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Re: The Lion, the Witch and the New Papers



--- On Mon, 6/30/08, Tim Williams <twilliams_alpha@hotmail.com> wrote:

> Rounding off with some nice biomechanical work (then again,
> I'm biased).
> 
> Moreno K, Wroe S, Clausen P, McHenry C, D'Amore DC,
> Rayfield EJ, and Cunningham E. (2008)  Cranial performance
> in the Komodo dragon (_Varanus komodoensis_) as revealed by
> high-resolution 3-D finite element analysis.  J Anat. 212
> (6): 736-746. 
> 
> Abstract: "The Komodo dragon (_Varanus komodoensis_)
> displays a unique hold and pull-feeding technique.  Its
> delicate 'space-frame' skull morphology differs
> greatly from that apparent in most living large prey
> specialists and is suggestive of a high degree of
> optimization, wherein use of materials is minimized.  Here,
> using high-resolution finite element modelling based on
> dissection and in vivo bite and pull data, we present
> results detailing the mechanical performance of the giant
> lizard's skull.  Unlike most modern predators, _V.
> komodoensis_ applies minimal input from the jaw muscles
> when butchering prey.  Instead it uses series of actions
> controlled by postcranial muscles.  A particularly
> interesting feature of the performance of the skull is that
> it reveals considerably lower overall stress when these
> additional extrinsic forces are added to those of the jaw
> adductors.  This remarkable reduction in stress in response
> to additional force is facilitated by both internal and
>  external bone anatomy.  Functional correlations obtained
> from these analyses also provide a solid basis for the
> interpretation of feeding ecology in extinct species,
> including dinosaurs and sabre-tooth cats, with which _V.
> komodoensis_ shares various cranial and dental
> characteristics."

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Just thought I'd chime in a bit with this one (as Tim knows, I am also somewhat 
biased here :) )

Moreno et al did an excellent job using FE analysis on Komodos. Their results 
show that oras actually have rather weak bites, but the skull bones are aligned 
in such a way that they "lock up" rather well when pulling back. This allows 
them to exert pullback forces that can be an order of magnitude greater than 
those produced by the jaw adductors. A great design for an animal that takes 
down large vertebrate prey using a skull composed of struts and beams.

Oh, and extra points for not bringing up the erroneous statements about oras 
killing their prey by "bite and release" "envenomation."

Jason