C17: from Latin crētāceus, from crēta, literally: Cretan earth, that is, chalk
Cretaceous in British English
(krɪˈteɪʃəs)
adjective
1.
of, denoting, or formed in the last period of the Mesozoic era, between the Jurassic and Tertiary periods, lasting 80 million years during which chalk deposits were formed and flowering plants first appeared
noun
2. the Cretaceous
cretaceous in American English
(krɪˈteɪʃəs; kriˈteɪʃəs)
adjective
1. Rare
containing, composed of, or having the nature of, chalk
2. [usuallyC-]
designating or of the third and last geologic period of the Mesozoic Era, characterized by the formation of huge oil and chalk deposits, the development of the first flowering plants and placental mammals, and the extinction of toothed birds, ammonites, and dinosaurs