RE: The new Archaeopteryx from... Wyoming?

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

> From: Guy Leahy [mailto:xrciseguy@sbcglobal.net]
>
> Wow... a very cool specimen indeed:
>
> http://www.sciencemag.org/cgi/content/full/sci;310/5753/1483
>
> I find it interesting that Archeopteryx and Rahonavis
> fall out in the cladogram as closer to troodontids
> than dromaeosaurs.

Actually, they found their Archie-Rahonavis clade as the sister taxon to 
Deinonychosauria as a whole, but have Confuciusornis as the
sister taxon to Microraptor within an otherwise-conventional Dromaeosauridae.

>  Perhaps powered flight was
> acquired (and lost) multiple times within Paraves.

Perhaps. Or (as I have argued before), perhaps actual powered flight is limited 
to Pygostylia or even a more restricted clade
(Ornithothoraces perhaps?), and small members of the other paravian branches 
had limited aerodynamic ability (WAIR, gliding, etc.)
rather than actual powered flight.

> I had the opportunity a few weeks ago to view the
> mounted Buitreraptor skeleton at the Field Museum.  I
> was struck by how gracile the skeleton was.  It looked
> more like a long-armed troodontid in general form than
> most dromaeosaurs... :-)

Quite so. In fact, as we get more basal specimens from each of Pygostylia, 
Dromaeosauridae, Troodontidae, and Archaeopterygyidae,
they are getting far tougher to tell apart...

                Thomas R. Holtz, Jr.
        Senior Lecturer, Vertebrate Paleontology
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/
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