Re: Archaeopteryx, Sinornithosaurus, Rahonavis, Unenlagia...]

[Josh Smith <smithjb@sas.upenn.edu>]

"Thomas R. Holtz, Jr." wrote:

> > From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> > Josh Smith
> >
> > > Josh Smith wrote:
> > >
> > > > ...If we have critters
> > > > with edentulous beaks, true pygostyles and such coeval with
> > > > _Archaeopteryx_, this is a big problem.
> > >
> > > No problem at all.  Modern birds coexist with lizards, bats with
> > > various gliding mammals.
> >
> >     Well, actually, it IS a big problem in this case because we have
> > been supposing that _Archaeopteryx_ is the ancestral taxon to this
> > animals with the pygostyles.  If they are coeval, then it becomes
> > difficult for _Archaeopteryx_ to be the ancestral taxon.
> >
>
> Of course, this is only a problem if you are still actively searching for
> direct ancestors, rather than sister taxa...

    Oh, Oh right.  Bring systematics into it.  Right!  Well, be that way...
    Unfortunately, you need to bring that argument to the Ji's and to Sun et
al. and some others, who are calling for pulling _Archaeopteryx_ out of the
direct bird line because of the "Jurassic" age of Sihetun.


--
Josh Smith
Department of Earth and Environmental Science
University of Pennsylvania
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