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Advice and a New Paper



If I might...  If you're going to be snippy, especially in public, you
should be extra cautious about the things you're asserting as facts.
For instance, it's not a good idea to state:

>  I have not actually been talking about _sounds_, nor apparently was
>  the person you initially responded to when you brought up "earth
>  shaking," "earthquakes," etc.

when trying to end a thread that effectively began:

] It would be amazing to see one of these animals alive.  I wonder
] what the sound was like when they walked by on earth

and the initial response to the earth shaking message included:

} Well, I wasn't expecting a huge thumping noise but a four-foot wide or
} wider foot coming down in scrub foilage had to be a bit noisy

Of course I suspect everyone here is familiar with the Jurassic Park
scene showing the vibrations in the cup as the tyrannosaur was walking
some tens of meters away.  Great drama.  Horrible science (as Nick
implied).  Yes, sound would propagate through the ground, and as
Martin indicated with his story about the wood, it would propagate
better than through air.  But the water in Ian Malcolm (Jeff
Goldblum)'s cup wouldn't be noticeably disturbed nor would he hear a
sound like someone pounding on drums.  And it's more than a little
unlikely that you'd hear much from sauropods walking by.  But speaking
of smacking thingss...

Blanco, R., E., Jones, W., W., and Rinderknecht, A. (2009). "The
sweet spot of a biological hammer: the centre of percussion of
glyptodont (Mammalia: Xenarthra) tail clubs", Proc. R. Soc. B 22
November 2009 vol. 276 no. 1675 3971-3978.

Abstract

The importance of the centre of percussion (CP) of some hand-held
sporting equipment (such as tennis rackets and baseball bats) for
athletic performance is well known. In order to avoid injuries it is
important that powerful blows are located close to the CP. Several
species of glyptodont (giant armoured mammals) had tail clubs that can
be modelled as rigid beams (like baseball bats) and it is generally
assumed that these were useful for agonistic behaviour. However, the
variation in tail club morphology among known genera suggests that a
biomechanical and functional analysis of these structures could be
useful. Here, we outline a novel method to determine the CP of the
glyptodont tail clubs. We find that the largest species had the CP
very close to the possible location of horny spikes. This is
consistent with the inference that they were adapted to delivering
powerful blows at that point. Our new analysis reinforces the case for
agonistic use of tail clubs in several glyptodont species.

Anyone doing this for Ankylosaurs?  Anyhoo, this is the same issue
that has the  description of _Qiaowanlong kangxii_, so that's out now.

-- 
Mickey P. Rowe     (mrowe@lifesci.ucsb.edu)