DOCSLIB.ORG

The First Well-Preserved Coelophysoid Theropod Dinosaur from Asia

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The First Well-Preserved Coelophysoid Theropod Dinosaur from Asia Zootaxa 3873 (3): 233–249 ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ Article ZOOTAXA Copyright © 2014 Magnolia Press ISSN 1175-5334 (online edition) http://dx.doi.org/10.11646/zootaxa.3873.3.3 http://zoobank.org/urn:lsid:zoobank.org:pub:4441BCDF-E4A9-4C67-AE08-5D6D418706CC The first well-preserved coelophysoid theropod dinosaur from Asia HAI-LU YOU1,5, YOICHI AZUMA2, TAO WANG3, YA-MING WANG4 & ZHI-MING DONG1 1Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 142 Xizhimenwai Dajie, Beijing, 100044, P. R. China. Email: [email protected] 2Fukui Prefectural University, 4-1-1 Kenjojima, Matsuoka, Eiheiji-cho, Yoshida-gun, Fukui 910-1195, Japan 3 Bureau of Land and Resources of Lufeng County, Yunnan Province, 651207, P. R. China 4School of Earth Sciences and Resources, China University of Geosciences (Beijing), Beijing 100083, P. R. China 5Corresponding author Abstract Coelophysoid dinosaurs represent the earliest major radiation of neotheropods. These small-to-medium-sized agile bipeds lived throughout much of Pangaea during the Late Triassic–arly Jurassic. Previously reported coelophysoid material from Asia (excluding the Gondwanan territory of India) is limited to two specimens that comprise only limb fragments. This paper describes a new genus and species of coelophysoid, Panguraptor lufengensis, from the Lower Jurassic Lufeng For- mation of Yunnan Province, China. The new taxon is represented by a well-preserved skeleton, including the skull and lower jaw, the presacral vertebral column and partial ribs, the right scapula, a partial forelimb, part of the pelvic girdle, and an almost complete hind limb. It is distinguished from other coelophysoid theropods by the unique combination of the following three character states: 1) diagonal (rostrodorsal-caudoventral) ridge on lateral surface of maxilla, within an- torbital fossa, 2) elliptical, laterally facing fenestra caudodorsal to aforementioned diagonal ridge, and 3) hooked cranio- medial corner of distal tarsal IV. Cladistic analysis recovers Panguraptor lufengensis deeply nested within Coelophysoidea as a member of Coelophysidae, and it is more closely related to Coelophysis than to “Syntarsus”. Pan- guraptor represents the first well-preserved coelophysoid theropod dinosaur from Asia, and provides fresh evidence sup- porting the hypothesis that terrestrial tetrapods tended to be distributed pan-continentally during the Early Jurassic. Key words: Theropoda, Coelophysoidea, new genus and species, Early Jurassic, Lufeng Formation, Lufeng Introduction Coelophysoid dinosaurs are small-to-medium-sized agile bipedal meat-eaters that lived throughout much of Pangaea during the Late Triassic and Early Jurassic (Tykoski 2005; Tykoski & Rowe 2004). They are among the earliest well documented dinosaurs and represent the earliest major radiation of neotheropods (Brusatte et al. 2010; Colbert 1989; Cope 1889; Sereno 1999). A recent study indicated that late Norian–Rhaetian theropod assemblages were dominated by basal (early diverging) coelophysoids, whereas Early Jurassic ones were composed of coelophysids (Coelophysis bauri + "Syntarsus" kayentakatae and all descendents of their most recent common ancestor), dilophosaurids and basal averostrans (Ezcurra 2012). However, despite the well-documented discoveries of derived coelophysoids in North America and Africa, the coelophysoid material that has previously been reported from Asia is limited to two specimens comprising only limb fragments and perhaps belonging to one individual (Irmis 2004). Here we describe a new genus and species of coelophysoid