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Re: "No Bolides!"



> The effects of a
> bolide impact as described would have wiped out all animals and certainly
> more species than survived the K/T boundary extinctions!  What is the current
> thought on this?

      Its important to keep in mind that the earth has alsmost certainly 
been creamed by as many meteors and comets as the moon, and that the 
impact craters have simply been eroded or subducted or whatever.  This 
means not only that species CAN survive impacts, but that impacts are 
frequent enough (geologically speaking) to be considered as possible 
causes of extinction. (This brings up a point I beleive Gene Shoemacher 
made.  The majority of the objects that cross the earth's orbits are comets, 
making the most likely object to strike the earth a comet.  Wouldn't this imply 
that most of the craters on the moon were caused by comets?)
     Also, no one should discount the affect more mundane things like 
climate change (which can result in part by continental drift altering 
warm and cold ocean currents as well as global temperature change) can 
have on extinction.  A species has to deal with its day to day 
environment and its alterations more frequently than it has to deal with 
impacts.  Climate can change fast, and a species that can't evolve to 
keep up with it is doomed.  
     Also, I've heared it mentioned that a species could migrate to 
escape climate change.  To me this implies that a concious decision on 
the part of the organism to leave ("Hm, getting chilly.  Think I'll move 
to Tahiti.")  Are you implying that the animal has an academic grasp 
of the relationship of climate to geography?

LN Jeff
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"You're sort of the Dan Quayle of dinosaurs."