The Paleoproterozoic Era is first era in the Proterozoic Eon, occurring after the Neoarchean Period, and before the Mesoproterozoic Era. This era accounts for 20% of Earth's geological history.
2,500–1,600 million years ago
Statherian Period: 1,800–1,600 Ma
Orosirian Period: 2,050–1,800 Ma
Rhyacian Period: 2,300–2,050 Ma
Siderian Period: 2,500–2,300 Ma
Continents and crust stabilized
Supercontinent, named Columbia, starts to form (1.5-2.0 Ga)
The atmosphere was dominated by methane, nitrogen, ammonia, and carbon dioxide
Oxygen levels were extremely low, but starting to increase by the end of this era
The Earth was closer to the sun, but it was 70% weaker than today.
A "day" was approximately 20 hours, and there were 450 days to an annual cycle (Feulner, 2012)
Cyanobacteria flourish along coastlines
First reported green sulfur bacteria
First acritarchs appear around 1.8 Ga
Many anaerobic bacteria go extinct
First possible eukaryotes (Grypania) arise around 2.1 Ga