1 天前 · The Cambrian explosion (also known as Cambrian radiation [1] or Cambrian diversification) is an interval of time beginning approximately in the Cambrian period of the early Paleozoic, when a sudden radiation of complex life occurred and practically all major animal phyla started appearing in the fossil record. [2] [3] [4] It lasted for about 13 [5] [6] [7] to 25 [8] [9] …