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Sinosauropteryx: 2 Questions



The '97 JVP annual meeting abstracts are out, with enough tantalizing
morsels to jam the list for months!  I won't make it to the meeting, but I
bet some of you will, you lucky dogs!

Of special interest to me is a talk entitled:
_Implications of Soft Tissue Preservation in the Compsognathid Dinosaur,
<Sinosauropteryx>_, presented by Nicholas R. Geist, Terry D. Jones, and
John A. Ruben, Department of Zoology, Oregon State University.

Paraphrasing the abstract, the presenters will state that the specimens'
"proto-feathers" show no feather microstructure, but are organized in a
fashion consistent with the collagenous connective tissue fibers which
support midline frills of extant (semi-aquatic) animals.  This apparent
frill feature, along with the extremely long tail, may suggest that
_Sinosauropteryx_ was a semi-aquatic theropod (according to Geist et al).

Having read the comments of Alan Brush, which compared the fibers to those
that support the frill of an iguana (and, notably, are so arranged as to
compare most closely with the frill found on extant _marine_ iguanas), I
was wondering when the semi-aquatic lifestyle theory would surface.  Now on
to my 2 questions:

1. Is there a simple explanation for why fossils may reveal integumentary
impressions in the plane of the rock -- but not elsewhere on a fossil --
when the living animal had sported a more complete insulating coat (i.e. on
the sides of the body in the case of the _Sinosauropteryx_ specimens)?  I
have heard that this is precisely the sort of preferential preservation one
finds in fossil birds, but I know neither whether this is indeed the case
in such fossils, nor why it should be so.

2. Do all extant birds sport feathers which are clearly identifiable as
such?  I have photocopied a full-page color close-up photo of a penguin
chick (Emperor Penguin, I believe) and I must say that the integument on
view looks indistinguishable from the fur of a mammal.  Naturally,
eyeballing a glossy magazine image cannot compare with viewing the actual
feathers under magnification, but I wonder what level of resolution of
microstructure is evident in the fossils of _Sinosauropteryx_ -- enough to
settle the issue?

I recognize that this discussion may seem premature in light of the fact
that Geist, Jones, and Ruben have not yet had their say, and I want all of
you to know that I mean no ill will or disrespect to the above-named
scientists.  I welcome any new data they can bring to this puzzle.

Ralph Miller III <gbabcock@best.com>

_Sordes_:               Fur sure!
_Sinosauropteryx_:  Get down!
_Pelicanimimus_:    Not so fast, "reptile-wing."  I tell ya it's a
bald-faced lie!