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RE: gigantism in mammals vs. dinos. (was: crocs eating hadrosaurs



John Bois wrote:

>On Sun, 5 Jan 1997, Nathan Myhrvold wrote:
>> Large mammalian herbivores like wildebeest, zebra, elk, bison etc.
>> typically carry only a single baby per year...
>
>And yet their numbers dominate the large-animal, open-field niches of the
>world (similar niches that dinos used to own).
>
>> Bjorn Kuretin, and other mammalian paleontologists have specualted that
>> mammalian reproduction is a fundamental limiting factor that has limited
>> mammals (particularly terrestrial mammals) to smaller sizes (generally
>> speaking) than the upper limits for dinosaurs.
>
>"Limiting" here must be used in a strictly technical sense.  Being big
>for dinos may have been a response to ultimately dooming selective
>pressures.  Since mammals don't have the same fecundity problems as
>dinos (after all, they only have to have one offspring to maintain
>populations), they don't have to resort to such ultimately unfit
>strategies as gigantism (relatively speaking).

        Forgive me if I sound thick, but I don't follow you here.  Are you
speaking only of _large_ mammals?  When you say that mammals only have to
have one offspring to maintain populations, I flash onto
bottom-of-the-food-chain mammals like mice and voles.  These of course
breed like mad to stay ahead of predation.


bruce

        "The more television I watch, the more I wonder why I'm not already
supreme ruler of earth."  --Dogbert