Proterozoic Eon

The Great Oxidation Event (GOE), sometimes also called the Great Oxygenation Event, Oxygen Catastrophe, Oxygen Crisis, Oxygen Holocaust, or Oxygen Revolution, was when Earth's atmosphere and the shallow ocean experienced a rise in oxygen around 2.4 billion years ago (2.4 Ga) to 2.1-2.0 Ga during the Paleoproterozoic era. Geological, isotopic, and chemical evidence suggests that biologically induced molecular oxygen (dioxygen, O2) started to accumulate in Earth's atmosphere and changed Earth's atmosphere from a weakly reducing atmosphere to an oxidizing atmosphere. The causes of the event remain unclear.

The Huronian glaciation (or Makganyene glaciation) was a glaciation that extended from 2.4 billion years ago (Gya) to 2.1 Gya, during the Siderian and Rhyacian periods of the Paleoproterozoic era. The Huronian glaciation followed the Great Oxygenation Event (GOE), a time when increased atmospheric oxygen decreased atmospheric methane. The oxygen combined with the methane to form carbon dioxide and water, which do not retain heat as well as methane does.   It is the oldest and longest ice age, occurring at a time when only simple, unicellular life existed on Earth. This ice age led to a mass extinction on Earth.

End of the Huronian Glaciation.

Earliest known eukaryote fossils found

The Francevillian biota (also known as Gabon macrofossils or Gabonionta) is a group of 2.1-billion-year-old Palaeoproterozoic, macroscopic organisms known from fossils found in Gabon in the Palaeoproterozoic Francevillian B Formation, a black shale province. The fossils are regarded as evidence of the earliest form of multicellular life.

The Great Oxidation Event (GOE), sometimes also called the Great Oxygenation Event, Oxygen Catastrophe, Oxygen Crisis, Oxygen Holocaust, or Oxygen Revolution, was when Earth's atmosphere and the shallow ocean experienced a rise in oxygen around 2.4 billion years ago (2.4 Ga) to 2.1-2.0 Ga during the Paleoproterozoic era.