Paleoproterozoic Era

Increase in Earth's oxygen

The Paleoproterozoic Era is first era in the Proterozoic Eon, occurring after the Neoarchean Period, and before the Mesoproterozoic Era.

Geologic Age

  • 2,500–1,600 million years ago



What happened during this time?


  • Continents and crust stabilized

    • Super continent, named Columbia, starts to form (1.5-2.0 Ga)

  • Earth had about 450 days in a year, and 20 hour days

  • Oxygen levels continue to increase


  • 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

Above: stromatolite, layers of fossilized cyanobacteria