DOCSLIB.ORG

The Vertebrate-Bearing Late Triassic Fleming Fjord Formation of Central East Greenland Revisited: Stratigraphy, Palaeoclimate and New Palaeontological Data

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Vertebrate-Bearing Late Triassic Fleming Fjord Formation of Central East Greenland Revisited: Stratigraphy, Palaeoclimate and New Palaeontological Data Downloaded from http://sp.lyellcollection.org/ by guest on December 18, 2015 The vertebrate-bearing Late Triassic Fleming Fjord Formation of central East Greenland revisited: stratigraphy, palaeoclimate and new palaeontological data LARS B. CLEMMENSEN1, JESPER MILA` N2,3*, JAN SCHULZ ADOLFSSEN2, ELIZA JARL ESTRUP4, NICOLAI FROBØSE1, NICOLE KLEIN5, OCTA´ VIO MATEUS6,7 & OLIVER WINGS8,9 1Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark 2Geomuseum Faxe/Østsjællands Museum, Østervej 2, DK-4640 Faxe, Denmark 3Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen K, Denmark 4Geocenter Møns Klint, Stenga˚rdsvej 8, DK-4751 Borre, Denmark 5Staatliches Museum fu¨r Naturkunde Stuttgart, Rosenstein 1, 70191 Stuttgart, Germany 6Department of Earth Sciences, GeoBioTec, Faculdade de Cieˆncias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal 7Museu da Lourin˜ha, Rua Joa˜o Luis de Moura 95, 2530-158 Lourinha˜, Portugal 8Niedersa¨chsisches Landesmuseum Hannover, Willy-Brandt-Allee 5, 30169 Hannover, Germany 9Museum fu¨r Naturkunde Berlin, Invalidenstraße 43, D-10115 Berlin, Germany *Corresponding author (e-mail: [email protected]) Abstract: In Late Triassic (Norian–Rhaetian) times, the Jameson Land Basin lay at 408 N on the northern part of the supercontinent Pangaea. This position placed the basin in a transition zone between the relatively dry interior of the supercontinent and its more humid periphery. Sedimen- tation in the Jameson Land Basin took place in a lake–mudflat system and was controlled by orbi- tally forced variations in precipitation. Vertebrate fossils have consistently been found in these lake deposits (Fleming Fjord Formation), and include fishes, dinosaurs, amphibians, turtles, aetosaurs and pterosaurs. Furthermore, the fauna includes mammaliaform teeth and skeletal material. New vertebrate fossils were found during a joint vertebrate palaeontological and sedimentological expe- dition to Jameson Land in 2012. These new finds include phytosaurs, a second stem testudinatan specimen and new material of sauropodomorph dinosaurs, including osteologically immature indi- viduals. Phytosaurs are a group of predators common in the Late Triassic, but previously unre- ported from Greenland. The finding includes well-preserved partial skeletons that show the occurrence of four individuals of three size classes. The new finds support a late Norian–early Rhaetian age for the Fleming Fjord Formation, and add new information on the palaeogeographical and palaeolatitudinal distribution of Late Triassic faunal provinces. Late Triassic (Norian–Rhaetian) lake sediments of The vertebrate fauna of the Fleming Fjord For- the Fleming Fjord Formation are very well exposed mation is both abundant and diverse, and includes along the eastern margin of the Jameson Land Basin fishes, dinosaurs, amphibians, turtles, aetosaurs and in East Greenland (Fig. 1). These lake deposits have pterosaurs (Jenkins et al. 1994; Sulej et al. 2014). been the subject of detailed stratigraphical, sedi- Furthermore, the fauna includes both teeth and skel- mentological and palaeontological studies since the etal elements of mammaliforms (Jenkins et al. 1994, late 1970s (e.g. Clemmensen 1980a, b; Jenkins et al. 1997), such as Haramiyavia clemmenseni, Brachy- 1994; Kent & Clemmensen, 1996; Clemmensen zostrodon and Kuehneotherium. The association of et al. 1998; Mila`n et al. 2004). several vertebrate groups is shared with well-known From:Kear, B. P., Lindgren, J., Hurum, J. H., Mila`n,J.