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Re: Pollen From Permian/Triassic Extinction Show UV Induced Mutations




On Sun, 19 Oct 2003, David Marjanovic wrote:

> OK. But then we need at least 2 causes for the P-Tr mass extinctions.

There is almost always more than one cause for ecological
events.  That should be the starting point for any discussion on
extinction.

> And what could have killed off animals with small
> adult size but not small juveniles of bigger species?

Recent Nature paper notes that smaller (adult) animals are limited by
predation, whereas larger animals are limited by food supply--and, there
is little predation on their juveniles.  Reasons for this are that small
adults spend more time in an age range that is targeted by more predators;
juveniles of large animals are just passing through that age range.