DOCSLIB.ORG

TOOTH REPLACEMENT in MANIDENS CONDORENSIS: BASELINE STUDY to ADDRESS the REPLACEMENT PATTERN in DENTITIONS of EARLY ORNITHISCHIANS by MARCOS G

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
TOOTH REPLACEMENT in MANIDENS CONDORENSIS: BASELINE STUDY to ADDRESS the REPLACEMENT PATTERN in DENTITIONS of EARLY ORNITHISCHIANS by MARCOS G [Papers in Palaeontology, 2020, pp. 1–27] TOOTH REPLACEMENT IN MANIDENS CONDORENSIS: BASELINE STUDY TO ADDRESS THE REPLACEMENT PATTERN IN DENTITIONS OF EARLY ORNITHISCHIANS by MARCOS G. BECERRA1 ,DIEGOPOL1 , JOHN A. WHITLOCK2,3 and LAURA B. PORRO4 1Consejo Nacional de Investigaciones Cientıficas y Tecnicas (CONICET), Museo Paleontologico Egidio Feruglio, Fontana 140, Trelew, Chubut U9100GYO, Argentina; [email protected], [email protected] 2Biology Department, Mount Aloysius College, Admiral Peary Highway 7373, Cresson, PA 16630, USA; [email protected] 3Section of Vertebrate Paleontology, Carnegie Museum of Natural History, 4400 Forbes Avenue, Pittsburgh, PA 15213, USA 4Centre for Integrative Anatomy, Department of Cell & Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK; [email protected] Typescript received 4 March 2020; accepted in revised form 2 July 2020 Abstract: Dental replacement in Heterodontosauridae has Newly erupted teeth imbricate in a mesial cavity–distal been debated over the last five decades primarily on indirect crown base relationship during eruption, so that imbrication evidence, such as the development of wear facets and the of the midposterior dentition remains unaltered during tooth position of erupted teeth. Direct observation of unerupted replacement. The presence/absence of a small caniniform teeth provides unambiguous data for understanding tooth tooth in the D3 position of several specimens suggests possi- replacement but this has been done only for Heterodon- ble intraspecific dimorphism in Manidens. On longitudinal tosaurus and Fruitadens. This study addresses dental replace- sections of isolated crowns the histological features such as ment in Manidens condorensis based on the positioning of Howship’s lacunae and odontoclast spaces are similar in size functional and replacement teeth using microcomputed to extant reptiles. The differential wear decreasing posteriorly tomography data, differential wear along the dentition and and hypothetical Z-spacing below 2.3 in Manidens are simi- the differences in labiolingual/apicobasal level of functional lar to basal ornithischians. Tooth replacement in Heterodon- teeth. Dental replacement in Manidens condorensis was con- tosauridae (and other early ornithischians) provides key tinuous in an anterior-to-posterior wave pattern, with asyn- information for understanding the dynamics of jaw function chronous tooth eruption and the addition of new teeth and craniomandibular specialization to herbivory. posteriorly to the toothrow during ontogeny. Manidens shows the first evidence of dental replacement for the large Key words: Ornithischia, Heterodontosauridae, tooth dentary caniniform in Heterodontosauridae, which possibly replacement, 3D reconstruction, intraspecific dimorphism, had replacement timing distinct from the cheek dentition. dentition. T HE development of precise occlusion and tooth wear is a non-cerapodan ornithischians, non-hadrosaurid dry- recurrent trend that has improved chewing efficiency in omorphs and early ceratopsians (Norman & Weishampel different herbivorous lineages (Janis & Fortelius 1988; 1985; Weishampel & Norman 1989; Sander 1997; Norman MacFadden 2000; Kaiser et al. 2013; Madden 2014; Erick- 2004; Tanoue et al. 2009; Strickson et al. 2016). The condi- son et al. 2016). The consequences of extensive tooth wear tion of high replacement rates alongside tightly packed can be overcome by the appearance of high-crowned (hyp- dental batteries that form a continuous grinding surface is sodont) dentitions or high rates of tooth replacement a derived stage of polyphyodonty that appeared indepen- (D’Emic et al. 2013; Erickson et al. 2016). High replace- dently in ceratopsids, hadrosaurids, and some neosauro- ment rates have been inferred for many dinosaur clades, pods (Dodson et al. 2004; Horner et al. 2004; Sereno & including polyphyodont dentitions (i.e. dentitions with Wilson 2005; Bell et al. 2009). Within Heterodontosauridae continuous tooth replacement) with spaced teeth as in (and convergently shared with Therizinosauria; Button © The Palaeontological Association doi: 10.1002/spp2.1337 1 2 PAPERS IN PALAEONTOLOGY et al. 2017), more derived species had polyphyodont high- midposterior toothrow that allows close-packing, thick- crowned and tightly packed dentitions with low replace- ened enamel in the cutting edges of denticles (although ment rates, mixing two different evolutionary stages that only dentary teeth bear crenulated edges), and the devel- represent a novel adaptive path to increased herbivory in opment of apical and basal wear facets that indicate a the Ornithischia (Norman et al. 2011; Sereno 2012). The novel and complex pattern of tooth–tooth occlusion, above-mentioned cases indicate that different clades of her- making this taxon unique in terms of its adaptations to bivorous dinosaurs developed different adaptations to her- herbivory (Becerra et al. 2014, 2018). Here we describe bivory. However, there is still a lack of understanding of tooth replacement inferred for this taxon based on dental evolution in dinosaurs due to the small number of microcomputed tomography (lCT) of its dentition and studies of species representing early adaptive stages to her- interpret its significance for the early evolution of bivory (Stirton 1947; Erickson et al. 2016; Strickson et al. heterodontosaurids and ornithischians. 2016; Button et al. 2017). Furthermore, studies on tooth replacement in early ornithischians are rare despite their Institutional abbreviations. BP, Bernard Price Institute for importance for understanding the evolution of herbivory Palaeontological Research, Johannesburg, South Africa; in this diverse and successful clade (Sciscio et al. 2017; IVPP, Institute of Vertebrate Paleontology and Paleoan- Chen et al. 2018). thropology, Beijing, China; MPEF, Museo Paleontologico The middle–late Toarcian to Aalenian–Bajocian Egidio Feruglio, Trelew, Chubut, Argentina; NHMUK, Canad~ on Asfalto Formation (Cuneo et al. 2013) has The Natural History Museum London, UK; NM, Nazio- yielded one of the most important continental vertebrate nale Museum, Bloemfontein, South Africa; SAM, Iziko faunas from the early Jurassic of the southern hemi- South African Museum, Cape Town, South Africa; YPM, sphere (Bonaparte 1979; Rauhut et al. 2001; Escapa et al. Peabody Museum of Natural History, Yale University, 2008; Pol & Rauhut 2012). The record of ornithischians New Haven, USA. from this unit is so far limited to the heterodontosaurid Manidens condorensis (Pol et al. 2011); a second heterodontosaurid species lacking diagnostic features MATERIAL AND METHOD (Becerra et al. 2016); and an isolated ungual referred to Cerapoda (Rauhut & Lopez-Arbarello 2008). Manidens is Material the most complete early Jurassic ornithischian from South America and one of the most complete heterodon- All the fossil material used in this study is housed in tosaurids. The holotype material MPEF-PV 3211 of the the vertebrate palaeontology collection of the MPEF in small-sized heterodontosaurid Manidens condorensis, Trelew (Chubut), Argentina. All specimens included in which includes cranial and postcranial remains, preserves this study were found in the Queso Rallado locality a posteriorly incomplete right maxillary dentition and a except for MPEF-PV 3808, which was found in the nearly complete dentary dentition in both dentaries (Pol Frenguelli fossil site. Both localities belong to the lower et al. 2011). Regardless of its preservation, the maxillary levels of the Canad~ on Asfalto Formation (Pol et al. and dentary dentitions in known specimens range 2011; Cuneo et al. 2013; Becerra et al. 2014, 2018, between 10 and 13 tooth positions, a low count that is Becerra & Pol 2020). characteristic for Heterodontosauridae (Pol et al. 2011; Becerra et al. 2014, 2018). The morphology of the maxil- Specimen MPEF-PV 3211. The preserved elements on this lary dentition was characterized based on MPEF-PV 3211 specimen consist of at least 80% of the cranial bones, and 3809 by Becerra et al. (2018) as symmetric diamond- scattered vertebrae representing all axial regions (cervical, shaped teeth with a low number of denticles, enlarged dorsal and caudal vertebrae, and the complete sacral labial and lingual crests in the crown bases (cingular region), the left scapula and coracoid, an almost complete mesial and distal entolophs and ectolophs), with both pelvic girdle, and rib fragments (Pol et al. 2011; Becerra entolophs in a