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• cretaceous
  cretaceous

  adjective

  resembling or containing chalk.
• Cretaceous
  Cretaceous

  adjective

  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

cretaceous

American  

[kri-tey-shuhs] / krɪˈteɪ ʃəs /

adjective

1. resembling or containing chalk.

2. (initial capital letter) 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.

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noun

1. (initial capital letter) the Cretaceous Period or System.

Cretaceous ¹ British  

/ 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

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noun

1. the Cretaceous period or rock system

cretaceous ² British  

/ krɪˈteɪʃəs /

adjective

1. consisting of or resembling chalk

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Cretaceous Scientific  

/ krĭ-tā′shəs /

1. The third and last period of the Mesozoic Era, from about 144 to 65 million years ago. During this time the supercontinent Pangaea continued to split up, with modern-day South America and Africa splitting apart, the Atlantic Ocean widening, and India disconnecting itself entirely from the other landmasses to which it was attached. Dinosaurs continued to be the dominant terrestrial animals, but many insect groups, modern mammals and birds, and the angiosperms (flowering plants) also first appeared. The Cretaceous Period ended with a mass extinction event in which about 75 percent of all species, including marine, freshwater, and terrestrial organisms, became extinct.

2. See Chart at geologic time

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Other Word Forms

• noncretaceous
  adjective
• postcretaceous
  adjective
• supercretaceous
  adjective
• cretaceously
  adverb

Etymology

Origin of cretaceous

1665–70; < Latin crētāceus, equivalent to crēt ( a ) chalk, clay ( cf. crayon) + -āceus -aceous; the geological period was defined from the chalk beds of SE England and associated formations

Example Sentences

This dinosaur would have lived 82 million years ago during the Late Cretaceous Period when Antarctica was very different from how it is today.

From BBC • Jun. 29, 2026

The Cretaceous Period ended about 66 million years ago, shortly before the extinction of non-avian dinosaurs.

From Science Daily • Jun. 22, 2026

"These findings indicate that unenlagiids were widely distributed during the Late Cretaceous," Dr. Motta says.

From Science Daily • May 29, 2026

Researchers classified the dinosaur as an unenlagiid, a group of small to medium sized theropod dinosaurs known from Late Cretaceous rocks in South America, Antarctica, Australia, and Madagascar.

From Science Daily • May 29, 2026

“They lived from the late Triassic to the Cretaceous period, though technically they’re not dinosaurs,” Kavita says in a know-it-all sort of way.

From "Dragons in a Bag" by Zetta Elliott