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Re: Protarchaeopteryx



At 09:02 AM 1/21/98 EST, Alan Brush wrote:
>The main reason that Protarchaeopteryx is called a bird, is because in the
>only available publication, Ji & Ji (1997) refer to it as a bird. The
>specimen in the Bejing museum is casually refered to as a bird. This is due
>in large part to the presence of feather impressions.
>  In the discription (in Chinese) they assign it to the Archaeopterygiformes
>Furbringer, 1888.
>  There are, at present, no discriptions in the English literture.

Ji & Ji also called Sinosauropteryx a bird...

Having received some new photos of Protarchie (thanks, [name withheld to
prevent excessive requests to the individual in question]!), it actually
does have some "birdy" features:

It's tail is reduced in length more so than any non-ornithothoracine
(advanced birds) Iberomesornis, Enantiornithes + Ornithurae) or
non-Confusciusornis theropod.  In other words, it is shorter compared to
trunk length than in all nonavian theropods AND shorter than in
Archaeopteryx, but longer than in all other birds.  It does not seem to have
a pygostyle, which makes it more primitive than all birds except for Archie.

It's hand is less derived than all birds (INCLUDING Archie, but excluding
Confuciusornis in this case), in that the relative length of the thumb is
not reduced (the end of the thumb claw is at the level of the midlength of
phalanx 2 of digit II (as in dromaeosaurids, oviraptorosaurs, etc.), rather
than at midlength of phalanx 1 of digit II (as in basal birds).

The pubis? Can't say from the photos I've seen so far.  Good bet on
opisthopuby, though, given the tail reduction.

So, contra yesterday's posting, there is some evidence for it being closer
to birds than are dromaeosaurs.  However, it does seem to be a bit of a
mosaic (big surprise there... :-), so its precise phylogenetic position will
be best approximated using a more complete database, rather than one or two
cherished characters.

Back to doing up the syllabi...

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661