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Re: Re[4]: Swimming mammoths and climate change

>See other postings about elephant swimming endurance.  See my prior
>posting about herds.  The author of _The Aquatic Ape_ has some 
>interesting theories about elephants being secondarily terrestrial, 

You don't need to go to this contraversial book for the evidence for
proboscidean secondary terrestriality (type THAT three times fast... :-)

Proboscideans are deeply nested within the clade Tethytheria.  Among their
outgroups are the sirenians (manatees and dugons) and the extinct
desmostylians, which look like, well, hmmm...  You have to seem them for
yourself.  In any case, desmosylians were also marine.

Furthermore, ancestral proboscideans, especially _Moeritherium_ does *not*
look like a pig or hippo (the way I've normally seen it restored).  It's
skeleton is long, low, and torpedo shaped.  It actually doesn't look very
far from a point of common ancestry with the sirenians: it looked like a
manatee with legs.

So, phylogenetic evidence strongly suggests a major aquatic component in the
life habit of the elephant lineage.

>>5)Inevitable interbreeding leading to genetic mutation, sterility and 

This is a common misconception.  Small populations WILL drift from the
mainstream, true.  However, this does not necessarily lead to sterility and
extinction.  In many cases (as many as there have been allopatric
speciations), the small population drifted far enough so that they were no
longer reproductively compatible with the mainstream.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661