Ordovician

The Ordovician period was a time period in Earth's history, following the Cambrian and preceding the Silurian.

Real life
The Ordovician period lasted from 485 to 443 million years ago. During this time, life continued to flourish as it had in the Cambrian, although land-based life still had yet to evolve. Invertebrates such as molluscs and arthropods dominated the oceans, while fishcontinued to evolve. There was, however, a major extinction event at the end of the Ordovician.