From Longman Dictionary of Contemporary EnglishMesozoicMes‧o‧zo‧ic /ˌmezəˈzəʊɪk, ˌmes- $ -ˈzoʊ-/ adjective belonging or relating to the period of time in the Earth’s history, from about 250 million years ago to about 65 million years ago, when dinosaurs, birds, and plants with flowers first started to exist the Mesozoic era