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Re: Theories on the extinction of dinosaurs



> > Seosamh wrote:
> >>  The combined effects
> > > of these two on the atmosphere change its chemistry to something
> > > higher in oxygen.

and

> Since .... (......., increased atmospheric oxygen) are accepted
> as real events occurring near the end of the Cretaceous,

Both statements imply INCREASING oxygen levels in the late Cretaceous.  From 
memory,
according to Dudley's paper, oxygen near the end of the Cretaceous was 
DECLINING rapidly
and had been doing so for some time, though (still according to him, and I 
think maybe he
also quotes Rubin) it had not yet fallen to our present level.  If they are 
correct, you
may need to look further at your supposition of increasing oxygen at the end of 
the
Cretaceous being a 'real' event.  I have no personal opinion on this, not having
researched it myself.

> I'm trying to define the problem more clearly. It's habitual <G>. I'm not a 
> scientist,
> nor do I have any training in biology or earth sciences. But I do have a 
> preferred
> approach to problem solving.

Sounds good to me.  I'm not a scientist either,  only an engineer.  I just 
doubted that
the impact could have caused the earlier volcanism, or that the volcanism could 
have
caused the impact.  Either or both could have caused a declining free oxygen 
level due to
fires, though I suspect the impact could also have temporarily increased free 
oxygen
levels due to the disassociation of cubic miles of sea water.  However, most 
would have
immediately reattached to the hydrogen (what a fireball that would make), or 
have reacted
with anything burnable during planetwide fires subsequent to the impact.

All the best,

Jim