Project 5133: J. G. Quinn, E. R. Matheau-Raven, D. I. Whiteside, J. E. Marshall, D. J. Hutchinson, M. J. Benton. 2023. The relationships and paleoecology of Pachystropheus rhaeticus , an enigmatic latest Triassic marine reptile (Diapsida: Thalattosauria). Journal of Vertebrate Paleontology. 43 (6):e2350408.
Specimen: Pachystropheus rhaeticus (BRSMG/Rhaetian:BRSMG Cg3102)
View: Whole specimen

Abstract

ABSTRACT–– Pachystropheus rhaeticus is a primarily marine diapsid reptile found in Late Triassic (Rhaetian) deposits in Britain and continental Europe. Although known for a long time, Pachystropheus remains an enigma. It was identified as the oldest choristodere based on similarities between postcranial bones and a sole cranial element. Here, we re-study all available Pachystropheus material, including new specimens, identifying all skeletal elements that are plausibly referrable to the genus. We reject some previous dubious identifications and show that reports of an ectopterygoid, the only cranial element of Pachystropheus described, were incorrect and that supposed skull elements belong to coelacanth fishes. Furthermore, we present CT data for the first time and new palynological data from Pachystropheus-bearing strata, providing a clearer picture of its stratigraphic distribution and the paleoecology of the Penarth Group. The reassessment of its phylogeny using new character informative data, places Pachystropheus as the last of the thalattosaurs, a lineage of marine reptiles abundant throughout the Triassic. We demonstrate that a specimen of Pachystropheus previously reported from the Lower Jurassic is more likely from the Late Rhaetian, and therefore the taxon does not extend across the ETE. Moreover, this extends the known geological range of thalattosaurs from Norian-Rhaetian boundary to the latest Rhaetian. Similarities in the postcranial skeleton between Pachystropheus and other askeptosauroid thalattosaurs, particularly Endennasaurus acutirostris, suggests it was able to move on land, but was most likely a primarily marine predator with an ecological niche distinct from coeval marine reptiles (placodonts, ichthyosaurs) and carnivorous fishes (hybodont sharks, actinopterygians).


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Article DOI: 10.1080/02724634.2024.2350408

Project DOI: 10.7934/P5133, http://dx.doi.org/10.7934/P5133
This project containsMatrices
  • 2 Media
  • 1 Matrix
  • 1 Document
  • 43 Taxa
  • 2 Specimens
  • 357 Characters
Total size of project's media files: 25.4M

Download Project SDD File
Total scored cells: 9674
Total media associated with cells: 0
Total labels associated with cell media: 0
Characters
Total characters: 357
Total characters with associated media: 0
Total characters with media with labels: 0
Total character states: 778
Total character states with associated media: 0
Total character states with media with labels:0
Total unordered/ordered characters:357/0
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MorphoBank Project 5133
  • Creation Date:
    15 March 2024
  • Publication Date:
    05 June 2024

    Authors' Institutions

    • Bristol City Museum and Art Gallery, Bristol

    • Natural History Museum, London

    • University of Southampton

    • University of Bristol



    Members

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    Jacob Quinn
    Project Administrator
    432235700009674
    (9119, 0, 555)
    0000
    Michael Benton
    Full membership
    000000000
    (0, 0, 0)
    0000
    David Whiteside
    Full membership
    000000000
    (0, 0, 0)
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    Taxonomic Overview for Matrix 'M29713' (42 Taxa)