based on a well-preserved skeleton from the same rock unit, the Lower Jurassic Lufeng Formation of Yunnan Province, China, that yielded both previously reported specimens. Our cladistic analysis shows that the new taxon is a coelophysid coelophysoid, and is more closely related to Coelophysis than to "Syntarsus". This new taxon represents the most basal theropod dinosaur currently known in China, and provides fresh evidence supporting the hypothesis that terrestrial tetrapods tended to be distributed pan-continentally during the Early Jurassic. Institutional abbreviations: AMNH, American Museum of Natural History, New York, New York, USA; Accepted by S. Brusatte: 9 Sept. 2014; published: 16 Oct. 2014 233 FMNH, Field Museum of Natural History, Chicago, Illinois, USA; LFGT, Bureau of Land and Resources of Lufeng County, Lufeng, Yunnan, China; MNA, Museum of Northern Arizona, Flagstaff, Arizona, USA; NMMNH, New Mexico Museum of Natural History and Science, Albuquerque, New Mexico, USA; QG, Natural History Museum of Zimbabwe, Bulawayo, Zimbabwe. Systematic palaeontology Dinosauria Owen, 1842 Saurischia Seeley, 1887 Theropoda Marsh, 1881 Neotheropoda Bakker, 1986, sensu Sereno, 1998 Coelophysoidea Nopcsa, 1928, sensu Sereno, 1998 Coelophysidae Nopcsa, 1928, sensu Holtz, 1994 Panguraptor lufengensis gen. et sp. nov. Holotype: Bureau of Land and Resources of Lufeng County LFGT-0103, an articulated partial skeleton that includes the skull and lower jaw, the presacral vertebral column, part of the ribs, the right scapula and partial right forelimb, part of the pelvic girdle and parts of both hind limbs, the right hind limb being almost complete. Type locality and horizon. Lufeng County, Yunnan Province, China. Shawan Member of the Lufeng Formation (Fang et al. 2000). This is equivalent to the Dull Purplish Beds of the Lower Lufeng Formation (Series) as defined by Bien (1940). In the Lufeng area, the Lufeng Formation overlies the Lower Jurassic Yubacun Formation and is disconformably overlain by the Middle Jurassic Chuanjie Formation (Cheng et al. 2004). The age of the Lufeng Formation is probably early - middle Early Jurassic (Hettangian - Pliensbachian), based on biostratigraphic correlations (Luo & Wu 1995). Magnetostratigraphic analysis has indicated late Sinemurian – ?Toarcian for the age of the Lufeng Formation (Huang et al. 2005). Etymology. The genus name is from “Pangu” (Chinese), well known in Chinese mythology as the first living being and the creator of all reality, and “raptor” (Latin), meaning “thief” or “robber”. The specific name refers to “Lufeng County”, one of the world’s richest sources of Early Jurassic terrestrial vertebrate fossils. Differential diagnosis (for genus and species by monotypy). A coelophysid theropod with the unique combination of the following three character states (autapomorphies marked with *): 1*) diagonal (rostrodorsal- caudoventral) ridge on lateral surface of maxilla, within antorbital fossa; 2) elliptical, laterally facing fenestra caudodorsal to diagonal ridge mentioned in previous character state, also present in Zupaysaurus rougieri (Ezcurra 2006); 3*) distal tarsal IV with hooked craniomedial corner. Description and comparisons. LFGT-0103 is an articulated partial skeleton, exposed mainly in right lateral view (Fig. 1). The specimen is small, with a preserved skull length (taken from the rostral end of the maxilla to the ventral end of the quadrate because the premaxilla is missing) of 11.1 cm, presacral vertebral column length of ~58 cm (trunk/neck length ratio about 1.3), scapula length of 8.6 cm, femur length of 16.4 cm, and tibia length of 18.2 cm (Table 1). Early theropods normally had a long tail contributing more than half of the total body length, implying that this dinosaur may have measured around