Project 1076: O. W. M. Rauhut,A. M. Heyng,A. López-Arbarello,A. Hecker. 2012. A new rhynchocephalian from the Late Jurassic of Germany with a dentition that is unique amongst tetrapods. PLOS ONE. 7 (10):e46839.
Specimen: oenosaurus (BSPG:2009 I 23)

Abstract

Rhynchocephalians, the sister group of squamates (lizards and snakes), are only represented by the single genus Sphenodon today. This taxon is often considered to represent a very conservative lineage. However, rhynchocephalians were common during the late Triassic to latest Jurassic periods, but rapidly declined afterwards, which is generally attributed to their supposedly adaptive inferiority to squamates and/or Mesozoic mammals, which radiated at that time. New finds of Mesozoic rhynchocephalians can thus provide important new information on the evolutionary history of the group.
A new fossil relative of Sphenodon from the latest Jurassic of southern Germany, Oenosaurus muehlheimensis gen. et sp. nov., presents a dentition that is unique amongst tetrapods. The dentition of this taxon consists of massive, continuously growing tooth plates, probably indicating a crushing dentition, thus representing a previously unknown trophic adaptation in rhynchocephalians.
The evolution of the extraordinary dentition of Oenosaurus from the already highly specialized Zahnanlage generally present in derived rhynchocephalians demonstrates an unexpected evolutionary plasticity of these animals. Together with other lines of evidence, this seriously casts doubts on the assumption that rhynchocephalians are a conservative and adaptively inferior lineage. Furthermore, the new taxon underlines the high morphological and ecological diversity of rhynchocephalians in the latest Jurassic of Europe, just before the decline of this lineage on this continent. Thus, selection pressure by radiating squamates or Mesozoic mammals alone might not be sufficient to explain the demise of the clade in the Late Mesozoic, and climate change in the course of the fragmentation of the supercontinent of Pangaea might have played a major role.


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Project DOI: 10.7934/P1076, http://dx.doi.org/10.7934/P1076
This project containsMatrices
  • 1 Media
  • 1 Matrix
  • 22 Taxa
  • 1 Specimen
  • 70 Characters
Total size of project's media files: 1 MB

Download Project SDD File
Total scored cells: 1090
Total media associated with cells: 0
Total labels associated with cell media: 0
Characters
Total characters: 70
Total characters with associated media: 0
Total characters with media with labels: 0
Total character states: 168
Total character states with associated media: 0
Total character states with media with labels:0
Total unordered/ordered characters:70/0
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MorphoBank Project 1076


    Members

    member name taxa specimens media media
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    Oliver Rauhut
    Project Administrator
    Last logged in 11/19/13
    2211170070001090
    (1090, 0, 0)
    00000


    Taxonomic Overview for Matrix 'M2358' (22 Taxa)

    taxon unscored
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    [1] younginia
    Last Modified in 12/05/13
    14565600001
    [2] squamata
    Last Modified in 12/05/13
    11635900001
    [3] gephyrosaurus
    Last Modified in 12/05/13
    7636300001
    [4] brachyrhinodon
    Last Modified in 12/05/13
    18525200001
    [5] Clevosaurus hudsoni
    Last Modified in 12/05/13
    0707000001
    [6] Clevosaurus wangi
    Last Modified in 12/05/13
    24464600001
    [7] cynosphenodon
    Last Modified in 12/05/13
    51191900001
    [8] diphydontosaurus
    Last Modified in 12/05/13
    4676600001
    [9] eilenodon
    Last Modified in 12/05/13
    48222200001
    [10] homoeosaurus
    Last Modified in 12/05/13
    10626000001
    [11] kallimodon
    Last Modified in 12/05/13
    12585800001
    [12] oenosaurus
    Last Modified in 12/05/13
    34363600001
    [13] opisthias
    Last Modified in 12/05/13
    27434300001
    [14] palaeopleurosaurus
    Last Modified in 12/05/13
    6656400001
    [15] planocephalosaurus
    Last Modified in 12/05/13
    15555500001
    [16] pleurosaurus
    Last Modified in 12/05/13
    10606000001
    [17] pamizinsaurus
    Last Modified in 12/05/13
    45252500001
    [18] priosphenodon
    Last Modified in 12/05/13
    7636300001
    [19] sapheosaurus
    Last Modified in 12/05/13
    29414100001
    [20] sphenodon
    Last Modified in 12/05/13
    0707000001
    [21] toxolophosaurus
    Last Modified in 12/05/13
    55151500001
    [22] zapatadon
    Last Modified in 12/05/13
    31393900001


    Project views

    type number of views Individual items viewed (where applicable)
    Total project views12168
    Project overview2621
    Matrix views1868Matrix landing page (1636 views); Rauhut et al. Oenosaurus matrix (232 views);
    Media views4115Media search (3606 views); M309964 (509 views);
    Taxon list1216
    Specimen list1944
    Bibliography403
    Documents list1




    Project downloads

    type number of downloads Individual items downloaded (where applicable)
    Total downloads from project190
    Project downloads182
    Matrix downloads7Rauhut et al. Oenosaurus matrix (7 downloads);
    Media downloads1M309964 (1 download);