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“前三叶虫统”和3“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.

对为们没有发大量的属比寒武纪还要早的时期的化石，无法给出满意的答案。