Re: T. Rex sex(es)

[Tom Holtz <tholtz@geochange.er.usgs.gov>]

>I apologize if this question has already been answered in the past year.
> (I've been a member of this list for about four months):
>What is the latest research on T. Rex? Do the robust and gracille versions
>represent two species or two sexes? Or is it still a giant guess?
>I'd appreciate whatever information anyone can provide.
>Thanks a lot,
>Fossilman (a true amateur)

The latest I've seen are some of Peter Larson's papers, both titled
"Tyrannosaurus Sex", one in the DinoFest volume, one in the Dinosaurs of
Wyoming volume (sorry, don't have the refs on me at the moment).  With the
exception of Bob "I've never met a taxon I didn't like" Bakker, I think
everyone else is pretty satisfied with the two morphs being two sexes of a
single species.  Given the vast similarity within the rest of the skeleton,
that seems to be the most likely.

However, it is still a "giant guess" in a certain sense, because there is
always some question as to how much of the variation we find in fossils is
due to individual differences, and how much is due to other forces
(separate species, different sexes, different ages, etc.).

                                
Thomas R. Holtz, Jr.                                   
tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092
U.S.A.