V- to Z-shaped disposition and bearing et al. 2014). The specimen corresponds to the holotype denticles/serrations. The morphology of the dentary den- material of Manidens condorensis, as defined by Pol et al. tition as detailed by Pol et al. (2011) and Becerra et al. (2011). (2014), is based on MPEF-PV 3211 and isolated teeth, and consists of an enlarged caniniform in the first tooth Specimen MPEF-PV 3808. This new specimen consists of position and symmetrical diamond-shaped (‘hand- partially exposed fossil remains at the face and back of a shaped’) postcaniniform teeth. Although these dentitions lacustrine tuffaceous shale rock fragment, corresponding to show a strongly contrasting morphology, they share a a right dentary, at least five dorsal vertebrae, most of a sca- height–width proportion heterodonty along the toothrow, pula, and other unidentified elements inside the rock (see the presence of a mesial cavity in teeth from the below). The poor preservation of the fossil prevents its BECERRA ET AL.: DENTAL REPLACEMENT IN MANIDENS
Load more

Recommended publications
  • 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]
  • 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 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]
  • Guides Level Ii Manual 2005 December
    GUIDING LEVEL II A TRAINING MANUAL DESIGNED TO ASSIST WITH PREPARATION FOR THE FGASA LEVEL II AND TRAILS GUIDE EXAMS All rights reserved. No part of the material may be reproduced or utilized in any form or by any means, electronic or mechanical including photocopying, recording or by an information storage retrieval system, without the written permission of Lee Gutteridge. (INCLUDING MORE THAN FOUR HUNDRED PHOTOS AND DIAGRAMS) COMPILED BY LEE GUTTERIDGE THIS STUDY MATERIAL CONFORMS TO THE SYLLABUS SET BY FGASA FOR THE LEVEL II EXAMS AND IS APPROVED BY PROFESSOR W.VAN HOVEN OF THE CENTRE FOR WILDLIFE MANAGEMENT AT THE UNIVERSITY OF PRETORIA P.O. Box 441, Mookgopong, 0560, Limpopo, South Africa. Cell 083 667 7586 2 LEVEL TWO TRAINING MANUAL This manual has been compiled from the perspective of a guide in the field. In writing it I asked myself what can I use on a game drive, or game walk as regards information. These aspects covered in this manual will give the guide good, interesting and factual information for direct discussion with the guest. No one book will cover every aspect so here I have included sections on the following topics. 1. Ecology 2. Mammals 3. Birds 4. Reptiles and Amphibians 5. Astronomy 6. Botany 7. Insects, Arachnids and their relatives 8. Geology and Climatology 9. Fish 10. Survival 11. AWH and VPDA The problem for guides is not always finding the answers, but also what is the question to be researched in the first place? It is difficult for a guide to pre-empt what guests will ask them over their guiding careers, but many of the questions and answers which will come into play have been covered here.
    [Show full text]
  • Lesothosaurus, "Fabrosaurids," and the Early Evolution of Ornithischia Author(S): Paul C
    Lesothosaurus, "Fabrosaurids," and the Early Evolution of Ornithischia Author(s): Paul C. Sereno Source: Journal of Vertebrate Paleontology, Vol. 11, No. 2 (Jun. 20, 1991), pp. 168-197 Published by: Taylor & Francis, Ltd. on behalf of The Society of Vertebrate Paleontology Stable URL: https://www.jstor.org/stable/4523370 Accessed: 28-01-2019 13:42 UTC JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at https://about.jstor.org/terms The Society of Vertebrate Paleontology, Taylor & Francis, Ltd. are collaborating with JSTOR to digitize, preserve and extend access to Journal of Vertebrate Paleontology This content downloaded from 69.80.65.67 on Mon, 28 Jan 2019 13:42:40 UTC All use subject to https://about.jstor.org/terms Journal of Vertebrate Paleontology 11(2): 168-197, June 1991 © 1991 by the Society of Vertebrate Paleontology LESOTHOSAURUS, "FABROSAURIDS," AND THE EARLY EVOLUTION OF ORNITHISCHIA PAUL C. SERENO Department of Organismal Biology and Anatomy, University of Chicago, 1025 E. 57th Street, Chicago, Illinois 60637 ABSTRACT -New materials of Lesothosaurus diagnosticus permit a detailed understanding of one of the earliest and most primitive ornithischians. Skull proportions and sutural relations can be discerned from several articulated and disarticulated skulls. The snout is proportionately long with a vascularized, horn-covered tip.
