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Tyrant boots (was RE: Questions)



> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Mickey Mortimer
>
> Steven Mahon wrote-
>
> > > Tyrannosaurids lack an ischial foot.
> >
> > What?! Do they or do they not?! Does Eotyrannus have
> > it or not!?
>
> Well, the holotype of Tyrannosaurus has an ischial foot.  But
> RTMP 81.61 and
> AMNH 5027 lack one (Carpenter, 1990).  The holotype of Gorgosaurus also
> lacks a foot (Lambe, 1907), as does juvenile specimen AMNH 5664
> (Matthew and
> Brown, 1922), and Tarbosaurus (PIN 551-2; Maleev, 1974).  So much like
> ornithomimids are coded as having a foot because all but one specimen (a
> Dromiceiomimus) has it, tyrannosaurids are coded as lacking a foot because
> all but one specimen does.

Indeed. Also, questions of invididual variation, preservation, and improper
restoration apply when examining these things.

(Speaking of which, it might be worth it to get to Pittsburgh again to
confirm if the boot is real or not...)

> Eotyrannus doesn't preserve an ischium, Dryptosaurus' is too poorly
> preserved to tell, and other basal tyrannosauroids lack described
> ischia as
> well.

Quite so. If, for example, Santanaraptor proves to be a basal tyrannosauroid
(** speculation **), then the probability that other, more derived
tyrannosauroids would ALSO lack an ischial boot would be pretty good.

                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