Eon Proterozoic Eon

Proterozoic Eon 10

• 2450 Ma – 2320 Ma Great Oxidation Event Oxygen fills the atmosphere Cyanobacteria flood the atmosphere with oxygen, rusting the oceans and enabling complex aerobic organisms.
• 2400 Ma – 2100 Ma Huronian Glaciation First Snowball Earth candidate Possibly the earliest global glaciation, lasting ~300 million years, triggered by rising oxygen levels.
• 2100 Ma First Eukaryotes Cells with a nucleus appear First cells with a true nucleus and organelles — ancestors of all plants, animals and fungi.
• 1820 Ma – 1350 Ma Columbia Supercontinent First confirmed supercontinent The supercontinent Columbia assembles from earlier cratons — earliest well-documented supercontinent.
• 1200 Ma First Sexual Reproduction Genetic mixing evolves Evidence in red algae fossils suggests sexual reproduction evolved, dramatically accelerating evolution.
• 1100 Ma – 750 Ma Rodinia Assembles Second supercontinent The supercontinent Rodinia forms. Its later breakup triggers Snowball Earth glaciations.
• 717 Ma – 660 Ma Snowball Earth — Sturtian First global glaciation Glaciers advance to the equator, freezing the entire ocean surface. Life survives in isolated refugia.
• 650 Ma – 635 Ma Snowball Earth — Marinoan Second global glaciation Second global glaciation; its dramatic end triggers the Ediacaran explosion of animal life.
• 600 Ma – 550 Ma Gondwana Begins Assembling Southern supercontinent forms Components of future Gondwana come together as Rodinia breaks apart.
• 575 Ma First Animals Ediacaran biota appear First unambiguous multicellular animals — soft-bodied Dickinsonia and Charnia, preserved as seafloor impressions.