DOCSLIB.ORG

Ontogeny in Dysalotosaurus Lettowvorbecki

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Ontogeny in Dysalotosaurus Lettowvorbecki Ontogeny in Dysalotosaurus lettowvorbecki Dissertation der Fakultät für Geowissenschaften der Ludwig-Maximilians-Universität München von Diplom-Geologe Tom Hübner Antrag auf Zulassung zur Promotion: 11.08.2010 1. Gutachter: Dr. O.W.M. Rauhut Bayerische Staatssammlung für Paläontologie und Geobiologie München 2. Gutachter: Prof. Dr. P.M. Sander Steinmann-Institut für Geologie, Mineralogie und Paläontologie der Universität Bonn Tag der Disputation: 12.01.2011 „Jemand hat mir mal gesagt, die Zeit würde uns wie ein Raubtier ein Leben lang verfolgen. Ich möchte viel lieber glauben, dass die Zeit unser Gefährte ist, der uns auf unserer Reise begleitet und uns daran erinnert, jeden Moment zu genießen, denn er wird nicht wiederkommen. Was wir hinterlassen ist nicht so wichtig wie die Art, wie wir gelebt haben. Denn letztlich [...] sind wir alle nur sterblich.“ Jean Luc Picard The new mount of a skeleton of Dysalotosaurus lettowvorbecki (individual “dy I”), on display in the Museum für Naturkunde, Berlin. „Mein alter Glitschball-Trainer pflegte immer zu sagen: Finde raus, was Du nicht gut kannst, und dann lass es bleiben!“ Gordon Shumway Summary This study was inspired by many recent scientific projects, which gave new insight into the ontogeny of an increasing number of extinct species in more detail. The knowledge of the ontogeny and its development is very important for understanding the taphonomy and paleobiology, the taxonomic value of phylogenetic characters, and the evolutionary relationship of an extinct species. Several qualitative and quantitative methods were used in these studies including the observation of suture closure, bone surface texture, bivariate and multivariate statistics, morphometrics, and bone histology. However, most of the published studies dealt only with one or two of these topics and further concentrated only on one or two methods. The importance of the combination of methods to get a more complete picture on the life history and phylogenetic relationships of extinct animals is recognized, however, and more recent studies combine the discovery of a new species with statements on its ontogenetic stage or the description of monodominant bonebeds with the reconstruction of growth patterns and life history for instance. This scientific frame is the starting point for the present study, in which almost all of the mentioned methods were combined for the first time resulting in the most comprehensive ontogenetic study on a single dinosaur species up to date. The small Upper Jurassic ornithopod dinosaur Dysalotosaurus lettowvorbecki was the subject in this study. It was found during the famous German Tendaguru Expedition (1909-1913), which is named after the type locality of the respective Formation, the Tendaguru Hill. This hill is located approximately 60 kilometers west of the seaport of Lindi in the Southeast of Tanzania, East-Africa. In contrast to the gigantic sauropod dinosaurs and the stegosaur Kentrosaurus, Dysalotosaurus is known from only a single locality 2.5 kilometers northwest of Tendaguru Hill, but the numbers of preserved bones within the two bonebeds were extraordinarily high (more than 14000 catalogue numbers). Additionally, several ontogenetic stages were preserved for the majority of skeletal elements. The bones were mostly isolated, but often well preserved. Plenty of material is housed in collections in Berlin, Göttingen, London, Munich, Stuttgart, and Tübingen, making this dinosaur one of the best known ornithopods of the world and the ideal object for an ontogenetic study. The methods used here contain qualitative observations of the timing and degree of suture closure, of the bone surface texture, and of morphological changes in single elements during growth. Furthermore, quantitative calculations were carried out by using the values of the measured bones mainly for bivariate allometric statistics. Ratios between long bones, multivariate statistics, and morphometrics were abandoned due to the lack of articulated material and due to the rather high amount of missing values. The study of the bone histology was also extensive, because each of the chosen skeletal elements was numerously represented in several ontogenetic stages. Thus, variation of bone microstructure of Dysalotosaurus could be evaluated and its life history