Re: Gasosaurus (was Re: MJ coelurosaurians)

["Thomas R. Holtz, Jr." <th81@umail.umd.edu>]

At 12:27 AM 2/12/99 -0800, Jaime A. Headden wrote:

><It has additional features not used by Greg Paul which do securely
>place it within Coelurosauria, making it the oldest secure
>coelurosaurian at present (pending confirmation of the identity of the
>Yunnan "therizinosauroid").>
>
>  What characters might these be? I see a lot of characters linking
>*Procerato* to basal tetanurines, such as the form of its maxilla. The
>teeth characters are found in *Torvosaurus* and *Monolophosaurus*, as
>are the jaw, and form of the lachrymal ... I _really_ don't see
>coelurosaur on this fellow. I may be blind, " but, well, there it
>is... "

Don't have much time for this today, so just a brief post:

A) Don't forget, similarity does not indicate affinity; *derived*
similarity, however, might.  The tooth characters found in _Procerat._,
_Torvo._, and _Monolopho._ are all pretty primitive for Tetanurae (even for
Neotheropoda); all but the ventralmost part of the lacrimals in _Procerat._
are lost, and what is preserved is typical for Tetanurae in general.  What
particular derived states do you see in _Pro._, _Torv._, and _Mono._?


B) _P._, however, does manifest the following synapomorphies of Coelurosauria:

Maxillary antorbital fossa greater than 40% of the rostrocaudal length of
the antorbital cavity;
Quadrate articulation rostral to caudalmost point of occipital condyle

(as well as other, more homoplastic characters including reversals which, on
the MPTs, results in a coelurosaurian position).

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:tholtz@geol.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661