THE TRIASSIC PERIOD is the geologic time period that extends from about 251 to 199 million years ago. This is the first period of the Mesozoic era, following the Permian and preceding the Jurassic period. Both the start and end of the Triassic are marked by major extinction events. During the Triassic period, both marine and continental life showed an adaptive radiation, beginning from the starkly impoverished biosphere that followed the Permian-Triassic extinction. The first flowering plants may have evolved during the Triassic, as did the first flying vertebrates, the pterosaurs. The Triassic period is further separated into Early, Middle, and Late Triassic epochs.

During the Triassic period, almost all the Earths land mass was concentrated into a single superconti-nent centered more or less on the ...