A kill curve for Phanerozoic species is developed from an analysis of the stratigraphic ranges of 17,621 genera, as compiled by Sepkoski. The kill curve shows that a typical species' risk of extinction varies greatly, with most time intervals being characterized by very low risk. The mean extinction rate of 0.25/m.y. is thus a mixture of long periods of negligible extinction and occasional pulses of much higher rate. Because the kill curve is merely a description of the fossil record, it does not speak directly to the causes of extinction. The kill curve may be useful, however, to limit choices of extinction mechanisms.

中文翻译：

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显生宙海洋物种的杀灭曲线

显生宙物种的杀灭曲线是根据 Sepkoski 编制的 17,621 个属的地层范围分析得出的。杀灭曲线显示，典型物种的灭绝风险差异很大，大多数时间间隔的特征是风险非常低。因此，0.25/my 的平均消光率是长时间可忽略不计的消光和偶尔更高速率的脉冲的混合。因为杀灭曲线只是对化石记录的描述，它并不能直接说明灭绝的原因。然而，杀灭曲线可能有助于限制灭绝机制的选择。