Re: taxonomy is not stratigraphy (was Re: JVP 25(2): New Dinos, Birds, Discoveries)

[Tim Williams <twilliams_alpha@hotmail.com>]

Tim Donovan wrote:

>   Brochu said TMM 41436-1 was T. rex or a close relative. The latter is 
> probably true given the age of the Javelina and the relatively small size 
> of TMM 41436-1. (Carpenter also mentioned a short face compared to T. rex.)

A more recent paper dealt with this.  TMM 41436-1 is probably _T. rex_.

> It must have been a smaller ancestor of T. rex.

Why "must"?

> No wonder its tyrannosaurs were rather rare and Alamosaurus so common.

Actually, as pointed out in previous postings, _Alamosaurus_ is a 
wastebasket/dustbin for LK titanosaur material from North America.  Several 
titanosaur taxa may in fact be represented across the southern U.S.A.

> They hadn't yet evolved the size necessary to take on the titanosaurs in an
> environment dominated by them.

Even the largest of titanosaurs were small when they were young.  BTW, it's 
my personal opinion that theropod predators (including tyrannosaurs) 
typically targeted the smaller or weaker members of a sauropod herd anyway, 
and avoided the larger and stronger individuals.  This would be more in 
keeping with the behavior of modern predators.

Cheers

Tim