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Re: really big question



Cliff Green wrote-

>        After the Chinese small feathered dromaeosaurs came to light a few
years ago, every paleoartist, Myself included, has portrayed every kind of
remotely 'raptorish dinosaur with feathers of one kind or another. Well
that's only fair, using Occham's Razor. Right?

Yes, members of the Sinosauropteryx + Aves clade are most parsimoniously
feathered.

>     OK. Many professionally rendered Ostrich Mimic dinosaurs in the past
decade have been portrayed as being feathered also. I am assuming that this
is due to Ostrich mimics supposedly being cladestically close to
dromeaosaurs. Or are they?

Well, according to Hwang et al.'s (2004) analysis, it would be equivocal.
According to Senter et al.'s (2004), they fall within the feathered clade.
The problem is the exact position of Sinosauropteryx relative to
tyrannosauroids and ornithomimosaurs.  If alvarezsaurids are ornithomimosaur
relatives though (sensu Sereno, 1999), Shuvuuia's feathers support feathered
ornithomimosaurs no matter where Sinosauropteryx goes.

>     I recently came across this while doing research for a potential
commission. Pelecanomimis Polyodon, ( pelican mimic with many teeth ) a
small two meter ornithomimid, was found in Spain just over ten years ago. It
has amazing muscle and internal organ preservation. It also has great skin
impressions with not only zero plumage, but no scales as well. It has smooth
skin with a dewlap and a occipital crest on the back of it's head. It also
has a keritaneous beak with a mouth full of 200 small teeth. It is
considered to be a primitive form.

Ah, here's where the problem lies.  Pelecanimimus was originally reported as
having extensive impressions of feathers (Perez-Moreno et al., 1994).  Later
(Briggs et al., 1997), it was shown these were actually muscle fibers and
microbial mats.  But there has been no report as to how much are muscle mats
and how much is skin.  The only naked spot specified by Briggs et al. was
the throat pouch.  Lots of feathered birds have naked throat pouches, so
that doesn't tell us much about the majority of Pelecanimimus' integument.

Incidentally, Santanaraptor preserves extensive impressions of naked skin,
and seems to be a basal coelurosaur of some sort.  If it's related to
Ornitholestes, as my brief review suggested in 2000, and we use Hwang et
al.'s topology-
(Allo(Tyranno(Ornithom(Ornithol(Sinosaur(Alvarez,Enigmo,Paraves)))))), then
the (sometimes ambiguously) unfeathered taxa are all conveniently more basal
than the feathered ones.  Then again, I don't agree with that topology, so
it's just coincidence in my mind at the moment.

Mickey Mortimer
Undergraduate, Earth and Space Sciences
University of Washington
The Theropod Database - http://students.washington.edu/eoraptor/Home.html