题型分类：推论题
题干分析：关键词before，Cambrian period；用关键词可以定位到全文第一句话 It was not until the Cambrian period, beginning about 600 million years ago, that a great proliferation of macroscopic species occurred on Earth and produced a fossil record that allows us to track the rise and fall of biodiversity. 大意为：直到C期我们才能追溯生物多样性。not until关键词可以根据逻辑推断出在C期之前不能追溯。

选项分析：

B选项：是定位句的同义转述，和其中that allows us to track the rise and fall of biodiversity部分对应，故正确。

A选项：和定位句中的the rise and fall of biodiversity矛盾，故错误。

C选项：对应原文biodiversity has generally risen, but there have been some notable exceptions...，并没有说most dramatic，属于无中生有，错误。

D选项：原文中未提到microscopic species，只提到了a great proliferation of macroscopic species occurred，并没说前者减少，属于无中生有，错误。