two metres long at the time of death. Height at the hip was probably about half a metre. LFGT-0103 probably represents a sub-adult individual, as indicated by the relatively small body size of the specimen, the large orbit, the lack of fusion between the scapula and coracoid, the lack of ossification of distal tips of the ischia, and the separation of the astragalus and calcaneum. However, the neurocentral sutures are fused, cervical ribs are fused to their respective centra, the ilium is fused to the ischium, and distal tarsal 3 is probably fused to metatarsal III, indicating that the specimen may be close to an adult individual. Growth curves of femur 234 · Zootaxa 3873 (3) © 2014 Magnolia Press YOU ET AL. length vs. age for C. rhodesiensis (Chinsamy 1994) and C. bauri (Rinehart et al. 2009) suggest, respectively, that this dinosaur died at a sub-adult age of around four years or around two years. TABLE 1. Measurements of selected elements of Panguraptor lufengensis gen. et sp. nov. LFGT-0103. All right side, in mm. skull length (from preserved rostral end to ventral end of quadrate) 111 preorbital length (preserved) 60 length of internal antorbital fenestra 37 height of antorbital fossa along at caudal margin along lacrimal 20 orbit length 30 orbit height 35 maximum height of skull across orbit midpoint 48 length of infratemporal fenestra 23 height of infratemporal fenestra 31 width of skull above middle antorbital fossa 12 narrist width of skull above orbit 10 length of low jaw (preserved) 111 Cervicals centrum length total height axis 18.5 22 C3 24 14.5 C4 28 16 C5 29 15 C6 31 23 C7 30.5 22 C8 28.5 - C9 28 - C10 23 - Dorsals centrum length total height D9 24 32 D10 26 36 D11 26 35 D12 25 34 D13 23 23+ sacral 1 length 22+ scapula length 86 maximum width of scapular blade 20 minimum width of scapular blade 11 humerus length 58+ metacarpal I length 10+ metacarpal II length 36 metacarpal II width at midportion 5 metacarpal III length 34 metacarpal III width at midportion 3.5 metacarpal IV length 22 metacarpal
Load more

Recommended publications
  • A New Crested Theropod Dinosaur from the Early Jurassic of Yunnan
    第55卷 第2期 古 脊 椎 动 物 学 报 pp. 177-186 2017年4月 VERTEBRATA PALASIATICA figs. 1-3 A new crested theropod dinosaur from the Early Jurassic of Yunnan Province, China WANG Guo-Fu1,2 YOU Hai-Lu3,4* PAN Shi-Gang5 WANG Tao5 (1 Fossil Research Center of Chuxiong Prefecture, Yunnan Province Chuxiong, Yunnan 675000) (2 Chuxiong Prefectural Museum Chuxiong, Yunnan 675000) (3 Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences Beijing 100044 * Corresponding author: [email protected]) (4 College of Earth Sciences, University of Chinese Academy of Sciences Beijing 100049) (5 Bureau of Land and Resources of Lufeng County Lufeng, Yunnan 650031) Abstract A new crested theropod, Shuangbaisaurus anlongbaoensis gen. et sp. nov., is reported. The new taxon is recovered from the Lower Jurassic Fengjiahe Formation of Shuangbai County, Chuxiong Yi Autonomous Prefecture, Yunnan Province, and is represented by a partial cranium. Shuangbaisaurus is unique in possessing parasagittal crests along the orbital dorsal rims. It is also distinguishable from the other two lager-bodied parasagittal crested Early Jurassic theropods (Dilophosaurus and Sinosaurus) by a unique combination of features, such as higher than long premaxillary body, elevated ventral edge of the premaxilla, and small upper temporal fenestra. Comparative morphological study indicates that “Dilophosaurus” sinensis could potentially be assigned to Sinosaurus, but probably not to the type species. The discovery of Shuangbaisaurus will help elucidate the evolution of basal theropods, especially the role of various bony cranial ornamentations had played in the differentiation of early theropods.
