Re: Siamotyrannus and early tyrannosaurids

[Thomas_R_HOLTZ@umail.umd.edu (th81)]

Tim Williams wrote:

>Aren't there at least two tyrannosaurs of equal or older age than
>_Siamotyrannus_?
>
>I heard of a braincase from the Dinosaur National Monument of Utah 
>(i.e. Late Jurassic) that supposedly comes from a small tyrannosaur.  
>The last I heard of this braincase is that it had been provisionally 
>referred to _Stokesosaurus_ (which was regarded as a tyrannosaurid by 
>Jim Madsen back in the 1970's).

The braincase refered to Stokesosaurus DOES look like a primitive
tyrannosaurid, and is even closer to Itemirus (which may be a basal
tyrannosauroid, but may be closer to dromaeosaurids).

>There's also a small, headless tyrannosaurid from the Early 
>Cretaceous of Mongolia.  (I only know of this one through 
>Dinogeorge.)  _Tonouchisaurus_ is it's name (_still a nomen nudum_ 
>as far as I know).

This is a ~1 m long, two-fingered creature from the Gobi.  Presumably, like
many other Mongolian Early K dinosaurs, it is Aptian-Albian (and thus,
younger than Siamotyrannus).

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661

"There are some who call me...  Tim."