could be reconstructed by the calculation of growth curves. Dysalotosaurus belongs to the basal Iguanodontia. This is a derived and highly diverse group of ornithopod dinosaurs, which comprises the most primitive member Tenontosaurus from the Early Cretaceous of North America, the European Late Cretaceous rhabdodontids, the dryosaurids including Dysalotosaurus, the transatlantic Upper Jurassic genus Camptosaurus, and all more derived large ornithopods including the famous Iguanodon and the hadrosaurs. Dysalotosaurus can be treated as the perfect intermediate taxon within ornithopods because it represents the connection between primitive ornithopods and more derived basal iguanodontians on one hand and between small and large ornithopods on the other hand. It was therefore very interesting to explore ontogenetic changes within Dysalotosaurus in an evolutionary and size-related context. In 1977, Dysalotosaurus was synonymized with its close relative Dryosaurus from the Upper Jurassic of North America due to many morphological similarities. Numerous differences in skull and postcranial bones challenge this view, however. Even the morphology of the pelvic and hindlimb skeleton, which is actually relatively conservative among small ornithopods, shows more differences than between different genera of hadrosaurs or ceratopsids. Thus, the name Dysalotosaurus is resurrected for now and therefore also used throughout this study. A very important first step before starting observations and analyses of ontogenetic characters was the revised interpretation of the taphonomy of the two monodominant bonebeds of Dysalotosaurus. Mainly due to the lack of information on the sedimentology and stratigraphy of the locality and on the spatial arrangement of the bones, it was not clear, if this mass accumulation represents the result of one or two catastrophic mass death events or just the result of attritional mortality. Several lines of evidence let now conclude that the bonebeds indeed represent a single mass death event of a Dysalotosaurus herd, because there are no taphonomic differences between them and there are also no traces of preburial abrasion caused by long transport or of preburial weathering due to long exposure on the surface. The two-peaked size frequency distribution, usually interpreted as the result of attritional mortality, is also only unambiguously usable for populations with one offspring per female per year. This is highly unlikely for any dinosaur. The lack of hatchlings in the size frequency distribution could also be explained by the time of the death event, which probably took place well outside the breeding season. The underrepresentation of young age classes is probably the result of slight sorting of the bones in favor of large and robust elements. Finally, the underrepresentation of mid-sized age classes is explainable by the banishment or higher mortality rate around the time of sexual maturity, as in many modern gregarious mammals. In the end, the evidence for a single mass death event dominates and possible hints for attritional mortality can be explained alternatively, so that the hypothesis of a single Dysalotosaurus herd could be used as the null hypothesis in all following ontogenetic studies on this dinosaur. The ontogeny of the skull of Dysalotosaurus was carried out separately, because the best preserved skull, housed in the collections of the Bayerische Staatssammlung für Paläontologie and Geobiologie in Munich, was hitherto unstudied. This juvenile specimen is fully described and reconstructed. Apart from the palatine and the quadratojugal, all elements of the skull are now known and the comparison with all other preserved cranial material revealed several ontogenetic trends for the skull. The suture closure pattern, although variable in the timing, could be reconstructed. The elements of the basicranium and the parietals fuse first and the elements of the pre-orbital region fuse obviously very late or never during life. The overall skull proportions are also changing to relatively smaller orbits, an elevated posterior skull roof, and a longer snout. This indicates that peramorphic heterochrony is a dominant evolutionary tendency in the skull shape of ornithopods, supporting the development towards larger size and full herbivory. Further juvenile ontogenetic characters could be identified during this study: (1) the basioccipital has a characteristic rhomboidal shape, with the condyle