The Mesozoic ERA, also known as the Age of Reptiles, was a period of time that lasted from about 252 million to 66 million years ago. It is divided into three periods: Triassic, Jurassic, and Cretaceous. The term Mesozoic is derived from the Greek words mesos, meaning 'MIDDLE, ' and zōon, meaning 'ANIMAL.' During this ERA, the Earth saw the rise of the dinosaurs, the first birds, and the first mammals. The ERA crossword solution refers to this period of time.