寒武纪的

The new framework, comprising a pre-trilobite series and three trilobite-dominated series, reflects the major evolutional stages of the life on Earth during Cambrian Period.

新的划分方案包括1个“前三叶虫统”和3个“三叶虫优势统”，反映了生命发展的主要阶。

To the question why we do not find rich fossiliferous deposits belonging to these assumed earliest periods prior to the Cambrian system, I can give no satisfactory answer.

为什么我们没有发大量的属这个比还要早的时期的化石，我无法给出满意的答案。