When did the dinosaurs live?
Dinosaurs first appeared about 230 to 250 million years ago, during the Triassic Period. Their large size and vast numbers meant that they dominated animal life on Earth for millions of years. Dinosaurs became extinct around 65 million years ago, at the end of the Cretaceous Period. Earth was much different when dinosaurs roamed the planet. Several hundred million years ago, instead of there being seven continents, or large land masses, there was just one giant mass of land that was surrounded by ocean. This land mass gradually broke apart into separate continents. Areas that are now covered with tall buildings or mountain ranges were once beneath the sea, and scientists believe the climate was fairly warm throughout the year. By the end of the era in which dinosaurs lived, temperatures had cooled and distinct seasons had developed.