record of ornithischian dinosaurs now comprises only three probable occurrences: Pisanosaurus and an unnamed heterodontosaurid from Argentina, and an unnamed specimen from the uppermost Triassic of South Africa. This revised Triassic record suggests that ornithischians were not very diverse or abundant through the Triassic, and there are large gaps in the Triassic ornithischian fossil record. Moreover, traditional living analogues for interpreting the feeding ecology of early ornithischians from their tooth morphology are generally inappropriate, and “herbivorous” archosaur teeth such as those found in early ornithischians are not necessarily diagnostic of herbivorous feeding. Keywords: Ornithischia, Triassic, Pisanosaurus, Revueltosaurus, Dinosauria, Archosauria Introduction most ornithischian synapomorphies (Sereno 1991), and sheds little light on the initial stages of Despite their extensive fossil record and exceptional ornithischian evolution. diversity during the later Mesozoic, the origin of the Recently, the record of Triassic ornithischians has Ornithischia is poorly understood. Although all been depleted further with the discovery that at least phylogenetic hypotheses in the past 20 years have some isolated teeth previously assigned to the placed ornithischians as the sister-group to the Ornithischia actually belong to other non-dinosaurian Saurischia (SauropodomorphaCTheropoda), basal archosaurs (Parker et al. 2005). This complicates the forms that actually support this phylogenetic relation- identification of isolated ornithischian material in the ship are scarce. Putative Late Triassic records are rare, Triassic, especially teeth. With this new view of criteria representing a handful of occurrences scattered for recognizing Triassic ornithischians, what can we throughout Laurasia and Gondwana (Figure 1), say about the origin, timing, and initial radiation of the most represented only by teeth (Sereno 1991; Hunt Ornithischia? Here, we review worldwide records of and Lucas 1994). The best-known Triassic putative Triassic ornithischians and discuss the ornithischian, Pisanosaurus mertii from Argentina implications of this revised record. (Casamiquela 1967; Bonaparte 1976), is the only Identifying and assigning isolated and fragmentary specimen that includes appreciable post-cranial remains to particular clades requires the recognition of remains. Even the first well-known basal phylogenetically informative character-states. In the ornithischian, Lesothosaurus diagnosticus from the context of a phylogenetic analysis, some character- Lower Jurassic of South Africa, has already acquired states may provide in-group resolution and be Correspondence: R. B. Irmis, Museum of Paleontology and Department of Integrative Biology, 1101 Valley Life Sciences Building, University of California, Berkeley, CA, 94720-4780, USA. E-mail: [email protected] ISSN 0891-2963 print/ISSN 1029-2381 online q 2007 Taylor & Francis DOI: 10.1080/08912960600719988 Published online 10 Oct 2011 4 R. Irmis et al. Butler 2005a); presence of a separate predentary bone (Sereno 1999; Butler 2005a); and a coronoid process formed by a posterior process of the dentary (Sereno 1999; Butler 2005a). Postcranial character-states include: strap-like preacetabular process of the ilium that extends anteriorly beyond the pubic peduncle (Butler 2005a); posteroventrally rotated pubis with enlarged prepubic process (Butler 2005a); enlarged anterior trochanter of the femur that is anteroposter- iorly wide and separated from the body of the femur by a distinct cleft (Butler 2005a); and posterolateral Figure 1. Global distribution of reported Late Triassic flange of the distal tibia extends posterolaterally ornithischian dinosaur occurrences. Black stars indicate those behind entire distal end of fibula (Butler 2005a). occurrences confirmed in this study. Paleogeographic map modified Institutional abbreviations: AMNH, American from Smith et al. (1994). Abbreviations: AF, Africa; AN, Antarctica; Museum of Natural History, New York;BRSMG, Bristol AS, Asia; AU, Australia; IN, India; NA, North America; SA, South America. City Museum and Art Gallery, Bristol, England; CPBA, synapomorphies of a clade; however, they may have a Ca´tedra de Paleontologı´a de la Facultad de Ciencias wider distribution among distantly related taxa or Exactas de la Universidad de Buenos Aires, Argentina; those not included in the analysis. If these other taxa IRSNB, Institut royal des Sciences naturelles de Belgique, are found in similarly aged strata, the character-states Brussels,Belgium;MNA,MuseumofNorthernArizona, that diagnosed a clade in the phylogenetic analysis Flagstaff, Arizona; NMMNH, New Mexico Museum of cannot be used alone to assign isolated remains to this Natural History and