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> Maybe he lost his cool for the same reason I did. People don't like
> being labelled "unscientific" because they advocate the impact hypothesis
> as a major contributor to the K/T extinctions.
If I ever imply such a thing, let me know. Disagreements are
healthy in science, and should not be decried as unscientific
without a great deal of reason.
> What would happen to an ecosystem(including dinosaurs) if there were
> suddenly a very thick dust cloud introduced to earth's atmosphere?
> (Assume the cloud persists for 3-4 months.)
At only 3-4 months, probably very little lasting change.
The most sensitive light-loving plants would die, leaving
a widespread successional vegetation, which would rapidly
(over decades to centuries) return to a new dynamic equilibrium.
A few (very few) specialist plant eaters would die in large
numbers, some might even become extinct (if they lacked time
lagged reproduction - as in eggs, and also lacked dormancy
capability sufficient to last them through the darkness).
It would take several years of dust clouds to truly disrupt
an ecosystem for more than a millenium or so.
> How much sampling do we need to do before we can have confidence that
> the dinos definately were checking out before the Ir layer was deposited?
> (Or have we already done enough?)
This is difficult to say, since, due to their large size,
the best possible temporal resolution for dinos is rather large.
Also, deposition in terrestrial environments is notoriously
uneven in both space and time. This means that it is difficult
to estimate durations from sediment depths.
Nonetheless, in at least the Hell Creek formation, the abundance
of dinosaur remains drops sharply a few meters below the siderophile
layer (aka boundary clay). I would say that if the same pattern
shows up in at least two other major depositional basins with
more or less continuous deposition across the K-T boundary, the
pure impact hypothesis would be denied.
[The Hell Creek is the lower part of a continuous series of
continental deposits that spans the Late Maastrichtian through
most of the Paleocene - the upper parts go by names like Tullock
and Fort Union - or at least it is as continuous as riparian
deposits ever get].
The peace of God be with you.