Earth’s geological era lasting from about 252 to 66 million years ago was the Mesozoic.
The Mesozoic is the middle of the three eras in the Phanerozoic Eon, positioned between the Paleozoic and the Cenozoic. It is divided into three periods: the Triassic, Jurassic, and Cretaceous. Together, they span the interval from the aftermath of the Permian–Triassic mass extinction to the Cretaceous–Paleogene extinction.
The era is popularly called the Age of Dinosaurs because dinosaurs dominated many terrestrial ecosystems, although mammals, birds, pterosaurs, marine reptiles, and diverse plants also evolved substantially. Gymnosperms such as conifers, cycads, and ginkgoes were especially important, while flowering plants became widespread during the Cretaceous.
The Mesozoic also saw Pangaea break apart, gradually creating the broad arrangement of continents recognizable today. The Cenozoic began after the extinction event 66 million years ago, while the Paleozoic ended at the start of the Mesozoic.