ammonoid

American

[am-uh-noid] / ˈæm əˌnɔɪd /

noun

any cephalopod mollusk of the extinct order Ammonoidea, from the Devonian to the Cretaceous periods, having a coiled, chambered shell.

ammonoid Scientific

/ ăm′ə-noid′ /

Any of various extinct cephalopods of the subclass Ammonoidea living from the Devonian to the Cretaceous Periods. Ammonoids had a symmetrical, coiled, chambered shell with angular sutures between the chambers. They are closely related to the nautiloids, including the modern-day chambered nautilus.

Etymology

Origin of ammonoid

1880–85; < New Latin Ammonoidea, equivalent to Ammon ( ites ) name of the order + -oidea -oidea; see ammonite ²

Example Sentences

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ammonoid

Late in the succeeding Carboniferous period appear shells with a truly ammonoid complexity of sutures, and in the Permian their number and variety cause them to form a striking element of the marine faunas.

From Darwin and Modern Science by A. C. (Albert Charles) Seward

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