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Re: Pre-archosaur



On Fri, 7 Apr 2000, Larry Febo wrote:

> I don`t like the fact that it splits prolacertiforms off from the
> archosauriformes.

Archosauromorpha is all animals sharing more recent ancestry with
Archosauria (=={Crocodylia + Neornithes}) than with Lepidosauria
(=={Rhynchocephalia + Squamata}). Prolacertiformes are widely held to
belong to this group. Archosauriformes includes the most recent common
ancestor of _Proterosuchus_ and Archosauria, plus all of its descendants.
Prolacertiforms are generally thought not to belong to this group.

> Prolacertiforms is perhaps a bad term.

Yes. (And strangely enough, the other term for the group, Protorosauria,
also has to do with the idea that they are lizard ancestors.)

> Some say it is questionable that they led to modern day squamata.

It is certainly questionable -- Prolacertiformes is no longer regarded as
related to Squamata (note the absence of Lepidosauria on both of those
cladograms).

> I`m not sure,...(maybe they actually did), but I also think they led
> to the archosaurs as well. Mainly because many of them possess an
> antorbital fenestra, a key feature of true archosaurs

Actually of archosauromorphs in general, I think.

>, and they appear at an early enough time to be ancestral.

The monophyly of this group has been questioned, so this could be the
case.

-- T. Michael Keesey .................................. <tmk@dinosauricon.com>
   My Worlds (including The Dinosauricon) ... <http://dinosauricon.com/keesey>
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