Cretaceous
/krɪˈteɪʃəs/adjective
1- Geology of, relating to, or denoting the last period of the Mesozoic era, between the Jurassic and Tertiary periods【地质】（与）白垩纪（有关）的。
1.1
- as noun the Cretaceous the Cretaceous period or the system of rocks deposited during it白垩纪; 白垩纪（岩石）系。
The Cretaceous lasted from about 146 to 65 million years ago. The climate was warm and the sea level rose; the period is characterized especially in NW Europe by the deposition of chalk. The first flowering plants emerged and the domination of the dinosaurs continued, although they died out quite abruptly towards the end of it.
词源
late 17th cent.:from Latin cretaceus （from creta 'chalk'） + -OUS.