About 300 million years ago, Earth didn't have seven continents, but instead one massive supercontinent called Pangaea, which was surrounded by a single ocean called ... But the existence of Pangaea overlapped with the worst mass extinction in history, the Permian-Triassic (P-TR) extinction event. read more
Pangaea formed through a gradual process spanning a few hundred million years. Beginning about 480 million years ago, a continent called Laurentia, which includes parts of North America, merged with several other micro-continents to form Euramerica. read more