They suffered greatly during the last three of five great Phanerozoic dyings-latestPermian, latest Triassic, and latest Cretaceous.

Sometimes too you will see the term Phanerozoic used to describe the span encompassing the Cenozoic, Mesozoic, and Paleozoic eras.

They build upon work done by Sloss by applying statistical methods to the Phanerozoic (past 550 million years) sedimentary rock record of North America.