    [Show full text]
  • Preliminary Description of Coelophysoids (Dinosauria:Theropoda) from the Upper Triassic (Revuletian:Early-Mid Norian) Snyder Quarry, North-Central New Mexico
    Lucas, S.G., and Heckert. A.B., eds., 2000, Dinosaurs of New Mexico. New Mexico Museum of Natural History and Science Bulletin No. 17. 27 PRELIMINARY DESCRIPTION OF COELOPHYSOIDS (DINOSAURIA:THEROPODA) FROM THE UPPER TRIASSIC (REVULETIAN:EARLY-MID NORIAN) SNYDER QUARRY, NORTH-CENTRAL NEW MEXICO ANDREW B. HECKERT!, KATE E. ZEIGLER!, SPENCER G. LUCAS2, LARRY F. RINEHARP, and JERALD D. HARRIS2 'Deparbnent of parth & Planetary Sciences, University of New Mexico, Albuquerque, NM 87131-1116; 'New Mexico Museum of Natural History and Science, 1801 Mountain Road NW, Albuquerque, NM 87104 Abstract-The Upper Triassic Snyder quarry is the second-most productive theropod locality in the Chinle Group. Skull and postcranialelements, particularly tibiae, collected from the Snyder quarry during the last three field seasons demonstrate the presence of at least four individuals of two taxa. The smaller theropod strongly resembles, but is distinct from, the holotype of Eucoelophysis baldwini Sullivan and Lucas and represents either a sexual dimorph or, more likely, a new species of Eucoelophysis. The larger theropod is represented by a single, incomplete fused tibia-fibula-astragalus-calcaneum. Most striking about this taxon is the proximal fusion of the tibia and fibula. These theropods are a small fraction of a rich and diverse assemblage of Upper Triassic vertebrates and invertebrates from the most productive Chinle Group vertebrate fossil assemblage discovered in the last 50 years. INTRODUCTION In 1998, Mark Snyder of Del Mar, California, discovered a spectacular assemblage of fossil vertebrates in the badlands of the Upper Triassic Petrified Forest Formation near Ghost Ranch, north-central New Mexico (Fig. 1).
    [Show full text]
  • Bulletin 63 New Mexico Museum of Natural History & Science A
    Bulletin 63 New Mexico Museum of Natural History & Science A Division of the DEPARTMENT OF CULTURAL AFFAIRS ANALYSIS OF INTRASPECIFIC AND ONTOGENETIC VARIATION IN THE DENTITION OF COELOPHYSIS BAURI (LATE TRIASSIC), AND IMPLICATIONS FOR THE SYSTEMATICS OF ISOLATED THEROPOD TEETH by LISA G. BUCKLEY and PHILIP J. CURRIE Albuquerque, 2014 Bulletin 63 New Mexico Museum of Natural History & Science A Division of the DEPARTMENT OF CULTURAL AFFAIRS ANALYSIS OF INTRASPECIFIC AND ONTOGENETIC VARIATION IN THE DENTITION OF COELOPHYSIS BAURI (LATE TRIASSIC), AND IMPLICATIONS FOR THE SYSTEMATICS OF ISOLATED THEROPOD TEETH by LISA G. BUCKLEY and PHILIP J. CURRIE New Mexico Museum of Natural History & Science Albuquerque, 2014 STATE OF NEW MEXICO Department of Cultural Affairs Veronica Gonzales, Secretary NEW MEXICO MUSEUM OF NATURAL HISTORY AND SCIENCE Charles Walter, Executive Director BOARD OF TRUSTEES Susanna Martinez, Governor, State of New Mexico, ex officio Charles Walter, Executive Director, ex officio Gary Friedman, President Deborah Dixon Maya Elrick, Ph.D. Peter F. Gerity, Ph.D. Laurence Lattman, Ph.D. Morton Lieberman, Ph. D. Imogene Lindsay, Emerita Viola Martinez Marvin Moss John Montgomery, Ph.D. Jennifer Riordan Laura Smigielski-Garcia David Smoak Steve West Cover illustration: NMMNH P-42200, skull of Coelophysis bauri in left lateral view. Original Printing ISSN: 1524-4156 Available from the New Mexico Museum of Natural History and Science, 1801 Mountain Road NW, Albuquerque, NM 87104; Telephone (505) 841-2800; Fax (505) 841-2866; www.nmnaturalhistory.org NMMNH Bulletins online at: http://nmnaturalhistory.org/bulletins BULLETIN OF THE NEW MEXICO MUSEUM OF NATURAL HISTORY AND SCIENCE EDITORS Spencer G. Lucas New Mexico Museum of Natural History and Science, Albuquerque, NM, USA (NMMNHS) Robert Sullivan NMMNHS Lawrence H.
