3 min read The Cambrian period, part of the Paleozoic era, produced the most intense ... world's oceans until they were wiped out in the Permian extinctions about 250 million years ago.

The Permian period occurred during the last part of the Paleozoic Era. It ended with the largest mass extinction in Earth's history. Sign up for Chip Chick's newsletter and get stories like this ...

It also paved the way for the rise of reptiles in the Permian period that followed ... to demonstrate that the climate of the Late Paleozoic era was closely regulated by CO₂.

The Paleozoic era's Silurian period saw animals and plants finally emerge on land. But first there was a period of biological regrouping following the disastrous climax to the Ordovician.