(biology) The Cambrian explosion(the rapid appearance, around 541 million years ago, of most major animal phyla).
2022 November 22, Donna Lu, “The real paleo diet: researchers find traces of world’s oldest meal in 550m-year-old fossil”, in The Guardian[1]:
Brocks said the new study suggested the Ediacaran biota “already contained some of the creatures that gave rise to the [Cambrian] explosion, to the rise of modern animals”. The Cambrian explosion, also called the biological big bang, was a period about 538.8m years ago when almost all major animal groups started to appear in the fossil record.
