Re: So-called Sickle Claws

[Dann Pigdon <dannj@alphalink.com.au>]

Peter Von Sholly wrote:
> 
> I disagree.  I believe there was a large "heel pad" under the distal ends
> of the 3 metatarsals and that all three toes bent forward from there, with
> pads of their own, especially under the claw of digit 2, the so-called
> killer claw.  There is plenty of room for that toe to reach the ground.  I
> think one can easily get the wrong idea by looking only at the bones and
> foregetting what the soft tissues would do and the space they would fill.
> And what about the animal's ability to walk, run and balance?  You don't
> think that would be compromised by the need to walk only on its two outer
> toes?  To me it creates an unrealistically awakward , compromised creature.
> Also, absence of evidence may indeed not be evidence of absence, but where
> are the two-toed footprints, after all?
> 

Ostriches cope quite well with only two toes per foot. I think the
closest modern analogy for dromaeosaurs would probably be the
cassowarie. It has a modified inner toe claw that is quite distinct
in shape from the others. It is shaped like a long bladed carving
knife, and it uses this as a weapon to defend itself, its young,
or its territory. However the claw is still straight and the toe
bears weight like the other two. I would expect that if dromaesaur
inner foot claws also bore as much weight as the other two load
bearing ones it would probably have been straighter that it was.
To suggest that such a large curved claw was part of a toe that
bore as much weight as the others to me suggests a creature that
would have been even more disabled that one that had only two
fully load bearing toes.

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        Dann Pigdon
        Melbourne, Australia
        http://www.geocities.com/capecanaveral/4459/

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