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more dinosaur extinction stuff
Well, I'm gonna try again.(this time for sure...)
I have a small addition (or complication) to add to the general idea of
the Meteor-Extinction Theory. I'm one who agrees with this theory, but, I
was wondering one day about the possible dinosaur finds above the KT barrier
and trying to think of possible explanations, when a stray thought smacked me
upside the head. Instead of why did the dinosaurs go extinct I wondered why
did the mammals, lizards, fish, birds etc survive the same calamity? Then I
wondered what this group would have in common that dinosaurs did not, and
truth to tell, I woke up one day wondering why the remains of the primitive
third eye seemed to survive so late into modern times, since it seemed such a
vestigal thing. Then I tried to remember what creatures' behaviors currently
is believed to be affected by the effects of light on the receptors of the
pineal gland, and realised that these were mammals, lizards,fish, birds, etc.
"Could this mean something?" I said to myself. So I took my copy of The
Dinosauria (UC Berkely Press) and tried to research whether or not Late
Creataceous dinosaurs had pineal glands, AND YOU KNOW WHAT....? Most of the
larger, dominant species seem to not have the presence of a pineal gland, or,
the parietal bone(which according to a comparitve anatomy text I'm using is
the bone usually laid over the pineal gland) was thick enough that the
receptors would not have been triggered by light, as in the Ceratopians. The
Sauropods(which were on their ways out, anyways) didn't seem to have one, T.
Rex seemed to have cartilage in his, Troodon probably had an effective
pineal gland, but not anklyosaurs, or pachysephalosaurs(heads were too thick)
did not. The Raptors may or may not have had one.
See what I'm getting at. If the presence of a pineal gland that
functioned however the damn things do was needed to survive the KT calamity,
then that could be why we see mammals,lizards,etc survive and not 80% of the
dinosaur species. If the remainder of the dinosaur species that did have the
possible use of a functioning pineal gland were also dependant on the
presence of some or all of that 80% surviving, perhaps when those guys went,
thay all did.
Perhaps the pineal gland, whose function is to measure exposures to
light, came in awfully handy if the Meteor smashing in large amounts of the
planet wrecked havoc with the weather.
If you are a migrating species, in order to find food, or to reach
better breeding grounds, were dependant on seasonal weather changes to tell
you when to move, and not say, on the length of daylight vs nightfall, and
suddenly there was global unseasonal weather for say, 10 years( does this
sound reasonable for the effects of a meteor of this size, that did as much
damage as it did to the Earth's mantle?) would you survive as a species if
suddenly your breeding times were gone, you no longer felt the need to move
in a particular direction looking for food, or perhaps even were triggered
into false patterns of behavior untimely? If things with Pineal glands
survived because they could still tell what time of year it was(or what time
of day, for that matter) maybe the dinosaurs that show up after the KT
barrier were of the groups that had pineal glands, and they died off later as
the environmental effects of having 80% of all dinosaur species gone so
quickly took effect.
Whoosh, I feel better. I've been saving that back for a long time. Some
where I still have my footnotes describing the actual skulls listed in The
Dinosauria, and I have a large blank spot under Hadrosaurs and Lambeosaurs,
since there is so much variation in skull design. Does anybody know where I
can look to find out general characteristics of these guys' head bones? Do
they have thick or thin parietal bones? do they have pineal glands?