Ordovician period

Ordovician marine life

Ordovician marine life.

Ordovician marine scene

The Ordovician is a period of the Paleozoic era that spans the time between the Cambrian and the Silurian, about 490 to 443 million yr ago. The Ordovician period is best known for the presence of its diverse marine invertebrates, including graptolites, trilobites, brachiopods, and the conodonts (early vertebrates).