New in Nature: Sinornithosaurus feathers

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

This just in:

Xu, X., Z.-h. Z. & R.O. Prum.  2001.  Branched integumental structures in
_Sinornithosaurus_ and the origin of feathers.  Nature 410: 200-204.

The authors point out that, in general, the filamentous integumental
appendgages as preserved of _Sinornithosaurus_, _Beipiaosaurus_, and
_Microraptor_ are indistinguishable from the contour feathers as preserved
in _Confuciusornis_, _Eoenantiornis_, and _Chanchengornis_.

Furthermore, additional preparation of the body coverings of
_Sinorthosaurus_ reveals a LOT more detail.  These are not solitary fibres,
but compound structures of multiple filaments, joined together at least at
the base, and in some cases with a central shaft.  Those joined only at the
base are identical in structure to avian natal down.  Those with a central
shaft are identical in structure to the barbs and rachis of pennaceous
feathers.  However, there is no sign of barbules on these elements, so these
don't form a nice closed pennaceous vane.

In other words, SOME of the feathers in _Sinornithosaurus_ are the same as
bird natal down, and some represent a previously hypothesized (Prum. 1999.
J. Experimentlal Zool. Mol. Dev. Evol. 285: 291-306) intermediate stage in
feather history.

Cool stuff.

                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