cretaceous: Meaning and Definition of

cre•ta•ceous

1. resembling or containing chalk.
2. (cap.)noting or pertaining to a period of the Mesozoic Era, from 140 million to 65 million years ago, characterized by the greatest development and subsequent extinction of dinosaurs and the advent of flowering plants and modern insects. See table under

1. (cap.)the Cretaceous Period or System.