Definitions for "Cambrian period"
Keywords:  paleozoic, ago, oldest, geologic, era
The earliest geologic period of the Phanerozoic Eon of Earth's history, extending from 543 to 495 Ma ago.
from 544 million to about 500 million years ago; marine invertebrates
the first and oldest period of the Paleozoic Era which occurred from 570 milllion years ago and lasted seventy milllion years ago until 500 imllion years ago