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

Example Sentences

Recent Examples on the Web Earlier this year, scientists announced the discovery of a new giant sea lizard — a mosasaur — known as Thalassotitan atrox. Sean Mowbray, Discover Magazine, 14 Oct. 2022 The mosasaur fossils Kruse found were jutting out of the rocky creek bed. Dallas News, 2 Aug. 2022 Last month, paleontologists from the Perot Museum of Nature and Science in Dallas unearthed fossils near the North Sulphur River of a mosasaur, a 30-foot marine lizard that existed around 80 million years ago. Ariana Garcia, Chron, 23 Aug. 2022 The Paleo Lab team made great progress on the Ovilla #mosasaur block over the past week. Ariana Garcia, Chron, 2 Aug. 2022 Ron Tykoski, the Perot Museum's director of paleontology and curator of vertebrae paleontology, told the Morning News that during the mosasaur's time, most of Central Texas was underwater. Ariana Garcia, Chron, 2 Aug. 2022 From a swimming Tyrannosaurus rex to the grooming habits of a gigantic marine reptile mosasaur, audiences should get ready to have their minds blown during the five-episode series, which debuts new episodes daily beginning Monday on Apple TV+. John Benson, cleveland, 23 May 2022 The first mosasaur vertebrae of the day was found sitting on a pedestal by Benji Deason of Trussville. Dennis Pillion |, al, 9 Dec. 2021 Paleontologists believe the largest mosasaur yet discovered would have been about 56 feet long. Dennis Pillion |, al, 9 Dec. 2021 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'mosasaur.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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 25 Mar. 2023.

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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