Re: Selective Extinction

[Chris Campbell <sankarah@ou.edu>]

Dale wrote:
> 
> Peter Von Sholly wrote:
> >
> > An old and often asked question about the final dinosaur extinction is why
> > certain animals went and others didn't.  I read somewhere recently about an
> > impact theory wherein a wave of hot gasses swept across the land destroying
> > most everything in its path.
>   It has been suggested before that a radio-active cloud could have
> been the cause of the extiction of large anamals; large animals will
> suffer greater damage from gamma or other hard radio-active exposure
> and to the reasons you stated (close to the ground, or in a burrow
> out of the line of direct exposure). this is a pet project of mine
> and its very intriguing. any input to me would be very welcome.

Be sure to explain how Velociraptor and like sized dinos (certainly in
the size range of mammals of the time) got aced.  We have to remember
that the extinctions were very selective; it wasn't large critters that
ate it, it was dinos, and pterosaurs, and marine reptiles, and sharks,
and so on.  Any theory we deal with has to account for this.  The only
one I've seen that even comes close is the regression/continental drift
theory; in combination with other factors (among them the India/Asia
impact, climatic changes, and yes, an asteroid impact) it pretty much
does the trick.

Chris