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RE: Caudipteryx not a bird and more from APP



> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Dora Smith
>
> My understanding is that caudpteryx and some other close relatives of birds
> are controversial as to whether they are birds.

Although the very first paper on Caudi suggested it was closer to birds than it 
was to other dinosaurs, all subsequent phylogenetic
analyses that include other non-avian dinosaurian taxa put at least some of 
those closer to modern birds than is Caudipteryx. In
fact, part of the fun experience's at the Ostrom Symposium about six years ago 
(damn, was it really six years ago!) was to see
analysis after independant analysis all converging on the "Caudipteryx is an 
oviraptorosaur or oviraptorosaur-relative" answer.

So in terms of the morphology of the animal, it isn't especially "bird-like" 
any more so than  Microvenator (for instance), and less
bird-like than Microraptor.

> It is also sometimes
> argued that they are evidence that archeopteryx are not birds' direct
> ancestor but a dead end.

Yes, some have argued that. But see above.

> It would be really good to be able to do genetic studies to determine if all
> modern birds are really descended from teh same lineage of dinosaurs - I see
> real cause to wonder.

Of course, exactly which non-avian dinosaur genetic sequences were you going to 
compare them too?

More importantly, though, is the fact that the morphology of all modern birds 
shares numerous specialized features (and by no means
just flight-related features, but features in all part of the anatomy) which 
are more similar to each other and to fossil Cenozoic
and maybe a couple late Late Cretaceous forms than any of these are to typical 
Mesozoic birds. So it is certainly reasonable to
suspect that Archaeopteryx and/or Rahonavis and/or Confuciusornis might have 
independantly derived from non-avian dinosaurs. But
modern Aves are a strong a monophyletic group (relative to the traditional 
non-avian dinosaurs) as exists in Nature.

>    More than one line of dinosaurs were evolving in
> birdlike directions.

This has been advocated by various workers.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
        Mailing Address:
                Building 237, Room 1117
                College Park, MD  20742

http://www.geol.umd.edu/~tholtz/
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796