neck thicker than the condyle itself in very young individuals, (2) the frontals are very slender and long, with just a small and flat central dome, (3) the deepest point of the postorbital suture has an anterior position on the postorbital process of the jugal, and (4) the tooth number is smaller (ten compared with up to 13 in older ones) in lower and upper jaws, among others. These results were then used in two other ornithopod species. The juvenile stage of the holotype skull of Gasparinisaura could be independently confirmed and the example of Thescelosaurus has demonstrated that more than one or two characters are necessary to determine the ontogenetic stage of an extinct animal unambiguously. The intermediate stage of Dysalotosaurus between less derived small
Load more

Recommended publications
  • CPY Document
    v^ Official Journal of the Biology Unit of the American Topical Association 10 Vol. 40(4) DINOSAURS ON STAMPS by Michael K. Brett-Surman Ph.D. Dinosaurs are the most popular animals of all time, and the most misunderstood. Dinosaurs did not fly in the air and did not live in the oceans, nor on lake bottoms. Not all large "prehistoric monsters" are dinosaurs. The most famous NON-dinosaurs are plesiosaurs, moso- saurs, pelycosaurs, pterodactyls and ichthyosaurs. Any name ending in 'saurus' is not automatically a dinosaur, for' example, Mastodonto- saurus is neither a mastodon nor a dinosaur - it is an amphibian! Dinosaurs are defined by a combination of skeletal features that cannot readily be seen when the animal is fully restored in a flesh reconstruction. Because of the confusion, this compilation is offered as a checklist for the collector. This topical list compiles all the dinosaurs on stamps where the actual bones are pictured or whole restorations are used. It excludes footprints (as used in the Lesotho stamps), cartoons (as in the 1984 issue from Gambia), silhouettes (Ascension Island # 305) and unoffi- cial issues such as the famous Sinclair Dinosaur stamps. The name "Brontosaurus", which appears on many stamps, is used with quotation marks to denote it as a popular name in contrast to its correct scientific name, Apatosaurus. For those interested in a detailed encyclopedic work about all fossils on stamps, the reader is referred to the forthcoming book, 'Paleontology - a Guide to the Postal Materials Depicting Prehistoric Lifeforms' by Fran Adams et. al. The best book currently in print is a book titled 'Dinosaur Stamps of the World' by Baldwin & Halstead.
    [Show full text]
  • And the Origin and Evolution of the Ankylosaur Pelvis
    Pelvis of Gargoyleosaurus (Dinosauria: Ankylosauria) and the Origin and Evolution of the Ankylosaur Pelvis Kenneth Carpenter1,2*, Tony DiCroce3, Billy Kinneer3, Robert Simon4 1 Prehistoric Museum, Utah State University – Eastern, Price, Utah, United States of America, 2 Geology Section, University of Colorado Museum, Boulder, Colorado, United States of America, 3 Denver Museum of Nature and Science, Denver, Colorado, United States of America, 4 Dinosaur Safaris Inc., Ashland, Virginia, United States of America Abstract Discovery of a pelvis attributed to the Late Jurassic armor-plated dinosaur Gargoyleosaurus sheds new light on the origin of the peculiar non-vertical, broad, flaring pelvis of ankylosaurs. It further substantiates separation of the two ankylosaurs from the Morrison Formation of the western United States, Gargoyleosaurus and Mymoorapelta. Although horizontally oriented and lacking the medial curve of the preacetabular process seen in Mymoorapelta, the new ilium shows little of the lateral flaring seen in the pelvis of Cretaceous ankylosaurs. Comparison with the basal thyreophoran Scelidosaurus demonstrates that the ilium in ankylosaurs did not develop entirely by lateral rotation as is commonly believed. Rather, the preacetabular process rotated medially and ventrally and the postacetabular process rotated in opposition, i.e., lateral and ventrally. Thus, the dorsal surfaces of the preacetabular and postacetabular processes are not homologous. In contrast, a series of juvenile Stegosaurus ilia show that the postacetabular process rotated dorsally ontogenetically. Thus, the pelvis of the two major types of Thyreophora most likely developed independently. Examination of other ornithischians show that a non-vertical ilium had developed independently in several different lineages, including ceratopsids, pachycephalosaurs, and iguanodonts.
