Cretaceous, Cretaceous period - from 135 million to 63 million years ago; end of the age of reptiles; appearance of modern insects and flowering plants

Jurassic, Jurassic period - from 190 million to 135 million years ago; dinosaurs; conifers

Triassic, Triassic period - from 230 million to 190 million years ago; dinosaurs, marine reptiles; volcanic activity

geological era, era - a major division of geological time; an era is usually divided into two or more periods