Time in history of exceptional increase in animal as viewed through the fossil record.

The Cambrian explosion, also known as the Cambrian radiation, is an important example of . It is particularly exciting, though, because multiple lineages appear to have been simultaneously as well as the appearance in the fossil record of many of those animal forms that remain with us today.

The Cambrian explosion occurred during, not surprisingly, the , which lasted from approximately 544 to 490 million years ago, though the Cambrian explosion occurred over millions of years relatively early during this .

Note that the term "explosion" is used to mean substantial adaptive radiation.