ich·​thyo·​saur ˈik-thē-ə-ˌsȯr How to pronounce ichthyosaur (audio)
: any of an order (Ichthyosauria) of extinct marine reptiles of the Mesozoic specialized for aquatic life by a streamlined body with a long snout, limbs reduced to small fins for steering, and a large lunate caudal fin
ichthyosaurian adjective or noun

Examples of ichthyosaur in a Sentence

Recent Examples on the Web At the same time that Lomax and his team were confirming the species of ichthyosaur in the U.K., a graduate student in Germany was examining bone fragments from around the world to confirm the internal bone structure of all ichthyosaurs. Irene Wright, Miami Herald, 18 Apr. 2024 During the Rhaetian, gigantic ichthyosaurs swam while dinosaurs walked on land. Laura Baisas, Popular Science, 17 Apr. 2024 Even with their impressive length, Fraser says that the larger ichthyosaurs of the era — massive marine reptiles that once ruled the seas — may have preyed on Dinocephalosaurus. Joshua Rapp Learn, Discover Magazine, 20 Mar. 2024 Several groups of dolphin-like ichthyosaurs also died out. Howard Lee, Ars Technica, 8 Feb. 2023 Stomach contents reveal a regular diet of cephalopods, but some also include sharks, fish, turtles, ichthyosaurs, other marine reptiles, and even dinosaur dermal scutes. Jeanne Timmons, Ars Technica, 23 Mar. 2023 The ichthyosaurs harvest huge numbers of small squid. Robert Baker, Discover Magazine, 12 Nov. 2019 In the ecological shakeup that followed, competing predators such as the fish-like ichthyosaur and ancient marine crocodile relatives suffered while the pliosaur prospered and diversified. Matt Hrodey, Discover Magazine, 21 Nov. 2023 Pterosaurs took to the skies, while ichthyosaurs flourished in the oceans. Sean Mowbray, Discover Magazine, 20 Sep. 2023

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

Word History


ultimately from Greek ichthy- + sauros lizard

First Known Use

1830, in the meaning defined above

Time Traveler
The first known use of ichthyosaur was in 1830

Dictionary Entries Near ichthyosaur

Cite this Entry

“Ichthyosaur.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ichthyosaur. Accessed 17 Jun. 2024.

Kids Definition


ich·​thyo·​saur ˈik-thē-ə-ˌsȯ(ə)r How to pronounce ichthyosaur (audio)
: any of an order of extinct marine reptiles with a fish-shaped body and a long snout

More from Merriam-Webster on ichthyosaur

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!