RE: K/T Extinction

[Dan Tapster <dan.tapster@bbc.co.uk>]

K/T extinction.

Thanks to everyone who contributed to the K/T debate (and those who enjoyed
the peculiar tangent of whether gravity is a theory or not.

As promised here is a summary of the 95 (and counting) replies I received.

There is virtually no doubt that at the K/T boundary a bolide did impact the
Earth (only 3 people thought that the evidence of such a collision was not
overwhelming)  However only 30% of people went for the asteroid impact being
the one and only cause.

A whopping 65% of you have difficulty with the asteroid hypothesis
especially when you phrase it thus: "A big rock fell out of the sky and
killed all the plants and animals, expect those that it didn't kill."
Instead people think that the bolide was the 'period' at the end of the
sentence as far as the Cretaceous extinction was concerned.  That is to say
that dinosaurs were on the steep decline already.  There were various
suggestions as to why this was the case and the first two each received
about half of the votes.

- increase of volcanic activity
- retreat of the seas in some parts of the world
- reconnection of long separated animals which led to the spreading   of
parasites and diseases for which the separated animals were not   adapted.
- air pollution, 
- cooling temperatures and more variable weather conditions.

Having said some 'boliders' retorted with the fact that. The dinosaurs were
probably not in such a decline if you're looking to the fossil-record in
Southern France. They showed changes in the composition of the faunas (i.e.
titanosaurids replaced by hadrosaurs) in the last millions years of their
history, but no real decline though.

However, these change points out a fragility of the ecosystem, probably
linked to climatic changes.

The 5% of people who thought that a bolide did not hit the Earth opted for
sea level regression and increased volcanic activity.

Finally,  there are other theories out there as  someone's junior hiugh kids
revealedl:

Asteroid
Comet
Shooting Stars (plural)
It was like that Goldilocks story... too hot  and too cold.  They needed it
just right.
Lots of lava
Earthquakes separated families (direct reference to the movie Land Before
Time)
The space rocks bopped them on the head.
no plants, no plant eaters, no food for meat eaters. Everything dies.
Thanks for your help,

Dan Tapster