JurassicJu‧ras‧sic /dʒʊˈræsɪk/ adjective 
belonging or relating to the period of time from about 210 million years ago to about 140 million years ago, when there were dinosaurs and the first mammals and birds: 
the Jurassic period
belonging or relating to the period of time from about 210 million years ago to about 140 million years ago, when there were dinosaurs and the first mammals and birds: the Jurassic period