Science, Albuquerque, New Mex- clade. For example, several dental character-states ico; NSM, Nova Scotia Museum, Halifax, Nova Scotia; PVL, Instituto Miguel Lillo, Tucuma´n, Argentina; SAM, may diagnose the Ornithischia in phylogenetic ana- South African Museum, Cape Town, South Africa; lyses of the Dinosauria, but they cannot be used alone UCMP, University of California Museum of Paleontol- to identify isolated Triassic ornithischian teeth, ogy, Berkeley, California; YPM, Yale Peabody Museum, because these character-states are found in other New Haven, Connecticut. Triassic non-dinosaur archosaurs (Parker et al. 2005). To be useful in identification of specimens, these character-states need to be used in association with Records of alleged Triassic ornithischians unambiguous synapomorphies that can be recognized in the specimen of interest. North America Given that this restricts the number of character- Hunt and colleagues (e.g. Hunt 1989; Hunt and states available to diagnose fragmentary early Lucas 1994; Hunt et al. 1998; Heckert 2002, 2004) ornithischian specimens, what unambiguous synapo- identified a variety of Triassic ornithischian dinosaur morphies provide robust evidence for an ornithischian taxa based on isolated teeth collected from Upper affinity? The monophyly of Ornithischia has not been Triassic strata throughout North America, especially questioned by any recent phylogenetic analysis, so the south-western US. The first of these taxa synapomorphies diagnosing the clade Ornithischia published was Revueltosaurus callenderi (Hunt 1989) provide a good starting point provided they are not from the Norian-aged Bull Canyon Formation of New found in other early Mesozoic archosaurs. The Mexico. Hunt (1989) referred this taxon to the following character-states are unambiguous synapo- Ornithischia because of the presence of several dental morphies of the clade Ornithischia, and have been synapomorphies proposed by Sereno (1986) including demonstrated as such by recent phylogenetic analyses low, triangular tooth crowns in lateral view, the (Sereno 1999; Butler 2005a). The status of some of absence of recurvature in maxillary and dentary these character-states, as well as other characters not teeth, and a well-developed neck separating crown included in this list but traditionally used to diagnose from root. Hunt (1989) noted that R. callenderi lacked Ornithischia will be discussed later. This list of “cingula” and differed from other ornithischians in synapomorphies includes character-states not pre- having incisiform premaxillary teeth. served or otherwise known in Pisanosaurus, because Padian (1990) supported the referral of Revuelto- its status is explicitly re-assessed below without saurus to the Ornithischia and referred to the taxon assuming a priori that Pisanosaurus is
Load more

Recommended publications
  • Peerj-Review-5963
    An unusual archosauromorph tooth increases known archosauromorph diversity in the Comment [1]: Be consistent with the clade you assign the tooth. lower portion of the Chinle Formation (Late Triassic) of southeastern Utah, USA Deleted: tetrapod Comment [2]: Is this formal? If so, Lopez, Andres; St. Aude, Isabella; Alderete, David; Alvarez, David; Aultman, Hannah; Busch, capitalize it. Comment [3]: Remember, readers from around the world could be citing you! Dominique; Bustamante, Rogelio; Cirks, Leah; Lopez, Martin; Moncada, Adriana; Ortega, Elizabeth; Verdugo, Carlos; Gay, Robert J *. Mission Heights Preparatory High School, 1376 E. Cottonwood Ln., Casa Grande, Arizona 85122 *[email protected] 520-836-9383 Abstract: An unusual tetrapod tooth was discovered in the Upper Triassic Chinle Formation of Deleted: Late southeastern Utah. The tooth was originally hypothesized to pertain to Revueltosaurus but Deleted: thought Deleted: belong further investigations have rejected that hypothesis. In this paper, we compare MNA V10668 to other known fossil teeth found in the Chinle Formation and assign the tooth to the least inclusive Comment [4]: Use tooth crowns (there is no root) throughout the text. clade currently available. Using data found in other publications and pictures of other teeth, we Deleted: identify Deleted: it may belongs to compare this specimen to other Triassic dental taxa. MNA V10668 shares some similarities with Crosbysaurus, Tecovasaurus, and several other named taxa but possesses a unique combination Deleted: characteristics of characteristics not found in other archosauromorph teeth. We conclude that it is most likely an Deleted: diapsid archosauromorph and possibly an archosauriform. This increases the known diversity of Deleted: probably archosauromorph from the Chinle Formation and represents the first tooth morphotype Deleted: tetrapods completely unique to Utah in the Late Triassic.
