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



In a message dated 4/7/2000 8:53:17 AM Pacific Daylight Time, 
larryf@capital.net writes:

> Could Euparkeria be evolved from prolacertilians? (otherwise,....where did 
it 
> come from?) Are dinosaurs considered derived from something else,....(not 
yet 
> discovered)? I`d just like to know what the general opinion is on this 
early 
> aspect of archosaur evolution.

Between basal dinosaurs and any prolacertilian-like ancestors are the 
Crurotarsi (including the large, quadrupedal rauisuchians, phytosaurs, 
aetosaurs, and crocodilians), the Proterosuchia (quadrupedal and sprawling), 
and *Euparkeria*.  Thus, basal archosaurians were likely fairly large and 
quadrupedal, and it is difficult to see how any direct transition from a 
prolacertilian-like body form to a theropodan one could have taken place.

--Nick P.