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RE: Theories on the extinction of dinosaurs

There is NO accepted theory of extinction. In short, people are still
looking for the 'smoking gun'.

There are however three main theories.

1. Impact.
It is accepted that an extraterrestrial body struck the earth in Mexico at
the right time. It is accepted that this alone is not enough to fully
account for the complete extinction of all the life that was extinguished at
the end of the Cretacious.

2. Volcanism.
Volcano's errupting at or near to the end of the Cretacious, in the Indian
sub continent, formed the Deecan Traps. It was a massive erruption, nothing
on the same scale has been seen since. This would have had a massive effect
on the atmosphere.

3. Atmosphere.
Studies of the atmospheric content contained within amber dated to the end
of the Cretacious period has shown that towards the end of the last period
of the dinosaurs reign contained a smaller ammount of Oxygen in the mix, and
towards the end of the Cretacious the Oxygen content shot up by some 20 -
23%. This is a significant increase.

NONE of the above theories on their own can account for the mass extinction.

I do, however, believe that a combination could well go a long way to
explaining the catashrophic loss of species at the end of the dino period.

We KNOW the Deccan Traps happened. We KNOW something hit the earth at the
right time, and we know the amber does not lie about the atmospheric
changes, so, all in all, life had it in for our favourite beasts at the end
of the Cretacious. The fact that any survived (ie Birds and mammals) seems

Tony Hedges

        Gawd they'll let anyone in!!
If at first you don't succeed, read the
              instruction manual.

> ----------
> From:         Pedro José Lorca Hernando[SMTP:pjlorca@msl.es]
> Sent:         04 November 1999 11:23
> To:   dinosaur@usc.edu
> Subject:      Theories on the extinction of dinosaurs
> Hello all:
> What is the most accepted theory for the extinction of dinosaurs? A
> meteorite? The explosion of a supernova?
> Pedro José Lorca Hernando