English Extinction event Cited by user Grahbudd on 21 Nov 2018 An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth.
English Cambrian explosion Cited by user Grahbudd on 13 Nov 2018 The Cambrian explosion or Cambrian radiation was an event approximately in the Cambrian period when most major animal phyla appeared in the fossil record.