RE: II CLPV talk summaries: Day 2

[Michael Mortimer <mickey_mortimer111@msn.com>]

Scott Hartman wrote-

> Sterling Nesbitt gave one of my favorite talks of the conference.  He 
> showed that Shuvosaurus is not an ornithomimid (no real surprise there), 
> but is rather a derived suchian.  And he demonstrated this pretty 
> convincingly, since he has a number of specimens with post crania 
> conveniently attached to skulls.

Interesting.  Rauhut (1997) wrote-
"Shuvosaurus differs from rauisuchians and other basal crurotarsans in the 
following characters: loss of the postfrontal, paroccipital process directed 
ventro-laterally, lacrimal dorso-ventrally elongated, inverted L-shaped and 
exposed on the skull roof, presence of a deep basisphenoid recess, and 
ectopterygoid with expanded medial part and deep ventral fossa. All of these 
characters are found in theropods, and the latter three probably represent 
synapomorphies for this group (Gauthier 1986); therefore, Shuvosaurus can be 
referred to the Theropoda."
But if we have postcrania...

> Randall Irmis was up next, and picked up where Sterling left off; they feel 
> that a lot of North American Triassic dinosaurs aren?t and made a pretty 
> convincing argument for it.  A (non-comprehensive) list includes 
> Eucoelophysis, which they feel pretty strongly is a silesaurid.

Ack.  This is pretty scary considering most paleontologists would have had 
no problems sinking Eucoelophysis into Coelophysis, and probably E. baldwini 
into C. bauri.  Makes one wonder about all those other fragmentary 
coelophysoids.

> Gojirosaurus they feel is a chimera (Ken, want to comment?), made up of 
> theropod material and Shuvosaurus (or shuvosaur-like suchian) material.

Well, the tooth isn't shuvosaurid (though the edentulous premaxilla found 
nearby probably is).  The dorsal vertebrae have hyposphenes, so should be 
saurischian.  The scapula and tibia are very similar to Liliensternus.  
Surely shuvosaurids haven't developed theropod-like pubes too?

> He did note the similarity to Silesaurus, but rather than concluding that 
> his new animal(s) are not dinosaurs, he inferred that Silesaurus is itself 
> a basal ornithischian.

Wouldn't it be funny if what we had here was the return of dinosaurian 
polyphyly?
Theropods from shuvosaurid suchians...
Sauropodomorphs from Azhendohsaurus-like basal archosaurs...
Ornithischians from silesaurid 'avemetatarsalians'...
;)

Mickey Mortimer