&Vajda, V. (eds) Mesozoic Biotas of Scandinavia and its Arctic Territories. Geological Society, London, Special Publications, 434, http://doi.org/10.1144/SP434.3 # 2015 The Author(s). Published by The Geological Society of London. All rights reserved. For permissions: http://www.geolsoc.org.uk/permissions. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics Downloaded from http://sp.lyellcollection.org/ by guest on December 18, 2015 L. B. CLEMMENSEN ET AL. Fig. 1. Location map of East Greenland showing the Mesozoic deposits in the Jameson Land Basin. Small inset: Greenland. Large inset shows a close-up of the eastern part of the basin near Carlsberg Fjord, and the two localities with Upper Triassic sediments at Lepidopteriselv and Wood Bjerg–Macknight Bjerg. Figure modified from Stemmerik et al. (1997). European Norian faunas, and the Greenland mate- The published reptile taxa from the Late Triassic rial adds new information to our understanding of of Greenland are cf. Proganochelys (Testudinata), the palaeogeographical distribution of Late Triassic Aetosaurus ferratus and Paratypothorax andressi fauna provinces. The vertebrate assemblage con- (Aetosauria: Stagonolepididae), Plateosaurus eng- strains the Jameson Land fauna in the Norian (Jen- elhardti (Dinosauria: Sauropodomorpha: Plateo- kins et al. 1994). sauridae), Theropoda? indet., and Eudimorphodon Downloaded from http://sp.lyellcollection.org/ by guest on December 18, 2015 LATE TRIASSIC VERTEBRATE FAUNA, GREENLAND cromptonellus (Pterosauria: Eudimorphodontidae: underwent regression and continental emergence Eudimorphodontinae). This list is largely based later in the early Triassic (Clemmensen 1980a, b; on the brief descriptions by Jenkins et al. (1994), Nøttvedt et al. 2008). Continental sediments com- except for Eudimorphodon cromptonellus, which prised alluvial fan, floodplain, aeolian dune, saline was the focus of a later monographic work (Jenkins lake and freshwater lake deposits (Clemmensen et al. 2001). Therapsids are represented by the 1980a; Clemmensen et al. 1998). The freshwater cynodont Miltredon cromptoni (Shapiro & Jenkins lake deposits in the uppermost part of the Triassic 2001), and amphibians represented by Gerrotho- succession (the Fleming Fjord Formation) are par- rax pulcherrimus and Cylcotosaurus cf. posthumus ticular well exposed in steep cliff sides facing the (Jenkins et al. 1994, 2008). Classification of the Carlsberg Fjord (Fig. 2). remains attributed to theropods is not supported by any clear diagnostic theropodan feature and might alternatively be phytosaurian in origin. Methods New data from an expedition in 2012 (briefly reported in Mila`n et al. 2012) shows the presence The area around Lepidopteriselv (Fig. 1; Jenkins of phytosaurs, a second testudinatan specimen and et al. 1994, area II) was intensively prospected, new material of sauropodomorph dinosaurs. Phyto- revealing many isolated bones, bone fragments and saurs are an archosaurian group of top predators tracks; all suitable material on the surface was col- common in the Late Triassic, but previously unre- lected. After several bone fragments were found at ported from Greenland. The finds include well- the Plateosaurus site described by Jenkins et al. preserved partial skeletons that show the occurrence (1994), two trenches, each several metres long and of four individuals of three size classes (Mateus about 50 cm deep, were excavated in the unsuccess- et al. 2014). ful search for more articulated bones. Work focused The aims of this paper are to redescribe the strati- during the first half of the expedition on several graphical, palaeoenvironmental and palaeoclimatic dinosaur tracksites and a new site on the mountain setting of the vertebrate-bearing lacustrine succes- slopes east of the camp, which was named the ‘Phy- sion, to provide a first description and classification tosaur Bone Bed’ (718 15.584′ N, 228 31.785′ W). A of the new vertebrate finds from the Late Triassic of few teeth and bones were found on the surface near a East Greenland, and to briefly discuss the palaeo- small ledge, and cleaning of the surface over an area geographical and chronological implications of the of several square metres was commenced in order to vertebrate assemblage. identify the bone-bearing layers. Prospecting, sur- face collection and excavation was continued at Wood Bjerg and Macknight Bjerg (Fig. 1) close to Geological setting area V of Jenkins et al. (1994). Excavation here focused at the old Jenkins quarry (718 22.262′ N, During Triassic times, East Greenland was located 228 33.381′ W), which was named ‘Iron Cake’ due at the northern rim of the Pangaean supercontinent to the iron-rich matrix of the bone-bearing sediment. and bounded to the north by the Boreal Sea The concretion-like iron-rich matrix was impossible (Nøttvedt et al. 2008). Triassic sediments are well to remove via field preparation and, hence, entire exposed in the Jameson Land Basin, which is blocks of sediment were excavated. located in central East Greenland at about 718 Nat Sediment grain size, depositional structures, bed the present-day land areas of Jameson Land and geometry, and the relationship to the over- and Scoresby Land (Fig. 1). The basin was situated at underlying facies were investigated for each bone- the southern end of the East Greenland rift system, and track-bearing layer. Special attention was given which formed part of a larger rift complex separat- to beds with wave ripples as they contain informa- ing Greenland from Norway prior to the opening tion on the palaeoclimatic events that brought rain of the Atlantic (Ziegler 1988). It was bounded to to the basin (cf. Clemmensen et al. 1998). Sedimen- the west by a major north–south-trending fault and tological logs on the scale of 1:10 were measured in to the east by the Liverpool Land structural high. the uppermost Carlsberg Fjord beds and the lower- A possible NW–SE-trending
Load more

Recommended publications
  • University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark
    Triassic lithostratigraphy of the Jameson Land Basin (central East Greenland), with emphasis on the new Fleming Fjord Group Clemmensen, Lars B.; Kent, Dennis W.; Mau, Malte; Mateus, Octávio; Milàn, Jesper Published in: Bulletin of the Geological Society of Denmark DOI: 10.37570/bgsd-2020-68-05 Publication date: 2020 Document version Publisher's PDF, also known as Version of record Document license: CC BY Citation for published version (APA): Clemmensen, L. B., Kent, D. W., Mau, M., Mateus, O., & Milàn, J. (2020). Triassic lithostratigraphy of the Jameson Land Basin (central East Greenland), with emphasis on the new Fleming Fjord Group. Bulletin of the Geological Society of Denmark, 68, 95-132. https://doi.org/10.37570/bgsd-2020-68-05 Download date: 01. okt.. 2021 BULLETIN OF THE GEOLOGICAL SOCIETY OF DENMARK · VOL. 68 · 2020 Triassic lithostratigraphy of the Jameson Land Basin (central East Greenland), with emphasis on the new Fleming Fjord Group LARS B. CLEMMENSEN, DENNIS V. KENT, MALTE MAU, OCTÁVIO MATEUS & JESPER MILÀN Clemmensen, L.B., Kent, D.V., Mau, M., Mateus, O. & Milàn, J. 2020. Triassic lithostratigraphy of the Jameson Land basin (central East Greenland), with em- phasis on the new Fleming Fjord Group. Bulletin of the Geological Society of Denmark, vol. 68, pp. 95–132. ISSN 2245-7070. https://doi.org./10.37570/bgsd-2020-68-05 The lithostratigraphy of the Triassic deposits of the Jameson Land Basin in central East Greenland is revised. The new Scoresby Land Supergroup is now Geological Society of Denmark composed of the Wordie Creek, Pingo Dal, Gipsdalen and Fleming Fjord Groups.
