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Re: thoughts on Dinocephalosaurus (long)




T. Michael Keesey wrote:

- whether or not pterosaurs are part of the same group (i.e., whether or not
they are pterosauromorphs)

After flirting with prolacertiform affinities for a brief perioid, I think current opinion is swinging back behind dinosauromorph affinities for the Pterosauria. This study is Exhibit A in the case for pterosaurs as dinosauromorphs:


Kellner, A.W. (2004). The ankle structure of two pterodactyloid pterosaurs from the Santana Formation (Lower Cretaceous), Brazil. Bulletin AMNH 285: 25-35.

Quoting from the abstarct: "The main movement between the crus and foot in the PAJ occurs between the proximal and distal tarsals as in the advanced mesotarsal-reversed joint (AM-R). The main differences from the latter are the lack of an ascending process and the extreme reduction of the calcaneum that make the PAJ unique. The absence of an astragalar groove and the reduction of the calcaneum reinforce the hypothesis that pterosaurs are basal ornithodirans and closely related to the Dinosauromorpha. As has been demonstrated by this and other studies, the ankle structure (a complex of characters) isphylogenetically informative and, in light of characters from other parts of the animal's body, can contribute to a better understanding of archosaur relationships."


BTW, I believe that the taxon _Dinocephalsoaurus orientalis_ was first described in:


Li, C. (2003) First record of protorosaurid reptile (Order Protorosauria) from the Middle Triassic of China: Acta Geologica Sinica 77 (4): 419-423.

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