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  3. Scientists have asked important questions about this explosion for more than a century. Why did it occur so late in the history

Scientists have asked important questions about this explosion for more than a century. Why did it occur so late in the history

admin2014-09-29  104
问题     Scientists have asked important questions about this explosion for more than a century. Why did it occur so late in the history of Earth? The origin of multicellular forms of life seems a relatively simple step compared to the origin of life itself. Why does the fossil record not document the series of evolutionary changes during the evolution of animals? Why did animal life evolve so quickly? Paleontologists continue to search the fossil record for answers to these questions.
    One interpretation regarding the absence of fossils during this important 100-million-year period is that early animals were soft bodied and simply did not fossilize. Fossilization of soft-bodied animals is less likely than fossilization of hard-bodied animals, but it does occur. Conditions that promote fossilization of soft-bodied animals include very rapid covering by sediments that create an environment that discourages decomposition. In fact, fossil beds containing soft-bodied animals have been known for many years.
According to paragraph 2, which of the following is NOT a question that paleontologists asked about the Cambrian explosion?
选项 A、Why was the origin of life a simple step in Earth’s history?
B、Why did it take so long for multicellular organisms to develop?
C、Why did animal life evolve so rapidly?
D、Why does the fossil record lack evidence of animal evolution during that time?
答案A
解析
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