    [Show full text]
  • A New Basal Ornithopod Dinosaur from the Lower Cretaceous of China
    A new basal ornithopod dinosaur from the Lower Cretaceous of China Yuqing Yang1,2,3, Wenhao Wu4,5, Paul-Emile Dieudonné6 and Pascal Godefroit7 1 College of Resources and Civil Engineering, Northeastern University, Shenyang, Liaoning, China 2 College of Paleontology, Shenyang Normal University, Shenyang, Liaoning, China 3 Key Laboratory for Evolution of Past Life and Change of Environment, Province of Liaoning, Shenyang Normal University, Shenyang, Liaoning, China 4 Key Laboratory for Evolution of Past Life and Environment in Northeast Asia, Ministry of Education, Jilin University, Changchun, Jilin, China 5 Research Center of Paleontology and Stratigraphy, Jilin University, Changchun, Jilin, China 6 Instituto de Investigación en Paleobiología y Geología, CONICET, Universidad Nacional de Río Negro, Rio Negro, Argentina 7 Directorate ‘Earth and History of Life’, Royal Belgian Institute of Natural Sciences, Brussels, Belgium ABSTRACT A new basal ornithopod dinosaur, based on two nearly complete articulated skeletons, is reported from the Lujiatun Beds (Yixian Fm, Lower Cretaceous) of western Liaoning Province (China). Some of the diagnostic features of Changmiania liaoningensis nov. gen., nov. sp. are tentatively interpreted as adaptations to a fossorial behavior, including: fused premaxillae; nasal laterally expanded, overhanging the maxilla; shortened neck formed by only six cervical vertebrae; neural spines of the sacral vertebrae completely fused together, forming a craniocaudally-elongated continuous bar; fused scapulocoracoid with prominent
    [Show full text]
  • Synoptic Taxonomy of Major Fossil Groups
    APPENDIX Synoptic Taxonomy of Major Fossil Groups Important fossil taxa are listed down to the lowest practical taxonomic level; in most cases, this will be the ordinal or subordinallevel. Abbreviated stratigraphic units in parentheses (e.g., UCamb-Ree) indicate maximum range known for the group; units followed by question marks are isolated occurrences followed generally by an interval with no known representatives. Taxa with ranges to "Ree" are extant. Data are extracted principally from Harland et al. (1967), Moore et al. (1956 et seq.), Sepkoski (1982), Romer (1966), Colbert (1980), Moy-Thomas and Miles (1971), Taylor (1981), and Brasier (1980). KINGDOM MONERA Class Ciliata (cont.) Order Spirotrichia (Tintinnida) (UOrd-Rec) DIVISION CYANOPHYTA ?Class [mertae sedis Order Chitinozoa (Proterozoic?, LOrd-UDev) Class Cyanophyceae Class Actinopoda Order Chroococcales (Archean-Rec) Subclass Radiolaria Order Nostocales (Archean-Ree) Order Polycystina Order Spongiostromales (Archean-Ree) Suborder Spumellaria (MCamb-Rec) Order Stigonematales (LDev-Rec) Suborder Nasselaria (Dev-Ree) Three minor orders KINGDOM ANIMALIA KINGDOM PROTISTA PHYLUM PORIFERA PHYLUM PROTOZOA Class Hexactinellida Order Amphidiscophora (Miss-Ree) Class Rhizopodea Order Hexactinosida (MTrias-Rec) Order Foraminiferida* Order Lyssacinosida (LCamb-Rec) Suborder Allogromiina (UCamb-Ree) Order Lychniscosida (UTrias-Rec) Suborder Textulariina (LCamb-Ree) Class Demospongia Suborder Fusulinina (Ord-Perm) Order Monaxonida (MCamb-Ree) Suborder Miliolina (Sil-Ree) Order Lithistida
    [Show full text]
  • University of Birmingham New Specimens of the Basal Ornithischian Dinosaur Lesothosaurus Diagnosticus Galton, 1978 from the Earl
    University of Birmingham New specimens of the basal ornithischian dinosaur Lesothosaurus diagnosticus Galton, 1978 from the Early Jurassic of South Africa Barrett, Paul; Butler, Richard; Yates, Adam; Baron, Matthew; Choiniere, Jonah License: Creative Commons: Attribution (CC BY) Document Version Publisher's PDF, also known as Version of record Citation for published version (Harvard): Barrett, P, Butler, R, Yates, A, Baron, M & Choiniere, J 2016, 'New specimens of the basal ornithischian dinosaur Lesothosaurus diagnosticus Galton, 1978 from the Early Jurassic of South Africa', Palaeontologia africana , vol. 50. <http://hdl.handle.net/10539/19886> Link to publication on Research at Birmingham portal General rights Unless a licence is specified above, all rights (including copyright and moral rights) in this document are retained by the authors and/or the copyright holders. The express permission of the copyright holder must be obtained for any use of this material other than for purposes permitted by law. •Users may freely distribute the URL that is used to identify this publication. •Users may download and/or print one copy of the publication from the University of Birmingham research portal for the purpose of private study or non-commercial research. •User may use extracts from the document in line with the concept of ‘fair dealing’ under the Copyright, Designs and Patents Act 1988 (?) •Users may not further distribute the material nor use it for the purposes of commercial gain. Where a licence is displayed above, please note the terms and conditions of the licence govern your use of this document. When citing, please reference the published version. Take down policy While the University of Birmingham exercises care and attention in making items available there are rare occasions when an item has been uploaded in error or has been deemed to be commercially or otherwise sensitive.
