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T. rex monograph & CD



Greetings,

Just wanted to do a brief review of the SVP Memoir 7:

Brochu, C.A. 2003. Osteology of _Tyrannosaurus rex_: Insights from a nearly
complete skeleton and high-resolution computed tomographic analysis of the
skull.  SVP Memior 7. 138 pp.
&
Brochu, C.A. & R.A. Ketcham. 2003.  Computed Tomographic Analysis of the
Skull of _Tyrannosaurus rex_. SVP Memior 7 Supplemental X-ray CT data.

Details the anatomy of FMNH PR2081, aka "Sue".  Dispels many myths about
this specimen: in previous mentions of Brochu & co.'s various presentations
about this individual I've talked about on the list, I've said that
"everything you've heard about it in the public press is wrong".  Here's a
sampling:
* The so-called "missing chevron", whose absence was used to indicate that
this is a female, is not missing.  It's present.  If one accepts the
(essentially untested) chevron-sex link, then "Sue" is male.

* The alleged "dimorphism" among _T. rex_ is also untested.  There is
variation, yes.  Some of that variation might be due to growth, some to
individual variation, some to regional variation, some to sexual variation,
some to taphonomic factors, some to restoration errors.  In order to support
the statement "_T. rex_ comes in two morphs, gracile and robust", you need
to demonstrate this with measurements and numbers.  This has not been done.
        (As a side note, Brochu points out that "reversed sexual dimorphism"
(female larger) is most marked in those predatory birds which fly after
other birds, a behavior which (I quote) is "something tyrannosaurs likely
did not do."  :-)

* The anteriormost gastralia of _T. rex_ are fused into a plate-like mass,
as previously observed in _Tarbosaurus bataar_.  This mass is very similar
to that which Lambe called the "sternum" of _Gorgosaurus libratus_.  This
calls into question the presence of an ossified sternum in any
tyrannosaurid.  Futhermore, as I and others discuss elsewhere, there are
problems with the identification of all non-maniraptoran sterna among
theropods.  It may be that ossification of the sternum is a maniraptoran
trait.

* The supposed "bite marks" on the skull do not appear to be such; however,
there is a pattern of breaks to the right scapula, humerus, and ribs that
are consistent with a single traumatic episode. The pathological left fibula
may not be fractured, so claims that "Sue" would have definitely have been
incapacitated for a long healing period (during which it had to be
provisioned) are not supported.

* The supposedly "blade-like" teeth in the snout of "Nanotyrannus" are made
of plaster.  Their tooth sockets, however, are circular, rather than
elliptical.  (Okay, the posterior teeth, though, are more bladelike, as they
are in many tyrannosaurids).

The CD-Rom contains CAT scan animations and slice data.  I haven't found any
Easter eggs on it (as on the Alligator CD some years ago...).

Extremely cool stuff.

                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