Learn about the climate changes that followed the end-Permian extinction, allowing select species to take over the planet's oceans.

Creatures adapt to changing environments ... the fact that at the end of the Permian Period they were gone seems unthinkable.

After Earth's worst mass extinction, surviving ocean animals spread worldwide. Stanford's model shows why this happened.

These toughened-up creatures represented a crucial innovation ... the world's oceans until they were wiped out in the Permian extinctions about 250 million years ago. Photograph by James L.

Toward the end of the Permian period, Earth was reeling from ... where the die-offs of certain predator and competitor creatures allow one surviving group of organisms to go gangbusters.

About 250 million years ago, at the end of the Permian period, something killed some 90 percent of the planet's species. Less than 5 percent of the animal species in the seas survived. On land ...