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  3. Fossil formations like the Burgess Shale show that evolution cannot always be thought of as a slow progression. The Cambrian exp

Fossil formations like the Burgess Shale show that evolution cannot always be thought of as a slow progression. The Cambrian exp

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问题     Fossil formations like the Burgess Shale show that evolution cannot always be thought of as a slow progression. The Cambrian explosion involved rapid evolutionary diversification, followed by the extinction of many unique animals. Why was this evolution so rapid? No one really knows. Many zoologists believe that it was because so many ecological niches were available with virtually no competition from existing species. 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.
What can be inferred from paragraph 7 about why the Cambrian explosion is so unusual?
选项 A、It generated new ecological niches through the extinction of many unique animals.
B、It was a period of rapid evolution, and evolution is often thought of as a slow process.
C、It is a period whose evolutionary sequences are clearly marked.
D、It generated a very large number of ancient fossil beds containing soft-bodied animals.
答案B
解析
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