    [Show full text]
  • A Juvenile Coelophysoid Skull from the Early Jurassic of Zimbabwe, and the Synonymy of Coelophysis and Syntarsus
    A juvenile coelophysoid skull from the Early Jurassic of Zimbabwe, and the synonymy of Coelophysis and Syntarsus Anthea Bristowe* & Michael A. Raath Bernard Price Institute for Palaeontological Research, School of Geosciences, University of the Witwatersrand, Private Bag 3, WITS, 2050 South Africa Received 23 September 2004. Accepted 5 December 2004 Several authors have drawn attention to the close similarities between the neotheropod dinosaurs Coelophysis and Syntarsus. Recon- struction and analysis of a skull from a juvenile specimen of Syntarsus (collected from the Forest Sandstone Formation of Zimbabwe) show that cranial characters previously used to distinguish these taxa and justify their generic separation (namely the presence of a ‘nasal fenestra’ in Syntarsus and the length of its antorbital fenestra), were based on erroneous reconstructions of disassociated cranial elements. On the basis of this reinterpretation we conclude that Syntarsus is a junior synonym of Coelophysis. Variations are noted in three cranial characters – the length of the maxillary tooth row, the width of the base of the lachrymal and the shape of the antorbital maxillary fossa – that taken together with the chronological and geographical separation of the two taxa justify separation at species level. Keywords: Dinosaurs, Neotheropoda, Coelophysoid, taxonomy, Triassic, Jurassic. INTRODUCTION Following the work of Gauthier (1986), these taxa were Ever since the theropod Syntarsus rhodesiensis was first suggested to belong to a monophyletic clade known as described (Raath 1969), a succession of authors have Ceratosauria. However, more recent works by a number commented on the close morphological similarity be- of authors (Sereno 1997, 1999; Holtz 2000; Wilson et al. tween it and Coelophysis bauri (Raath 1969, 1977; Paul 1988, 2003; Rauhut 2003) have re-evaluated theropod interrela- 1993; Colbert 1989; Rowe 1989; Tykoski 1998; Downs tionships.
    [Show full text]
  • Tyrannosaurus
    Natural Sciences 360 Legacy of Life Lecture 16 Dr. Stuart S. Sumida Theropoda (Including Birds) Recall: Crocodylomorpha Pterosauria Eoraptor Herrerasauridae Saurischia Ornithischia Dinosauria Archosauria THEROPODA •Pronograde bipeds. •Pneumatic (hollow) bones. •Enlarged hand. •Vestigial digits IV and V on hand. •Highly extendable digits I-III on hand. •Compact, elongate, narrow foot – usually missing digit V. Theropod Feet: Note missing V. I IV II III CERATOSAURIA: COELOPHYSOIDEA Difficult to diagnose, as they retain many primitive features: •Pronograde bipeds. •Relatively small. •Skulls are narrow, not boxy in shape. •Many undifferentiated teeth. Best known taxa: Coelophysis Dilolphosaurus “Syntarsus” Dilophosaurus: a crested ceratosaur (No, they didn’t spit.) Coelophysis, skull Coelophysis: reconstructed in northern New Mexico Sauropodomorpha THEROPODA Coelophysoidea Saurischia * Abelisauridae Theropoda Spinosauroidea Allosauroidea Tetanurae Compsognathidae Tyrannosauroidea Coelurosauria Ornithomimosauria Oviraptorisauria Maniraptora Dromaeosauridae Ceratosauria * Troodontidae Avialae CERATOSAURIA: ABELISAURIDAE •Bony outgrowths over the orbits. •Relatively short skull compared to Coelophysoidea. •Blunt snout. •Ornamentation on skull •Reduced forelimbs (like T. rex), but retain a well-developed pectoral girdle. Bony outgrowths over the orbits. Blunt snout. Relatively short skull compared to Coelophysoidea. Carnotaurus Majungatholus Sauropodomorpha THEROPODA Coelophysoidea Saurischia * Abelisauridae Theropoda Spinosauroidea Allosauroidea
    [Show full text]
  • Cranial Ontogenetic Variation in Early Saurischians and the Role of Heterochrony in the Diversification of Predatory Dinosaurs
    A peer-reviewed version of this preprint was published in PeerJ on 18 January 2016. View the peer-reviewed version (peerj.com/articles/1589), which is the preferred citable publication unless you specifically need to cite this preprint. Foth C, Hedrick BP, Ezcurra MD. 2016. Cranial ontogenetic variation in early saurischians and the role of heterochrony in the diversification of predatory dinosaurs. PeerJ 4:e1589 https://doi.org/10.7717/peerj.1589 Cranial ontogenetic variation in early saurischians and the role of heterochrony in the diversification of predatory dinosaurs Foth Christian, Brandon P Hedrick, Martin D Ezcurra Non-avian saurischian skulls underwent at least 165 million years of evolution and shapes varied from elongated skulls, such as in Coelophysis, to short and box-shaped skulls, such as in Camarasaurus. A number of factors have long been considered to drive skull shape, including phylogeny, dietary preferences and functional constraints. However, heterochrony is increasingly being recognized as a major factor in dinosaur evolution. In order to quantitatively analyse the impact of heterochrony on saurischian skull shape, we have analysed five ontogenetic trajectories using two-dimensional geometric PrePrints morphometrics in a phylogenetic framework. This allowed for the evaluation of how heterochrony affected overall skull shape through both ontogenetic and phylogenetic trajectories and how it impacted modular changes within the skull. Using principal component analyses and multivariate regressions, it was possible to quantify different ontogenetic trajectories in light of heterochrony. The results recovered here indicate that taxa underwent a combination of local paedomorphosis and peramorphosis within the skull along individual ontogenies and phylogenies, but that either peramorphosis or paedomorphosis dominated when the skull was considered as a whole.
