Re: Avians and their Kin

["David Marjanovic" <david.marjanovic@gmx.at>]

----- Original Message -----
From: "Dino Guy and Computer Gal" <gbabcock@best.com>
To: <dinosaur@usc.edu>
Sent: Tuesday, October 16, 2001 8:31 PM
Subject: Avians and their Kin


> The earliest known articulated maniraptoran theropods, _Microraptor_ and
> _Sinornithosaurus_ (right?),

Excluding *Archaeopteryx*, isn't *Deinonychus* earlier? (And is it
articulated?)

> are also apparently the most anatomically
> bird-like dinosaurs (undescribed Liaoning specimens notwithstanding).

IMHO they are the most *Archaeopteryx*-like ones, not the most bird-like
ones, and even that only because of symplesiomorphies. This of course
depends on one's phylogenetic hypotheses.

> Questions:
>
> Given the fossil record as it is currently understood, what criteria can
> we apply to objectively determine whether the preponderance of evidence
> at hand supports or refutes the hypothesis that oviraptorosaurs,
> dromaeosaurs, and troodontids are secondarily flightless (as per Gregory
> S. Paul)?

AFAIK rather few because few is described. A well-supported cladistic
analysis that finds some of the groups you mention closer to Pygostylia than
*Archaeopteryx* would be pretty good evidence for it, but at the moment
there is AFAIK nothing that can compete with the enormous analyses of
certain list members that usually don't find such topologies.

> Where do therizinosaurs fit in?

Phylogenetically? Next to oviraptorosaurs including *Caudipteryx* and
apparently *Protarchaeopteryx*.

> And what of _Mononykus_ and its friends?

Now this is a very good question. I personally still think they are very
close to Pygostylia (see posts by me and HP Mickey Mortimer a week or two
ago), but less and less people agree. We'll have to wait for the huge paper
on the new *Shuvuuia* specimen.

> Squawk!  I'll read Paul's book when it comes out.

Add me to the list of addicts on withdrawal... but first I'll cure my sleep
withdrawal :-)