    [Show full text]
  • Krzyzanowskisaurus, a New Name for a Probable Ornithischian Dinosaur from the Upper Triassic Chinle Group, Arizona and New Mexico, Usa
    Heckert, A.B., and Lucas, S.G., eds., 2005, Vertebrate Paleontology in Arizona. New Mexico Museum of Natural History and Science Bulletin No. 29. 77 KRZYZANOWSKISAURUS, A NEW NAME FOR A PROBABLE ORNITHISCHIAN DINOSAUR FROM THE UPPER TRIASSIC CHINLE GROUP, ARIZONA AND NEW MEXICO, USA ANDREW B. HECKERT Department of Geology, Appalachian State University, ASU Box 32067, Boone, NC 28608-2067; [email protected] Abstract—Recent discoveries have demonstrated that Revueltosaurus callenderi Hunt is not an ornith- ischian dinosaur, so it is probably not congeneric with the putative ornithischian Revueltosaurus hunti Heckert. Revueltosaurus Hunt, 1989 is the senior generic name, so I propose here the generic name Krzyzanowskisaurus for “Revueltosaurus” hunti. Because the teeth of K. hunti appear more derived than R. callenderi, and are in fact more “typically” ornithischian than those of R. callenderi, I tentatively suggest that it does in fact represent an ornithischian dinosaur. Both R. callenderi and K. hunti have biostratigraphic significance. The former is an index taxon of the Revueltian land-vertebrate faunach- ron (lvf), and the latter is an index taxon of the Adamanian lvf. Indeed, the stratigraphic range of R. callenderi discriminates a discrete interval of Revueltian time (Barrancan) and that of K. hunt a subset of Adamanian time (St. Johnsian). Keywords: Krzyzanowskisaurus, Triassic, ornithischian, Adamanian, St. Johnsian, Arizona INTRODUCTION AND HISTORY OF STUDY Included species: Restricted to the type species. Diagnosis: Same as for type species (see below). Archosauriform teeth (sensu Godefroit and Cuny, 1997) Distribution: Upper Triassic strata of New Mexico (Los are among the most commonly recovered fossils from the Upper Esteros Member of the Santa Rosa Formation) and Arizona (Blue Triassic Chinle Group in the southwestern USA.
