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Re: Follow-up: the truth about killer dinosaurs

T. Michael Keesey wrote-

> Though none of the tyrannosaurid skin impressions has been specified to a
> certain body area, are we to believe they were all pedal?

If they can't be assigned to a specific body area, are we even sure
they're tyrannosaurid? (I admit I don't know the details very well.)

One was found by the ilium and gastralia, but the skeleton was disarticulated (Tanke, DML 1996). The Gorgosaurus impression which lacked scales (Currie, 2001) and MOR impressions noted by Tanke haven't had their position described.

> I can't picture replacing feathers with scales, but what if the juveniles
> had scales with feathers in between (like opossum tails have scales and
> fur), then shed the feathers perminantly on the way to adulthood. Of
> course, if I'm going to posit that, I wonder if impressions of interspersed
> feathers would be preserved at all in Judith River sediments (or Morrison or
> La Colonia for that matter).

Moreover, _Dilong_ doesn't show this, so it would have to be a derived
trait of tyrannosaurids. Simpler hypothesis: sparse feathers in adult
tyrannosaurids, along with areas of scutellae (including at least the

Dilong doesn't not show it though. Remember, the soft tissue over the body often decayed in Yixian animals. That's why we get halos of integument for the most part in coelurosaurs. In Dilong, we have tail feathers dorsal and ventral to the vertebrae and chevrons, with absolutely nothing preserved where any skin or scales would be.

Mickey Mortimer