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Re: ?Latest paper on the extinction of dinosaurs in North America



"David Marjanovic" <david.marjanovic@gmx.at> writes:
> 
> Pearson et al. [2001] seem to agree, and that's IMHO why they only
write 
> "is
> consistent with" rather than, say, "shows" -- they imply that 
> they've tried
> to falsify the hypothesis of an abrupt extinction and have so far 
> failed.

None-the-less, the Pearson et al. paper was a real contribution.
One problem with previous studies on the Hell Creek formation is that the
stratigraphically-highest occurrences of fossils had been measured from
the Hell Creek Fm - Fort Union Fm contact, *not* from the iridium layer
(Pearson et al. also noted this in their paper).  Since the formational
contact is diachronous, any conclusions that involve the impact event
become meaningless.

In contrast, Pearson et al. mapped the highest-occuring fossils in
relation to the iridium layer, and I believe that makes their conclusions
very important.

<pb>
--








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