    taxon unscored
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    [1] Petrolacosaurus kansensis
    Taxon name last Modified on 03/15/24
    82264264011003
    [2] Proganochelys queensdedti
    Taxon name last Modified on 03/15/24
    32305305020003
    [3] Odontochelys semitestacea
    Taxon name last Modified on 03/15/24
    227119119011003
    [4] Hovasaurus boulei
    Taxon name last Modified on 03/15/24
    17317817806003
    [5] Acerosodontosaurus piveteaui
    Taxon name last Modified on 03/15/24
    22612512506003
    [6] Hupehsuchus nanchangensis
    Taxon name last Modified on 03/15/24
    17717517505003
    [7] Parvinatator wapitiensis
    Taxon name last Modified on 03/15/24
    263929202003
    [8] Gulosaurus helmi
    Taxon name last Modified on 03/15/24
    21213813807003
    [9] Utatsusaurus hataii
    Taxon name last Modified on 03/15/24
    169176176012003
    [10] Mixosaurus panxianensis
    Taxon name last Modified on 03/15/24
    119226226012003
    [11] Prolacerta broomi
    Taxon name last Modified on 03/15/24
    37310308012003
    [12] Protorosaurus speneri
    Taxon name last Modified on 03/15/24
    122223223012003
    [13] Tanystropheus longobardicus
    Taxon name last Modified on 03/15/24
    115224223019003
    [14] Langobardisaurus pandolfii
    Taxon name last Modified on 03/15/24
    197140140020003
    [15] Megalancosaurus preonensis
    Taxon name last Modified on 03/15/24
    217130130010003
    [16] Macrocnemus
    Taxon name last Modified on 03/15/24
    123227224010003
    [17] Pachystropheus rhaeticus
    Taxon name last Modified on 03/15/24
    287656505003
    [18] Endennasaurus acutirostris
    Taxon name last Modified on 03/15/24
    175169169013003
    [19] Askeptosaurus italicus
    Taxon name last Modified on 03/15/24
    62279279016003
    [20] Xinpusaurus kohi
    Taxon name last Modified on 03/15/24
    164175174019003
    [21] Philydrosaurus proseilus
    Taxon name last Modified on 03/15/24
    129215215013003
    [22] Champsosaurus lindoei
    Taxon name last Modified on 03/15/24
    91250250016003
    [23] Trilophosaurus buettneri
    Taxon name last Modified on 03/15/24
    60280279018003
    [24] Mesosuchus browni
    Taxon name last Modified on 03/15/24
    4730330307003
    [25] Howesia browni
    Taxon name last Modified on 03/15/24
    22013413403003
    [26] Teyumbaita sulcognathus
    Taxon name last Modified on 03/15/24
    96246246015003
    [27] Hyperodapedon huenei
    Taxon name last Modified on 03/15/24
    68274274015003
    [28] Proterosuchus
    Taxon name last Modified on 03/15/24
    6329628905003
    [29] Euparkeria capensis
    Taxon name last Modified on 03/15/24
    5929129008003
    [30] Erythrosuchus africanus
    Taxon name last Modified on 03/15/24
    8726126109003
    [31] Largocephalosaurus qianensis
    Taxon name last Modified on 03/15/24
    133209209015003
    [32] Sinosaurosphargis yunguiensis
    Taxon name last Modified on 03/15/24
    170166166021003
    [33] Cyamodus hildegardis
    Taxon name last Modified on 03/15/24
    171175175011003
    [34] Placodus gigas
    Taxon name last Modified on 03/15/24
    23313311023003
    [35] Wumengosaurus delicatomandibularis
    Taxon name last Modified on 03/15/24
    154193193010003
    [36] Serpianosaurus mirigioliensis
    Taxon name last Modified on 03/15/24
    64275274019003
    [37] Lariosaurus calcagnii
    Taxon name last Modified on 03/15/24
    93248248016003
    [38] Pistosaurus longaevus
    Taxon name last Modified on 03/15/24
    175161161021003
    [39] Pleurosaurus
    Taxon name last Modified on 03/15/24
    114221221022003
    [40] Sphenodon punctatus
    Taxon name last Modified on 03/15/24
    2333332023003
    [41] Aigialosaurus
    Taxon name last Modified on 03/15/24
    138201200019003
    [42] Varanus salvator
    Taxon name last Modified on 03/15/24
    6334333018003


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