The past life of the earth 1 地球上的昔日生命

It is animals and plants which lived in or near water whose remains are most likely to be preserved, for one of the necessary conditions of preservation is quick burial, and it is only in the seas and rivers, and sometimes lakes, where mud and sit have been continuously deposited, that bodies and the can be rapidly covered over and preserved.

只有生活在水中或水边的动植物尸体最有可能被保存下来，因为保存的必要条件之一是迅速掩埋，所以只有在泥沙不停淤积的海洋和江河里，有时在湖泊里，尸体之类的东西才能被迅速地覆盖而保存下来。

But even in the most favourable circumstances only a small fraction of the creatures that die are preserved in this way before decay sets in or, even more likely, before scavengers eat them. After all, all living creatures live by feeding on something else, whether it be plant or animal, dead or alive, and it is only by chance that such a fate is avoided. The remains of plants and animals that lived on land are much more rarely preserved, for there is seldom anything to cover them over.

即使是在最有利的环境中，死去的生物中也只有一小部分能在开始腐烂前，或更可能在被食腐动物吃掉之前，被这样保存下来。因为一切生物都是靠吃别的东西来活命的，不管这种东西是植物还是动物，死的还是活的，因此，生物偶尔才能避免被吃掉的命运。曾在陆地上生活过的动植物的遗体被保存下来的更为罕见，因为陆地上几乎没有什么东西覆盖它们。�

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New words and expressions 生词和短语

preservation

n. 保存

silt

n. 淤泥

scavenger

n. 食腐动物

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