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Meet Protopteryx: two Yixian maniraptorans in one week!



Howdy,

It is a banner week for Yixian maniraptorans.  First, in Nature,
_Microraptor_ a dromaeosaurid/troodontid/basal avialian.  Now, in Science,
the enantiornithine _Protopteryx fengningensis_:
F. Zhang and Z. Zhou, 2000.  A Primitive Enantiornithine Bird and the Origin
of Feathers.  Science 290:1955-1959.

_Protopteryx_ is a nearly-complete enantiornithine, with a good skull.  Lots
of great skeletal information there, potentially.  The article focuses on
the long _Confuciusornis_ like tail feathers, which lacks barbs or rami at
the proximal end.  The authors suggest the following evolutionary series in
the development of feathers:
(i) elongation of scales
(ii) appearance of a central shaft
(iii) differentiation of vanes into barbs
(iv) appearance of barbules and barbicel

However, they do consider the idea that since _Protopteryx_ is an
enanitornithine, and thus derived relative to birds with fully modern
feathers (_Archaeopteryx_, _Confuciusornis_), that these structures might be
secondary specializations rather than primitive retentions.

The Supplementary Information includes a cladistic analysis on Mesozoic
birds, with the characters and the matrix but not (at least currently) the
single most parsimonious cladogram that is supposed to be there.
Dromaeosauridae and _Archaeopteryx_ are used as the outgroups.  I ran the
tree, and it comes out with _Confuciusornis_ as the sister group to all
later birds, _Protopteryx_ as basal to other enantiornithines, and a
non-contraversial arrangement of ornithurines.

Nevertheless, in the AP news item on the subject
(http://www.msnbc.com/news/500149.asp?0nm=-21D)
Martin & Feduccia claim that this paper directly contradicts the idea of the
dinosaurian origin of birds.  Okay, to be fair, maybe this could be
interpreted as "in our view, the new information provided by these feathers
directly contradicts the idea of the dinosaurian origin of birds."  However,
the Supplementary Text shows unequivocally a standard model interpretation
of dromaeosaurids as the sister group to birds.  I REALLY wish I had seen
the supplementary information prior to talking to the reporter, so that I
could have made a bigger deal about it!!

In any case, a very cool new bird.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
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