Introduction to the Age of Dinosaurs Exhibition: The era when dinosaurs lived is about 250 million to 65 million years ago, which is called the Mesozoic Era in geological time. The Mesozoic era is divided into three periods: the Triassic period from 250 million to 210 million years ago, the Jurassic period from 210 million to 140 million years ago, and the Jurassic period from 210 million to 140 million years ago. The period from 140 million to 65 million years ago is called the Cretaceous period. The Mesozoic Era lasted for about 180 million years, and is also nicknamed the "Age of Reptiles."