When did the Mesozoic era begin?

The Mesozoic era began between 251 and 199.6 million years ago with the Triassic time period. Two other time periods belonging to this era are the Jurassic period, which began 199.6 to 145.5 million years ago, and the Cretaceous period, which started between 145.5 to 65.5 million years ago.

The word Mesozoic, which translates to "middle animals", refers to the era when the world fauna changed and evolved a great deal when compared to those seen in the Paleozoic era. The Mesozoic era also resulted in significant changes in terrestrial vegetation. The early period of this era was predominately made up of plants such as cycads, ginkophytes, ferns and bennettitaleans.