acid Sig-Lipps

[Doug Erwin <MNHPB028@xxxxxxxxxxx>]

I largely agree with Jere regarding the role of paleontology in analyzing
mass extinctions - although I think this is largely true for what Underwood
termed "pulse" events - very rapid catastrophic events.  This may not be
true for "press" events which have a longer duration. In contrast to Stanley's
recent Science Paper, I think the P/Tr was a rather prolongued event, with
a very rapid extinction pulse close to the apparent P/Tr boundary.  The
F/F seems to be a series of several stepped extinctions, whether press or
pulse isn't really clear.  This distinction may also have important implication
s for the nature of the recoveries following mass extinctions.
Doug Erwin