K-T boundary

noun

: the transition between the Cretaceous and Tertiary periods of geologic time characterized by a mass extinction of many forms of life including the dinosaurs

also : a geologic stratum marking this boundary

Examples of K-T boundary in a Sentence

Recent Examples on the Web Kring was foundational in confirming the role of the Chicxulub crater’s impact event in the K-T boundary mass extinction. —

Anna Funk, Discover Magazine, 14 Nov. 2018

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'K-T boundary.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

K (alternative for C as abbreviation for Cretaceous) + Tertiary

First Known Use

1983, in the meaning defined above

Time Traveler

The first known use of K-T boundary was in 1983

See more words from the same year

Cite this Entry

Style

“K-T boundary.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/K-T%20boundary. Accessed 1 Oct. 2023.

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Kids Definition

K-T boundary

noun

: the transition between the Cretaceous and Tertiary periods of geologic time marked especially by the extinction of the dinosaurs

also : a layer of rock marking this boundary

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