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.

新的划方案包括1个“前三叶虫统”和3个“三叶虫优势统”，反映了寒武纪生命发展的主要阶段。

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.

对于为什么我们没有发大量的属于这个比寒武纪还要早的时期的化石，我无法给出满意的答案。