When did the Triassic Period begin and end?

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Triassic paleogeography — Triassic Period Distribution of landmasses, mountainous regions, shallow seas, and deep ocean basins during the early Triassic Period. Included in the paleogeographic reconstruction are the locations of the interval's subduction zones.

The Triassic Period began approximately 252.2 million years ago and ended about 201.3 million years ago.1

These dates mark the interval of the Mesozoic Era during which the supercontinent Pangea began to rift and significant evolutionary developments occurred, including the appearance of the first dinosaurs and early mammals. Because reliable radiometric dating of sedimentary rocks can be challenging, these absolute ages are subject to revision as more accurate data becomes available.12