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Re: Climbing dromaeosaurs?



At 02:01 PM 12/11/98 -0800, William Monteleone wrote:
>Randy King wrote:
>
>> >We've bandied about theories here concerning the utility of
>> >dromaeosaurs' enlarged hindclaws, and discussed the difficulty they'd
>> >have had slashing with them.  Some have suggested that the claw may
>> >have been used instead to climb trees.
>> 
>> I've never liked this theory.  There are many successful strategies
>> for climbing trees, and nothing like the dromaeosaur claw.  Although
>> it seems that such a claw would work, it doesn't seem like it would
>> work that well.  And if it did, three or four suck claws should work
>> better.  And it seems a sicle would work much better on a hand or
>> foreleg than the rear leg.
>
>In fact dromaeosaurs do have rather large sickle shaped claws on their
>hands. Those claws are smaller than the largest pes claw, but they are
>still incredibly large for the size of the animal.
>
>Also, when humans climb trees or telephone poles we strap on cleats with
>a single large spike on the inside of our foot. Hmm, that #II claw
>doesn't seem like a bad idea after all. There was an article in Science
>two or three years ago correlating pes claw curvature with perching
>behaviour in extant birds and -Archaeopteryx-. I wonder how the various
>dromaeosaurs would fit in the analysis.

Human climbing is different, even with these tools.  For one, the sicle 
is attached to a boot, so the whole leg is used for climbing, not just a 
toe.  Although practical, that is diffent from it being a viable evolutionary 
step that would essentially require every step to be an improvement.  The
climbing spikes are quite different from a sicle toe, and come in varied 
forms.   Did the toe have sufficient strength to support the animal's 
weight?  I would think that if it was used for climbing, the toe would 
be ossified to the foot, or some similar reinforcement.  What is the muscle 
attachment like?  Would the muscle be sufficiently massive?

Always with the questions.

-Randy