The Mesozoic, or "Middle Life", Era is commonly called the Age of Dinosaurs. It began with the catastrophic Permian/Triassic mass extinction, and was truncated by the Cretaceous/Tertiary mass extinction, and is composed of the Triassic, Jurassic, and Cretaceous Periods. This category is for any website dealing with the fossil reocrd of the Mesozoic.
