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RE: DINO EXTINCTIONS
Your causitive link is flawed though. It would have debistated everything,
not selective groups of taxa, while leaving closely related, and extremely
similar ones untouched.
We may be looking at the wrong kind of causation.
We have to be careful about saying that one "taxon" was "untouched" while
another was destroyed. In fact, 99.9% of the individuals in both may have
been killed, quite unselectively. By chance or otherwise, one was able to
reestablish itself quickly, while the other was not.
The point you make about devastation being easy to ramp up to the point
that everything is dead is a good one. The killing itself is likely to be
quite unselective from any major natural disaster. On the other hand, it
is remarkably difficult to kill off *every single breeding pair* of any
species. It might make more sense to assume that -- at least in most cases
-- some individuals survived. The selectivity of the extinctions is then
not so much a function of selectivity in the initial killing event, but
selectivity in the ability to survive post-catastrophic conditions. This
is the causation which might be more relevant to the debate.