Dinosaurs dominated the land for more than 150 million years. The Mesozoic Era, lasting from about 252 to 66 million years ago, is often called the Age of Reptiles. It comprises the Triassic, Jurassic, and Cretaceous periods.

The supercontinent Pangaea broke apart during the Mesozoic, opening the Atlantic Ocean and setting continents on paths toward their modern positions. Climate was generally warmer than today, with high sea levels flooding continental interiors. Flowering plants appeared in the Cretaceous and rapidly diversified.

The era ended with a mass extinction that eliminated non-avian dinosaurs, ammonites, and many other groups. Evidence points to a large asteroid impact and extensive volcanism as causes. Mesozoic rocks and fossils remain among the most studied in the geologic record because of their rich content and the dramatic story they tell.

• Geologic era from 252 to 66 million years ago
• Age of dinosaurs and reptiles
• Includes Triassic, Jurassic, and Cretaceous
• Ended by a major mass extinction