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Re: Extinction scenarios



TomHopp@aol.com wrote:

>     Regarding survival of non-burrowing mammals in Montana:  Did they survive
> in Montana or Asia or Newfoundland?  Any small population could have spread
> out to reclaim a devastated world in a geological trice, so how do we really
> know ANYTHING survived in Montana?

Laurie Bryant's study of Montana nondinosaur vertebrates found a total of more
than forty species that occur on both sides of the K-T boundary: 10 fish, 7
salamander, 3 frog, over a dozen turtle, 1 champsosaur, 4 lizard, 1 snake, 3
crocodilian.  Exactly how many turtle taxa survived is unclear because turtle
fossils are extremely common in the study area, and their taxonomy is somewhat
muddled.  I submit that while the replacement scenario may explain one or two 
or a
few species appearing both before and after, it does not explain the 
reappearance
of a combination of forty different species.  Were _all_ of these species so
cosmopolitan that they occured both in Montana and in a refugium half a world
away?  Rather unlikely, I think.

-- Jon W.