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Re: question about plants in Mesozoic

On Thu, 3 Apr 1997 dis@gj.net wrote:

> I'm no expert, but most Jurassic plant groups are not known for their 
> nutritional value. 
>       Perhaps part of the large size in many dinosaurs is a result of 
> dealing with food resources of limited nutritional value.

In fact you would predict the larger dinosaurs would have consumed large
quantities of low nutritional value foods (the herbivores, at any rate).
The Jarmen-Bell relationship, right? The arguement here is that the
surface area to volume ratio is lower as size increases (area increases
with the square, volume with the cube), so that larger animals can take
advantage of the low valued food supply, while smaller homeotherms would
have to utilize the high nutritional value foods in order to keep up their
increased metabolic rates due to excessive heat loss (higher A/V ratio).

It certainly works in one direction, that is as the animal increases size,
the food nutritional value requirements drop.  But does it work in reverse
as a selective pressure, driving evolution to larger sizes?  Maybe.  If
the food supply is "lousy", then the only way to utilize it might be to
increase size.



Matt Fraser
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