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Re: Archosaur Origins...was:MESENOSAURUS ERRATA.



-----Original Message-----
From: Dinogeorge@aol.com <Dinogeorge@aol.com>
To: dinosaur@usc.edu <dinosaur@usc.edu>
Date: Wednesday, August 22, 2001 3:03 AM
Subject: Re: MESENOSAURUS ERRATA.



>After reading Dave Peters' recent paper on pterosaur
>origins and prolacertiforms, I think prolacertiforms come the closest to
>being archosaur ancestors within Diapsida. Not to mention [1] several
>prolacertiforms show antorbital fenestrae, which was (once) an archosaur
>autapomorphy, and [2] prolacertiforms include Cosesaurus, Longisquama, and
>Megalancosaurus in various places in their cladogram, all of which I once
>included in Archosauria as basalmost archosaurs or dinosaurs. Dave's paper
>gives us a much better handle on the relationships of these reptiles and
>indirectly explains why pterosaurs were considered archosaurs for so long.
>

Interesting George,..and though I agree with you that prolacertiformes could
be ancestral to archosaurs, I don`t believe Dave Peters sees it that way. I
get the impression that his claim is that Pterosaurs are not archosaurs, and
don`t belong to the group Ornithodira. Characteristics such as preorbital
fenestra, and AM ankle joints are just convergences.

I`m curious,...are you implying that since birds have a prolacertilian
ancesty, they might be considered close sister group to pterosaurs?