[sometimesm-] designating or of the middle geologic era of the Phanerozoic Eon, subdivided into the Triassic, Jurassic, and Cretaceous periods and characterized by the development and extinction of the dinosaurs and the development of the first birds, mammals, and flowering plants
Origin of Mesozoicmeso- + zo- + -ic
the Mesozoic Era or its rocks
Of, relating to, or being the era of geologic time from about 251 to 66 million years ago. The Mesozoic Era includes the Triassic, Jurassic, and Cretaceous Periods and is characterized by the development of flying reptiles, birds, and flowering plants and by the appearance and extinction of dinosaurs. geologic time
The Mesozoic Era.