Re: Daspletosaurus: Part 2

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

At 05:58 PM 2/3/98 -0600, Seth wrote:

>So does anyone think they know what the evolutionary history of this animal
>was?  Direct line to Tyrannosaurus rex?  Crossed to Asia, gave rise to T.
>bataar, which crossed to U.S. and became T. Rex?  Who did it come from and
>where did it go?  No way whatsoever to even begin to tell?

Too derived to be directly ancestral to Tyrannosaurus.  Given our current
(relatively poor) sample size of tyrannosaurid taxa, and a spotty record of
Asian tyrannosaurids (what's going on between the Iren Dabasu and the
Nemegt?), it is difficult to say for certain a particular migration pattern:
very likely multiple crossings.

Basic cladogram (see forthcoming Tree of Life page):
Tyrannosauridae
   Aublysodontinae (very weakly supported)
      Aublysodon mirandus
      Alectrosaurus olseni
      "Aublysodon" molnari
   Shanshanosaurus (not certain that this is a) an adult and b) if its
premax teeth are serrated.  Would love to get to China to check this out!)
   Tyrannosaurinae
      Alioramus remotus
      advanced tyrannosaurines
         Gorgosaurus libratus
         Albertosaurus sarcophagus
         very advanced tyrannosaurines
            Daspletosaurus torosus
            Tyrannosaurus
               (Nanotyrannus, if real)
               (Maleevosaurus, if real)
               Tyrannosaurus bataar
               Tyrannosaurus rex

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