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Size limits of terapods?

A colleague posed a question to me recently about the limits to size in
animals. I'm hoping that someone on this list could suggest articles to
read since dinosaurs are much larger than other terapods. I'm less
concerned with the actual estimates than by the models by which these
estimates were made. For example, it isn't clear to me if the main
limitations are imposed by:

1. Structural limits. The cellular structure of bones (particularly in fast
   growing animals which may have less regular patterns of cells) may
   have strict limits for stress and strain, thus providing some limits
   on the size of the animal.

2. Physiology limits.  Limits to how much can be eaten, how hard the heart
   could pump without damaging either blood cells or the vascular system.

3. Thermodynamic limits. Can body temperature be maintained within certain
   norms *and* not overheat when the temperature rises.

4. Informational. Are there limits imposed by having a central nervous
   system for extremely large animal. Neurons require a finite amount of
   time to carry messages from the extremities.

5. None of the above. :-)

I'm sorry if this question is posed too simplistically. #2 (for example)
might be sensitive to the percentage of oxygen in the atmosphere. I'm sure
that this is old ground... any pointers would be welcomed.

Sean Doyle
home: doyle@tiac.net
work: mesozoic@mit.edu