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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
> NJPharris@aol.com
> Sent: Tuesday, April 11, 2000 12:04 PM
> To: dinosaur@usc.edu
> Subject: Re: Pre-archosaur...was : What came before Eoraptor?
>
>
> In a message dated 4/11/2000 3:48:37 AM Pacific Daylight Time,
> larryf@capital.net writes:
>
> > Many of the prolacertilians seem all but "quadrupedal and sprawling".
>
> Read my original post.  I did not say that prolacertilians were
> quadrupedal
> and sprawling.  I said that basal archosaurs (which are more
> closely related
> to dinosaurs than prolacertilians are) were quadrupedal and
> sprawling, which
> implies that any advanced locomotory characteristics seen in
> dinosaurs and
> prolacertilians were most likely derived independently from a
> quadrupedal,
> sprawling condition.


Also important to note that there are alternatives to the habitually bipedal
reconstructions of prolacertilians by Peters.  In particular, there are many
lizards today with a large disparity between forelimb and hindlimb length,
and long slender tails which nonetheless are sprawlers and quadrupedal at
walking speed (and sprawlers and bipedal at high speeds).

It would take more detailed study of the pelvic and femoral anatomy of the
critters in question to determine if some of these Triassic guys were
dinosaur/rauisuchian analogues in terms of posture.

                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