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Subject: Re: Cretaceous Mass Extinction



On Sun, 09 Mar 1997 18:53:30 -0800 Bettyc <Bettyc@flyinggoat.com> writes:
>so far, it seems that the dinosaurs of the late Cretaceous did not have
>their pineal gland where it would do much good.  Much of my assumptions
>is based that the pineal gland on these animals would be under the
parietal bone and in a simple perusal of THE DINOSAURIA the majority of
the late Cretaceous dinosaurs had huge horn-things or big knobby things
over the area which would have needed to have light shine on to be
functional-like the ceratopians, and the therapods seem to have filled in
the area with cartilage-meaning the gland wasn't very effective, 
and the hadrosaurs had so many different head ornaments that each type
may or may not have had a knob over the pineal gland.  A loss from any
area of any one of these animal groups would have devestated most of the
other animals dependant on them-like losing the African Elephant today
would ruin the african environment.
>       Earlier dinosaurs seemed to have less ornament over their
parietal bone.>

What about all the other reptiles that went extinct, like mosasaurs,
pterosaurs, ichthyosaurs, plesiosaurs?  What pineal evidence is there for
them?  And lizards (presumably with pineals) made it through the event. 
Why?  Mammals have pineals too, they just don't function in exactly the
same way as reptiles' pineals do.
If dinosaur failure is so intricately tied up with pineal function, why
would they evolve a thick parietal bone in the first place?  What could
possibly be so evolutionarily important that it's selective pressure
would override the pineal's function?

Judy Molnar
Education Associate
Virginia Living Museum
vlmed@juno.com
jamolnar@juno.com