Re: T. rex the Licensed Hunter

["Larry Dunn" <larrydunn@hotmail.com>]

gbabcock@best.com wrote:

>Let me begin by saying that I greatly respect John R. Horner, but 
disagree
>with his characterization of _Tyrannosaurus rex_ as being primarily an
>obligate scavenger.  

Agreed on both points.

(snip)

>I propose a different modern analog: the 53-ton sperm
>whale!  It is the largest extant predator (excluding filter-feeding 
baleen
>whales, which clearly don't compare with theropods at all), 

I think there's no evidence that there's *ever* been a larger predator 
upon large life-forms than P. catodon (old thread turns over in grave).  
But I must say I don't see any analogy between P. catodon and T. rex 
either.

(snip)

>Unlike the tyrannosaurid, it is a swimming animal, but, like a
>tyrannosaurid, it has no forearms and grabs prey with huge jaws which 
are
>studded with robust teeth (although, unlike a tyrannosaurid, the whale 
only
>has teeth on the mandible).  

I must say that I see no comparative value here.  I think you're 
implying that Horner's argument concerning useless forearms is weakened 
by the example of P. catodon, but life in the water has it's own 
entirely separate set of demands and allowances. For that matter, so 
does life on land as a quadruped (many have compared T. rex's mouth-only 
pursuit strategy to wolves, dogs and other predators, but T. rex was not 
a quadruped and did not weigh eighty pounds).

What (terrestrial) animals have ever existed that can be analogized to 
theropod dinosaurs in terms of both body configuration *and* mass?  None 
to my knowledge.  This must make rigorous study of theropods both 
frustrating and intriguing.  It certainly seems to limit useful 
comparisons to those within the group itself (theropod to theropod).

So I'd propose that the better question to ask is: how does T. rex 
compare to other theropods?  If they fairly obviously used their 
forelimbs as part of their predation tactics, what does this mean about 
T. rex?  Does T. rex compensate in other ways to satisfy assumed 
required criteria for active predation?

This leads to the next query: is Horner correct in saying that theropods 
actively pursuing their prey required useful forelimbs as well as jaws 
to secure and subdue prey?  If so, do T. rex's unique features (if I am 
correct: robustness of teeth, neck vertebrae and jaws, and length of 
legs) compensate for the lack of effective grasping forelimbs?

For what it's worth, I've been convinced by the many persuasive 
arguments that a jaws-alone strategy for T. rex was viable.  But put a 
few glasses on wine in me and I'll believe anything.

Larry

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