Paleontologists David M. Raup and Jack Sepkoski have proposed that an excess of extinction events occurs roughly every 26 million years (though many are relatively minor).
古生物學家大衛·駱普（David M. Raup）和傑克·塞科斯基（Jack Sepkoski）提出大約每2600萬年就會發生一次滅絕事件，雖然很多是較小規模的。