ammonite

noun am·mo·nite \ ˈa-mə-ˌnīt \

Updated on: 12 Apr 2018

Definition of ammonite

: any of a subclass (Ammonoidea) of extinct cephalopods especially abundant in the Mesozoic age that had flat spiral shells with the interior divided by septa into chambers

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ammonitic

play \ˌa-mə-ˈni-tik\ adjective

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Recent Examples of ammonite from the Web

In some cases -- some extremely rare cases -- ammonites can fetch between $40,000 to $50,000.

— CNN, "A 6-year-old girl goes digging in the dirt at her sister's soccer game -- and finds a 65 million-year-old fossil," 21 Mar. 2018
What the girl had found was the fossil of an ammonite, a sea creature that went the way of the dinosaurs millions of years ago.

— CNN, "A 6-year-old girl goes digging in the dirt at her sister's soccer game -- and finds a 65 million-year-old fossil," 21 Mar. 2018
Fed by a constant stream of nutrients, the ocean supported all walks of life, from snails and ammonites to the massive Mosasaurus, an extinct group of marine reptiles.

— maya wei-haas, Smithsonian, "What Shrinking Fossil-Rich National Monuments Means for Science," 19 Dec. 2017
But as the shell was pulled along by the current the impression widened, till 18 ridges become visible before the ammonite plopped over.

— jason daley, Smithsonian, "Ancient Creature Left a 28-Foot Drag Mark After It Died," 11 May 2017
Tsujita and Westermann also cataloged the positive evidence that mosasaurs bit ammonites.

— brian switek, WIRED, "Mosasaur Bites and Limpet Scrapes," 11 Apr. 2012
This wasn’t to say that mosasaurs never ate ammonites, though.

— brian switek, WIRED, "Mosasaur Bites and Limpet Scrapes," 11 Apr. 2012
But as the shell was pulled along by the current the impression widened, till 18 ridges become visible before the ammonite plopped over.

— jason daley, Smithsonian, "Ancient Creature Left a 28-Foot Drag Mark After It Died," 11 May 2017

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