Proterozoic Period

Detailed Overview

The Proterozoic eon was a time of crucial biological and geological transitions. It witnessed the rise of eukaryotic cells, sexual reproduction, and the first multicellular organisms. The Great Oxidation Event occurred early in this period, dramatically increasing atmospheric oxygen. The end of this eon saw the emergence of the first complex animals, including the mysterious Ediacaran biota. Several major glacial periods ("Snowball Earth" events) also occurred during this time.