Cambrian explosion
Palaeontology
noun
A short episode of intense diversification of marine animal forms apparent from the fossil record of the Cambrian period (including the development of mineralized skeletons in many groups and the appearance of ancestral forms of most modern metazoan phyla) which is dated to about 535 to 525 million years ago.
Origin
1970s; earliest use found in Stephen Jay Gould (1941–2002), paleontologist and science writer.