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Re: Theories on the extinction of dinosaurs



:]  This is my theory that I've discussed on the list before- 

As for adaptations that the surviving tetrapods forms all seem to have;
light-sensitive pineal glands. (Crocs, mammals, birds, amphibians,
reptiles, etc)

late Cretaceous dinosaurs- T rex, late surviving sauropods, ceratopians,
etc*- all seem to have modified the skull about the pineal gland- I
suggest this was in the area of the parietal bone- to such an extent
that the pineal gland suggested-function of measuring daylight hours
(and thus identifying seasons) was limited or was fully inoperable.

Animals unable to identify season changes (and the passing of time) in a
bolide winter don't breed at the same rate as animals that can identify
season by light-dark changes.
The surviving forms could tell when to breed vs species that couldn't.

-Betty Cunningham

* hadrosaurs are tough to get a consistant overall species view of the
conditions of the parietal bone.  I have no idea about the parietals of
pterosaurs.

Martin Barnett wrote:
> If that is then the case, we should be looking for adaptations that Triassic
> and Jurassic archosaurs have that they all subsequently lost come the end of
> the cretaceous.  Or what adaptations mammals as a whole gained in the
> cretaceous that gave them the skills necessary to overcome the new wave of
> archosaurs in the Permian.


-- 
Flying Goat Graphics
http://www.flyinggoat.com
(Society of Vertebrate Paleontology member)
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