Ordovician radiation: Quick Facts

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A colorful diagram of the geologic time scale shows major eons, eras, and periods, with illustrations of key prehistoric life forms such as bacteria, jellyfish, trilobites, fishes, dinosaurs, mammals, and humans, spanning from 4,000 million years ago to the present. Measurement bars at the top and bottom indicate the passage of time in millions of years, and each section is color-coded to highlight evolutionary milestones.

Ordovician paleogeography

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Ordovician Period Cambrian explosion evolution human evolution Lamarckism What Darwin Got Right (and Wrong) About Evolution last universal common ancestor adaptation extinction coevolution inclusive fitness mutation theory emergence

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