Re: Tyrannosaur species

["Thomas R. Holtz, Jr." <th81@umail.umd.edu>]

At 11:37 PM 4/8/99 -0600, John M. Dollan wrote:
>Some questions on Tyrannosaur classification....
>
>Is it Tyrannosaurus bataar or Tarbosaurus bataar?

Yes.  Most analyses place _T. bataar_ and _T. rex_ as each other's sister
taxon.  Whether you place _bataar_ in _Tyrannosaurus_ or put it in its own
genus _Tarbosaurus_ is a matter of taste.

Despite the inevitable Dinogeorge pro-"Jenghizkhan" posting, it is difficult
to distinguish _T. bataar_ from _T. rex_ when you take into account the
variablity of the different specimens (i.e., when you don't just use the
type _T. bataar_ skull and AMNH 5027, for example).  When you plot up
morphometrically the variations in the skull of the _T. bataar_ type
specimen and at least those smaller individuals I've had a chance to
measure, they have a LOT of overlap with those of _T. rex_.

>Is it Tyrannosaurus lancensis, or Nanotyrannus, or is it now believed to
>be a juvenile rex?

Standard Holtz reply #1: wait for the goddam paper!! :-)  (Okay, based on
the material presented at SVP, Thom Carr has established that "Nano." is a
juvenile, and made the very convincing argument that it is a juvie _T. rex_.
However, as that paper is not currently available to the general public,
let's just say that that hypothesis is the better supported right now).

>Thanks, and have a good Friday!!!

To you, too.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:tholtz@geol.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661