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Re: T-rex arms




On Tue, 5 Dec 1995 Rab3@aol.com wrote:

> In a message dated 95-12-04 19:00:10 EST, you write:
> 
> >Allosaurus hands might have been just big enough to do the job (though I
> doubt it) but what about Tyrannosaurus?
> 
> Do we really know enough about Tyrannosaurus' nesting behavior and the
> juveniles to speculate?  It seems the arms were utilized at some point in
> time.  Whether to climb trees, break out of an egg or to build nests.
>  Considering the precariousness of their balance, the added frontal weight of
> the arms must have served some purpose other than a vestigal remnant.
>  Perhaps while still young (and moderately sized) the arms assisted in
> grabbbing onto prey, becoming less functional as their size and jaws grew.

        The casts I saw showed a nasty looking gnarl of bone where the 
bicep had been pulled off the &*%$# bone of the T. rex forelimb. T. rex 
does NOT get such injuries by using these limbs to gather nest materials, 
scratch its butt, or whatever. The interpretation I heard: T. rex was 
holding something big. That something pulled away. That something was 
probably an Edmontosaurus or Triceratops or T. rex. 
The estimate, from muscle scars, 
mechanics, etc., was that the males could generate 450 lbs. of pull per 
arm, females 800. Again, this is not vestigial. Highly specialized yes, 
perhaps in Albertosaurus, where the limbs are much smaller, maybe 
vestigial, but not in T. rex, if these estimates are correct, and if the 
interpretation of this damage on the arm bone is correct. I agree, these 
arms were used for something, if they had that much muscle, and if they
 show this kind of traumatic injury and musculature. 

        -nick L.