RE: New tyrannosaur articles

["Jaime A. Headden" <qilongia@yahoo.com>]

Nick Pharris (npharris@umich.edu) wrote:

<And was then lost in the basalmost members of all three groups?  Hmmm...>

  In the Bayesian constraint, Snively et al. used the Theropod Working
Group's analysis (Clark et al. 2002), which places all arctomet taxa apart
from one another, so that none form a closely monophyletic clade except
*Avimimus* with Caenagnathidae. Otherwise, Tyrannosauroidea is basal to
Ornithomimosauria + Aves, Ornithomimosauria is basal to Alvarezsauridae +
Birds, and Alvarezsauridae is basal to Oviraptorosauria + Aves. The
presence of the arctomet did not alter the other phylogenies under the
constraint, and the support for nodes did not change. But this does show a
more functional relationship between the development and subsequent nature
of the arctomet and the Troodontidae, Ornithomimosauria, and
Tyrannosauroidea, suggesting these features can be added to the analyses
to test for their relationship.

  Ref:

  Clark, J. M., M. A. Norell, and P. J. Makovicky. 2002. Cladistic
approaches to the relationships of birds to other theropod dinosaurs. pg.
31-61 in Chiappe, L. M. and L. M. Witmer (eds.) _Mesozoic Birds:
Above the Heads of Dinosaurs_. (Berkeley: University of California
Press.)

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


        
                
__________________________________ 
Do you Yahoo!? 
Yahoo! Mail - You care about security. So do we. 
http://promotions.yahoo.com/new_mail