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.

a mere blip in Earth's 4.5-billion-year history. A lot has happened in that time. Earth formed and oxygen levels rose in the foundational years of the Precambrian. The productive Paleozoic era ...

The largest extinction events define a change in era. The end of the Paleozoic and beginning of the Mesozoic 251 million years ago marks the largest mass extinction in the history of the planet, which ...