    [Show full text]
  • Triassic Lithostratigraphy of the Jameson Land Basin (Central East Greenland), with Emphasis on the New Fleming Fjord Group
    BULLETIN OF THE GEOLOGICAL SOCIETY OF DENMARK · VOL. 68 · 2020 Triassic lithostratigraphy of the Jameson Land Basin (central East Greenland), with emphasis on the new Fleming Fjord Group LARS B. CLEMMENSEN, DENNIS V. KENT, MALTE MAU, OCTÁVIO MATEUS & JESPER MILÀN Clemmensen, L.B., Kent, D.V., Mau, M., Mateus, O. & Milàn, J. 2020. Triassic lithostratigraphy of the Jameson Land basin (central East Greenland), with emphasis on the new Fleming Fjord Group. Bulletin of the Geological Society of Denmark, vol. 68, pp. 95–132. ISSN 2245-7070. https://doi.org/10.37570/bgsd-2020-68-05-rev File replaced 2021-05-08: Erroneous rotation directions in the original publication Geological Society of Denmark are now correct. https://2dgf.dk The lithostratigraphy of the Triassic deposits of the Jameson Land Basin in central East Received 26 August 2019 Greenland is revised. The new Scoresby Land Supergroup is now composed of the Wordie Accepted in revised form Creek, Pingo Dal, Gipsdalen and Fleming Fjord Groups. This paper only deals with the 23 April 2020 lithostratigraphy of the late Early-Late Triassic continental deposits of the latter three Published online groups with emphasis on the vertebrate-bearing Fleming Fjord Group. The new Pingo 05 June 2020 Dal Group consists of three new formations, the Rødstaken, Paradigmabjerg and Klitdal © 2020 the authors. Re-use of material is Formations (all elevated from members), the new Gipsdalen Group consists of three new permitted, provided this work is cited. formations, the Kolledalen, Solfaldsdal (with the new Gråklint Member) and Kap Seaforth Creative Commons License CC BY: Formations (all elevated from members), and the new Fleming Fjord Group is subdivided https://creativecommons.org/licenses/by/4.0/ into three new formations, the Edderfugledal, Malmros Klint and Ørsted Dal Formations (all elevated from members).
    [Show full text]
  • Evolutionary Origin of the Turtle Shell
    Current Biology 23, 1113–1119, June 17, 2013 ª2013 Elsevier Ltd All rights reserved http://dx.doi.org/10.1016/j.cub.2013.05.003 Report Evolutionary Origin of the Turtle Shell Tyler R. Lyson,1,2,3,* Gabe S. Bever,4,5 Torsten M. Scheyer,6 debated throughout the 20th and early 21st centuries (see Allison Y. Hsiang,1 and Jacques A. Gauthier1,3 [16]) with support falling largely along disciplinary lines [3–9, 1Department of Geology and Geophysics, Yale University, 17–25]. Paleontological explanations relied heavily on the 210 Whitney Avenue, New Haven, CT 06511, USA composite model [19–25], but their efficacy was hampered 2Department of Vertebrate Zoology, National Museum of by the large morphological gap separating the earliest, fully Natural History, Smithsonian Institution, Washington, shelled turtles (e.g., Proganochelys quenstedti [26]) from all DC 20560, USA other known groups. In contrast, developmental biologists 3Division of Vertebrate Paleontology, Yale Peabody Museum promoted the de novo model and viewed the lack of clear tran- of Natural History, New Haven, CT 06511, USA sitional fossils as support for a rapid evolution of the shell, 4New York Institute of Technology, College of Osteopathic perhaps coincident with the appearance of a bone morphoge- Medicine, Old Westbury, NY 11568, USA netic protein (BMP) developmental pathway critical to shell 5Division of Paleontology, American Museum of Natural construction in modern turtles [3–9, 27]. The lack of osteo- History, New York, NY 10024, USA derms in the recently discovered stem turtle Odontochelys 6Pala¨ ontologisches Institut und Museum, Universita¨ tZu¨ rich, semitestacea [2] strongly supports the de novo model of shell Karl-Schmid-Strasse 4, 8006 Zu¨rich, Switzerland origination and liberates the paleontological search for the even deeper history of the turtle stem from its previously self-imposed constraint of osteoderm-bearing forms.
