化石记录中有丰富的生物灭绝证据。海洋动物中平均寿命大约只有4Ma。生物种的这个寿命转换成平均更新率为每百万年25％。如果这种计算用于整个生物群的话,并假设地球上大约有1000万个物种,那么平均每年有2～3个物种会自然灭绝。这种逻辑是简单的,但有点使人误解,因为有些平均年份可以极少发生灭绝。化石记 Fossil record is rich in evidence of biological extinction. The average life expectancy of marine animals is only about 4Ma. This life expectancy of living species translates to an average update rate of 25% per million years. If this calculation is used for the entire biota, and assuming that there are about 10 million species on Earth, an average of 2-3 species extinct on average each year. This logic is simple, but somewhat misleading, as some average years can be rarely extinct. Fossil mind