STAGES OF THE EVOLUTION OF MICROFOSSILS A ND PHYTOLITHS AS A PALEONTOLOGICAL BASE FOR THE LATE PRECAMBRIAN EVENT STRATIGRAPHY

Comparative analysis of all presently known findings of algal microbio tas (silicified and with organic walls) from the deposits of Precambri an age and genetically related to phytolith algae has revealed some re gularities in the development of ancient algae and established stages of their evolution. In the Early Proterozoic and Early Riphean the evo lution of algae is of pulse character: powerful, comparatively short-t erm radiations (2.2-1.8 Ga; 1.4-1.35 Ga) are followed by long periods of depressed evolution of algae. In the Late Riphean (since 1.15 Ga) a nd Vendian, the evolution of algal microbiotas was continuous and wave -like; along with procaryotes, eucaryotes became abundant. At the pres ent state of the art, we can speak about four large stages of the evol ution of algae: Early Proterozoic, Early Riphean, Late Riphean, and Ve ndian.