re:re: K/T sharks

[@lepomis.psych.upenn.edu, @uga.cc.uga.edu:Schwimm@USCN.BITNET (Paleontology Columbus College, Georgia)]

Chris Illes asks why sharks aren't affected through food webs (chains) in
the K/T scenarios:

My answer is that they may well have been affected, -if- we assume the
darkness component of the impact scenario (remember please, this is an
assumption still to be proven).

However, I argue they would be relatively less affected than most marine clade ,
ades, because of their realtive tolerance for a variety of
conditions.  Remember, not all marine taxa went extinct at the K/T boundary;
therefore, many (or most) food webs remained intact or relatively
intact.

  Or to put it another way, when all around is falling apart, the most
versatile and tolerant are most likely to survive.  In the marine realm,
I assume sharks (specifically galeomorphs and batoids) fit that role.
Parenthetically, chimaeroids also survivev the boundary intact (species
to species across, in fact) but their environmental niche seemed to
 collapse after the Eocene and they retreated from the upper shelves to the
bathyal zones.

david schwimmer
schwimm@uscn.cc.uga.edu