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Re: Theories on the extinction of dinosaurs



>>
That's an interesting thing to say about a group of creatures (dinosaurs)
that, at the time of KT extinction, had been around for 100+ million years
and that arguably constitute a major percentage of extant vertebrate
species.

What is your evidence for claiming that dinosaurs did not adapt to changing
circumstances very well?<<

Here I must interject.  I was not going to get into this arguement because I
thought someone more knowlegable than I would take on the mantall, but
apparently not.  The most _accepted_ theory (not nessisarily the correct ont)
is an asteriod.  There is some pretty good evidence to support such a theory
(hell, they found the crater).  Also, there is a great deal of the element
iridium, an element rare on Earth, but more common in asteriods around the K-T
boundary.  There are . . .complications, however.  There may also have been
violent volcanic eruptions (in the vicinity of India?) around that time too,
which could have made things hairy.  Most everyone beleives in the asteriod
theory.

As to why didn't the dinosaurs adapt?  They did.  The K-T extinction (whatever
caused it) killed off all animals bigger than about 2 meters long (that's a
huge estimate, and I wouldn't mind someone with the refs or some hard data for
that).  All of the big (non-avian) dinosaurs, reptiles, pterosaurs, fish,
mammals, etc.  couldn't make it through becuase, in times of need, there isn't
enough nutrition to fill the belly of a big animal.  So, only the little
dinosaurs, the birds, survived the extinction.  If the extinction had happened
at the end of the Jurassic, we would still be seeing the descendents of
Ornitholestes and Pterodactylus.  (wouldn't that be fun :)

Dan