Jump To:

• 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.

---

noun

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

cretaceous ¹ British  

/ krɪˈteɪʃəs /

adjective

1. consisting of or resembling chalk

---

Cretaceous ² 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

---

noun

1. the Cretaceous period or rock system

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

---

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

See Examples For:

cretaceous Cretaceous

Earliest known mammalian stapes from an early cretaceous eutriconodontan mammal and implications for evolution of mammalian middle ear.

From Nature ● Nov. 12, 2017

Five miles below sea level, and beneath a shifting layer of cretaceous salt deposits, the discoveries have been estimated at 50 billion to 100 billion barrels.

From BusinessWeek ● May 10, 2012

Princeton paleontologists under the leadership of Dr. Glenn L. Jepsen. digging in a cretaceous formation near Red Lodge in southern Montana, found some old broken eggs.

From Time Magazine Archive

Their southern edge is covered with cretaceous deposits, and their eastern edge is covered as well with the tertiary deposits of the Gulf plains.

From Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 5 "Arculf" to "Armour, Philip" by Various

It is believed, however, that the depth of the cretaceous sea over the island was probably never very great.

From The History of Cuba, vol. 1 by Willis Fletcher Johnson

T. rex lived during the Cretaceous Period, when Earth's climate was much warmer than today.

From Science Daily ● Sep. 20, 2026

That exceptional preservation has made Pedrera de Meià an important site for studying Lower Cretaceous fish, amphibians, reptiles, and plants.

From Science Daily ● Sep. 15, 2026

Langer coordinates the project "Exploring the Diversity of South American Cretaceous Dinosaurs and Their Associated Faunas," which is supported by FAPESP.

From Science Daily ● Sep. 8, 2026

"Our local dinosaurs are like missing jigsaw pieces that help establish evolutionary connections, particularly around the Jurassic and Cretaceous period transition, approximately 140 million years ago."

From Barron's ● Sep. 3, 2026

Both conveniently mean "chalk," which is also what Cretaceous means.

From "A Short History of Nearly Everything" by Bill Bryson