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RE: 3 questions about Longisquama



> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Ken Kinman
>
I'll give these a shot (okay, at least 2 and 3)

>      (2) Thomas Holtz said that "most" archosauromorphs have at least 8
> cervical vertebrae.  Anybody know any of the exceptions that
> don't have at
> least 8 cervical vertebrae?

Actually, I can't recall any with less than 8, although either way is fine.
In my somewhat clumsy prose I had meant to say "at least 8", since some have
more than 8.

>      (3) Is it possible that Sharov was mistaken in stating that
> Longisquama
> is acrodont.  Could it possibly be subthecodont or something in between
> acrodont and subthecodont?

It IS indeed possible, given the quality of the preservation.  I thought it
important to note (in the orginal posting) that whereas fans of
_Longisquama_-as-archosaur unfailingly cite Sharov's suggestion of an
antorbital fenestra, they also seem unfailingly to cite his comment about
the dentition.

It would still be nice for someone to demonstrate SOME synapomorpy on this
animal with some other diapsid group (we may have found a few: hopefully
later this summer we can do something with it).  At present, though, calling
this animal an archosaur, or even an archosauromorph, is unwarrented.
Diapsida incertae sedis is most accurate.

For those interested, just remind yourself: on what physical evidence (that
is, something in the specimen itself rather than Sharov's assignment) makes
you think this animal is an archosaur?

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-314-7843