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Re:Dinosaur extinction



>Flood type eruptions, however, had not occurred for many millions of years
>previously.  And the Deccan Traps are second only to the Siberian Traps (of
>the Permo-Triassic boundary) in volume.
>So, it is not merely the fact of volcanic eruptions, it is the existence of
>a *temporally* *rare*, unusually voluminous type of eruptions across the
>boundary.

Hmmm--and the Permo-Triassic was an even greater extinction.  Any evidence
of an even larger bolide impact (or impacts) associated with that one?  I
tend to think, based purely on educated guesses, that we'll find out that
extinctions occur when a combination of changes puts stress on certain
types of organisms, the actual extinctions then probably being triggered by
catastrophic events that happen to occur at those times.  The larger the
changes and/or events, the more types of organisms find themselves under
enough stress that they can't cope with the event (IE the lower the stress
level required to send them over the edge).

>The closest we have today are the Iceland volcanics.  (And it is
>interesting to note, the Late Pliestocene/Holocene has been a time of
>moderate extinctions).

"Holocene".  That seems to be a false division to me, one based on culture
rather than significant changes in the turnover of life on Earth.  Perhaps
it will eventually be incorporated into a new, "sliding" cultural scale (IE
with "Holocene" always the current period), semi-parallel to the geological
scale.  For my money we're still living in the Pliestocene.  Depending of
course on the ammount that it turns out _we_ effect climate change.


Seth A. Ellestad.