TPO5-3 The Cambrian Explosion
寒武纪生命大爆发(Cambrian Explosion)是古生物学和地质学上的一大悬案，但介绍历史谜题的本文中题目设置却不难。我们一起通过下面的句子研究下有特点的句子吧。
1) Although named after a site in Australia, the Ediacara formation is worldwide in distribution and dates to Precambrian times.(转折逻辑关系是重要的出题点，侧重转折后的信息。)
2)At one time, the animals present in these fossil beds were assigned to various modern animal groups, but most paleontologists now agree that all Tommotian fossils represent unique body forms that arose in the early Cambrian period and disappeared before the end ofthe period, leaving no descendants in modern animal groups. (转折逻辑关系，句子简化题来源。捋顺地质年代的名称及顺序。)
3) These fossil beds provide evidence of about 32 modern animal groups, plus about 20 other animal body forms that are so different from any modern animals that they cannot be assigned to any one of the modern groups.(前后两个that引导不同的从句。修辞目的题的观点句。)
4) Why was thisevolution so rapid? No one really knows. (设问句也是阅读段落中引起注意的一种写作手法，结合上文一起构成出题点。)
5) Many zoologists believe that it was because so many ecological niches were available with virtually no competition from existing species.
6) Will zoologists ever know the evolutionary sequences in the Cambrian explosion? Perhaps another ancient fossil bed of soft-bodied animals from 600-million-year-old seas is awaiting discovery.
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