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Re: Re: Removing segnosaurs from ...



>>And, while we're at it, from what condition did
>>the sauropod pes evolve?
>
>The pentadactyl sauropod pes is primitive for Dinosauria. The prosauropod,
>segnosaur, and ornithischian pedes derive FROM the sauropod pes by
>progressive loss of phalanges of digit V and reduction of metatarsal V until
>not even a splint remains. (PROsauropoda is a misnomer, by the way.) Likewise
>the herrerasaur and theropod pedes, but independently.

So goes one phylogeny.  Another would have the tetradactyl pes of
herrerasaurids, theropods, prosauropods, and ornithischians being primitive,
with sauropod feet a "reversal" of sorts.  As to the relationship of
prosauropods and sauropods: I see good arguments for prosauropods as the
ancestors of the Sauropoda, as the sister group to the Sauropoda, or as the
sister group to the Ornithischia (as per Dinogeorge). Anyone want a PhD
project that will get you a lot of attention? ;-)

Thomas R. Holtz, Jr.
Vertebrate Paleontologist
Dept. of Geology
University of Maryland
College Park, MD  20742
Email:Thomas_R_HOLTZ@umail.umd.edu (th81)
Fax: 301-314-9661
Phone:301-405-4084