The Jurassic Period was a time of significant geological and biological change, lasting from approximately 201.3 to 145 million years ago. It was part of the Mesozoic Era, commonly known as the "Age of Reptiles". During this time, giant plant-eating dinosaurs roamed the land, while marine reptiles and the first birds emerged. The Earth's climate shifted from hot and dry to humid and subtropical, and the supercontinent Pangaea began to break up.