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Re: Dino down

One thing that we must recognize is that whatever the preserved
_Sinosauropteryx prima_ fibers are, they are apparently not comparable to
down feathers as we know them today.  The description of the fibers in the
January 8 _Nature_ article on _Sinosauropteryx_ does concur with Philip
Currie in characterizing the fibers as being apparently hollow, and seems
to accept his interpretation that there is an apparent branching aspect in
some of the preserved fibers.

But the authors of the _Nature_ paper also point out that the fibers are
considerably thicker than the fur fibers of comparably sized mammals, so in
this important respect, the fibers are anything but downy, and "may" have
performed more like the coarse fiber of a large mammal.  However, this does
not mean that the fibers are so stiff as, say, porcupine quills, for Philip
Currie has characterized them (based on his study of the fiber shape and
position as preserved in the fossils) as having been flexible structures
(in the living animal).  So, whatever the superficial anatomical
similarities may be to the down of extant birds (and these features are not
to be dismissed, for they hint at the possible tie between the integument
of this theropod and the feathers of birds), the fibers on _Sinosauropteryx
prima_ may have functioned somewhat differently than down, and therefore
their performance should not be judged on the basis of the efficiency of
the down feathers of extant birds.

-- Ralph Miller III     gbabcock@best.com