Mesozoic era | definition of Mesozoic era by Medical dictionary
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Mesozoic era the geological era that began 225 million years ago and lasted about 155 million years. The era includes the CRETACEOUS PERIOD, JURASSIC PERIOD, and TRIASSIC PERIOD. During this era GYMNOSPERMS became dominant plants, dinosaurs became the dominant animals, reptiles (Pterosaurs) conquered the air, and birds and mammals evolved.