Mesozoic

The Mesozoic Era, lasting from roughly 252 to 66 million years ago, is famously celebrated as the "Age of Reptiles". It is bounded by two of Earth's most severe mass extinctions: the Permian-Triassic extinction at its start and the Cretaceous-Paleogene event at its close. The Mesozoic is characterized by the absolute dominance of dinosaurs on land, pterosaurs in the skies, and massive marine reptiles like ichthyosaurs in the oceans. This era also witnessed the origin of the first true mammals, birds, and flowering plants. Geologically, the supercontinent Pangea began fracturing and drifting apart, opening up new oceans and fundamentally altering global climates and ocean currents. The climate remained generally warm and tropical worldwide, lacking polar ice sheets and fostering a highly biodiverse planetary ecosystem before a massive asteroid impact ended the era.