The extinction of biological clusters refers to the sudden death of a large number of organisms within more than one geographic area in a relatively short geological period, causing the number of biological species to suddenly and drastically drop in a short time.
At the end of the Permian period, about 250 million years ago, 96% of the species on the earth became extinct, of which 90% of marine life and 70% of terrestrial vertebrates became extinct belongs to the extinction of biological clusters according to the above definition.