    [Show full text]
  • The Integumental Appendages of the Turtle Shell: an Evo-Devo Perspective JACQUELINE E
    COMMENTARY AND PERSPECTIVE The Integumental Appendages of the Turtle Shell: An Evo-Devo Perspective JACQUELINE E. MOUSTAKAS-VERHO1* 2 AND GENNADII O. CHEREPANOV 1Institute of Biotechnology, University of Helsinki, Helsinki, Finland 2Department of Vertebrate Zoology, Faculty of Biology, St. Petersburg State University, St. Petersburg, Russia ABSTRACT The turtle shell is composed of dorsal armor (carapace) and ventral armor (plastron) covered by a keratinized epithelium. There are two epithelial appendages of the turtle shell: scutes (large epidermal shields separated by furrows and forming a unique mosaic) and tubercles (numerous small epidermal bumps located on the carapaces of some species). In our perspective, we take a synthetic, comparative approach to consider the homology and evolution of these integumental appendages. Scutes have been more intensively studied, as they are autapomorphic for turtles and can be diagnostic taxonomically. Their pattern of tessellation is stable phylogenetically, but labile in the individual. We discuss the history of developmental investigations of these structures and hypotheses of evolutionary and anomalous variation. In our estimation, the scutes of the turtle shell are an evolutionary novelty, whereas the tubercles found on the shells of some turtles are homologous to reptilian scales. J. Exp. Zool. (Mol. Dev. Evol.) 324B:221–229, 2015. © 2015 Wiley Periodicals, Inc. J. Exp. Zool. (Mol. Dev. Evol.) How to cite this article: Moustakas-Verho JE, Cherepanov GO. 2015. The integumental 324B:221–229, appendages of the turtle shell: An evo-devo perspective. J. Exp. Zool. (Mol. Dev. Evol.) 324B: 2015 221–229. EVOLUTIONARY ORIGIN AND DEVELOPMENT OF TURTLE Turtles can often be recognized by the pattern of scutes, or lack SCUTES thereof, on their shell.
    [Show full text]
  • A Late Triassic Lake System in East Greenland: Facies, Depositional Cycles and Palaeoclimate
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Columbia University Academic Commons ELSEVIER Palaeogeography, Palaeoclimatology, Palaeoecology 140 (1998) 135±159 A Late Triassic lake system in East Greenland: facies, depositional cycles and palaeoclimate Lars B. Clemmensen a,Ł,DennisV.Kentb, Farish A. Jenkins, Jr. c a Geological Institute, University of Copenhagen, DK-1350 Copenhagen K, Denmark b Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA c Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138, USA Received 24 May 1996; accepted 18 January 1997 Abstract The Upper Triassic Fleming Fjord Formation of the Jameson Land Basin in East Greenland contains a well-exposed succession, 200±300 m thick, of lake deposits. The Malmros Klint Member, 100±130 m thick, is composed of cyclically bedded intraformational conglomerates, red siltstones and ®ne-grained sandstones and disrupted dolomitic sediments (paleosols). The cyclicity is composite with cycles having mean thicknesses of (25), 5.9 and 1.6 m. The overlying Carlsberg Fjord beds of the érsted Dal Member, 80±115 m thick, are composed of structureless red mudstones rhythmically broken by thin greyish siltstones. This unit also has a composite cyclicity with cycles having mean thicknesses of 5.0 and 1.0 m. The uppermost Tait Bjerg Beds of the érsted Dal Member, 50±65 m thick, can be divided into two units. A lower unit is composed of cyclically bedded intraformational conglomerates or thin sandstones, red mudstones, greenish mudstones and yellowish marlstones. An upper unit is composed of relatively simple cycles of grey mudstones and yellowish marlstones.
