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Re: FW: A Perspective on Cope's Rule



Tim Williams wrote:

> Also, the small animals = higher metabolism thing
> really only holds for endotherms.

+++++++++++++++++++

While the disparity in metabolism vs size, is greater
in automatic endotherms, I disagree that the small
animals = higher metabolisms statement doesn't hold
true for the rest of the animal world. The metabolism
of a little whiptail lizard, or anole, is noticeably
faster than that of a large iguana, or Komodo dragon.
That smaller reptiles have larger metabolic
fluctuations with temperature should be beside the
point, as the small critters usually work hard at
keeping their body temperatures high enough for their
metabolism to be at optimum efficiency. Hence why one
can go a few days between feeding an iguana, with no
ill effect (barring voracity). Whereas one would wind
up with a dead anole if one were to do the same with
it. It also helps explain why a little red eared
slider can live to 25-27 years of age, while a
Galapagos tortoise is considered to be near
bicentennial.

Of course there are the weird ones, such as tuataras,
but they are the exceptions, rather than the rules.

My minor quibble,

Jason

=====
"I am impressed by the fact that we know less about many modern [reptile] types 
than we do of many fossil groups." - Alfred S. Romer


                
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