Cambrian Period

Earliest time division of the Paleozoic Era, extending from about 540 to 505 million years ago. The Cambrian Period is often divided into the Early Cambrian Epoch (540 to 520 million years ago), the Middle Cambrian Epoch (520 to 512 million years ago), and the Late Cambrian Epoch (512 to 505 million years ago). Rocks formed or deposited during this time are assigned to the Cambrian System, which was named