The Mesozoic, or “middle life,” began about 250 million years ago and ended about 65 million years ago. It is divided into the Triassic, Jurassic, and Cretaceous Periods and is referred to as the age of reptiles. The Mesozoic was a time of warm climate and reptiles, many of them large, dominated the land, water, and air. Among these were dinosaurs. Mammals first appeared late in the Triassic, birds in the Jurassic, and flowering plants (angiosperms) in the Cretaceous. All of these groups would prosper after the end of the Mesozoic when dinosaurs and many other, but not all, reptile groups became extinct.