Permian ExtinctionS (was RE: Mega eruption may have wiped out [Cambrian] life)

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu]On Behalf Of
> Dora Smith
>
> Am I mixed up?   There was one major extinction during the Permian; at its
> end, supposed to have been caused by the Siberian traps, right?
>
One thing that seems to have confused you here is that the newly discovered 
flood basalt being discussed is from the Cambrian
Period, and thus as far from the Permo-Triassic extinction as we are today!

The other--and something that a lot of people don't appreciate--is that there 
is still good evidence of two major extinction events
during the Late Permian. The first of these, far less well studied, is the 
Middle-Late Permian boundary event (Guadalupian/Lopingian
or Capitanian/Wuchiapingian extinction). This would still be considered one of 
the great mass extinctions of the Phanerozoic, but is
greatly overshadowed by the even more phenomenal, Era-ending Permo/Triassic 
(Changhsingian/Induan) extinction event.

The latter IS being well-studied, and despite the occasional pronouncements of 
evidence of impacts at the time, most the lines of
research seem to point to an ultimate cause of the Siberian Traps volcanism, 
although a LARGE number of actual proximate causes
might have been implicated in the actual deaths of organisms (phenomenal 
greenhouse from the ignited coalfields of Siberia;
degassing of the methane clathrates of the ocean, themselves released due the 
aforementioned global warming; hypoxia in the
atmosphere; hypercapnia in the oceans; etc.). Basically a sucky time to be on 
Planet Earth.

Doug Erwin's recent book Extinctions gives an excellent very recent overview, 
as are Peter Ward's Gorgon and Mike Benton's When Life
Nearly Died.

                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/
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