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Re: JFC-Bloodiest Battle ??
On Friday, August 22, 2008, at 04:44 PM, Dan Chure wrote:
Take a look at the dorsal view of the skull of Monolophosaurus or
Sinraptor. While vertical loads might be accommodated, I am less
certain about resistance to torque along the long axis of the
preorbital region, especially given all the pneumatic penetration of
They do indeed have quite narrow rostra. Resistance to torsion is
related to the polar moment, however - the sum of the section moduli
about any two orthogonal axes. In this case, that means that the
lateral breadth and dorsoventral breadths both matter. So, allosaur
skulls might be a bit weak under lateral bending loads, but I wouldn't
expect them to be especially weak against torsion, as compared to an
animal with a dorsally flattened skull (obviously a skull that's broad
in both directions resists torsion the most). There is a bit of a
difference imparted by the fact that the source of resistance is along
a broad surface in one type, and a narrow one in the other, but the
specifics of bracing and strain distributions around foramina will
probably make a bigger difference in that regard.
(Note that the statements regarding torsional resistance are purely
general and qualitative in this particular case - a precise
relationship can be easily predicted for a long bone, or similar
element, but skulls require something like FEA to get a real value).
Michael Habib, M.S.
Center for Functional Anatomy and Evolution
Johns Hopkins School of Medicine
1830 E. Monument Street
Baltimore, MD 21205
(443) 280 0181