    [Show full text]
  • (Archosauria, Pseudosuchia) Coprolite from the Late Trias-Sic Fleming Fjord Group of Jameson Land, Central East Greenland
    A possible phytosaurian (Archosauria, Pseudosuchia) coprolite from the Late Trias-sic Fleming Fjord Group of Jameson Land, central East Greenland Milàn, Jesper; Octávio, Mateus; Mau, Malte; Rudra, Arka; Sanei, Hamed; Clemmensen, Lars B. Published in: Bulletin of the Geological Society of Denmark DOI: 10.37570/bgsd-2021-69-05 Publication date: 2021 Document version Publisher's PDF, also known as Version of record Document license: CC BY Citation for published version (APA): Milàn, J., Octávio, M., Mau, M., Rudra, A., Sanei, H., & Clemmensen, L. B. (2021). A possible phytosaurian (Archosauria, Pseudosuchia) coprolite from the Late Trias-sic Fleming Fjord Group of Jameson Land, central East Greenland. Bulletin of the Geological Society of Denmark, 69, 71-80. https://doi.org/10.37570/bgsd-2021- 69-05 Download date: 02. okt.. 2021 BULLETIN OF THE GEOLOGICAL SOCIETY OF DENMARK · VOL. 69 · 2021 A possible phytosaurian (Archosauria, Pseudosuchia) coprolite from the Late Triassic Fleming Fjord Group of Jameson Land, central East Greenland JESPER MILÀN, OCTÁVIO MATEUS, MALTE MAU, ARKA RUDRA, HAMED SANEI & LARS B. CLEMMENSEN Milàn, J., Mateus, O., Mau, M., Rudra, A., Sanei, H. & Clemmensen, L.B. 2021: A possible phytosaurian (Archosauria, Pseudosuchia) coprolite from the Late Trias- sic Fleming Fjord Group of Jameson Land, central East Greenland. Bulletin of the Geological Society of Denmark, vol. 69, pp. 71-80. ISSN 2245-7070. https://doi.org/10.37570/bgsd-2021-69-05 Geological Society of Denmark A large, well-preserved vertebrate coprolite was found in a lacustrine sediment in the https://2dgf.dk Malmros Klint Formation of the Late Triassic Fleming Fjord Group in the Jameson Land Basin, central East Greenland.
    [Show full text]
  • Phylogenetic Relationships Among Extinct and Extant Turtles: the Position of Pleurodira and the Effects of the Fossils on Rooting Crown-Group Turtles
    Contributions to Zoology, 79 (3) 93-106 (2010) Phylogenetic relationships among extinct and extant turtles: the position of Pleurodira and the effects of the fossils on rooting crown-group turtles Juliana Sterli1, 2 1 CONICET - Museo Paleontológico Egidio Feruglio, Av. Fontana 140, 9100 Trelew, Chubut, Argentina 2 E-mail: [email protected] Key words: molecules, morphology, phylogeny, Testudinata, Testudines Abstract Taxonomic nomenclature ........................................................ 94 Taxonomic sampling ................................................................ 94 The origin and evolution of the crown-group of turtles (Crypto- Character sampling ................................................................. 95 dira + Pleurodira) is one of the most interesting topics in turtle Phylogenetic analyses ............................................................. 95 evolution, second perhaps only to the phylogenetic position of Results ............................................................................................... 97 turtles among amniotes. The present contribution focuses on Morphological analysis with extinct taxa .......................... 97 the former problem, exploring the phylogenetic relationships Molecular analyses .................................................................. 97 of extant and extinct turtles based on the most comprehensive Morphological and molecular analysis excluding phylogenetic dataset of morphological and molecular data ana- extinct taxa ................................................................................
    [Show full text]
  • THE ORIGIN of the TURTLE BODY PLAN: EVIDENCE from FOSSILS and EMBRYOS by RAINER R
    [Palaeontology, 2019, pp. 1–19] REVIEW ARTICLE THE ORIGIN OF THE TURTLE BODY PLAN: EVIDENCE FROM FOSSILS AND EMBRYOS by RAINER R. SCHOCH1 and HANS-DIETER SUES2 1Staatliches Museum fur€ Naturkunde, Rosenstein 1, D-70191, Stuttgart, Germany; [email protected] 2Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA; [email protected] Typescript received 4 June 2019; accepted in revised form 23 September 2019 Abstract: The origin of the unique body plan of turtles plan within a phylogenetic framework and evaluate it in light has long been one of the most intriguing mysteries in evolu- of the ontogenetic development of the shell in extant turtles. tionary morphology. Discoveries of several new stem-turtles, The fossil record demonstrates that the evolution of the tur- together with insights from recent studies on the develop- tle shell took place over millions of years and involved a ment of the shell in extant turtles, have provided crucial new number of steps. information concerning this subject. It is now possible to develop a comprehensive scenario for the sequence of evolu- Key words: turtle, carapace, plastron, development, phy- tionary changes leading to the formation of the turtle body logeny. T URTLES are unique among known extant and extinct tet- name Testudines to the clade comprising the most recent rapods, including other forms with armour formed by common ancestor of Chelonia mydas and Chelus fimbria- bony plates (e.g. armadillos), in their possession of a tus (matamata) and all descendants of that ancestor. bony shell that incorporates much of the vertebral col- The origin of the turtle body plan has long been one of umn and encases the trunk (Zangerl 1969; Fig.
