In my recent book on POLE SHIFTS, one of the inescapable conclusions is that many species go extinct when such a cataclysm occurs, and surviving species branch out into newly available lands. Massive evolution occurs in short bursts. Eldredge and Gould published their thesis on this (allopatric speciation - or punctuated equilibrium) in 1972 - but it hasn't been easy for the rest of the scientific community - or the world - to accept period catastrophes and short bursts of mass extinctions followed by bursts of surviving species branching out and diversifying rapidly.