ichthyosaur

American  

[ik-thee-uh-sawr] / ˈɪk θi əˌsɔr /

noun

1. any fishlike marine reptile of the extinct order Ichthyosauria, ranging from 4 to 40 feet (1.2 to 12 meters) in length and having a round, tapering body, a large head, four paddlelike flippers, and a vertical caudal fin.

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ichthyosaur British  

/ ˈɪkθɪəˌsɔː, ˌɪkθɪəˈsɔːrəs /

noun

1. any extinct marine Mesozoic reptile of the order Ichthyosauria, which had a porpoise-like body with dorsal and tail fins and paddle-like limbs See also plesiosaur

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ichthyosaur Scientific  

/ ĭk′thē-ə-sôr′ /

1. Any of various extinct sea reptiles of the genus Ichthyosaurus and related genera, that had a medium-sized to large dolphin-like body with a dorsal fin, four flippers, and a large, crescent-shaped tail. The head had a long beak with sharp teeth, large eyes and earbones, and nostrils near the eyes on top of the skull. Ichthyosaurs were most common and diverse in the Triassic and Jurassic Periods and died out well before the end of the Cretaceous.

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Other Word Forms

• ichthyosaurian adjective
• ichthyosauroid adjective

Etymology

Origin of ichthyosaur

First recorded in 1820–30; see origin at ichthyosaurus

Example Sentences

A remarkably complete skeleton uncovered along the UK's Jurassic Coast has been identified as a previously unknown species of ichthyosaur -- a group of prehistoric marine reptiles that once dominated the world's oceans.

From Science Daily • Feb. 24, 2026

Researchers identified several anatomical traits in Xiphodracon that have never been documented in any other ichthyosaur.

From Science Daily • Feb. 24, 2026

Her mineralized vertebra of a juvenile Jurassic ichthyosaur exudes: “Now I am a treasure for you to love—a part of me to call your own.”

From The Wall Street Journal • Jan. 16, 2026

"I thought long and hard about the name," said ichthyosaur expert Dr Dean Lomax, who co-authored authored the paper identifying the skeleton as a new species.

From BBC • Oct. 9, 2025

Buckland, I think, once indulged in the jeu d'esprit of supposing an ichthyosaur lecturing on the human skull.

From A journey in other worlds A romance of the future by Astor, John Jacob