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Date: 13 Sep 88 22:15:49 GMT
From:  (Jim Giles)
Subject: Dinosaur extinction compared to others (was: are we terraforming?)

>From article <4468@brspyr1.BRS.Com>, by miket@brspyr1.BRS.Com (Mike Trout):
> [...]
> Why did so many non-dinosaur reptiles survive?  Snakes, turtles, lizards,
> crocodilians, and such appear to have suffered no such losses at the time.
> And it doesn't have anything to do with size, either.  Although most of the
> "big" dinosaurs get all the attention, most dinosaurs actually were not all
> that large--many were no larger than modern-day lizards, and their average size
> seems to be little different from today's crocodilians.  Yet not one single
> dinosaur, regardless of size, survived whatever it was.  It's difficult to
> come up with a plausible scenario in which all dinosaurs die and most lizards
> live, even though biologically they are extremely similar.  A baffling
> mystery, to say the least.

Too much attention is paid to dinosurs.  The iridium even marks a significant
mass extinction event.  Over half the families of marine mollusks, flowering
plants, echinoderms, etc. were killed off (for half the _families_ to
disappear, more than 90% of the species must be killed off).

The question is not: why did the dinosaurs die off?  The question is: how
did all these others survive.  Actually, they probably didn't.  Mammals
are probably all derived from only one or two dinosaur contemporaries.
The same goes for birds.  Each family of living reptiles and amphibians
probably owes its existance to only one or two survivor species.  In fact,
the asteroid theory is quite adequate to explain all the extinctions -
the robustness of life is necessary to explain the survivors.

J. Giles

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