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| Mesozoic | Cretaceous | 144 | | Extensive mountain building at the end, climate cooled worldwide. Extinction of archaic birds and many reptiles by the end of this period. |
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| | Jurassic | 208 | | First reptilian birds. Reptilian diversity was high in all habitats. Climate was warm and stable with little seasonal variation. |
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| | Triassic | 245 | | Earliest dinosaurs, flying reptiles, marine reptiles. Primitive mammals appeared. Continents were high with few shallow seas. Climate warm. |
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| Paleozoic | Permian | 286 | | Rise of primitive reptiles. Extinction of the trilobites. Climate was cold at the beginning but warmed progressively. Widespread extinctions at the end of this period. |
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| | Pennsylvanian | 330 | | Earliest know insects, large arthropods. Climate generally warm and humid. Extensive coal producing swamps. Many specialized amphibians and the first appearance of reptiles |
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| | Mississippian | 360 | | Extinction of some fish lineages and expansion of others. Beginning of large coal production swamps. Extensive radiation of amphibians. |
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| | Devonian | 408 | | Explosion of fish and disappearance of many jawless varieties. First winged insects and tetrapods. Land was higher climate cooler. |
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| | Silurian | 438 | | Earliest know land animals. Primitive plants. Rise of fishes. Abundant trilobites. |
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| | Ordovician | 505 | | Earliest know vertebrates. Primitive plants. Trilobites and cephalopods abundant. |
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| | Cambrian | 550-590 | | Extensive shallow seas. Brachiopods and trilobites common. |
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| Precambrian | Proterozoic | | 2,500 | | Primitive water dwelling plants and animals. Changes in the lithosphere produced major land masses and shallow seas. |
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| | Archean | | 4,600 | | Oldest know life (mostly indirect evidence). Formation of the earth and slow development of the lithosphere, hydrosphere and atmosphere. Development of life in the hydrosphere. |