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Re: K-T mammals

----- Original Message -----
From: "John Bois" <jbois@umd5.umd.edu>
To: "David Marjanovic" <david.marjanovic@gmx.at>
Cc: "The Dinosaur Mailing List" <dinosaur@usc.edu>
Sent: Sunday, May 12, 2002 8:13 AM
Subject: Re: K-T mammals

> They're not talking about elimination before--they're saying that there
> was a steep decline in diversity and numbers (if memory serves) in the
> Hell Creek formation.  They are leaning (according to Dobb) to the
> asteroid as a knockout blow, a coup de grace after some other phenomena
> had already played out--or was still playing out.  The great thing is that
> they are actually gathering data.  So, we'll see.

Many data have already been gathered by the Pioneer Trails Regional Museum,
and they published a short paper in 2001. My search of the archives found no
mention of it on the list, so here's the citation along with the abstract:

Pearson, Dean A., Terry Schaefer, Kirk R. Johnson, Douglas J. Nichols, 2001:
Palynologically calibrated vertebrate record from North Dakota consistent
with abrupt dinosaur extinction at the Cretaceous-Tertiary boundary.
Geology: Vol. 29, No. 1, pp. 39-42.

New data from 17 Cretaceous-Tertiary (K-T) boundary sections and 53
vertebrate sites in the Hell Creek and Fort Union Formations in southwestern
North Dakota document a 1.76 m barren interval between the highest
Cretaceous vertebrate fossils and the palynologically recognized K-T
boundary. The boundary is above the formational contact at 15 localities and
coincident with it at two, demonstrating that the formational contact is
diachronous. Dinosaurs are common in the highest Cretaceous vertebrate
samples and a partial dinosaur skeleton in the Fort Union Formation is the
highest recorded Cretaceous vertebrate fossil in this area.

The PTRM is doing something that isn't done very often in paleontology: take
good stratigraphic data!!!! Believe it or not, geology is still a necessary
part of paleo. :-P As I understand, Jack and his team are starting to work
out the stratigraphy of the Hell Creek in Montana. I'll be interested to see
how it correlates with what Dean, Kirk, Terry and Doug have found in North
Dakota. There is still lots to do in the Hell Creek--we really have a poor
understanding of how things correlate across Montana, South Dakota, and
North Dakota.