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Re: _Discover_ article

On the subject of nasal turbinates Nick Longrich wrote:

> the thing to do would be to look at animals with various lifestyles-
> say, polar bears, saiga and musk-oxen on the one hand, and animals
> that live in dry conditions on the other- camels, elephants,
> kangaroos- and see who has bigger RT structures.

I'm not so sure about the Arctic, but Antarctica is *extremely* dry.
Don't be fooled by the fact that there's a lot of solid water on the
ground; not much of that water makes it into the air.  

>       You know, that might make more sense, the heat loss bit. I
> mean, if it were there to conserve water, shouldn't it be in things
> like tortoises and desert lizards- some of which don't even drink,
> but take in their water from food.

I think you're missing an important point about the RT arguments here.
Endothermic animals potentially lose a lot of water via exhalation
because elevated body temperatures increase the capacity of the
exhaled air to carry water.  Combine that with the higher ventilation
rates necessary for maintaining metabolism...  A desert ectotherm
shouldn't be expected to lose nearly as much water as a desert
endotherm all other things (e.g. RT's) being equal.

Mickey Rowe     (mrowe@indiana.edu)