A

David

Darling

Ordovician period

Ordovician marine scene

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 years ago. The Ordovician period is best known for the presence of its diverse marine invertebrates, including graptolites, trilobites, brachiopods, and the conodonts (early vertebrates).