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Re: Dinosaur diversity (was Re: paleontologist, dinosaurs...)



> George Olshevsky wrote:
> > you name it. Not to mention about 50 million years of
> > pre-_Archaeopteryx_ avians.
        There's no reason to assume that they took so long to evolve.
Archaeopteryx-like birds might have evolved from tree-climbing (or, if you
prefer, running) theropods in something like fifteen million years, give
or take a few million.
        That sounds rapid, but remember that bats and whales appeared very
well formed in the Eocene. It is possible that a pre-KT radiation of the
cetacea and chiroptera was underway already, but it seems to me somewhat
more plausible that that after the great vaccum left by the extinction of
sea reptiles, most birds and pterosaurs, that swimming and flying forms
should evolve. I'm not saying it did happen this way, but it seems like a
possibility.