Proterozoic Eon

An age which marks the evolution of multicellular life

The Proterozoic is the third eon in Earth's geologic history, which occurs after the Archean Eon, and before the Phanerozoic Era.

Geologic Age

  • 2,500–538.8 million years ago


What happened during this time?


  • The origin of eukaryotes through endosymbiosis; origin of glaucophytes

  • Increasing complexity of life

  • The first multicellular organisms

    • Molecular clock analyses have estimated the origin of the green algae lineage between 700 and 1,500 mya (Douzery et al. 2004, Hedges et al. 2004, Berney and Pawlowski 2006, Roger and Hug 2006, Herron et al. 2009)


  • Continental drift, in its present form, begins to happen

    • The build-up of large continents and orogeny (mountain building), with modern plate tectonics

    • Land had grown and become stable enough to allow large inland seas, and strata deposited in these areas is relatively well preserved.

  • The gradual change in the atmosphere with the build up of oxygen

    • This build-up of oxygen in the atmosphere should have also created an ozone layer

    • Although, UV radiation may have been greater than originally assumed during the early to middle Proterozoic (Cooke et al. 2022)

  • Several ice ages

    • Snowball Earth event(s)

  • Precambrian "Pangaea" event