Re: Dromeosaur claws

["Jonathan" <spockjr@email.msn.com>]

Jeff said:

>
>       How does the curvature of dromeosaur sickle claws compare with those
>of other theropod claws?  Isn't a strongly recurved pedal claw a _derived_
>character, with less curved 2nd digit claws being primitve?  If so, it
>seems strange that dromeosaurs would evolve a recurved claw for slicing;
>I would think that a recurved claw would be better for holding then
>slicing.  How could you slice like a knife with a tighly recurved blade
>like that anyway?  You couldn't draw it very far (spare me analogies to
>scythes and sickles; we aren't talking about cutting skinny little stalks
>here).


Dromaeosaur (2nd pes) claws are extremely laterally compressed.
The shape is analogous to that of a, well, (sorry Jeff) sickle,
hence the nickname "sickle-claws".  It would have been quite
useful in slicing flesh.  They could be drawn far because the
joints are hyperextendable, reaching far beyond the point
of retraction of the other digits.  This is not to say that they
couldn't have used the claws for climbing or holding, but
looking at the rest of their anatomy, I would think the slicing
theory is the most parsimonious.  Besides, if the claw was for
holding, I wouldn't think it would be so laterally compressed
but would have had a rounder cross-section.  Claws used
for holding are generally much stouter.  Why have a claw shaped
like a blade if you're not going to slice something with it?

1 1/2 cents worth

Jonathan

Spockjr@msn.com