    [Show full text]
  • New Heterodontosaurid Remains from the Cañadón Asfalto Formation: Cursoriality and the Functional Importance of the Pes in Small Heterodontosaurids
    Journal of Paleontology, 90(3), 2016, p. 555–577 Copyright © 2016, The Paleontological Society 0022-3360/16/0088-0906 doi: 10.1017/jpa.2016.24 New heterodontosaurid remains from the Cañadón Asfalto Formation: cursoriality and the functional importance of the pes in small heterodontosaurids Marcos G. Becerra,1 Diego Pol,1 Oliver W.M. Rauhut,2 and Ignacio A. Cerda3 1CONICET- Museo Palaeontológico Egidio Feruglio, Fontana 140, Trelew, Chubut 9100, Argentina 〈[email protected]〉; 〈[email protected]〉 2SNSB, Bayerische Staatssammlung für Paläontologie und Geologie and Department of Earth and Environmental Sciences, LMU München, Richard-Wagner-Str. 10, Munich 80333, Germany 〈[email protected]〉 3CONICET- Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro, Museo Carlos Ameghino, Belgrano 1700, Paraje Pichi Ruca (predio Marabunta), Cipolletti, Río Negro, Argentina 〈[email protected]〉 Abstract.—New ornithischian remains reported here (MPEF-PV 3826) include two complete metatarsi with associated phalanges and caudal vertebrae, from the late Toarcian levels of the Cañadón Asfalto Formation. We conclude that these fossil remains represent a bipedal heterodontosaurid but lack diagnostic characters to identify them at the species level, although they probably represent remains of Manidens condorensis, known from the same locality. Histological features suggest a subadult ontogenetic stage for the individual. A cluster analysis based on pedal measurements identifies similarities of this specimen with heterodontosaurid taxa and the inclusion of the new material in a phylogenetic analysis with expanded character sampling on pedal remains confirms the described specimen as a heterodontosaurid. Finally, uncommon features of the digits (length proportions among nonungual phalanges of digit III, and claw features) are also quantitatively compared to several ornithischians, theropods, and birds, suggesting that this may represent a bipedal cursorial heterodontosaurid with gracile and grasping feet and long digits.
    [Show full text]
  • A. K. Rozhdestvensky HISTORY of the DINOSAUR FAUNA of ASIA
    A. K. Rozhdestvensky HISTORY OF THE DINOSAUR FAUNA OF ASIA AND OTHER CONTINENTS AND QUESTIONS CONCERNING PALEOGEOGRAPHY* The distribution and evolution of dinosaur faunas during the period of their existence, from the Late Triassic to the end of the Cretaceous, shows a close connection with the paleogeography of the Mesozoic. However these questions were hard to examine on a global scale until recently, because only the dinosaurs of North America were well known, where during the last century were found their richest deposits and where the best paleontologists were studying them — J. Leidy, E. Cope, O. Marsh, R. Lull, H. Osborn, C. Gilmore, B. Brown, and later many others. On the remaining continents, including Europe, where the study of dinosaurs started earlier than it did in America, the information was rather incomplete due to the fragmentary condition of the finds and rare, episodic studies. The Asian continent remained unexplored the longest, preventing any intercontinental comparisons. Systematic exploration and large excavations of dinosaur locations in Asia, which began in the last fifty years (Osborn, 1930; Efremov, 1954; Rozhdestvenskiy, 1957a, 1961, 1969, 1971; Rozhdestvenskiy & Chzhou, 1960; Kielan-Jaworowska & Dovchin, 1968; Kurochkin, Kalandadze, & Reshetov, 1970; Barsbold, Voronin, & Zhegallo, 1971) showed that this continent has abundant dinosaur remains, particularly in its central part (Fig. 1). Their study makes it possible to establish a faunal connection between Asia and other continents, correlate the stratigraphy of continental deposits of the Mesozoic, because dinosaurs are reliable leading forms, as well as to make corrections in the existing paleogeographic structure. The latter, in their turn, promote a better understanding of the possible paths of distribution of the individual groups of dinosaurs, the reasons for their appearance, their development, and disappearance.
    [Show full text]
  • Camptosaurus Dispar Legs; Although, the Smaller Juveniles Might Have Been Able to Do So
    Camptosaurus was too front heavy to walk on hind Camptosaurus dispar legs; although, the smaller juveniles might have been able to do so. e skull of Camptosaurus is about 15 inches long. It has no teeth at the front of the beak and broad crushing teeth in the cheeks. ese teeth are made stronger by ridges on the outer surface. Chewing causes these teeth to have a at, grinding surface. Unlike Allosaurus, these teeth cannot slice through esh, but they can pulverize vegetation. Our skeleton of Camptosaurus went on display Scienti c Name: Camptosaurus dispar at the museum around 1965 and was the Muse- Pronounced: KAMP-toe-SOR-us um’s second dinosaur skeleton. Originally, it was Name Meaning: Flexible lizard mounted in the kangaroo pose on its hind legs and Time Period: 147 Million Years Ago (MYA) Late using its tail as a prop. It was remounted into a new Jurassic four-legged pose in 2013 . e skeleton is 17¾ feet Length:16-23 feet (5-7 m) long long and 5 feet tall at the hips. It is a plaster of Paris Height: 3-4 feet (1 m) high at the hips cast of bones collected from the Cleveland Lloyd Weight: 2,200 pounds (1000 kg). Dinosaur Quarry, about 30 miles south of Price. Diet: Herbivore (plant eater) e pelvis is rather broad for its length and the Places Found: Camptosaurus was a distant relative of Iguanodon, upper bone, called the ilium, bows outwards. Discoverer: Marsh (1885) the dinosaur with the thumb-spike. In fact, the thumb (digit I) of Camptosaurus had little move- e hand of Camptosaurus has ve digits, but only ment and the claw was almost like a spike .
