— cretaceously , adv.
/kri tay"sheuhs/ , adj.
1. resembling or containing chalk.
2. ( cap. ) Geol. 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 geologic time .
n.
3. ( cap. ) Geol. the Cretaceous Period or System.
[ 1665-70; cretaceus, equiv. to cret ( a ) chalk, clay (cf. CRAYON) + -aceus -ACEOUS; the geological period was defined from the chalk beds of SE England and associated formations ]