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1 Earth Forms. 2 Fossils are rare.
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geological timescale
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1 First vertebrates appear. 2 Trilobites are common.
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1 Echinoderms appear. 2 Graptolites flourish.
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1 Eurypterids appear. 2 Animals appear.
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1 amphibians appear. 2 giant horses appear.
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1 amphibians flourish. 2 forest and swamps cover most land.
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1 giant cockroaches and dragonflies are common. 2 reptiles appear.
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1 Pangaea comes together. 2 mass extinctions mark the end of the Era.
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1 Dinosaurs appear. 2 ammonites are common.
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1 dinosaurs are the dominant life form. 2 Primitive birds and flying reptiles appear.
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1 Flowering plants and modern birds. 2 mass extinctions mark the end of the Mesozoic Era.
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1 age of mammals beings. 2 first primates appear.
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1 Horses, flying squirrels appear. 2 Bats and whales appear.
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1 Dear, pigs, camels appear. 2 cats and dogs appear.
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1 Grazing herds are abundant. 2 Raccoons and wolves appear.
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1 Large Carnivores appear. 2 Climatic cooling increased.
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1 woolly mammoths appear. 2 Rhinos and humans appear.
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1 the last glacial period ends. 2 Complex human societies develop.
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1 Nuclear tests. 2 domesticated chickens.