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Re: Re: Removing segnosaurs from ...

>About the foot.  Segnosaur feet are just about identicle to
>prosauropod feet.  Thom Holtz claims this is a reversion.  This cannot 
>be a reversion because to revert to a former condition, you MUST 
>have that condition in your ancestory; and unless Thom Holtz is 
>claiming that Prosauropods are ancestors of Theropods, theropods 
>never had a prosauropod foot in their ancestory, so the segnosaurs' 
>foot is not a reversion.

Take a look at the feet of Herrerasaurus sometime.  And, while you're at it,
the feet of basal lineages within the Ornithischia.  Now, see what the
probable foot of the ancestral dinosaur looked like.  That's right, Digits
I-IV as functional toes, digit V already reduced.  For a little outgroup
analysis, try the feet of basal pterosaurs and other ornithodirans.

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