Turtles as diapsid reptiles

  title={Turtles as diapsid reptiles},
  author={Olivier Rieppel and Michael Debraga},
THE traditional classification of reptiles is based on a single key character, the presence and style of fenestration in the temporal region of the skull. Snakes, lizards, crocodiles, dinosaurs and others are 'diapsids', in that they have (at least primitively) two holes in the temporal region. Reptiles in which the skull is completely roofed, with no temporal fenestration, are the 'anapsids'. These include many Palaeozoic forms such as captorhinomorphs, procolophonids and pareiasaurs, but also… 
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The Plesiosauria is found to by polyphyletic due to the inclusion of the Polycotylidae; this second clade is instead a member of the Plesiosauroidea, and thus more closely related to elasmosaurs than to other ‘pliosaurs’.
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Abstract. Consensus on the evolutionary position of turtles within the amniote phylogeny has eluded evolutionary biologists for more than a century. This phylogenetic problem has remained unsolved
The origin of turtles: a paleontological perspective.
  • W. Joyce
  • Environmental Science
    Journal of experimental zoology. Part B, Molecular and developmental evolution
  • 2015
The recently revived paleontological hypothesis that the Middle Permian Eunotosaurus africanus is an intermediate stem turtle is now robustly supported by numerous characters that were previously thought to be unique to turtles and that are now shown to have originated over the course of tens of millions of years unrelated to the origin of the turtle shell.
Phylogenomic analyses support the position of turtles as the sister group of birds and crocodiles (Archosauria)
Next-generation sequencing is used to obtain seven new transcriptomes from the blood, liver, or jaws of four turtles, a caiman, a lizard, and a lungfish, and provide a phylogenetic framework and timescale with which to interpret the evolution of the peculiar morphological, developmental, and molecular features of turtles within the amniotes.
At the feet of the dinosaurs: the early history and radiation of lizards
  • S. Evans
  • Geography, Environmental Science
    Biological reviews of the Cambridge Philosophical Society
  • 2003
Current understanding of the first 150 million years of squamate evolution in the light of the new data and changing ideas is examined, predicting that squamates had evolved by at least the middle Triassic, and diversified into existing major lineages before the end of this period.
Complete mitochondrial genome suggests diapsid affinities of turtles.
  • R. Zardoya, A. Meyer
  • Biology
    Proceedings of the National Academy of Sciences of the United States of America
  • 1998
The results challenge the classic view of turtles as the only survivors of primary anapsid reptiles and imply that turtles might have secondarily lost their skull fenestration.
Cranial Morphology of the Carboniferous-Permian Tetrapod Brachydectes newberryi (Lepospondyli, Lysorophia): New Data from µCT
The morphology of the skull of a partial growth series of the lysorophian Brachydectes newberryi is studied using x-ray micro-computed tomography and reveals similarities between the braincase of BrachydECTes and brachystelechid recumbirostrans, corroborating prior work suggesting a close relationship between these taxa.


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Turtles are the highly modified survivors of a radiation of poorly‐known reptiles commonly called ‘parareptiles’, and the procolophonoid hypotheses is supported by only one synapomorphy (the slender stapes).
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How profoundly the modern classification of the Amniota has been affected by the recognition of these points in the phylogenetic relationships of the various orders of Eeptilia is pointed out.
A reevaluation of early amniote phylogeny
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Correlated progression and the origin of turtles
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The importance of the critical fossils seems to reside in their relative primitive‐ness, and the simplest explanation for their more conservative nature is that they have had less time to evolve.
Studies on Skeleton formation in reptiles. IV. The homology of the reptilian (amniote) astragalus revisited
It is concluded that the reptilian (and probably also the mammalian) astragalus is a neomorph, which resulted from ontogenetic repatterning and is diagn...
The Phylogeny and Classification of Reptiles
It is only hesitatingly that I have ventured, for the first time, to express in tabular form my own views of the phylogeny and classification of the reptiles.
Development of the turtle carapace: Implications for the evolution of a novel bauplan
  • A. Burke
  • Biology
    Journal of morphology
  • 1989
Embryos of Chelydra serpentina were studied during stages of carapace development and tissue morphology, autoradiography, and indirect immunofluorescent localization of adhesion molecules indicate that the outgrowth of the embryonic carapACE occurs as the result of an epithelial–mesenchymal interaction in the body wall.
The homologies and early evolution of the shoulder girdle in turtles
  • Michael S. Y. Lee
  • Biology
    Proceedings of the Royal Society of London. Series B: Biological Sciences
  • 1996
The homologies of the highly distinctive shoulder girdle of turtles are reinterpreted in the light of recent phylogenetic studies and it is indicated that the acromion arose in the common ancestor of pareiasaurs and turtles, long before the plastron evolved.
The osteology of a Lower Permian eosuchian from Texas and a review of diapsid phylogeny
A phylogenetic analysis suggests that younginiforms are not part of the crown group of diapsids, and Apsisaurus witteri is identified as a diapsid, based on the presence of both a lateral temporal fenestra and a suborbital fenESTra.