    [Show full text]
  • Download a PDF of This Web Page Here. Visit
    Dinosaur Genera List Page 1 of 42 You are visitor number— Zales Jewelry —as of November 7, 2008 The Dinosaur Genera List became a standalone website on December 4, 2000 on America Online’s Hometown domain. AOL closed the domain down on Halloween, 2008, so the List was carried over to the www.polychora.com domain in early November, 2008. The final visitor count before AOL Hometown was closed down was 93661, on October 30, 2008. List last updated 12/15/17 Additions and corrections entered since the last update are in green. Genera counts (but not totals) changed since the last update appear in green cells. Download a PDF of this web page here. Visit my Go Fund Me web page here. Go ahead, contribute a few bucks to the cause! Visit my eBay Store here. Search for “paleontology.” Unfortunately, as of May 2011, Adobe changed its PDF-creation website and no longer supports making PDFs directly from HTML files. I finally figured out a way around this problem, but the PDF no longer preserves background colors, such as the green backgrounds in the genera counts. Win some, lose some. Return to Dinogeorge’s Home Page. Generic Name Counts Scientifically Valid Names Scientifically Invalid Names Non- Letter Well Junior Rejected/ dinosaurian Doubtful Preoccupied Vernacular Totals (click) established synonyms forgotten (valid or invalid) file://C:\Documents and Settings\George\Desktop\Paleo Papers\dinolist.html 12/15/2017 Dinosaur Genera List Page 2 of 42 A 117 20 8 2 1 8 15 171 B 56 5 1 0 0 11 5 78 C 70 15 5 6 0 10 9 115 D 55 12 7 2 0 5 6 87 E 48 4 3
    [Show full text]
  • Digital Reconstruction of the Mandible of an Adult Lesothosaurus Diagnosticus with Insight Into the Tooth Replacement Process and Diet
    Digital reconstruction of the mandible of an adult Lesothosaurus diagnosticus with insight into the tooth replacement process and diet Lara Sciscio1, Fabien Knoll2, Emese M. Bordy1, Michiel O. de Kock3 and Ragna Redelstorff1 1 Department of Geological Sciences, University of Cape Town, Cape Town, South Africa 2 Fundación Conjunto Paleontológico de Teruel-Dinópolis, Teruel, Spain 3 Department of Geology, University of Johannesburg, Johannesburg, South Africa ABSTRACT Fragmentary caudal ends of the left and right mandible assigned to Lesothosaurus diagnosticus, an early ornithischian, was recently discovered in the continental red bed succession of the upper Elliot Formation (Lower Jurassic) at Likhoele Mountain (Mafeteng District) in Lesotho. Using micro-CT scanning, this mandible could be digitally reconstructed in 3D. The replacement teeth within the better preserved (left) dentary were visualised. The computed tomography dataset suggests asynchronous tooth replacement in an individual identified as an adult on the basis of bone histology. Clear evidence for systematic wear facets created by attrition is lacking. The two most heavily worn teeth are only apically truncated. Our observations of this specimen as well as others do not support the high level of dental wear expected from the semi-arid palaeoenvironment in which Lesothosaurus diagnosticus lived. Accordingly, a facultative omnivorous lifestyle, where seasonality determined the availability, quality, and abundance of food is suggested. This would have allowed for adaptability
    [Show full text]
  • DINOSAUR SUCCESS in the TRIASSIC: a NONCOMPETITIVE ECOLOGICAL MODEL This Content Downloaded from 137.222.248.217 on Sat, 17
    VOLUME 58, No. 1 THE QUARTERLY REVIEW OF BIOLOGY MARCH 1983 DINOSAUR SUCCESS IN THE TRIASSIC: A NONCOMPETITIVE ECOLOGICAL MODEL MICHAEL J. BENTON University Museum, Parks Road, Oxford OX] 3PW, England, UK ABSTRACT The initial radiation of the dinosaurs in the Triassic period (about 200 million years ago) has been generally regarded as a result of successful competition with the previously dominant mammal- like reptiles. A detailed review of major terrestrial reptile faunas of the Permo- Triassic, including estimates of relative abundance, gives a different picture of the pattern of faunal replacements. Dinosaurs only appeared as dominant faunal elements in the latest Triassic after the disappear- ance of several groups qf mammal-like reptiles, thecondontians (ancestors of dinosaurs and other archosaurs), and rhynchosaurs (medium-sized herbivores). The concepts of differential survival ("competitive") and opportunistic ecological replacement of higher taxonomic categories are contrasted (the latter involves chance radiation to fill adaptive zones that are already empty), and they are applied to the fossil record. There is no evidence that either thecodontians or dinosaurs demonstrated their superiority over mammal-like reptiles in massive competitive take-overs. Thecodontians arose as medium-sized carnivores after the extinction of certain mammal-like reptiles (opportunism, latest Permian). Throughout most of the Triassic, the thecodontians shared carnivore adaptive zones with advanced mammal-like reptiles (cynodonts) until the latter became extinct (random processes, early to late Triassic). Among herbivores, the dicynodont mammal-like reptiles were largely replaced by diademodontoid mammal-like reptiles and rhynchosaurs (differential survival, middle to late Triassic). These groups then became extinct and dinosaurs replaced them and radiated rapidly (opportunism, latest Triassic).
    [Show full text]