    [Show full text]
  • Ischigualasto Formation. the Second Is a Sile- Diversity Or Abundance, but This Result Was Based on Only 19 of Saurid, Ignotosaurus Fragilis (Fig
    This article was downloaded by: [University of Chicago Library] On: 10 October 2013, At: 10:52 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Journal of Vertebrate Paleontology Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/ujvp20 Vertebrate succession in the Ischigualasto Formation Ricardo N. Martínez a , Cecilia Apaldetti a b , Oscar A. Alcober a , Carina E. Colombi a b , Paul C. Sereno c , Eliana Fernandez a b , Paula Santi Malnis a b , Gustavo A. Correa a b & Diego Abelin a a Instituto y Museo de Ciencias Naturales, Universidad Nacional de San Juan , España 400 (norte), San Juan , Argentina , CP5400 b Consejo Nacional de Investigaciones Científicas y Técnicas , Buenos Aires , Argentina c Department of Organismal Biology and Anatomy, and Committee on Evolutionary Biology , University of Chicago , 1027 East 57th Street, Chicago , Illinois , 60637 , U.S.A. Published online: 08 Oct 2013. To cite this article: Ricardo N. Martínez , Cecilia Apaldetti , Oscar A. Alcober , Carina E. Colombi , Paul C. Sereno , Eliana Fernandez , Paula Santi Malnis , Gustavo A. Correa & Diego Abelin (2012) Vertebrate succession in the Ischigualasto Formation, Journal of Vertebrate Paleontology, 32:sup1, 10-30, DOI: 10.1080/02724634.2013.818546 To link to this article: http://dx.doi.org/10.1080/02724634.2013.818546 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content.
    [Show full text]
  • Download Full Article in PDF Format
    A review of the systematic position of the dinosauriform archosaur Eucoelophysis baldwini Sullivan & Lucas, 1999 from the Upper Triassic of New Mexico, USA Martín D. EZCURRA Laboratorio de Anatomia Comparada y Evolución de los Vertebrados, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Av. Angel Gallardo 470, Buenos Aires (1405) (Argentina) [email protected] Ezcurra M. D. 2006. — A review of the systematic position of the dinosauriform archosaur Eucoelophysis baldwini Sullivan & Lucas, 1999 from the Upper Triassic of New Mexico, USA. Geodiversitas 28 (4) : 649-684. Abstract Eucoelophysis baldwini Sullivan & Lucas, 1999 is represented by several post- cranial elements from the Petrified Forest Formation (Norian), New Mexico, USA. Eucoelophysis Sullivan & Lucas, 1999 was widely considered as a coelo- physoid dinosaur by several authors, but the hindlimb anatomy of this genus clearly indicates that it belongs to neither of these groups. The following fea- tures exclude Eucoelophysis from Neotheropoda: absence of oblique ligament groove on caudal surface of femoral head, femoral medial epicondyle small and smoothly rounded, absence of caudal cleft between medial part of the proximal end of the tibia and fibular condyles, cnemial crest low, and fibular crest absent. Moreover, Eucoelophysis lacks dinosaurian synapomorphic characters, but has a plesiomorphic slightly inturned femoral head that prevents its assignment to Dinosauria. Interestingly, the morphology of the femur of Eucoelophysis is extremely similar to that of the basal dinosauriform Silesaurus opolensis Dzik, Key words Dinosauriformes, 2003 from the Late Triassic of Poland. In order to determine the phylogenetic Coelophysoidea, position of Eucoelophysis, a cladistic analysis was carried out, which depicts Eu- Eucoelophysis, coelophysis as a non-dinosaurian dinosauriform.
