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Re: So-called Sickle Claws

Rob Meyerson wrote:
> Ronald I. Orenstein writes,
> >Of course dromaeosaurs had (or at least some had?) remarkably-stiffened
> >tails.  These I have usually seen interpreted as stabilizers for balance
> >during sharp turns or other ground-based manouevres - but I am,
> >hesitatingly, wondering whether they might not have been useful in
> >tree-climbing as well.  Is there anything about the mechanical structure of
> >their tail that would make this unlikely?
> Personally, I like the idea of aboreal dromaeosaurs.  Yet, I have one concern.
> Imagine an animal the size of _Dienonychus_ hanging from the trunk of a tree.
> The majority of the weight of the animal would have to be borne by the two
> sickle-clawed toes.  Were the toes strong enough to bear all that weight?
> Wild speculation: Is it possible that the hand claws could have helped at all;
> or would the other toes have been of any help?
        Tree kangaroos do quite well with feet not much different
to their terrestrial relatives. They seem to use their clawed hands
just as much. I have often thought that the smaller dromaeosaurs
(< 2 metres long) would have been light and agile enough to
be able to climb. Perhaps they were not totally arborial, but I'm
sure they managed to scale fallen logs, embankments, and perhaps
the occational tree well enough. Infants may have particularly
benefited from being able to climb well. Perhaps the foot claws
were used mainly for climbing in infants, and adopted as hunting
tools when they were adults. The claws of the hoatzin come to mind,
they seem to be more well developed as chicks than in the adults.


        Dann Pigdon
        Melbourne, Australia