    [Show full text]
  • AMERICAN MUSEUM Norntates PUBLISHED by the AMERICAN MUSEUM of NATURAL HISTORY CENTRAL PARK WEST at 79TH STREET, NEW YORK, N.Y
    AMERICAN MUSEUM Norntates PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, N.Y. 10024 Number 3130, 29 pp., 25 figures, 2 tables May 24, 1995 The Morphology and Relationships of Australochelys, an Early Jurassic Turtle from South Africa EUGENE S. GAFFNEY,1 AND JAMES W. KITCHING2 ABSTRACT Australochelys from the Early Jurassic Elliot (Cryptodira plus Pleurodira) than to Proganoche- Formation of South Africa is the oldest African lys. These characters include a sutured basipter- turtle. Known only from the skull and a shell frag- ygoid articulation and middle ear region partially ment, Australochelys has many primitive chelo- enclosed laterally. Australochelys is hypothesized nian characters in common with the Late Triassic as the sister taxon to the Casichelydia; together Proganochelys, such as a large interpterygoid va- they form the Rhaptochelydia. The relationships cuity and a lacrimal foramen. Australochelys has of Australochelys show that the beginning stages large orbits and a ventral basioccipital tubercle, of the unusual turtle hearing mechanism evolved characters that only occur in Proganochelys. How- before the origin ofthe modem turtle groups. Ak- ever, because Australochelys has a series of ad- inesis preceded or accompanied the enclosure of vanced characters in common with the Casiche- the hypertrophied middle ear region in the early lydia, it is more closely related to the Casichelydia evolution of the hearing mechanism. INTRODUCTION Australochelys, the oldest turtle from Af- described in a short paper (Gaffney and rica, reveals an important stage in the early Kitching, 1994) that did not include a de- history ofturtles. Australochelys was recently tailed morphological description or extended 1 Curator, Department of Vertebrate Paleontology, American Museum of Natural History.
    [Show full text]
  • The Cranial Anatomy of the Early Jurassic Turtle Kayentachelys Aprix
    The cranial anatomy of the Early Jurassic turtle Kayentachelys aprix JULIANA STERLI and WALTER G. JOYCE Sterli, J. and Joyce, W.G. 2007. The cranial anatomy of the Early Jurassic turtle Kayentachelys aprix. Acta Palaeonto− logica Polonica 52 (4): 675–694. The fossil turtle Kayentachelys aprix is known from Early Jurassic sediments of the Kayenta Formation, Arizona, USA. The detailed description of this taxon’s cranium offered in this paper demonstrates that this turtle presents a mixture of primitive and derived character states. Among others, the presence of an interpterygoid vacuity, a basipterygoid process, a prootic that is exposed in ventral view, and a foramen posterius canalis carotici interni that is formed entirely by the basisphenoid are generally considered primitive for turtles. On the other hand, the presence of an undivided apertura narium, a well developed cavum tympani, an incipient cavum postoticum, and an unpaired vomer are considered to be de− rived. Kayentachelys aprix has previously been hypothesized to be the oldest stem cryptodiran turtle because of the pres− ence of a flat, vertical plate on the processus pterygoideus externus, and the presence of a processus trochlearis oticum. However, the presence of these characters cannot be confirmed in the available specimens. Other putative stem− cryptodiran characters, such as the prefrontal−vomer contact and the presence of an epipterygoid, are herein corroborated as being symplesiomorphies, because they generally appear to be present in basal turtles. Key words: Testudines, Cryptodira, cranial morphology, turtle evolution, stem turtles, Jurassic, Kayenta Formation. Juliana Sterli [[email protected]], CONICET−Departamento de Paleontología, Museo de Historia Natural de San Rafael, Parque Mariano Moreno s/n, (5600) San Rafael, Mendoza, Argentina; Walter G.