    [Show full text]
  • A New Archosauriform Reptile with Distinctive Teeth from the Middle Triassic (Ladinian) of Germany
    Journal of Vertebrate Paleontology ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/ujvp20 A new archosauriform reptile with distinctive teeth from the Middle Triassic (Ladinian) of Germany Hans-Dieter Sues , Rainer R. Schoch , Gabriela Sobral & Randall B. Irmis To cite this article: Hans-Dieter Sues , Rainer R. Schoch , Gabriela Sobral & Randall B. Irmis (2020) A new archosauriform reptile with distinctive teeth from the Middle Triassic (Ladinian) of Germany, Journal of Vertebrate Paleontology, 40:1, e1764968, DOI: 10.1080/02724634.2020.1764968 To link to this article: https://doi.org/10.1080/02724634.2020.1764968 View supplementary material Published online: 23 Jun 2020. Submit your article to this journal Article views: 200 View related articles View Crossmark data Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=ujvp20 Journal of Vertebrate Paleontology e1764968 (14 pages) The work of Hans–Dieter Sues was authored as part of his official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 USC. 105, no copyright protection is available for such works under US Law. Rainer R. Schoch, Gabriela Sobral and Randall B. Irmis hereby waive their right to assert copyright, but not their right to be named as co–authors in the article. DOI: 10.1080/02724634.2020.1764968 ARTICLE A NEW ARCHOSAURIFORM REPTILE WITH DISTINCTIVE TEETH FROM THE MIDDLE TRIASSIC (LADINIAN) OF GERMANY HANS-DIETER SUES, *,1 RAINER R. SCHOCH, 2 GABRIELA SOBRAL, 2 and RANDALL B. IRMIS3 1Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, MRC 121, P.O.
    [Show full text]
  • South Africa's Coalfields — a 2014 Perspective
    International Journal of Coal Geology 132 (2014) 170–254 Contents lists available at ScienceDirect International Journal of Coal Geology journal homepage: www.elsevier.com/locate/ijcoalgeo South Africa's coalfields — A 2014 perspective P. John Hancox a,⁎,AnnetteE.Götzb,c a University of the Witwatersrand, School of Geosciences and Evolutionary Studies Institute, Private Bag 3, 2050 Wits, South Africa b University of Pretoria, Department of Geology, Private Bag X20, Hatfield, 0028 Pretoria, South Africa c Kazan Federal University, 18 Kremlyovskaya St., Kazan 420008, Republic of Tatarstan, Russian Federation article info abstract Article history: For well over a century and a half coal has played a vital role in South Africa's economy and currently bituminous Received 7 April 2014 coal is the primary energy source for domestic electricity generation, as well as being the feedstock for the Received in revised form 22 June 2014 production of a substantial percentage of the country's liquid fuels. It furthermore provides a considerable source Accepted 22 June 2014 of foreign revenue from exports. Available online 28 June 2014 Based on geographic considerations, and variations in the sedimentation, origin, formation, distribution and quality of the coals, 19 coalfields are generally recognised in South Africa. This paper provides an updated review Keywords: Gondwana coal of their exploration and exploitation histories, general geology, coal seam nomenclature and coal qualities. With- Permian in the various coalfields autocyclic variability is the norm rather than the exception, whereas allocyclic variability Triassic is much less so, and allows for the correlation of genetically related sequences. During the mid-Jurassic break up Coalfield of Gondwana most of the coal-bearing successions were intruded by dolerite.
