RE: Dermal coverings

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> dbensen
>
> 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?

Based on their phylogenetic position, tyrannosaurids and ornithomimosaurs
(both of which are arguably closer to birds than are compsoganthids like
_Sinosauropteryx_) were feathered ancestrally.  Whether tyrant dinos would
have kept their "plumage" into adulthood is a separate question (and one
very difficult to answer at present), but the current best inference is that
tyrannosaurids were decendants of feathered animals.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.inform.umd.edu/SCHOLAR/programs/elt.html
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796