Cretaceous

adjective

Cre·​ta·​ceous kri-ˈtā-shəs 

: of, relating to, or being the last period of the Mesozoic era characterized by continued dominance of reptiles, emergent dominance of angiosperms, diversification of mammals, and the extinction of many types of organisms at the close of the period

also : of, relating to, or being the corresponding system of rocks see Geologic Time Table

Cretaceous noun

Examples of Cretaceous in a Sentence

Recent Examples on the Web

The deposit would have been on the seafloor when it was formed during the Cretaceous period. —Sara Hashemi, Smithsonian Magazine, 23 May 2025

But 66 million years ago, the Chicxulub impactor that wiped out the dinosaurs and much of the Cretaceous period’s fauna also kick-started a hydrothermal system that became a hotbed for life to recover in the local area. —Sean Mowbray, Discover Magazine, 23 May 2025

Among the rocks and marine fossils, scientists have found fossilized pollen from the Late Cretaceous and Early Paleocene periods that reflects changes in the surrounding ecosystems. —Francisca Oboh Ikuenobe, The Conversation, 20 May 2025

Scientists believe mosasaurs became extinct at the end of the Cretaceous period, according to Mississippi Department of Environmental Quality researchers. —Julia Jacobo, ABC News, 19 May 2025

Word History

Etymology

Latin cretaceus resembling chalk, from creta chalk

First Known Use

1832, in the meaning defined above

Rhymes for Cretaceous

• arenaceous
• argillaceous
• carbonaceous
• contumacious
• coriaceous
• efficacious
• farinaceous
• foliaceous
• membranaceous
• ochraceous
• olivaceous
• ostentatious

Kids Definition

Cretaceous

adjective

Cre·​ta·​ceous kri-ˈtā-shəs 

: of, relating to, or being the last period of the Mesozoic era of geological history marked by the extinction of the dinosaurs at the close of the period

also : relating to the corresponding system of rocks see geologic time

Cretaceous noun