The Proterozoic Eon, spanning from 2,500 million to 539 million ... However, the fossil record of Proterozoic life has been challenging to interpret due to its sparse and inconsistent nature.

The subsequent Archean eon (approximately 3,500 million years ago) is known as the age of bacteria and archaea. The Proterozoic eon was the gathering up of oxygen in Earth's atmosphere ...

Earliest animals evolved in the mid to late Proterozoic Eon and lie deep in the fossil record. Please give special attention to the photo credit, as it is from a participating researcher not from ...

2. Archean Eon: Tells about the earliest life on Earth, its ancient continents, and how bacteria transformed our planet's atmosphere. 3. Proterozoic Eon: Covers catastrophic global glaciations ...