Proterozoic Eon

The Proterozoic Eon was a geological eon extending from 2500 to 541 million years ago. During this eon, oxygenation of the Earth's atmosphere occured; oxygen was produced by life earlier, but it accumulated in mineral deposits forming iron and sulfur oxides instead of building up in the atmosphere. Towards the end of the proterozoic, the Ediacaran biota flourished, giving the first fossil evidence of multicellular life on Earth.

Eras
The Proterozoic Eon is split into three eras:
 * Paleoproterozoic Era
 * Mesoproterozoic Era
 * Neoproterozoic Era

Adjacent Eons
The Proterozoic Eon was preceded by the Archean Eon and succeded by the Phanerozoic Eon.