Before revision: Microbial mats of coexisting bacteria and archaea were the dominant form of life in the early Archean epoch and many of the major steps in early evolution are thought to have taken place in this environment.
After revision: Microbial mats of coexisting bacteria and archaea were the dominant form of life in the early Archean eon and many of the major steps in early evolution are thought to have taken place in this environment.