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Re: Quo vadis J-K extinctions?



Thomas Holtz writes:
> This is like using dinosaurs from the late Coniacian (85 Ma) and mammal
> assemblages from the earliest Paleocene (65 Ma) to argue for the asteroid
> impact hypothesis of the K-T boundary.

Has anyone tried this as a control experiment for the J-K crossover?  What
kind of population densities and upper masses of individual species are we
seeing from just the late Coniacian and the early Paleocene, as compared to
similar measures in the two closest late Jurassic and early Cretaceous
faunal beds?  Is there a correlation between the two pairs?  A good test of
this should also try 90Ma and 70 Ma in comparison too.  We may never have
the strata to prove a mass extinction or an impact event happened, but this
kind of test would surely tell us if either was likely and doing it over
several 20 million year time spans might even give us a prediction for when
an impact event would have to happen to fit the MO of the K-T extinction.
Ok, so ultimately we'd have no smoking gun, but it sounds to me from this
recent family of threads that we don't have a certified bullet hole in the
victims either - just dead subjects which is why I stipulated both things
seperatley for now.  Also:

Jerry D. Harris writes (ok, ok, so I nicked this from "big craters", not
"Quo vadis", but hey - they are sister threads :))
> someone had interpreted some seismic data as an outer ring that was
> the "real" size of the crater, making it almost twice as large as current
> estimates.  As with numerous things in paleontology, it appears that
> geophysicists have to wait for a consensus to be reached as well!

D'ya sometimes wonder if other science disciplines only lack hardened data
when they overlap into our realm?  Looks like the curse of the dinosaurs
strikes again! :)

Samuel Barnett