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Re: Extinction scenarios



In a message dated 8/17/98 10:13:01 AM, Jonathon Woolf wrote:

<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.>

My comments were directed to the question of how a NON-BURROWING, LAND-
DWELLING MAMMAL might appear in the fossil record on both sides of K/T.
Everything you mentioned either burrows, lives underwater or can hybernate in
mud.  These would all be EXPECTED to survive a momentary pulse of white heat
from an atmospheric pressure wave coming in from Chixulub.  I don't see a
problem if one or two agile land dwellers survived elsewhere, then returned in
a geological instant to their former range.
    Tom Hopp