    [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 Revised Taxonomy of the Iguanodont Dinosaur Genera and Species
    ARTICLE IN PRESS + MODEL Cretaceous Research xx (2007) 1e25 www.elsevier.com/locate/CretRes A revised taxonomy of the iguanodont dinosaur genera and species Gregory S. Paul 3109 North Calvert Station, Side Apartment, Baltimore, MD 21218-3807, USA Received 20 April 2006; accepted in revised form 27 April 2007 Abstract Criteria for designating dinosaur genera are inconsistent; some very similar species are highly split at the generic level, other anatomically disparate species are united at the same rank. Since the mid-1800s the classic genus Iguanodon has become a taxonomic grab-bag containing species spanning most of the Early Cretaceous of the northern hemisphere. Recently the genus was radically redesignated when the type was shifted from nondiagnostic English Valanginian teeth to a complete skull and skeleton of the heavily built, semi-quadrupedal I. bernissartensis from much younger Belgian sediments, even though the latter is very different in form from the gracile skeletal remains described by Mantell. Currently, iguanodont remains from Europe are usually assigned to either robust I. bernissartensis or gracile I. atherfieldensis, regardless of lo- cation or stage. A stratigraphic analysis is combined with a character census that shows the European iguanodonts are markedly more morpho- logically divergent than other dinosaur genera, and some appear phylogenetically more derived than others. Two new genera and a new species have been or are named for the gracile iguanodonts of the Wealden Supergroup; strongly bipedal Mantellisaurus atherfieldensis Paul (2006. Turning the old into the new: a separate genus for the gracile iguanodont from the Wealden of England. In: Carpenter, K. (Ed.), Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs.
    [Show full text]
  • 71St Annual Meeting Society of Vertebrate Paleontology Paris Las Vegas Las Vegas, Nevada, USA November 2 – 5, 2011 SESSION CONCURRENT SESSION CONCURRENT
    ISSN 1937-2809 online Journal of Supplement to the November 2011 Vertebrate Paleontology Vertebrate Society of Vertebrate Paleontology Society of Vertebrate 71st Annual Meeting Paleontology Society of Vertebrate Las Vegas Paris Nevada, USA Las Vegas, November 2 – 5, 2011 Program and Abstracts Society of Vertebrate Paleontology 71st Annual Meeting Program and Abstracts COMMITTEE MEETING ROOM POSTER SESSION/ CONCURRENT CONCURRENT SESSION EXHIBITS SESSION COMMITTEE MEETING ROOMS AUCTION EVENT REGISTRATION, CONCURRENT MERCHANDISE SESSION LOUNGE, EDUCATION & OUTREACH SPEAKER READY COMMITTEE MEETING POSTER SESSION ROOM ROOM SOCIETY OF VERTEBRATE PALEONTOLOGY ABSTRACTS OF PAPERS SEVENTY-FIRST ANNUAL MEETING PARIS LAS VEGAS HOTEL LAS VEGAS, NV, USA NOVEMBER 2–5, 2011 HOST COMMITTEE Stephen Rowland, Co-Chair; Aubrey Bonde, Co-Chair; Joshua Bonde; David Elliott; Lee Hall; Jerry Harris; Andrew Milner; Eric Roberts EXECUTIVE COMMITTEE Philip Currie, President; Blaire Van Valkenburgh, Past President; Catherine Forster, Vice President; Christopher Bell, Secretary; Ted Vlamis, Treasurer; Julia Clarke, Member at Large; Kristina Curry Rogers, Member at Large; Lars Werdelin, Member at Large SYMPOSIUM CONVENORS Roger B.J. Benson, Richard J. Butler, Nadia B. Fröbisch, Hans C.E. Larsson, Mark A. Loewen, Philip D. Mannion, Jim I. Mead, Eric M. Roberts, Scott D. Sampson, Eric D. Scott, Kathleen Springer PROGRAM COMMITTEE Jonathan Bloch, Co-Chair; Anjali Goswami, Co-Chair; Jason Anderson; Paul Barrett; Brian Beatty; Kerin Claeson; Kristina Curry Rogers; Ted Daeschler; David Evans; David Fox; Nadia B. Fröbisch; Christian Kammerer; Johannes Müller; Emily Rayfield; William Sanders; Bruce Shockey; Mary Silcox; Michelle Stocker; Rebecca Terry November 2011—PROGRAM AND ABSTRACTS 1 Members and Friends of the Society of Vertebrate Paleontology, The Host Committee cordially welcomes you to the 71st Annual Meeting of the Society of Vertebrate Paleontology in Las Vegas.
