Re: thoughts on Dinocephalosaurus (long)

[Tim Williams <twilliams_alpha@hotmail.com>]

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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