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Swimming mammoths and climate change
>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.
Actually, this can be easily refuted. I don't have the author's name on me,
but in a paper in the Journal of Biogeography in their early years, an
ecologist cited and document the very good swimming ability of elephantids.
(Part of their tethythere heritage?). Indian elephants habitually swim off
the mainland to islands several kilometers out to sea in search of food.
He did compare this to the mammoths off of the California coast, and showed
that the distances they would have to swim were comparable to those that
Elephas maximus does today.
(One place to find the ref, before I can dig it up, is McGowan's _Dinosaurs,
Sea Dragons, and Spitfires_. This was the original source from which I
found the paper).
Another note: for those who suggest that climate change cannot bring about
the extinction of large endotherms: the Cenozoic record contains many such
instances. Just because an individual animal can withstand a wide range of
temperatures does not mean that its food can, that it will be capable of
breeding in the new climate, that its offspring can survive the new
temperatures, humidity, etc.
Thomas R. Holtz, Jr.
Vertebrate Paleontologist Webpage: http://www.geol.umd.edu
Dept. of Geology Email:email@example.com
University of Maryland Phone:301-405-4084
College Park, MD 20742 Fax: 301-314-9661