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From: saouter@irisa.UUCP (saouter yannick)
Newsgroups: sci.astro,sci.space,sci.space.shuttle
Subject: Re: Asteroids and Dinosaurs (was Re: asteroid almost hits earth)
Message-ID: <1212@irisa.UUCP>
Date: 17 May 89 09:28:23 GMT
References: <256@ringwood.Morgan.COM> <3200009@hpindda.HP.COM> <4300@ucdavis.ucdavis.edu>
Organization: IRISA, Rennes (Fr)
Lines: 42

In article <4300@ucdavis.ucdavis.edu>, ccs013@castor.ucdavis.edu (Jason) writes:
> 
> In article <6101@nfs4.rl.ac.uk> kgd@inf.rl.ac.uk (Keith Dancey) writes:
> >>Sun for months or years, and causing mass extinctions of life -- including,
> >>many believe, the dinosaurs.
> >My understanding is that the demise of the dinosaurs extended over a period
> >of order of magnitude of a thousand years.
> 
> ...etc....
> 
> Please correct me if I am wrong, but is this one of the theories (proofs) behind
>  the "asteroid theory" of the extinction of the dinosaurs ?:
> 
> Layers of Iridium were found deep into the earth's crust ( i.e. in the layers
> of the Grand Canyon).  Now, being that Iridium is rare on earth but found
> to be relatively more bountiful in asteroids and meteors, it is suggested
> that the layer of this element was put on our planet by an extremely large
> (or as previously mentioned a few extremely large) asteroid(s) which hit
> earth and caused the clouds of dust ...etc., which eventually killed off the
> dinosaurs.  This dust, if the theory is accurate, was filled with Iridium and
> when settled created a solid layer over years of rain, erosion ...etc...
>    
I have heard about it,too. Dinosaurs might have been killed, in this theory for
few reasons :
- Herbivorous ones starved to death as the big forests burned with the energy
developped with the hit,and as the others plants died because of the Sun to be
darkened by the clouds. Then carnivorous ones starved to death,too.

- They might have choked with the carbonic anhydrid developped by the fires.

- The fishes died with the disappearance of the plancton, due to the first
reason.

- They could have died with the chill of the Earth due to the clouds.

- Moreover Iridium is poisonous.

However, all the dinosaurs would have been to disappear, that is to say, even
turtles and iguanes. And when all the creatures to be killed, then a great time
would be needed to repair this catastrophe (the first oxygen producers appears
in the sea 2 000 000 000 years ago, and this hit occurs 65 000 000 years ago).

saouter@sigle.irisa.fr