    [Show full text]
  • A New Theropod Dinosaur from the Early Jurassic of South Africa and Its Implications for the Early Evolution of Theropods
    A new theropod dinosaur from the Early Jurassic of South Africa and its implications for the early evolution of theropods Adam M. Yates Bernard Price Institute for Palaeontological Research, School of Geosciences, University of the Witwatersrand, Private Bag 3, WITS 2050, Johannesburg, South Africa E-mail: [email protected] Received 27 June 2005. Accepted 21 September 2005 A new theropod, Dracovenator regenti, from the upper Elliot Formation is described, based upon a fragmentary skull. It can be diagnosed on the basis of a bilobed fossa on the lateral surface of the premaxilla that is connected to the alveolar margin by a narrow channel, the presence of a deep, oblique, lateral notch on the articular and hypertrophied dorsal processes on the articular. Other aspects of its morphology display a mosaic of coelophysoid and advanced theropod characteristics. A cladistic analysis of basal Theropoda, including the new taxon finds that the new taxon is closely related to Dilophosaurus wetherilli and Zupaysaurus rougieri although the clade formed by these three taxa is not robustly supported. It also finds that Coelophysoidea sensu lato is paraphyletic with respect to Ceratosauria + Tetanurae but that this topology is not a significantly better explanation of the data than an inclusive, monophyletic Coelophysoidea. Keywords: Theropoda, Coelophysoidea, Dracovenator, upper Elliot Formation, South Africa. INTRODUCTION 2004). It is now the majority view amongst theropod Prior to Gauthier’s classic (1986) monograph, our under- systematists that Ceratosauria contains Ceratosaurus spp. standing of the interrelationships of theropod dinosaurs and Abelisauroidea and that this clade is more closely could be described as murky at best.
    [Show full text]
  • Large Neotheropods from the Upper Triassic of North America and the Early Evolution of Large Theropod Body Sizes
    Journal of Paleontology, 93(5), 2019, p. 1010–1030 Copyright © 2019, The Paleontological Society. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/ licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. 0022-3360/19/1937-2337 doi: 10.1017/jpa.2019.13 Large neotheropods from the Upper Triassic of North America and the early evolution of large theropod body sizes Christopher T. Griffin Department of Geosciences, Virginia Tech, Blacksburg, Virginia 24061, USA <[email protected]> Abstract.—Large body sizes among nonavian theropod dinosaurs is a major feature in the evolution of this clade, with theropods reaching greater sizes than any other terrestrial carnivores. However, the early evolution of large body sizes among theropods is obscured by an incomplete fossil record, with the largest Triassic theropods represented by only a few individuals of uncertain ontogenetic stage. Here I describe two neotheropod specimens from the Upper Triassic Bull Canyon Formation of New Mexico and place them in a broader comparative context of early theropod anatomy. These specimens possess morphologies indicative of ontogenetic immaturity (e.g., absence of femoral bone scars, lack of co-ossification between the astragalus and calcaneum), and phylogenetic analyses recover these specimens as early-diverging neotheropods in a polytomy with other early neotheropods at the base of the clade. Ancestral state recon- struction for body size suggests that the ancestral theropod condition was small (∼240 mm femur length), but the ances- tral neotheropod was larger (∼300–340 mm femur length), with coelophysoids experiencing secondary body size reduction, although this is highly dependent on the phylogenetic position of a few key taxa.
