Mesozoic Era

Mesozoic Era, one of the major divisions of geologic time. It is sometimes called the Age of Reptiles.

Mesozoic Era
PeriodBeganLastedAnimal life
Triassic 250 million years ago38 million yearsThe 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 ago68 million yearsThe 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 ago80 million yearsHorned and armored dinosaurs became common. Flowering plants developed. Dinosaurs, flying reptiles, and giant sea reptiles died out at the end of the period.