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FEATHERS AND FEATHER-LIKE STRUCTURES AS AN ORNITHODIRAN SYNAPOMORPHY



Or more simply, why ornithischians probably had some sort of non-scaly
integument.

Jaime Headden wrote:
<>

I must protest (as it seems, I have only been protesting to Jaime's posts
lately, nothing personal).  I find the idea that all ornithodirans, that is
dinos and pterosaurs ancestorally had some sort of non-scaly integument.

There is evidence of hollow filiments or fibres in pterosaurs that appear to
be rather straight (stiff).  This is remarkibly similar to the condition of
the fibres seen in Sinosauropteryx.  It is my position that these are
homologous to eachother and to feather rachi.  If this turns out to be the
case, it is most parsimonious to assume that ornithischians (and sauropods)
had similar skin structures.

There are numerous ways to test this theory.  First and foremost is good
microscopic studies of the fibres in Sordes and Sinosauropteryx, as well as
good chemical analyses of said structures by someone who's very qualified
(Mary Schweitzer comes to mind).  Also, some good ornithischians found in the
Yixian wouldn't hurt either.  Are there any new psittacosaurs that no one has
mentioned because this is the theropod mailing list?

Peter Buchholz
Tetanurae@aol.com

Some Ichthyosaurs were brown