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physical phenomena > event > era > geological era > paleozoic era > ordovician period |
ordovician period comparison table |
Subject | is a kind of | has duration | has start time |
---|---|---|---|
paleozoic era | geological era | 370 million years | 600 million years ago |
ordovician period | paleozoic era | 75 million years | 500 million years ago |
Next paleozoic era: pennsylvanian period Up: paleozoic era Previous paleozoic era: mississippian period