# cretaceous

/kɹɪˈteɪʃɪs/ (US) · /kɹɛtˈeɪʃəs/ (UK) · CEFR C2 · Adjective

Source: https://englishreference.com/word/cretaceous
Updated: 2026-08-15

## Definition

relating to the final period of the age of dinosaurs, which ended about 66 million years ago. It is famous for being the time when many well-known dinosaurs lived and then went extinct.

For teachers: relating to the final period of the Mesozoic Era, following the Jurassic and preceding the Paleogene. Often associated with the mass extinction event that concluded the age of non-avian dinosaurs.

## Examples

- The Tyrannosaurus rex lived during the late Cretaceous period.
- Geologists identify Cretaceous rock layers by the presence of specific chalk deposits and marine fossils found worldwide.
- The transition from the Cretaceous to the Paleogene is marked by a distinct sediment layer that suggests a catastrophic impact event fundamentally altered the planet's biosphere.

## Usage notes

- Typically used attributively to modify nouns like 'period', 'era', or 'strata'.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.