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



On Tue, 11 Apr 2000, Larry Febo wrote:

> Couldn`t there be an alternative path, like: prolacertilian to pterosaur to
> lagosuchian (secondarilly flightless) to dinosaur?
> 
> Or even what I propose, the more radical prolacertilian to pterosaur to
> avian to various secondarilly flightless theropod groups?

Since "lagosuchians" and dinosaurs show none of the derived traits of
pterosaurs, flight-related or not, these two seem highly unlikely.
However, change "ancestor-descendant" relationship to "sister group"
relationship, and the first one is likely correct (if incomplete). (Retain
"ancestor-descendant" relationship for "lagosuchians" and dinosaurs.)

Pterosaurs and avians are not very similar at all anatomically, apart from
a handful of convergences (like keeled sterna) and of course the traits
common to all ornithodirans. The wing structure, for one thing, is
completely different.

-- T. Michael Keesey .................................. <tmk@dinosauricon.com>
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