Pelecanimimus and Sinosauropteryx

[luisrey@ndirect.co.uk (luisrey)]

I disagree with Nino in his comparison of Pelecanimimus and Sinosauropteryx.

Comparing the two specimens, the soft tissue preserved in Pelecanimimus
shows indeed naked skin and no feathers or scales, but has nothing to do
with the 'mane' of Sinosauropteryx that runs down its back and actually
becomes a double row of parallel pre-feather clusters that continues all
along the tail to the very tip. There's no way those structures are
muscular remains.

The detailed close-up photographs of the fossil on the latest Audubon
magazine are so clear that I find it striking that anyone has doubts about
the structures being feathery or hairlike, although perhaps not in the
classic avian way. The preservation is perfect, almost Messel-like.

Olshevsky had a theory that bird feathers developed from a double row of
ornamental scales on the back of arboreal archosaurs. By the time of
Sinosauropteryx, those scales were well on its way of becoming feathers
(Developing as display or insulatory elements from the top midline of the
animal downwards).

If Pelecanimimus didn't have feathers or scales, that could be a good proof
that Pelecanimimus actually didn't need the feathers and shed them. Just
the typical featherless skin of a bird. Otherwise, it would be funny that
it actually shed its reptilian scales without passing through any stage of
feathery, hairlike or  insulatory material.That might be possible, but
unlikely.

I advocate the notion of pre-feathers as an archosaurian trait and a very
specific characteristic of the Dinosauria, wher it was taken to the extreme
of specialization in birds and proto-birds.

Regards.   Luis Rey

Luis Rey

Visit my website http://www.ndirect.co.uk/~luisrey