The Triassic period follows the Permian period on the geological time scale. During this time, dinosaurs first began to evolve from the early reptiles, the first primitive mammals appeared, and the armored amphibians and mammal-like reptiles died out. The Triassic was one of the first labeled divisions on the geologic time scale, and it is the first of three periods (the others are the Jurassic and Cretaceous) making up the Mesozoic era.

The Triassic was first named in 1834 by German geologist Friedrich August von Alberti (1795–1878) to describe a three-part division of rock types in Germany. It was originally called the Trias, and is still called this by many European geologists. It is named after three, or “tri,” layers of sedimentary rocks representative of the time period: from bottom to top, a sandstone, limestone, and copper-bearing shale. The three distinct rock formations are, from the bottom up, the Bunter (mostly Early Triassic), the Muschelkalk (Middle Triassic), and the Keuper (mostly Late Triassic).