Earth has seen five major extinction episodes in its time — the Ordovician, Devonian, Permian, Triassic, and Cretaceous, in that order — and many smaller ones. The Ordovician (440 million years ago) and Devonian (365 million) each wiped out about 80 to 85 percent of species. The Triassic (210 million years ago) and Cretaceous (65 million years) each wiped out 70 to 75 percent of species. But the real whopper was the Permian extinction of about 245 million years ago, which raised the curtain on the long age of the dinosaurs. In the Permian, at least 95 percent of animals known from the fossil record check out, never to return. Even about a third of insect species went — the only occasion on which they were lost en masse. It is as close as we have ever come to total obliteration.
地球已经目睹了5次大的灭绝事件——依次在奥陶纪、泥盆纪、二叠纪、三叠纪和白垩纪——以及许多小的灭绝事件。奥陶纪（44000万年以前）和泥盆纪（36500万年以前）分别消灭了大约80%——85%的物种。三叠纪（2l000万年以前）和自垩纪（6500万年以前）分别消灭了70%-75%的物种。但是，真正厉害的是大约24500万年前的二叠纪灭绝，它为漫长的恐龙时代揭开了序幕。在二叠纪，至少95%从化石记录中得知的动物退了场，再也没有回来。连大约三分之一的昆虫物种也消失了——这是它们惟一损失最惨重的一次。这也是我们最接近全军覆没的一次。

It was, truly, a mass extinction, a carnage of a magnitude that had never troubled the Earth before, says Richard Fortey. The Permian event was particularly devastating to sea creatures. Trilobites vanished altogether. Clams and sea urchins nearly went. Virtually all other marine organisms were staggered. Altogether, on land and in the water, it is thought that Earth lost 52 percent of its families — that's the level above genus and below order on the grand scale of life (the subject of the next chapter) — and perhaps as many as 96 percent of all its species. It would be a long time — as much as eighty million years by one reckoning — before species totals recovered.
“这确实是一次大规模的灭绝，一次大屠杀。是地球上以前从来没有发生过的。”理查德·福泰说。二叠纪事件对海洋动物的破坏性尤其严重。三叶虫完全消失了。蛤蜊和海胆几乎灭绝。实际上，所有的海生动物都七零八落。据认为，总起来说，在陆地和水里，地球损失了52%的“科”——那个层次在生命的大等级表上高于“属”，低于“目”（这是下一章的题材）——以及大约多达96%的全部物种。要过很长时间——有人估计，要过长达8000万年。物种的总量才会得以恢复。