Triassic period

The Triassic is a geologic period that extends from about 251 to 199  Ma (million years ago). As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events. The extinction event that closed the Triassic period has recently been more accurately dated, but as with most older geologic periods, the rock beds that define the start and end are well identified, but the exact dates of the start and end of the period are uncertain by a few million years.
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Noun
1. from 230 million to 190 million years ago; dinosaurs, marine reptiles; volcanic activity
(synonym) Triassic
(hypernym) period, geological period
(part-holonym) Mesozoic, Mesozoic era, Age of Reptiles

248-208 Million Years Ago
As the Mesozoic era begins, we see the rise of the what is known as the dinosaurs. Pterosaurs (flying reptiles) also made their first appearance here as well as frogs, turtles, and crocodiles. During the Late Triassic period, many small mammals also arose.
Triassic World 
Plateosaurus

see list of time periods