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.

The Silurian Hypothesis contemplates how long the ruins of a civilization would be detectable, on Earth or even other worlds, and if we could ever know if a world had once been inhabited by a ...

Learn about the time period that took place 416 to 359 million ... a group that first appeared during the Silurian with powerful jaws lined with bladelike plates that acted as teeth.