ichthyosaur

American

[ik-thee-uh-sawr] / ˈɪk θi əˌsɔr /

noun

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.

ichthyosaur British

/ ˈɪkθɪəˌsɔː, ˌɪkθɪəˈsɔːrəs /

noun

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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

ichthyosaur Scientific

/ ĭk′thē-ə-sôr′ /

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.

Other Word Forms

Etymology

Origin of ichthyosaur

First recorded in 1820–30; see origin at ichthyosaurus

Vocabulary lists containing ichthyosaur

Paleontology: Dinosaurs - Middle School and High School

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

However, this marks the first new genus of Early Jurassic ichthyosaur described from the region in more than 100 years.

From Science Daily • Feb. 24, 2026

After it was collected in 2001, the skeleton was acquired by the Royal Ontario Museum in Canada, where it joined one of the world's largest ichthyosaur collections.

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

First discovered by a prolific fossil hunter at Golden Cap in Dorset in 2001 the new ichthyosaur was then acquired by a museum in Canada.

From BBC • Oct. 9, 2025

The skin of the ichthyosaur was smooth like that of a whale, and its food was largely fish and cephalopods, as the fossil contents of its stomach prove.

From The Elements of Geology by Norton, William Harmon

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023