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RE: Tyrannosaurs with leathery skin, etc.
> From: firstname.lastname@example.org [mailto:email@example.com]On Behalf Of
> Larry Dunn
> Dinosaur restorations depicting leathery-
> ("elephant-") skinned animals are often criticized
> based on fossil evidence that some dinosaurs had scaly
> _Pelecanimimus_ at least apparently had smooth skin
> (and presumably feathers).
Importantly, the only patch of the integument clearly preserved was on the
dewlap/throat pouch/whatever. This was naked. Of course, throat pouches
are sometimes naked in animals with other sorts of integument (pelicans, for
> So what about
> _Tyrannosaurus rex_? That ballyhooed skin imprint was
> only *associated* with the T. rex find, correct?
> So, assuming it had feathers when newly-hatched as is
> currently being knocked about (a big assumption), and
> then shed its feathers as it grew, what would be left
> skinwise on an adult animal? Animals don't develop
> scales as they age, do they? Does this lead to
> elephant-skinned tyrannosaurs?
Animals CAN develop scales as they age: experimental mutant chickens show
that the same follicles that typically produce feathers can produce scales,
and vice versa.
> Further to this, if _T. rex_ chicks (or whatever the
> hell they are called) had feathers for insulation, how
> would "non-coelurosaur" theropod chicks be any
> different in terms of a need for feathers?
Not fully warm-blooded...?
Honestly, remember that the reason tyrannosaurids are now thought to be
descended from feathered animals is that they are phylogenetically bracketed
by known feathered critters. Thus, it may not have been a *need* of
tyrannosaurid chicks, but of the ancestral coelurosaur chicks.
Tyrannosaurids inherited this condition from their ancestors.
It is also important to point out that we currently do not have a secure
"lower bounds" on the origin of feathers: it COULD be a coelurosaur
character, but it could also be an avetheropod character, or a tetanurine
character, or even a general theropod character (requiring adult
_Carnotaurus_ to have lost their feathers). The coelurosaur position
represents the best "upper bound" position based on current evidence.
Thomas R. Holtz, Jr.
Department of Geology Director, Earth, Life & Time Program
University of Maryland College Park Scholars
College Park, MD 20742
Phone: 301-405-4084 Email: firstname.lastname@example.org
Fax (Geol): 301-314-9661 Fax (CPS-ELT): 301-314-7843> Yahoo! Shopping: