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Origin of Earth
Oldest known rocks on Earth's surface
Oldest fossils of cells (prokaryotes) appear
Concentration of atmospheric oxygen begins to increase
Proterozoic Eon/Ediacaran Period
Oldest fossils of eukaryotic cells appear/diverse algae and soft-bodied invertebrate animals appear
Extensive forests of vascular plants form
First seed plants appear
Origin of reptiles
Radiation of reptiles
Origin of most present-day groups of insects
Extinction of many marine and terrestrial organisms at end of period
Cone-bearing plants (gymnosperms) dominate the landscape
Dinosaurs evolve and radiate
Origin of mammals
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