Sorry to do a hit and run, but I thought I would mention
that Eldredge (in <Reinventing Darwin>) states that the
resolution of the fossil record is typically on the order
of 10's of thousands of years at best. It's good to
keep this in mind when talking about instantaneous jumps.
Nighttime is long and lonely for those poor paleontologists :).
Brian Harper
Associate Professor
Applied Mechanics
The Ohio State University
"... we have learned from much experience that all
philosophical intuitions about what nature is going
to do fail." -- Richard Feynman