ECTOthermic feathers? (was RE: Psittacosaurus Complexus)

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

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Garrison Hilliard
>
> On Thu, 6 Dec 2001, Jaime A. Headden wrote:
>
> <snip>
>
> I know this is tangential (but I think of interest in the endo-exothermic
> wars)... has any exothermic animal ever had feathers?

1) It is "ectothermic" for cold-bloods: that is, "outside heat" (as opposed
to "endothermic" = "inside heat").  Exothermic would be heat-projectors,
like Gojira or Smaug the Golden... :-)

2) There is only one group of feathered animals alive today: birds.  All
birds are warm-blooded.  However, all living birds ALSO represent a
monophyletic group which excludes plenty of extinct feathered animals, from
Apsaravis and Hesperornis through Confuciusornis and Archaeopteryx through
Caudipteryx and Sinornithosaurus and Sinosauropteryx.  So on a purely
phylogenetic basis (that is, not taking in other lines of evidence), one
could argue that endothermy evolved after feathers, possibly even after the
split between Apsaravis and modern birds.

3) The things on the psittacosaur have NEVER BEEN described in detail, and
calling them "feathers" is at the present time wholly inappropriate.

                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.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796