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Re: Cretaceous Mass Extinction



jamolnar@juno.com wrote:
  Dinosaurs rose in the Triassic, survived the extinctions
> of the Triassic and Jurassic, but don't make the Cretaceous boundary. Why
> didn't they adapt that last time?  Adaptive radiation doesn't answer my
> question entirely.

        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.

-- 
           Betty Cunningham  
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