 Columbia was dominant in the early-mid Proterozoic and not much is known about continental assemblages before then.There are a few plausible models that explain tectonics of the early Earth prior to the formation of Columbia, but the current most plausible hypothesis is that prior to Columbia, there were only a few independent cratons scattered around the Earth (not necessarily a supercontinent, like Rodinia or Columbia).The first advanced single-celled, eukaryotes and multi-cellular life, preserved as the Francevillian Group Fossils, roughly coincides with the start of the accumulation of free oxygen.