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New in Nature: Sinornithosaurus feathers
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
Thomas R. Holtz, Jr.
Department of Geology Director, Earth, Life & Time Program
University of Maryland College Park Scholars
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