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Re: Theories on the extinction of dinosaurs




"James R. Cunningham" wrote:
> 
> Seosamh wrote:
> 
> > I'm trying to assemble some meaningful description of the interactions
> > among these observed (in the fossil record) events. Crudely, the
> > body strikes the Yucatan, a concussion travels through the Earth and
> > half a globe away the Deccan eruptions begin. The combined effects
> > of these two on the atmosphere change its chemistry to something
> > higher in oxygen.
> 
> Er ah, the following is from memory, so may not be correct in all of its
> reconstructed details.  I'll fish out my sources over the weekend if you wish.
> 
> Your scenario may have a couple of problems with timing and direction of rate 
> of
> change.  

It's not my scenario; I don't yet have one. I'm looking for something that IS 
plausible. 

Since all three (impact, volcanism, increased atmospheric oxygen) are accepted 
as real events occurring near the end of the Cretaceous, and the world wide 
mass extinctions took place then, is there some obvious gap in how those three 
items might tie together? The portion of my text which you quoted was an 
admittedly inaccurate example of the *kind* of correlation that could be the 
"smoking gun" which Tony mentioned earlier in the thread.

I used the metaphor of a jigsaw puzzle. We have several pieces in the fossil 
record. We have a notion of the broad outline of the puzzle, i.e, a plausible 
description of the extinction event(s) with causes and effects. What kind of 
information would enable us to say, "Of course!" and clear up the mystery?

In other words, do we even know what additional information would be helpful in 
assembling an explanation of the K-T extinctions? At least in a TV show, the 
detective gets to look for the kind of weapon that inflicted the known insult 
to 
the murder victim, the "smoking gun." Outside TV land, are we at the point 
where 
we can say, for instance, "with more detailed understanding of the scope of the 
impact and the environmental changes it wrought the end of the Cretaceous we 
will understand why the largest life forms died out at that time?" That 
particular 
example is partially amenable to study via simulation. Then such simulations 
might be a prudent course in the search for the "smoking gun." Or perhaps our 
information about the impact itself is too sketchy to allow such simulations as 
more than an interesting exercise.

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.

 Thanks,

 Joe