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RE: Theropod limbs - how mobile?



 
Rutger Jansma wrote:

> Was there in the paper an image that I could possibly have or you can
> give additional information about it, for example, what the range of 
> finger movement was?

Alan Gishlick's article in the _Ostrom Symposium Volume_ describes the
movement of _Deinonychus_'s forelimbs in details, and includes some
excellent figures.


> Let's say he didn't, the following makes perfect in a neoflightless sort
> of way...: take Deinonychus, big bad Dromie. The immobility in it's 
> hands make it difficult for capturing prey, 

David provided a good answer to this, so I won't elaborate.  Suffice to say,
the forelimbs of dromies were specialized for a powerful and stable
two-handed grasp, not manipulation by one hand (like our hands are).

> >Sort of like what Ostrom proposed over 30 years ago.
>
> But not necesairry incorrect.

No; I was actually supporting Ostrom's idea that the hands and feet acted in
a coordinated fashion to grasp, hold and subdue prey.

> >It is interesting to note that, based on _Eotyrannus_, the craniodental
> > specializations seen in tyrannosaurids preceded truncation of the
> >forelimbs.
>
> Nasal rugosities don't count :)

Like David, I was thinking 'teeth'.  The specialized dentition of
tyrannosaurids has mentioned a lot on this list - and is covered extensively
in the literature, along with overall cranial morphology and what it infers
for their predation methods.

> Or they could not have had a function after all. When something get's
> progressively shorter, that is done for a reason and when it is getting
> shorter, it is not known for a fact that it had a function as time went
> by.

But, in the case of tyrannosaurids, the forelimbs were endowed with a
substantial musculature.

By the way, I can only guess what _Carnotaurus_'s lifestyle could have been.
I have wondered if this gracile theropod was a scavenger that used its short
horns to 'dig' into titanosaur carcasses, in concert with the tearing action
of the jaws.



Tim