    [Show full text]
  • The Anatomy of Asilisaurus Kongwe, a Dinosauriform from the Lifua
    THE ANATOMICAL RECORD (2019) The Anatomy of Asilisaurus kongwe,a Dinosauriform from the Lifua Member of the Manda Beds (~Middle Triassic) of Africa 1 2 3 STERLING J. NESBITT , * MAX C. LANGER, AND MARTIN D. EZCURRA 1Department of Geosciences, Virginia Tech, Blacksburg, Virginia 2Departamento de Biologia, Universidade de Sao~ Paulo, Ribeirao~ Preto, Brazil 3Sección Paleontología de Vertebrados CONICET—Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Buenos Aires, Argentina ABSTRACT The diagnosis of Dinosauria and interrelationships of the earliest dino- saurs relies on careful documentation of the anatomy of their closest rela- tives. These close relatives, or dinosaur “precursors,” are typically only documented by a handful of fossils from across Pangea and nearly all speci- mens are typically missing important regions (e.g., forelimbs, pelves, skulls) that appear to be important to help resolving the relationships of dinosaurs. Here, we fully describe the known skeletal elements of Asilisaurus kongwe, a dinosauriform from the Middle Triassic Manda Beds of the Ruhuhu Basin of Tanzania. The taxon is known from many disarticulated and partially articulated remains and, most importantly, from a spectacularly preserved associated skeleton of an individual containing much of the skull, pectoral and pelvic girdles, forelimb and hindlimb, and parts of the vertebral column including much of the tail. The unprecedented detail of the anatomy indi- cates that Asilisaurus kongwe had a unique skull that was short and had both a premaxillary and dentary edentulous margin, but retained a number of character states plesiomorphic for Archosauria, including a crocodylian- like ankle configuration and a rather short foot with well-developed meta- tarsals I and V.
    [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]
  • Meandering in the Main Karoo Basin, Eastern Cape, South Africa FIELD TRIP LEADERS: Emese Bordy & Goonie Marsh
    POST 10 Meandering in the main Karoo Basin, Eastern Cape, South Africa FIELD TRIP LEADERS: Emese Bordy & Goonie Marsh This comprehensive five day trip will take us through, via an unique route in the shortest travel time and distance, a geo-traverse through over 400 million years of South African geological history. The main focus of the field trip is the sedimentary fill of the southern main Karoo Basin, including the nature of some of the major Karoo intrusive and volcanic complexes of the Eastern Cape. Field Trip Leaders: Emese Bordy and Goonie Marsh Start: Port Elizabeth End: Port Elizabeth Dates: 3-8 September 2016 ITINERARY SUGGESTION OF FLIGHT BOOKING FROM CAPE TOWN TO PORT ELIZABETH: SOUTH AFRICAN AIRWAYS FLIGHT 1803 DEPARTING CAPE TOWN AT 07h00, ARRIVING PORT ELIZABETH AT 08h15 Day 1 3 September 2016, Saturday Arrival at Port Elizabeth Airport and transfer to Grahamstown Overnight at the Graham Hotel in Grahamstown BB via Addo Elephant Park Day 2 4 September 2016, Sunday Stop 1 : Overview of 400 million years of South African geological history though the rocks and landscape of Grahamstown, Eastern Cape. Topics covered: Cape and Karoo systems, formation of the main Karoo Basin and Cape Fold Belt, Gondwana breakup, Cenozoic sea level changes. Location : 1820 Settlers' Monument Features to be seen : Relationship of the geology and geomorphology Cape Fold Belt - large-scale geological and geomorphological features: Witteberg quartzite ridges with some mudstone lenses to the south (cut by the N2 national road) & to the north (called Botha’s Ridge) running across the horizon. City bowl overlying the E-W running contact between soft Witteberg mudstones to the south and Dwyka tillites to the north Flat peneplain underlain by hard silcretes (with Joza/ King’s Flat township on it), visible along the northeastern horizon.