    [Show full text]
  • From the Upper Triassic (Revueltian) Snyder Quarry
    Zeigler, K.E., Heckert, A.B., and Lucas, S.G., eds., 2003, Paleontology and Geology of the Snyder Quarry, New Mexico Museum of Natural History and Science Bulletin No. 24. 127 COELOPHYSIDS (DINOSAURIA:THEROPODA) FROM THE UPPER TRIASSIC (REVUELTIAN) SNYDER QUARRY ANDREW B. HECKERT, KATE E. ZEIGLER, SPENCER G. LUCAS and LARRY F. RINEHART New Mexico Museum of Natural History and Science, 1801 Mountain Road NW, Albuquerque, NM 87104-1375 Abstract—The Snyder quarry preserves one of the richest assemblages of Norian theropods in the world, and the second-most productive theropod locality in the Chinle Group. At least four coelophysid theropods are preserved at the Snyder quarry, based on tibiae. Most elements of these theropods are represented, including an incomplete skull and lower jaws, cervical, dorsal, sacral, and caudal vertebrae, a scapulocoracoid, ilia, ischia, femora, tibiae, a fibula, astragalocalcanea, and diverse carpals and tarsals. These specimens demonstrate that the Snyder quarry theropods pertain to the Revueltian theropod Eucoelophysis, only known from the type local- ity at Orphan Mesa 10 km to the east and Baldwin’s original collection described by Cope in 1881. Theropod dinosaurs at the Snyder quarry are the most abundant terrestrial predators, and outnumber rauisuchians and sphenosuchians. These theropods are, with the “Padian theropod” from the same unit in the Petrified Forest National Park and Procompsognathus from the Stubensandstein in Germany, part of an apparently Pangean radiation of coelophysid theropods during Revueltian (early-mid Norian) time. Keywords: Norian, theropod, ceratosaur, Eucoelophysis INTRODUCTION The Snyder quarry (NMMNH locality 3845) in north-central New Mexico is an extraordinarily rich bonebed that preserves an archosaur- dominated vertebrate assemblage that appears to represent the after- math of a catastrophic event (Heckert et al., 2000a; Zeigler, 2003).
    [Show full text]
  • Sacral Co‐Ossification in Dinosaurs: the Oldest Record of Fused
    Received: 10 July 2020 | Revised: 15 October 2020 | Accepted: 21 October 2020 DOI: 10.1111/joa.13356 ORIGINAL PAPER Sacral co-ossification in dinosaurs: The oldest record of fused sacral vertebrae in Dinosauria and the diversity of sacral co-ossification patterns in the group Débora Moro1,2 | Leonardo Kerber1,2,3 | Rodrigo T. Müller2 | Flávio A. Pretto1,2 1Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal Abstract de Santa Maria, Santa Maria, RS, Brazil The fusion of the sacrum occurs in the major dinosaur lineages, i.e. ornithischians, 2 Centro de Apoio à Pesquisa Paleontológica theropods, and sauropodomorphs, but it is unclear if this trait is a common ancestral da Quarta Colônia, Universidade Federal de Santa Maria, São João do Polêsine, RS, Brazil condition, or if it evolved independently in each lineage, or even how or if it is related 3Museu Paraense Emílio Goeldi, to ontogeny. In addition, the order in which the different structures of the sacrum Coordenação de Ciências da Terra e Ecologia, Belém, Brazil are fused, as well as the causes that lead to this co-ossification, are poorly under- stood. Herein, we described the oldest record of fused sacral vertebrae within dino- Correspondence Débora Moro and Flávio A. Pretto, Centro saurs, based on two primordial sacral vertebrae from the Late Triassic of Candelária de Apoio à Pesquisa Paleontológica - Sequence, southern Brazil. We used computed microtomography (micro-CT) to ana- CAPPA/UFSM. Rua Maximiliano Vizzotto, 598. CEP 97230-000. São João do Polêsine, lyze the extent of vertebral fusion, which revealed that it occurred only between Rio Grande do Sul, Brasil.
