"Matt Lewis"  wrote in message 
news:cj86nj$2tft$1{at}darwin.ediacara.org...
> I've been wondering for a while about this and it seems that the main
> advantage to maintaining a constant body temperature is that it allows
> mammals and similar animals to maintain a high rate of cellular
> respiration even in cold conditions.  This in turn allows the animal
> to perform activities requiring lots of power, e.g. hunting, even in
> very cold conditions.  However, animals such as sharks are apparently
> able to produce high enough levels of power to hunt even in arctic
> waters.  This seems to imply that they are able to respire rapidly
> regardless of their internal temperature.  If this is the case, why
> are mammals not able to perform the same trick and if they are why do
> they waste energy maintaining body temperature?
>
> Thanks for any help,


> Matt
Possibly because during the long mesozoic era, when dinosaurs ruled most of 
the earth, the mammals were only able to dominate the colder regions of the 
globe, such as high elevations and polar regions.  To do this, they would 
have had to be homeothermic (warm-blooded).
---
þ RIMEGate(tm)/RGXPost V1.14 at BBSWORLD * Info{at}bbsworld.com

---
 * RIMEGate(tm)V10.2áÿ* RelayNet(tm) NNTP Gateway * MoonDog BBS
 * RgateImp.MoonDog.BBS at 9/27/04 12:15:15 PM