This break in Earth's history is marked by a mass extinction, when as many as half the species on the planet became extinct.
地球历史上的这次重大灾难以物种的大量消亡为标志；当时，地球上多达一半的物种都灭绝了。
There is no natural foresight, no mechanism for warning that present selfish gains are leading to species extinction - and indeed, 99 per cent of all species that have ever lived are extinct.
没有自然的深谋远虑，没有什么机制会警告当前的自私收益将导致物种灭绝——事实上，99%曾经存在的物种现在都已经灭绝了。
Of the 388 mammal species found in Australia, 78 are listed as vulnerable, endangered or extinct in the wild while nearly 14% of amphibians, 5% of reptiles and 6% of birds are at risk of extinction.
在澳大利亚发现的388种哺乳动物中，78种被列为易危、濒危或野外绝灭，而近14%的两栖动物、5%的爬行动物及6%的鸟类则濒临灭绝。
Of the 12,151 plant types on the endangered list, there are 8,500 threatened with extinction and 112 believed to be extinct.
载入濒危名单的植物有12151种，其中8500种濒临灭绝，112种被认为已经消失。
Many animals are already extinct, or getting close to extinction.
不少动物已经灭绝或滨临灭绝。
We are all aware of how extinction affects our planet but to find a species that was thought to be extinct and is alive and well is the greatest find man could have ever made.
我们都意识到了物种的灭绝是如何影响我们的星球的，但是发现一个已经被确认灭绝了的物种还活的好好的，这是我们最伟大的发现。
An example is the KT Mass Extinction when the last dinosaur and ammonite species, among others, became extinct, perhaps as a result of an asteroid striking the Earth.
比如，白垩纪至第三纪所发生的大灭绝。当时，可能由于一颗小行星撞击地球，恐龙和众多同时代的物种都灭绝了。
Amphibians, too, are facing an extinction crisis, with at least 33 percent either threatened or extinct, the I. U. C. N. reported.
据世界自然保护联盟报告，两栖类动物，也正面临灭绝危机，濒危或灭绝的至少有百分之三十三。
Amphibians, too, are facing an extinction crisis, with at least 33 percent either threatened or extinct, the I. U. C. N. reported.
据世界自然保护联盟报告，两栖类动物，也正面临灭绝危机，濒危或灭绝的至少有百分之三十三。
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