Re: Nemegtian tyrannosaurs

["Tim Williams" <twilliams_alpha@hotmail.com>]

Dinogeorge@aol.com wrote:

> Incidentally, that skull is significantly different in morphology from any 
> T rex skull. For example, it lacks any significant jugal spread, so that 
> the eyes are directed mainly sideways rather than forward. I've seen the 
> actual specimen, which was on tour a few years ago in Los Angeles. If any 
> two tyrannosaurids belong in different genera, T rex and T bataar do.

In his allometric growth paper, Currie agrees: _Tyrannosaurus rex_ and 
_Tarbosaurus bataar_ are accorded separate genera.  As stated previously, 
_Stygivenator molnari_ and _Dinotyrannus megagracilis_ are considered most 
likely to be juveniles of _T. rex_; and _Shanshanosaurus huoyanshanensis_, 
_Gorgosaurus lancinator_, _G. novojilovi_, and _Tarbosaurus efremovi_ as 
growth stages of _Ta. bataar_.  Thus, _Jenghizkhan_ is sunk into 
_Tarbosaurus_.  (Darn, I liked the name _Jenghizkhan_.)

However, there is hope for _Nanotyrannus lancensis_; Currie writes 
"quantitative analysis cannot distinguish this genus from other 
tyrannosaurids, but tooth count suggests that it is not a juvenile 
_Tyrannosaurus_ ."

Reference:

Currie, P.J. (2003). Allometric growth in tyrannosaurids (Dinosauria: 
Theropoda) from the Upper Cretaceous of North America and Asia.  Can. J. 
Earth Sci 40: 651-665.




Tim

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