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Re: Tyrant stuff (no longer ranting) (was RE: Rant (was RE: Details on SVP 20...



In a message dated 10/16/02 7:40:12 AM Pacific Standard Time, 
tholtz@geol.umd.edu writes:

<< One could argue that potentially for me, Carr, Currie, and Brochu (of whom 
I
 have the only published matrix, but that would be potentially accessible to
 the other authors).  However, neither Ken Carpenter nor Greg Paul utilized
 such matricies, worked from a different taxonomic philosophy, yet arrived at
 the same conclusion. >>

Carr & Williamson's paper was key to my abandonment of Aublysodontinae as a 
separate taxon, as well as my agreement to implode tyrannosaurid taxa into 
just a few genera after accounting for ontogenetic changes. It's going to 
take a powerful lot of scholarship now to get me to believe in >adding more< 
new species. They better be >really< different from the others (like 
Alioramus, for example), something I have yet to see in what has so far been 
published about them.

About 13 years ago I, too, believed that rex and bataar were closely related 
within Tyrannosauridae, but I never found a satisfactory answer to the 
question of how bataar could have crossed the Bering Strait to give rise to 
rex in North America (bataar is a bit earlier in time than rex). Plus I 
actually got to see the bataar skull, and it is >so< different from the skull 
of rex. There aren't many genera described from both Mongolia and North 
America (Saurolophus seems to be one, and it may simply have swum the strait 
somehow, although I doubt it), so it's necessary to examine the known 
instance with a microscope to see whether there really is congenericity.

I think what really happened in Mongolia is that Tarbosaurus efremovi, which 
may turn out to be a complex of species just like Albertosaurus is in North 
America, gave rise to a giant Mongolian species, T. bataar, much like 
Albertosaurus produced a giant North American species,Tyrannosaurus rex. 
That's what it looks like to me right now, based on what has been published 
on tyrannosaurids thus far. I'm not wedded to this hypothesis, but I'd like 
to see some better data. Maybe the forthcoming Hurum et al paper on 
Tarbosaurus will provide some.