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Re: Extinction (of marbles)

While I only wish I understood hypergeometric distributions, it's
reassuring to see that, using the same data, my more primitive
computations yield the same results as those of Stan Friesen and Nathan

The difference in the data.  The analogy of a group of 100 marbles among
a total of 700 sounds similar to a group of 12 species among a total of
72.  However, at 90% overall random extinction, the group extinction
probability in the former case is only 0.000011, while in the latter
case it's 0.262.  (Is my math right?)

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?  

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.

- Stephen Throop