考研英语阅读理解中的文章，很多来自一些外刊杂志方面的题材。接下来，北京文都考研网为扩宽2020考研学子的知识面，整理了考研英语经济学人外刊:动物的魔法(下)，供考生参考。
2020考研英语经济学人外刊:动物的魔法(下)
Armed with this information, Dr Wei and his colleagues looked at the ratio of uranium isotopes in their rock samples and found two moments when 238U levels plunged with respect to those of 235U.
掌握了这些信息后，魏博士和他的同事们研究了他们岩石样本中铀同位素的比例，发现了有2个时期出现了238U含量相比于235U急剧下降。
The first was between 542m years and 541m years ago-that is, immediately before the Cambrian.
第一次是在5.42亿年到5.41亿年前，即稍微早于寒武纪。
The second was between 524m years and 523m years ago, after the Cambrian had been going for some time.
第二次是在5.24亿年到5.23亿年前，这时距离寒武纪时代已经有一段时间了。
Crucially, these dates match what look, from the fossil record, like two pulses of evolution in the history of the animals.
至关重要的一点是，这两个时期与化石记录的动物史上两股进化浪潮出现的时间相吻合。
The first saw the emergence of brachiopods and molluscs, the second that of annelids, cnidarians, echinoderms and chordates (a group that includes the vertebrates).
第一次是腕足类动物和软体动物的出现，第二次则是环节动物、刺胞动物、棘皮动物和脊索动物(包括脊椎动物在内的一群)的出现。
In Dr Wei's view, then, what happened in the Cambrian was similar to subsequent incidents of biological diversification, such as that of the mammals after the extinction of the dinosaurs.
因此，在魏博士看来，寒武纪生物大爆发与后来发生的许多生物多样性事件是类似的，比如恐龙灭绝后哺乳动物的繁盛。
First, some sort of environmental catastrophe wiped out many of the previous incumbents.
首先，某种生态环境的灾难摧毁了许多原先的物种。
Then, new groups emerged to fill the empty ecological niches.
接着，新的群体出现并填补空缺的生态位。
In the case of the dinosaurs, the catastrophe was an asteroid impact.
在恐龙的例子中，小行星撞击充当了灾难的角色。
In the case of the Cambrian it was periods of anoxia of as-yet-unknown cause.
在寒武纪的例子中，这种灾难则是由目前仍未知的原因引起的氧气缺乏。
It remains true that rising oxygen levels on Earth at the time were necessary to permit animals to prosper.
有一点仍然是确信的：地球上的氧含量上升对于动物繁盛是不可或缺的。
But the trigger for their diversity may well have been the reverse.
但是，引发多样性增加的很可能恰恰是相反的因素。
[重难点词汇]
diversification [dɪ,vɝsɪfɪ'keʃən] n. 多样化;变化
wipe out 消灭;彻底摧毁;垮台;(滑雪等时的)翻倒;封闭
以上是北京文都考研网给出的“2020考研英语经济学人外刊:动物的魔法(下)”，希望对备考2020考研英语的考生有所帮助!祝2020考研顺利!
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