Mesozoic Era, one of the major divisions of geologic time. It is sometimes called the Age of Reptiles.
|Triassic||250 million years ago||38 million years||The first turtles, crocodiles, dinosaurs, sea reptiles, flying reptiles, and mammals appeared. The huge supercontinent began to break up into separate continents.|
|Jurassic||213 million years ago||68 million years||The first birds appeared. Dinosaurs reached their greatest size. Insects were plentiful. Ammonites flourished in the sea. A few small mammals lived on land.|
|Cretaceous||145 million years ago||80 million years||Horned and armored dinosaurs became common. Flowering plants developed. Dinosaurs, flying reptiles, and giant sea reptiles died out at the end of the period.|