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Re: Deinonychus claws expalined as climbing adaptions



Jonathan R. Wagner wrote:
> 
>         To head off another argument on this topic: many tree climbing
> animals do indeed have more than one climbing claw, in addition to other
> adaptations (fingers get longer going out, etc.). 

Thanks, Jonathan.  This reminds me of something else funky (IMHO) about
_Deinonychus_'s feet.  

There's a beatiful closeup of a _Deinonychus_ foot on pp. 130-1 of
DISCOVERING DINOSAURS IN THE AMNH (Norell, Gaffney, Dingus).  This is a
left foot, seen in profile from the left.  The foot shows a total of
four digits, with the innermost one vestigial and the superclaw on the
second one from the inside.  

Each digit on this foot has a different number of phalanges.  The
vestigial digit has 1.  The superclaw has 2. The next digit out from the
superclaw has 3, and the outermost digit has 4.  This makes the four
digits four distinctly different lengths.  Correct me if I'm wrong, but
don't most dinosaurs' feet have a roughly similar number of phalanges in
the major digits?  I would at least expect to find the two
weight-bearing digits with the same number of phalanges.  What benefit
did _Deinonychus_ get from this odd shape to the foot?

-- JSW