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Re: Tyrannosaurus was not a fat boy or girl



In a message dated 10/24/11 12:16:28 PM, augustoharo@gmail.com writes:
>
> How is the degree at which pneumaticism reduces the density of the
 >body assessed in mass estimates?

We explicitly assumed that the pulmonary anatomy was restricted to
airsacs and lungs in the thoracic cavity (plus buccal, nasal and
pharyngeal cavities), and we varied the amount of the thoracic cavity
that the pumonary cavity filled between 25 and 50%, partitioned
horizontally (i.e. so that for the 50% iteration, the lungs/sacs fill
the dorsal 50% of the thoracic cavity). This was based approximately
on an experiment I did with a small pump, some tubing, a CT machine
and an intact chicken cadaver. Lungs/sacs etc were assumed to be
volumes of zero density, and their negative mass and negative effects
on CoM were used to adjust mass and CoM for the entire model. This
approach is better for CoM calculation as it does not assume
homogenous density. See Bates et al (2009), Allen et al. (2009) or
Hutchinson et al. (2011) for a more complete list of the assumptions
we made.

Viv