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RE: K-Pg extinction sum of multiple events?
I am no expert on this subject but I have just been reading Nichols and
Johnson's awesome book Plants and the K T Boundary (2008, Cambridge). It warns
repeatedly that the Signor - Lipps effect has been ignored in investigations of
the K T event. Signor-Lipps is an artifact of uneven fossil distribution that
can cause apparent stepwise extinctions right before a real extinction event.
In other words, it can cause false signals of extinction events right below
I got the Tobin et al. paper as a pdf and searched it. They do not mention the
Signor Lipps effect nor cite the work of Signor and Lipps 1982.
Nonetheless their data are interesting, their sample is said to be very
complete, and it is interesting to see that Antarctic average temperatures in
the Maastrichtian don't seem to go much above 9 or 10 degrees.
I have an open mind.
From: owner-DINOSAUR@usc.edu [owner-DINOSAUR@usc.edu] on behalf of Ben Creisler
Sent: Tuesday, July 10, 2012 12:05 PM
Subject: K-Pg extinction sum of multiple events?
From: Ben Creisler
A new online paper:
Thomas S. Tobin, Peter D. Ward, Eric J. Steig, Eduardo B. Olivero,
Isaac A. Hilburn, Ross N. Mitchell, Matthew R. Diamond, Timothy D.
Raub & Joseph L. Kirschvink (2012)
Extinction patterns, delta18O trends, and magnetostratigraphy from a
southern high-latitude Cretaceous – Paleogene section: Links with
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
Although abundant evidence now exists for a massive bolide impact
coincident with the Cretaceous-Paleogene (K-Pg) mass extinction event
(~ 65.5 Ma), the relative importance of this impact as an extinction
mechanism is still the subject of debate. On Seymour Island, Antarctic
Peninsula, the López de Bertodano Formation yields one of the most
magnetostratigraphy, and isotopic data from carbonate-secreting
macrofauna, we present a high-resolution, high-latitude
paleotemperature record spanning this time interval. We find two
prominent warming events synchronous with the three main phases of
Deccan Traps flood volcanism, and the onset of the second is
contemporaneous with a local extinction that pre-dates the bolide
impact. What has been termed the K-Pg extinction is potentially the
sum of multiple, independent events, at least at high latitudes.