Re: Nemegtian tyrannosaurs

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

Jaime A. Headden <qilongia@yahoo.com> wrote:

> George has stated his data is more right by invoking parsimony, but by the 
> basic
> understanding of parsimony, the _a priori_ rejection of the multitude of 
> data to favor one or two features for an alternate topology is not, in 
> fact, parsimonious. George has not shown why *T. efremovi*, 
> *Maleevosaurus*, and *G. lancinator* are not juveniles of *Tarbosaurus 
> bataar*, which is a questionable approach to regarding them as valid taxa
> versus the adult forms.

Jaime took the words out of my mouth.  In order to uphold the validity of 
_Maleevosaurus_ and _Jenghizkhan_ as genera separate from _Tarbosaurus_ 
(type species _T. efremovi_, in this context), one has to first demonstrate 
why Currie's allometric study is flawed.  In my opinion, he builds a very 
strong case, drawn from analysis of a very large data set.  I'm convinced.

George's thesis is that the apparent bias of adult over juvenile specimens 
of _T. rex_ in North America can be extrapolated to eastern Asia.  Ergo, the 
type specimens _T. bataar_, _T. efremovi_, and _Maleevosaurus novojilovi_ 
each probably represent adults, therefore the differences in body size are 
potential diagnostic characters of separate species.  This is not a robust 
argument, however, given the available evidence.  No way does it qualify as 
"parsimony".




Tim

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