mo·​sa·​saur ˈmō-zə-ˌsȯr How to pronounce mosasaur (audio)
: any of a family (Mosasauridae) of very large extinct marine fish-eating lizards of the Upper Cretaceous with limbs modified into paddles that are related to the recent monitor lizards

Examples of mosasaur in a Sentence

Recent Examples on the Web Regardless of how many times large mosasaurs independently evolved, the lizards thrived in the seas. Riley Black, Smithsonian Magazine, 2 May 2024 In broad strokes, mosasaurs tend to share the same body shape. Riley Black, Smithsonian Magazine, 2 May 2024 Beyond that, mosasaurs also boast a fascinating evolutionary history. Max Bennett, Discover Magazine, 13 Feb. 2024 Although mosasaurs did not survive past the K-Pg event, their story has not fizzled out. Jack Knudson, Discover Magazine, 22 Dec. 2023 Eustace also had a shorter tail than many other mosasaurs, and flippers with less cartilage and more bone. Joshua Rapp Learn, Discover Magazine, 29 Nov. 2023 What the researchers discovered is that this animal shares some traits with an earlier form of mosasaur known as Clidastes and other traits with a later mosasaur known as Mosasaurus. Jeanne Timmons, Ars Technica, 30 Oct. 2023 Meet Jorgie the mosasaur The new mosasaur was described Monday in the Bulletin of the American Museum of Natural History. Jeanne Timmons, Ars Technica, 30 Oct. 2023 This mosasaur, a predator that must have terrorized the Cretaceous marine community, had some interesting dental work. Avery Hurt, Discover Magazine, 10 Oct. 2023

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

Word History


New Latin Mosasaurus, from Latin Mosa the river Meuse + Greek sauros lizard

First Known Use

1841, in the meaning defined above

Time Traveler
The first known use of mosasaur was in 1841

Dictionary Entries Near mosasaur

Cite this Entry

“Mosasaur.” Dictionary, Merriam-Webster, Accessed 18 Jun. 2024.

Kids Definition


mo·​sa·​saur ˈmō-zə-ˌsȯr How to pronounce mosasaur (audio)
: any of various very large extinct fish-eating lizards of seas of the Cretaceous period with limbs resembling paddles

from Latin Mosa "the River Meuse" and Greek sauros "lizard"

More from Merriam-Webster on mosasaur

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