Re: paleonet Fwd: NYTimes.com Article: A Stark Explanation forMankind From an Unlikely Rebel

[Peter Ward <argo@xxxxxxxxxxxxxxxx>]

I defer to Doug Erwin and Sam Bowring on the marine P/T, but can tell you
that the highest Dicynodon sp. in the Karoo occurs just beneath a
laminated unit unique in the Karoo that coincides with a major C13 isotope
anomaly.  These results will appear in the next issue of Geology (Smith
and Ward, 2001) based on three years of field collecting.  So, at least in
the sections I am familiar with, the mass extinction as marked by the
vertebrate fossil record falls coincident with an event bed.  However, the
Triassic, once defined by the presence of the first Lystrosaurus sp, can
no longer be based on that taxon, since Lystrosaurus is definitely a
Permian taxon that survives the extinction.  From my experience the taxon
formerly known as Proterosuchus might best mark the base of the Triassic
if vertebrate fossils are used in non marine sections.  Plant microfossils
will obviously be better.



Professor Peter D Ward
Dept of Geological Sciences
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