What Caused the Biggest Kill of All?  By Susan
Kruglinski|Wednesday, December 03, 2003  Two hundred and fifty
million years ago, the Permian extinction wiped out virtually
all marine species and most life on land, clearing the path for
the dinosaurs and setting back the rise of mammals by 50 million
years. Gregory Ryskin of Northwestern University thinks he has
tracked down the cause of this mysterious die-off, the worst in
history: an underwater explosion, 10,000 times as powerful as
the detonation of every nuclear weapon in the world today.
Ryskin proposes that huge deposits of methane and other gases,
which are naturally produced in deep-sea waters, became trapped
under the pressure of a then-stagnant global ocean. Any forceful
disturbance—an earthquake or a volcanic eruption, for
instance—could have disrupted the pressurized gas. Rising
methane could have churned the oceans, suffocating aquatic
organisms, and flooded into the atmosphere, triggering a
worldwide hot spell. A single lightning strike could e