Re: Nemegtian tyrannosaurs

[Dinogeorge@aol.com]

In a message dated 5/28/03 9:51:13 AM Pacific Daylight Time, 
twilliams_alpha@hotmail.com writes:

<< 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". >>

No, Maleevosaurus is most likely a juvenile T efremovi. There would be only 
two species of tarbosaur--T. efremovi and T. bataar. There is then no need to 
invoke anything special about site taphonomy to explain anomalous abundance of 
juveniles/subadults. And indeed, adult/juvenile ratio in T efremovi then 
becomes very close to adult/juvenile ratio in T rex. This is >much< more 
parsimonious than building epicycles and deferents, so to speak, out of 
climate, 
environment, site taphonomy, preservational bias, etc., etc. Simply something 
like 
lions and leopards coexisting in modern Africa. Existence of same morphological 
features in T efremovi and T bataar is, as usual, due to close phyletic 
relationship between the two species, but not necessarily to identity of the 
species.