Extinction cycles over the last 270 MY

Major faunal extinctions occur at intervals of 26.2 MY, the slope of the line, except for two missing points (cycles 5 & 7). Cycle 4 is the K/T extinction, Cycle 10 is the "Permian Die-off"  (Sepkoski & Raup 1986, from Price 1996)

Text material © 2005 by Steven M. Carr