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Re: Extinction (of marbles)



From: stevet@shelby.net (Stephen Throop)

 > John Schneiderman speaks of 799 known dinosaur genera.  It sounds as if
 > many hundreds of species must have been alive at one time.  Is the
 > extinction question about the gradual disappearance of hundreds of
 > species or the faster disappearance of the last 12?  

Somewhat in between.  The mass extinction at the end of the Cretaceous
eliminated tha last dinosaurs.  There were certainly more than 12
species of dinosaurs alive then.  (There were 19 just in the Lance
and Hell Creek formations).

Still, the vast majority of dinosaur species were long gone by that time.
After all, extinctions happen all the time, not just during mass
extinctions.

 > Whether the explanation involves random probability or environmental
 > "bullets" that preferred dinosaurs, the disappearance of a huge number
 > of diverse species seems much harder to figure.

However, something of that sort must happen in a mass extinction. These
events have wiped out many groups at least as diverse as dinosaurs.

swf@elsegundoca.ncr.com         sarima@ix.netcom.com

The peace of God be with you.