    [Show full text]
  • The Dentition of Megalosaurid Theropods
    The dentition of megalosaurid theropods CHRISTOPHE HENDRICKX, OCTÁVIO MATEUS, and RICARDO ARAÚJO Hendrickx, C., Mateus, O., and Araújo, R. 2015. The dentition of megalosaurid theropods. Acta Palaeontologica Polo- nica 60 (3): 627–642. Theropod teeth are particularly abundant in the fossil record and frequently reported in the literature. Yet, the dentition of many theropods has not been described comprehensively, omitting details on the denticle shape, crown ornamentations and enamel texture. This paucity of information has been particularly striking in basal clades, thus making identification of isolated teeth difficult, and taxonomic assignments uncertain. We here provide a detailed description of the dentition of Megalosauridae, and a comparison to and distinction from superficially similar teeth of all major theropod clades. Megalosaurid dinosaurs are characterized by a mesial carina facing mesiolabially in mesial teeth, centrally positioned carinae on both mesial and lateral crowns, a mesial carina terminating above the cervix, and short to well-developed in- terdenticular sulci between distal denticles. A discriminant analysis performed on a dataset of numerical data collected on the teeth of 62 theropod taxa reveals that megalosaurid teeth are hardly distinguishable from other theropod clades with ziphodont dentition. This study highlights the importance of detailing anatomical descriptions and providing additional morphometric data on teeth with the purpose of helping to identify isolated theropod teeth in the future. Key words: Theropoda, Tetanurae, Megalosauridae, dentition, teeth, morphometry. Christophe Hendrickx [[email protected]] and Octávio Mateus [[email protected]], Universidade Nova de Lisboa, GeoBioTec (formerly CICEGe), Departamento de Ciências da Terra, Faculdade de Ciências e Tec- nologia, Quinta da Torre, 2829-516, Caparica, Portugal; Museu da Lourinhã, 9 Rua João Luis de Moura, 2530-158, Lourinhã, Portugal.
    [Show full text]
  • New Information on the Cranial Anatomy of Acrocanthosaurus Atokensis and Its Implications for the Phylogeny of Allosauroidea (Dinosauria: Theropoda)
    New Information on the Cranial Anatomy of Acrocanthosaurus atokensis and Its Implications for the Phylogeny of Allosauroidea (Dinosauria: Theropoda) Drew R. Eddy*¤, Julia A. Clarke¤ Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina, United States of America Abstract Background: Allosauroidea has a contentious taxonomic and systematic history. Within this group of theropod dinosaurs, considerable debate has surrounded the phylogenetic position of the large-bodied allosauroid Acrocanthosaurus atokensis from the Lower Cretaceous Antlers Formation of North America. Several prior analyses recover Acrocanthosaurus atokensis as sister taxon to the smaller-bodied Allosaurus fragilis known from North America and Europe, and others nest Acrocanthosaurus atokensis within Carcharodontosauridae, a large-bodied group of allosauroids that attained a cosmopolitan distribution during the Early Cretaceous. Methodology/Principal Findings: Re-evaluation of a well-preserved skull of Acrocanthosaurus atokensis (NCSM 14345) provides new information regarding the palatal complex and inner surfaces of the skull and mandible. Previously inaccessible internal views and articular surfaces of nearly every element of the skull are described. Twenty-four new morphological characters are identified as variable in Allosauroidea, combined with 153 previously published characters, and evaluated for eighteen terminal taxa. Systematic analysis of this dataset recovers a single most parsimonious topology placing Acrocanthosaurus atokensis as a member of Allosauroidea, in agreement with several recent analyses that nest the taxon well within Carcharodontosauridae. Conclusions/Significance: A revised diagnosis of Acrocanthosaurus atokensis finds that the species is distinguished by four primary characters, including: presence of a knob on the lateral surangular shelf; enlarged posterior surangular foramen; supraoccipital protruding as a double-boss posterior to the nuchal crest; and pneumatic recess within the medial surface of the quadrate.
    [Show full text]