Dermal coverings

[dbensen <dbensen@gotnet.net>]

Okay, this is my very first message to the Dinosaur Mailing List, so I
ought to ask some all-encompassing, impossible-to-answer question.

Alright, what about dinosaur dermal coverings?
We know from several new fossils (namely the ones at Laoning) that some
dinosaurs _did_ have feathers.  We also know (of cource) that birds have
feathers.  Therefore, any clads in-between advanced birds and dinosaurs
such as _Sinosauropteryx_ must have had some sort of feathers too.
Other fossils (those new therizinosaurs with feathers) verifies this
conclusion.  How far back do feathers go, though?  Did tyrannosaurs have
feathers?  Did ornithmimes?  Did ornithscians have feathers (I know we
have skin imprints of hadrosaurs, so the answer to that last question is
probably 'no').  Perhaps, since pterosaurs had hairlike dermal
structures, ALL advanced achosaurs had hairlike body coverings (and all
scaled dinosaurs are secondarily adapted).