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RE: pineal gland

> >Being the odd biological type
> > that I am, I was wondering to myself how much someone could "monkey
> > around" with the penguin's photoperiod before they would finally cease
> > exhibiting reproductive behavior.  From there, it just kind of dawned   
> on
> > me that this might be the crucial link that explains why certain plants
> > and animals were selected against at the Cretaceous Extinction, while
> > others were not.  In fact, by creating a simple chart representing (in
> > broad terms) the organisms alive today, a drastic and sudden change in
> > seasonal light cycles would result in an almost identical mass
> > extinction.  This explains why some seemingly hardy species went   
> extinct
> > (dinos), and why other "delicate" species (like tropical frogs) did   
> not.
> <snip>
> >Organisms that  were not sensitive to photperiodic cycles were fairly   
> unscathed by the
> > mass extinctions, while the sensitive species were wiped out.  Further,
> > a change in photoperiod would not neccessarily involve a signifigant
> > temperature change, either (although it probably did).
>  <snip>
> This ties in with the reasoning I posted many years ago that the land   
> animals with functional pineal glands survived the K-T extinction,  and   
> that the animals with no ability to measure seasons other than through   
> temperature changes, did not survive.   The pineal gland is a light   
> receptor that measures photoperiod in many animals.  The dinosaurs of the   
> late Cretaceous appear (supported so far in my research-but still   
> tracking hadrosaurs and late Cretaceous Asian dinosaurs) to have lacked a   
> functional pineal gland in 90% of all species checked (in text) so far.   
>  I base this on the thickness of the parietal bone over the supposed area   
> of the pineal gland.  The Dinosauria (UC BERKELEY Press) has been quite   
> helpful in describing many species' skulls as having cartilage filling   
> this area, as well.  I assume very thick parietal bones would not let   
> light hit the pineal gland.  Neither would excessive amounts of   
> cartilage.
>  My reasoning was similar; since the pineal gland is such a primitive   
> trait that has survived to today but isn't fully functional in all modern   
> species, why does it still exist?  Then "What animals had them that   
> survived the KT extinction?"  then "Did the dinosaurs have functional   
> pineal glands?".  After some discussion on this list, I was advised to   
> research more into it.  I haven't haven't spent a great deal of time   
> tracking it, but so far it looks good.
> ]
>  -Betty Cunningham
> (bettyc@flyinggoat.com)
The pineal gland is too deep a structure to receive photons directly 
in humans.  I doubt that it is in other animals, but this is just an 
educated guess.  Someone correct me if I'm wrong.  I just don't have 
time to research this right now.

Michael Teuton