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RE: Pre-archosaur...was : What came before Eoraptor?



> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Larry Febo
> Sent: Friday, April 07, 2000 2:54 PM
>
> I don`t like the fact that it splits prolacertiforms off from the
> archosauriformes. Prolacertiforms is perhaps a bad term. Some say it is
> questionable that they led to modern day squamata. I`m not sure,...(maybe
> they actually did), but I also think they led to the archosaurs as well.
> Mainly because many of them possess an antorbital fenestra, a key
> feature of
> true archosaurs, and they appear at an early enough time to be ancestral.
>
Be VERY VERY cautious about accepting the "antorbital fenestra" in
prolacertiforms.  First  hand examiners of these specimens often find that
they are not in fact there: what appear in older drawings as possible
antorbital fenestra are crushed parts of the snout, or badly prepared
specimens, or even other structures (such as the lacrimal foramen!!).

In terms of their postcranial anatomy, prolacertiforms do seem to be outside
archosauriforms, although closer to them than to squamates (so yes, the name
is unfortunate).

                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