Mass extinction

A mass extinction is an event where a large fraction of the world's species rapidly go extinct. Several mass extinctions have occurred since life evolved on Earth, although the specific cause of some is still uncertain. Five specific events are generally agreed upon by the scientific community. These "Big Five" mass extinctions were identified by Jack Sepkoski and David M. Raup in their 1982 paper and are widely agreed upon as some of the most significant: End Ordovician, Late Devonian, End Permian, End Triassic, and End Cretaceous.