Triassic

 Longman Dictionary of Contemporary English 5++朗文当代英语 5++LDOCE 5++朗文 5++Tri·as·sic /traɪˈæsɪk/ adjective  belonging or relating to the period between about 245 million and 202 million years ago, when life in the sea and on land changed and spread a lot, and dinosaurs first appeared 三叠纪的，三叠系的

Tri·as·sic adjectiveChineseSyllable  

Triassic
Tri‧as‧sic /traɪˈæsɪk/ adjective
belonging or relating to the period between about 245 million and 202 million years ago, when life in the sea and on land changed and spread a lot, and dinosaurs first appeared