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Re: Cretaceous Mass Extinction



Betty Cunningham wrote:

>       My theory as that many of these vertibrate animals have a
> physical light-sensor (the pineal gland) that would allow them to
> continue to regulate their breeding and migratory schedules
> regardless of the weather ...

According to one of my lab mates (one of the guys studying pineal
photoreceptors), crocodilians, snakes and armadilloes are reputed not
to have pineal glands.  If anybody knows different please let me know.

In a related story Jeff Hecht wrote:

] Recent data suggests that diversification of placental mammals and
] birds started in the late Cretaceous, not just after the impact.

More recent evidence suggests that current bird (and possibly mammal)
lineages may have begun diverging during the Early Cretaceous.  I
don't know how well this will hold up, but see:

    Mass Survival of Birds Across the Cretaceous- Tertiary
    Boundary: Molecular Evidence 
    by     Alan Cooper * and David Penny 
    in _Science_ Volume 275, Number 5303, Issue of 21 February 1997,
    pp. 1109-1113.

and the related news article:

    Did Birds Sail Through the K-T Extinction With Flying
    Colors? 
    by    Ann Gibbons
    in _Science_ Volume 275, Number 5303, pp. 1068

(Forgive my odd referencing style; I cut and pasted the above info
from _Science_'s website.  It's no longer free access or I'd have just
given you the URL).

--
Mickey Rowe     (mrowe@indiana.edu)