Mosasaur
family of extinct marine reptiles from the Cretaceous
Mosasaurs (from Latin Mosa meaning the 'Meuse', and Greek σαύρος sauros meaning 'lizard') are an extinct group of large aquatic reptiles within the family Mosasauridae that lived during the Late Cretaceous. Their first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764. They belong to the order Squamata, which includes lizards and snakes.
During the last 20 million years of the Cretaceous period (Turonian–Maastrichtian ages), with the extinction of the ichthyosaurs and pliosaurs, mosasaurids became the dominant marine predators. They themselves became extinct as a result of the K-Pg event at the end of the Cretaceous period, about 66 million years ago.
Description
Mosasaurs breathed air, were powerful swimmers, and were well-adapted to living in the warm, shallow inland seas prevalent during the Late Cretaceous period. Mosasaurs were so well adapted to this environment that they most likely gave birth to live young, rather than returning to the shore to lay eggs as sea turtles do.
The smallest-known mosasaur was Dallasaurus turneri, which was less than 1 m (3.3 ft) long. Larger mosasaurs were more typical, with many species growing longer than 4 m (13 ft). Mosasaurus hoffmannii, the largest known species reached up to 17 m (56 ft), but it has been considered to be probably overestimated by Cleary et al.
“Mosasaur” enters the record as family of extinct marine reptiles from the Cretaceous. Crown Archives preserves that source wording while asking what Mosasaur, family and extinct can confirm, complicate or overturn.
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Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Aug 2, 2026. The linked authority identifier is Q729456. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1764.
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This entry incorporates text from “Mosasaur” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.