Re: Sharovipteryx an ornithodiran??

[Tim Williams <twilliams_alpha@hotmail.com>]

David Peters wrote:

> PS If anyone is interested in the other half of Longisquama, plus detailed 
> drawings of the skull and forelimbs,

You know, I looked at _Longisquama_ using PhotoShop and I didn't see the 
"other half" of the skeleton.  (I did see an image of the Virgin Mary 
though...!)

> It's been five years since that Macrocnemus > pterosaurs theory hit the 
> presses. No one has dented it yet. No one has called it into question. They 
> all give it a tip of the hat, or tiptoe around it like the elephant in the 
> living room.

Well, there is this...

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

Not so much a "dent" to your theory - more of a head-on-collision.

ABSTRACT: "The extremely well-preserved tarsus of the tapejarid _Tapejara_ 
sp. and the anhanguerid _Anhanguera piscator_ (Pterosauria, 
Pterodactyloidea) are described and regarded as representative of the ankle 
structure of Pterosauria. The pterosaur ankle joint (PAJ) shows the 
following features: astragalus mediolaterally elongated forming a 
hemicylinder; proximal part of the astragalocalcaneal contact characterized 
by a ridge bordered on each side by a depression on the astragalus that has 
a perfect counterpart in the calcaneum, and distal part that is 
concavo-convex, with the concavity present in the astragalus; calcaneum 
extremely reduced not reaching the posterior portion of the tarsus; absence 
of an astragalar posterior groove, perforating foramen, calcaneal tuber, and 
astragalar ascending process; proximal tarsals fusing very early in 
ontogeny, forming a tibiotarsus. 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) is phylogenetically informative and, in light of characters from 
other parts of the animal's body, can contribute to a better understanding 
of archosaur relationships."


Cheers

Tim