RE: Major new paper on dromaeosaurids, with other significant maniraptoran info

[Tim Williams <twilliams_alpha@hotmail.com>]

Ronald Orenstein wrote:

> I've always thought (in my armchair-amateur way) that the best analogy for 
> the forelimbs of dromaeosaurs, from the point of view either of 
> prey-catching tools or tree-climbing implements, was a pair of ice tongs. 
> That would make the normal position of hands, with the claws facing inward, 
> perfect for grasping either prey (in which case the hind feet could be 
> brought forward with a disemboweling stroke, or the head downward for a 
> bite) or a tree trunk (in which case the hind limbs could hitch operated 
> while the front limbs maintain a grip, especially on a sloping trunk, such 
> as that on many arborescent cycads today). Thus, I can imagine a two-handed 
> scenario more easily than a one-handed, personally.

I like the ice-tongs analogy a lot (also in my armchair-amateur kinda way).  
Both forelimbs converged on large prey, and held it as the jaws (and feet?) 
went to town on the victim.  In the course of maniraptoran evolution, the 
precision one-handed grip was lost in favor of a specialized two-handed 
clasp.

The trunk-climbing hypothesis has been raised by Sankar Chatterjee, who 
further suggests that the synchronous trunk-climbing mechanism employed by 
the forelimbs was biomechanically equivalent to a rudimentary flight stroke. 
 Thus, here is another possible exaptive pathway for the evoluton of the 
flight stroke.


Tim

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