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Re: Chimeras (was Re: Protoavis & Drepanosauridae (sensu Renesto, 1999)



-----Original Message-----
From: R. Irmis <rbi@dana.ucc.nau.edu>
To: dinosaur@usc.edu <dinosaur@usc.edu>
Date: Monday, April 30, 2001 11:01 PM
Subject: RE: Chimeras (was Re: Protoavis & Drepanosauridae (sensu Renesto,
1999)


>I'm sorry, but everyone here is missing the point.  It doesn't matter if
>Protoavis is a chimera, as long as at least one element is avian.  If even
>one bone is from a bird, or protobird, than all bets are off as to how,
>when, and from who birds evolved.
>
>Regards,
>Randall Irmis

It seems to me that the acrocoracoid process alone is very avian, however,
someone had pointed out to me that other reptile groups also have an
acrocoracoid process. It seems there is always the arguement  of
"convergence" that is used to explain away similar morphological traits.
Those "quill nodes" on the metacarpals also seem convincing.

I see no problem of protoavis being a legitimate fossil of a Triassic bird.
Then again, perhaps I`m predjudiced in my views. I seem to have a unique
idea that both pterosaurs and birds are close sister groups, both having
developed from the prolacertiforms. So,...it is no surprise to me that there
are prolacertiform affinities to be seen in Protoavis as well.

My point of view is based on a "handfull" of morphological analogies
,perhaps not enough to present an "overwhelming" arguement. I`m hoping for
an abundance of Triassic fossils to be dug up, similar to the Cretaceous
finds in China. I`m sure that once the scant Triassic fossil record is
filled in, things will become much more clear.
Perhaps it takes many specimen to ascertain (convincingly) the  correct path
that evolution took.

I was wondering, in the Petrified Forest area, Chinle formation, there was
volcanic activity where gases could have asphixiated many Triassic birds.
Couldn`t areas of ancient lakebed be actively sought out, and mined for such
delicate fossils? How much prospecting for fossils is currently going on
there?

To get more of "my point of view" go to my website at:
http://www.capital.net/~larryf/