    [Show full text]
  • [I]Arenysaurus Ardevoli[I], First Paleoneuroanatomical Description of a European Hadrosaurid
    A peer-reviewed version of this preprint was published in PeerJ on 24 February 2015. View the peer-reviewed version (peerj.com/articles/802), which is the preferred citable publication unless you specifically need to cite this preprint. Cruzado-Caballero P, Fortuny J, Llacer S, Canudo J. 2015. Paleoneuroanatomy of the European lambeosaurine dinosaur Arenysaurus ardevoli. PeerJ 3:e802 https://doi.org/10.7717/peerj.802 Arenysaurus ardevoli, first paleoneuroanatomical description of a European hadrosaurid The neuroanatomy of hadrosaurid dinosaurs is well known from North America and Asia. In Europe only a few cranial remains have been recovered with the braincase. Arenysaurus is the first European endocast for which the paleoneuroanatomy has been studied. The resulting data have enabled us to draw ontogenetic, phylogenetic and functional inferences. Arenysaurus preserves the endocast and the inner ear. This cranial material was CT-scanned, and a 3D-model was generated. The endocast morphology supports a general pattern for hadrosaurids with some characters that distinguish to a subfamily PrePrints level, such as a brain cavity anteroposteriorly shorter or the angle of the major axis of the cerebral hemisphere to the horizontal in lambeosaurines. Both characters are present in the endocast of Arenysaurus. Moreover, osteological features indicate an adult ontogenetic stage while some paleoneuroanatomical features are indicative of a subadult ontogenetic stage and even a juvenile ontogenetic stage. Finally, a comparison with other hadrosaurids reveals that the low values for the angle of the dural peak may be an autapomorphy exclusive to the Parasaurolophus genus. It is hypothesized that the presence of puzzling characters that suggest different ontogenetic stages for this specimen, may reflect some degree of dwarfism in Arenysaurus.
    [Show full text]
  • Zootaxa, Glishades Ericksoni, a New Hadrosauroid
    Zootaxa 2452: 1–17 (2010) ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ Article ZOOTAXA Copyright © 2010 · Magnolia Press ISSN 1175-5334 (online edition) Glishades ericksoni, a new hadrosauroid (Dinosauria: Ornithopoda) from the Late Cretaceous of North America ALBERT PRIETO-MÁRQUEZ Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA. E-mail: [email protected] Abstract A new genus and species of hadrosauroid dinosaur, Glishades ericksoni, is described based on paired partial premaxillae collected from the Upper Cretaceous Two Medicine Formation of Montana, in the Western Interior of the United States of America. This taxon is diagnosed on the basis of a unique combination of characters: absence of everted oral margin, arcuate oral margin with wide and straight, obliquely oriented, and undeflected anterolateral corner, grooved transversal thickening on ventral surface of premaxilla posterior to denticulate oral margin, and foramina on anteromedial surface above oral edge and adjacent to proximal end of narial bar. Maximum parsimony analysis positioned G. ericksoni as a derived hadrosauroid. Exclusion of G. ericksoni from Hadrosauridae was unambiguously supported by the lack in AMNH 27414 of a dorsomedially reflected premaxillary oral margin. Furthermore, the maximum agreement subtree positioned G. ericksoni as the sister taxon to Bactrosaurus johnsoni. This position was unambiguously supported by posteroventral thickening on the ventral surface of the premaxilla (independently derived in saurolophid hadrosaurids and Ouranosaurus nigeriensis) and having foramina on each premaxilla on the anterior surface, adjacent to the parasagittal plane of the rostrum (reconstructed as independently derived in Brachylophosaurus canadensis, Maiasaura peeblesorum, and Edmontosaurus annectens).
