The Mesozoic Era, also known as the "Age of Reptiles," spanned from roughly 252 to 66 million years ago. It's characterized by the dominance of dinosaurs, the breakup of the supercontinent Pangaea, and significant changes in Earth's climate and vegetation. The era began after the Permian-Triassic extinction event and ended with the Cretaceous-Paleogene extinction event, which led to the extinction of the non-avian dinosaurs.