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Re: Selective Extinction



Jeffrey Martz wrote:
> 
> > No, sharks suffered tremendously.  They survived as a clade, but the
> > diversity in that clade dropped significantly.  Of course, if we make
> > the not unreasonable assumption that a number of species evolved in
> > tandem with inland seas, the regression of said seas would result in a
> > lot of dead sharks.  They wouldn't, of course, even notice an asteroid
> > (unless they happened to be skimming the surface that day).
> 
>      If the asteroid hit in or near the ocean (as it did if Chixulub is
> the smoking gun), you can bet they would notice it. Imagine what an impact
> and energy release like that could do to ocean currents world-wide.

To the currents themselves?  Not a whole heckuva lot.  The currents are
driven by the Earth's rotation, and I doubt the impact was big enough to
do much to *that*.  The impact would certainly heat a fair amount of
water (if it actually occurred at or near the water's edge) and I
imagine that would have a significan effect on the waters at or near the
Gulf; however, if I remember my oceanography correctly, the currents in
question wouldn't mix much with waters outside of the south Atlantic
gyre; sharks in Morth American waters wouldn't be affected, nor would
those in Australia, Hawaii, Japan, and so on.  In any event, we still
wouldn't expect much reaction at all from deep water animals; even if
you heat the surface water significantly, the waters 100 feet down will
remain as they always were -- a cool 4 degrees centigrade.  

Chris