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Re: mammal mystery



From: kmh <lonid@netone.com>
 > Okay, I got email from a kidlet asking why prehistoric mammals were so
 > small when so many dinosaurs were gigantic.  I'm assuming we can stick
 > to Mesozoic mammals like Haramiya and Alphadon on this one.  But
 > frankly, I don't have a clue why mammals remained relatively small in
 > comparison to dinosaurs.  Do you?  ...

My guess would be what is called competitive exclusion.  This is
a general phenomenon in ecology and evolution where an established
species (like an incumbent) tends to outcompete a newcomer in
areas of ecological overlap.  The general results is that the
newcomer is excluded from those resources the established species
uses effectively.

The application to this case is that dinosaurs already had the
large animal niches locked down, so the mammals were unable to
expand into them.  Once the dinosaurs were gone the mammals very
quickly were avble to expand into large animal niches.

swf@elsegundoca.ncr.com         sarima@ix.netcom.com

The peace of God be with you.