Re: Dynamic modeling deinonychosaur claws

[Phil Bigelow <bigelowp@juno.com>]

On Thu, 03 Nov 2005 08:40:44 -0500 "Andrew A. Farke"
<andyfarke@hotmail.com> writes:

> It is my hope that a simple (isotropic material properties) model of 
> a claw
> would adequately describe its behavior. However, we will never know 
> unless
> we try it first in a modern animal!


Yeah....
As soon as I posted the idea, I came down with a severe case of: 
I-doubt-this-is-gunna-work-itis.

The problem is exactly as you describe.

Actually, there are more than a few problems with such a study.  Let's
assume that we avoid casting the claw, and instead use CAD/CAM to carve a
Utahraptor claw from a cow bone.  Here are only a few  potential problems
(of many more):

1) Until we know the micro-osteology of Utahraptor's claw, we can't use
just any old cow bone as our carving blank.  The micro-textural
properties of the cow bone must be exactly the same as Utahraptor's claw
(or at least quite close).

2) Does Utahraptor's claw have a small medulary cavity?  If so, it must
be carved into the cow bone or else the test results will be meaningless.
 What about the percentages of spongy bone, woven bone, laminar bone in
Utahraptor's claw?  Their percentages, too, must be duplicated in the cow
bone, and in the proper order.

I feel a headache coming on......
But wait, there's more.

If we abandoned the idea of carving-up cow bones and instead use a
casting medium (which will probably be isotropic in its grain structure)
to create the test claw, will its properties accurately mimic fresh
Utahraptor bone (which is composed of  water-saturated, highly oriented
bone crystals, interlayered with collagen)?  That question can probably
be answered now:  "It's extremely doubtful".

I agree, however, that a study of the relative strengths of extant raptor
claws would be a good starting point.

<pb>
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