In evolutionary theory, the Cambrian explosion is the extremely rapid development of new animal phyla (body shapes) that occurred at the beginning of the Cambrian Period approximately 530-550 million years ago. The duration of time in which these new phyla occurred is approximately 10 million years.1
See the Geological Time Table
- 1. This chart was adapted from an insert called the Tower of Time by John Gurche as reproduced in The Thread of Life: The Smithsonian Looks at Evolution by Roger Lewin, Smithsonian Books, Washington, D.C., Distributed by W. W. Norton & Company, New York, N.Y. 1982.