    [Show full text]
  • New Material of the Platychelyid Turtle Notoemys Zapatocaensis from the Early Cretaceous of Colombia; Implications for Understanding Pleurodira Evolution
    Chapter 8 New Material of the Platychelyid Turtle Notoemys zapatocaensis from the Early Cretaceous of Colombia; Implications for Understanding Pleurodira Evolution Edwin A. Cadena, Carlos A. Jaramillo, and Jonathan I. Bloch Abstract Notoemys zapatocaensis is the youngest that N. zapatocaensis is a sister taxon of N. oxfordiensis, representative of the Platychelyidae, a group of Late and that Proterochersis robusta can be resolved in two Jurassic-Early Cretaceous pleurodires. Here we describe different positions in the testudines tree: (1) with Odont- two new specimens of this species represented by a partial ochelys semitestacea based on the fact that both taxa share carapace and a nearly complete articulated shell. Notoemys two mesoplastra meeting at midline, or (2) as the most basal zapatocaensis is different from other platychelyid turtles in pleurodire, based on a suture articulation of pelvis to shell. having: (1) two fairly reduced lateral tuberosities on the Anal notch shape and potentially fontanelle size are margin of the anterior plastral lobe, (2) a shallow notch on indicators of sexual dimorphism in platychelyids. the posterolateral margin of the epiplastra, giving a convex posterolateral edge to this bone, (3) gular scales that are Keywords Rosablanca Formation Á South America Á rectangular in shape and much wider than long, (4) a long Valanginian Zapatoca intergular scale that has a slight medial contact with the Á pectorals, resulting in a complete separation of the humeral scales, (5) a central plastral fontanelle that projects poste- Introduction riorly into the xiphiplastral region, (6) a very small marginal 3, (7) a slightly shorter neural 1 than neural 2, with an exclusive lateral contact with costal 1, resulting in a Turtles diverged in two infraorders (Pleurodira and Cryptodira) complete separation of neural 2 and costal 1, (8) narrower during the Late Triassic or earlier (Gaffney and Jenkins vertebral scales, and (9) peripheral 3 lacking a posterome- 2010), around 221 Ma, maximum estimated based on dial contact with costal 2.
    [Show full text]
  • 215–212 Ma, Late Triassic) Dip in Atmospheric Pco2
    Northward dispersal of dinosaurs from Gondwana to Greenland at the mid-Norian (215–212 Ma, Late Triassic) dip in atmospheric pCO2 Dennis V. Kenta,b,1 and Lars B. Clemmensenc aPaleomagnetics Lab, Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964; bDepartment of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854; and cDepartment of Geosciences and Natural Resource Management, University of Copenhagen, DK-1350 Copenhagen, Denmark Edited by Lisa Tauxe, University of California San Diego, La Jolla, CA, and approved January 7, 2021 (received for review October 4, 2020) The earliest dinosaurs (theropods and sauropodomorphs) are Here, we present an updated chronology for the Fleming Fjord found in fossiliferous early Late Triassic strata dated to about Group of Greenland based on a magnetostratigraphy (13) ex- 230 million years ago (Ma), mainly in northwestern Argentina and panded by data from a second sampling area, which necessitates southern Brazil in the Southern Hemisphere temperate belt of a revised older-age assignment for the documented fossil oc- what was Gondwana in Pangea. Sauropodomorphs, which are not currences of plateosaurid Plateosaurus (14–16). Together, with known for the entire Triassic in then tropical North America, an assessment linked to the APTS of the age of the Löwenstein eventually appear 15 million years later in the Northern Hemi- Formation in the Germanic basin that has the earliest occur- sphere temperate belt of Laurasia. The Pangea supercontinent was rences of Plateosaurus
    [Show full text]