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Psittacosaurid hair



"Gunter" <guntervanacker.mesozoic@pi.be> wrote:
 
> About a week ago, I received a shipment of newly
> published books that included "Dinosaurs of the Isle
> of Wight" (Martill & Naish) and "Extreme Dinosaurs"
> (Luis Rey). Both books contains images of
> Psittacosaurus with "hair-like" structures (mainly)
> on the dorsal side of the tail. > 
> On the interpretation of the gastroliths;

This is EXTREMELY exciting. I am absolutely thrilled!
But, before we jump to conclusions, we need more
details on this "hair-like" integument. Is it truly
hair, or just very elongate scales? If you took the
average anolis lizard (with its very fine scalation)
and elongated them a few centimeters, you would have
hair. We must be sure this feature is homologous with
that of basal coelurosaurs like Sinosauropteryx before
we begin making sweeping statements like "feathers are
plesiomorphic to the ornithodira" (not that i'm
accusing you of that). There is some evidence that
basal theropods had rows of scutes rather than
feathers. So, let's explore the other possibility; did
the predentates evolve an integument convergently?
While we don't have a varied sampling of unrelated
endothermic taxa, all of them do possess some form of
insulation. Perhaps hairy or feathery coats are a
predictable adaptation that arises in all organisms
with a heightened metabolism. Before I end this brief
response, I urge all of you to be cautious about this
discovery. Let's hope this isn't another
"Archaeoraptor" incident, and that something valuable
can be learned from the fossil, but until then I will
remain skeptical. Lastly, if one of you has a picture
of this fossil, I would love to see it. 

Cheers!

Waylon Rowley

"A _Psittacosaurus_ with hair?" 

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