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.
When many species went extinct around the same time, that might be marked as a change in the period on the time scale, such as the transition from Jurassic to Cretaceous 145.5 million years ago. The ...
3 min read During the Ordovician period, part of the Paleozoic era, a rich variety of marine life flourished in the vast seas and the first primitive plants began to appear on land—before the ...