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Re: Theories on the extinction of dinosaurs



Dan wrote:
>
> If a meteor impact doesn't produce stress, I'll eat my keybord.  :)
>
And John Bois wrote:
> Certainly, _any_ agent driving you to extinction would produce stress!


Sure and a whole lot of other things were going on at that time like the
volcano eruptions et al that would raise stress levels, but since these same
situations happened to all the animals and a dubious, cross section died
while others survived, I'd say it was the stress that killed them, not the
physical ramifications of the environment.  Animals deal with stress in
different ways.  Everything stresses - some things tear their hair out,
others deprive their babies of calcium :)

Yours sincerely,
                         Samuel Barnett

> >> Stress.
> Heinrich Erben of Bonn university's institute of Palaeontology did some
> research in the early 70's into
> thousands of eggshell fragments from the upper maastrichtian of the
> french pyrenees.  His studies
> showed that eggshells in the older layers had eggshells around 2.5mm
> thick.  The younger, more recent
> layers produced shell fragments a mere 1mm thick - too thin to provide
> enough calcium to the bones of
> the developing embryo within.  The thinning of the eggshell is a
> sure-fire sign of stress.  Seagulls in
> crowded colonies lay thinner eggshells than ones not subject to mass
> territoriality and food supply
> issues.  The previous 3 events, especially the top two, are known to
> have occured and all the animals at
> that time would have been subjected to the same conditions.  Perhaps it
> was their way of dealing with
> those conditions that decided who would survive and who wouldn't.<<