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Re: "No Bolides!"



In a message dated 96-04-05 17:19:43 EST, you write:

>>        What do people think about the Pleistocene extinctions in North 
>>America? They seem comparable to the Late Cretaceous. We've lost wooly 
>>mammoths, sabertooths, dire wolves, teratorns, lions, giant lions, 
>>horses, ground sloths, phorusrhacids, cheetahs, rhinos, those dog-bear 
>>things, and plenty of other animals.
>
> You're comparing apples to oranges.  The difference here is that the
> Pleistocene extinctions were caused by the extremely successful
> hunting techniques of one predator, namely us.

I might also add that _climate_change_ was the major cause of the mass
extinction of the Pleistocene. The last major retreat of the glaciers
ca 10Ka that destroyed mammoth habitat (among others) and a
concomitatnt increase in more efficient predation by our ancestors
just just did the large mammals in. Interestingly, I have seen two
NOVA programs that report mammoths surviving up until 4Ka on remote
Wrangel Island above the arctic circle. They survived by evolving into
pygmy forms. A more recent NOVA? showed a similar trent towards
pygyism by American mammoths (or was it mastadons?) escaping the
ecological disaster on the mainland and migrating to Catalina Island
of of California! Unfortunately with the latter, I have a problem with
the researchers notion that large mammoths could have swam the several
miles of Pacific ocean to reach the island. There must have been a
land bridge IMHO.

Regards,
Thomas R. Lipka
Paleontological/Geological Studies