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Re: mass extinction



> There was a major extinction of megafauna at the end of the Pleistocene on
> all major landmasses except Africa that was almost certainly caused by
> humans and affected a few hundred hundred species of mostly large mammals
> and smaller numbers of birds and reptiles.
>
> Also there was a *very* large extinction in the Pacific when it was
> colonized by the Polynesians. The size is uncertain since most islands
> haven't been studied yet, but it certainly affected many more species than
> 800. From the number of extinct species found on the islands that have
> been
> investigated David Steadman estimates >2000 species *of birds alone*, i e
> 20% of the extant bird species
> of the World.
>
> Another major extinction occurred on Madagascar 500-2,000 years ago. Total
> number of affected species is not known, since there has been very limited
> research as yet.
>
> In short major extinctions have occurred essentially everywhere where
> humans have settled, but particularly on islands. However it is not
> considered polite to mention extinctions that occurred before the
> Europeans
> arrived, hence that 500-year limit.

And we are in the midst of (potentially) a massive marine extinction due
to recent (last 50 years) changes in marine harvesting techniques
(including benthic trawlers) and phenomenal mismanagement of fisheries.

Keep in mind: the pre-human mass extinction record is only of common,
easily preservable taxa. We don't have that good a direct record of what
happened to the rare or the poorly-preserved at the K/T or P/Tr or what
have you.

Oh, and Crichton's science in "State of Fear" is laughably bad. But then
again he thinks that Uri Geller has magical psychic powers, too, so his
grasp of what is real science isn't that good.

                Thomas R. Holtz, Jr.
        Senior Lecturer, Vertebrate Paleontology
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
        Mailing Address:
                Building 237, Room 1117
                College Park, MD  20742

http://www.geol.umd.edu/~tholtz/
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796