[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
RE: Dynamic modeling deinonychosaur claws
> Phil Bigelow (firstname.lastname@example.org) wrote:
> <It may be useful to computer model and then test the relative shear
> and torsional strengths of the curved pedal unguals of various curved-claw
> predatory dinosaurs. It would be valuable to know the absolute maximum
> of force that each species' unguals can take before they break. Test for
> maximum sagital force, maximum lateral force, and maximum twisting force.
> knowing the maximum compressive force may prove informative.>
>And Jaime Headden wrote:
> I agree. With the history of attention to sickle claws (over 75 years)
> study has been done on the actually _strength_ of the unguals or the
> application of various forces to various points on the ungual. This would
> be a
> useful study, and I think it's actually rather simple to do. If we can
> the various unguals in 3D, there are rather simple FEA tests that can be
> to provide analysis, including testing for a keratin covering of various
This is probably a case of our ideas outpacing the current state of
research. The results of FEA are *strongly* affected by things such as
material properties (and with a claw, you don't want to assume an isotropic
bone fabric!), direction of stress application, etc. Without validation of
the proposed methods in an extant animal, the analysis is incomplete. So, I
don't know that FEA is necessarily the magic bullet (yet) to compare claw
strength across a variety of taxa.
To do this study properly, someone (not me. . .I've got enough on my hands
with the goat heads these days) needs to:
1) Get claws from a variety of extant animals (owls, eagles, wildcats, etc.)
with the help of the local wildlife management agency
2) Test the material properties of the claws in these animals (Young's
3) Wire the claws up with strain gauges
4) Load the claws in a biologically reasonable manner and measure the strain
5) Digitize the claws and model the claws using FEA, with realistic material
6) Compare the results between the FEA and the "real world" analyses. If
there is a correspondence, *then* proceed to step 7.
7) Model claws in dromaeosaurs, using FEA
8) Interpret results with extreme caution
In the world of computerized dinosaurs (whether locomotion studies, FEA,
beam theory, or whatever), steps 1-6 and 8 are sorely needed in most cases.
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!