Re: Evolution of tyrannosauroid bite power

[ptnorton <ptnorton@suscom-maine.net>]

I agree. Whatever it was doing with its arms was risky business. Attributing 
such damage to display behavior does, however, explain why such damage was 
apparently not necessarily fatal. My understanding of the literature is that 
most of these M. bicep avulsions show signs of healing. If the arms were 
being used for something as critical to survival as prey capture, we would 
not likely see that.  If you can't grab your meal, you can't eat. If it was 
related to display behavior, however, the animal was probably much more 
likely to survive, although they might have been lower on the hierarchical 
dominance "pecking order" than they were before.

PTJN

----- Original Message ----- 
From: "Graydon" <oak@uniserve.com>
To: <dinosaur@usc.edu>
Sent: Tuesday, January 01, 2008 5:12 PM
Subject: Re: Evolution of tyrannosauroid bite power


> On Tue, Jan 01, 2008 at 05:14:00PM -0500, ptnorton scripsit:
> > Carcass lifting is a plausible alternative hypothesis to prey
> > grappling as an explanation for forelimb function in T. rex, given the
> > strength parameters so nicely described by Carpenter and Smith (2001).
> > Carcass lifting is biomechanically possible, consistent with
> > behavioral science with respect to the nearly ubiquitous presence of
> > dominance display
>
> I have some doubts about this.
>
> We know for sure that whatever T. rex was doing with its forearms
> damaged them.
>
> While damage from direct dominance *competition* is common, damage from
> display behaviour is not.  (And even in the case of dominance
> competition, there's a lot of selection pressure against permanent
> damage, presumably because no organism starts as the dominant bull
> equivalent.)
>
> I would suggest that making a claim of display behaviour commonly
> leading to damage is a very strong claim, because this is an extremely
> uncommon behaviour across tetrapoda.
>
> -- Graydon