    [Show full text]
  • Phylogeny and Biogeography of Iguanodontian Dinosaurs, with Implications from Ontogeny and an Examination of the Function of the Fused Carpal-Digit I Complex
    Phylogeny and Biogeography of Iguanodontian Dinosaurs, with Implications from Ontogeny and an Examination of the Function of the Fused Carpal-Digit I Complex By Karen E. Poole B.A. in Geology, May 2004, University of Pennsylvania M.A. in Earth and Planetary Sciences, August 2008, Washington University in St. Louis A Dissertation submitted to The Faculty of The Columbian College of Arts and Sciences of The George Washington University in partial fulfillment of the requirements for the degree of Doctor of Philosophy August 31, 2015 Dissertation Directed by Catherine Forster Professor of Biology The Columbian College of Arts and Sciences of The George Washington University certifies that Karen Poole has passed the Final Examination for the degree of Doctor of Philosophy as of August 10th, 2015. This is the final and approved form of the dissertation. Phylogeny and Biogeography of Iguanodontian Dinosaurs, with Implications from Ontogeny and an Examination of the Function of the Fused Carpal-Digit I Complex Karen E. Poole Dissertation Research Committee: Catherine A. Forster, Professor of Biology, Dissertation Director James M. Clark, Ronald Weintraub Professor of Biology, Committee Member R. Alexander Pyron, Robert F. Griggs Assistant Professor of Biology, Committee Member ii © Copyright 2015 by Karen Poole All rights reserved iii Dedication To Joseph Theis, for his unending support, and for always reminding me what matters most in life. To my parents, who have always encouraged me to pursue my dreams, even those they didn’t understand. iv Acknowledgements First, a heartfelt thank you is due to my advisor, Cathy Forster, for giving me free reign in this dissertation, but always providing valuable commentary on any piece of writing I sent her, no matter how messy.
    [Show full text]
  • The Tendaguru Formation (Late Jurassic to Early Cretaceous, Southern Tanzania): Definition, Palaeoenvironments, and Sequence Stratigraphy
    Fossil Record 12 (2) 2009, 141–174 / DOI 10.1002/mmng.200900004 The Tendaguru Formation (Late Jurassic to Early Cretaceous, southern Tanzania): definition, palaeoenvironments, and sequence stratigraphy Robert Bussert1, Wolf-Dieter Heinrich2 and Martin Aberhan*,2 1 Institut fr Angewandte Geowissenschaften, Technische Universitt Berlin, Skr. BH 2, Ernst-Reuter-Platz 1, 10587 Berlin, Germany. E-mail: [email protected] 2 Museum fr Naturkunde – Leibniz Institute for Research on Evolution and Biodiversity at the Humboldt University Berlin, Invalidenstr. 43, 10115 Berlin, Germany. E-mail: [email protected]; [email protected] Abstract Received 8 December 2008 The well-known Late Jurassic to Early Cretaceous Tendaguru Beds of southern Tanza- Accepted 15 February 2009 nia have yielded fossil plant remains, invertebrates and vertebrates, notably dinosaurs, Published 3 August 2009 of exceptional scientific importance. Based on data of the German-Tanzanian Tenda- guru Expedition 2000 and previous studies, and in accordance with the international stratigraphic guide, we raise the Tendaguru Beds to formational rank and recognise six members (from bottom to top): Lower Dinosaur Member, Nerinella Member, Middle Dinosaur Member, Indotrigonia africana Member, Upper Dinosaur Member, and Ruti- trigonia bornhardti-schwarzi Member. We characterise and discuss each member in de- tail in terms of derivation of name, definition of a type section, distribution, thickness, lithofacies, boundaries, palaeontology, and age. The age of the whole formation appar- ently ranges at least from the middle Oxfordian to the Valanginian through Hauterivian or possibly Aptian. The Tendaguru Formation constitutes a cyclic sedimentary succes- sion, consisting of three marginal marine, sandstone-dominated depositional units and three predominantly coastal to tidal plain, fine-grained depositional units with dinosaur remains.
    [Show full text]