    [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]
  • The Sauropodomorph Biostratigraphy of the Elliot Formation of Southern Africa: Tracking the Evolution of Sauropodomorpha Across the Triassic–Jurassic Boundary
    Editors' choice The sauropodomorph biostratigraphy of the Elliot Formation of southern Africa: Tracking the evolution of Sauropodomorpha across the Triassic–Jurassic boundary BLAIR W. MCPHEE, EMESE M. BORDY, LARA SCISCIO, and JONAH N. CHOINIERE McPhee, B.W., Bordy, E.M., Sciscio, L., and Choiniere, J.N. 2017. The sauropodomorph biostratigraphy of the Elliot Formation of southern Africa: Tracking the evolution of Sauropodomorpha across the Triassic–Jurassic boundary. Acta Palaeontologica Polonica 62 (3): 441–465. The latest Triassic is notable for coinciding with the dramatic decline of many previously dominant groups, followed by the rapid radiation of Dinosauria in the Early Jurassic. Among the most common terrestrial vertebrates from this time, sauropodomorph dinosaurs provide an important insight into the changing dynamics of the biota across the Triassic–Jurassic boundary. The Elliot Formation of South Africa and Lesotho preserves the richest assemblage of sauropodomorphs known from this age, and is a key index assemblage for biostratigraphic correlations with other simi- larly-aged global terrestrial deposits. Past assessments of Elliot Formation biostratigraphy were hampered by an overly simplistic biozonation scheme which divided it into a lower “Euskelosaurus” Range Zone and an upper Massospondylus Range Zone. Here we revise the zonation of the Elliot Formation by: (i) synthesizing the last three decades’ worth of fossil discoveries, taxonomic revision, and lithostratigraphic investigation; and (ii) systematically reappraising the strati- graphic provenance of important fossil locations. We then use our revised stratigraphic information in conjunction with phylogenetic character data to assess morphological disparity between Late Triassic and Early Jurassic sauropodomorph taxa. Our results demonstrate that the Early Jurassic upper Elliot Formation is considerably more taxonomically and morphologically diverse than previously thought.
    [Show full text]
  • Late Triassic) Adrian P
    New Mexico Geological Society Downloaded from: http://nmgs.nmt.edu/publications/guidebooks/56 Definition and correlation of the Lamyan: A new biochronological unit for the nonmarine Late Carnian (Late Triassic) Adrian P. Hunt, Spencer G. Lucas, and Andrew B. Heckert, 2005, pp. 357-366 in: Geology of the Chama Basin, Lucas, Spencer G.; Zeigler, Kate E.; Lueth, Virgil W.; Owen, Donald E.; [eds.], New Mexico Geological Society 56th Annual Fall Field Conference Guidebook, 456 p. This is one of many related papers that were included in the 2005 NMGS Fall Field Conference Guidebook. Annual NMGS Fall Field Conference Guidebooks Every fall since 1950, the New Mexico Geological Society (NMGS) has held an annual Fall Field Conference that explores some region of New Mexico (or surrounding states). Always well attended, these conferences provide a guidebook to participants. Besides detailed road logs, the guidebooks contain many well written, edited, and peer-reviewed geoscience papers. These books have set the national standard for geologic guidebooks and are an essential geologic reference for anyone working in or around New Mexico. Free Downloads NMGS has decided to make peer-reviewed papers from our Fall Field Conference guidebooks available for free download. Non-members will have access to guidebook papers two years after publication. Members have access to all papers. This is in keeping with our mission of promoting interest, research, and cooperation regarding geology in New Mexico. However, guidebook sales represent a significant proportion of our operating budget. Therefore, only research papers are available for download. Road logs, mini-papers, maps, stratigraphic charts, and other selected content are available only in the printed guidebooks.
    [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]