RE: Many, many thoughts & responses re: the Hutchinson-Garcia pap er

["Williams, Tim" <TiJaWi@agron.iastate.edu>]

Philidor wrote:

>Just three questions in advance of finding out more:  have the potential
>prey animals for T. rex been checked with the same sort of models?  If
>it turns out they could escape consistently, that might have >implications.

Then again, it may have no implications whasoever.

Okay, let's say that some clever person calculates that _Triceratops_ and
_Edmontosaurus_ could achieve a top speed greater than possible for
_Tyrannosaurus.  (I doubt that this will prove to be the case, but for the
sake of argument, let's go with it.)  Does this mean that _Tyrannosaurus_
did not prey upon live _Triceratops_ and _Edmontosaurus_, and therefore it
was a scavenger?  Probably not.  If modern mammal predators are any guide,
then theropods probably targeted the less mobile members of a large prey
species - the old, the young, the wounded, the sick, the parasite-laden...  

A healthy _Tyrannosaurus_ would have to be very stupid (or very hungry, and
therefore desperate) to target a fully-grown 6-8 tonne _Edmontosaurus_ in
peak condition.  Sure, I'd bet money that _Tyrannosaurus_ would be most
likely to prevail in a head-to-head contest.  But any serious injury could
be lethal to a predator that has to be mobile in order to catch it's next
victim.  It would not be worth the risk.  



Tim




------------------------------------------------------------ 

Timothy J. Williams 

USDA-ARS Researcher 
Agronomy Hall 
Iowa State University 
Ames IA 50014 

Phone: 515 294 9233 
Fax:   515 294 3163