Definition of nautiloid in US English:



  • A mollusk of a group of mainly extinct marine mollusks which includes the pearly nautilus.

    Subclass Nautiloidea, class Cephalopoda: Nautilus is the only surviving genus

    • ‘Most of the nautiloids exhibited broken shells; however, the rest of the mollusks were well preserved.’
    • ‘About this time the ammonoids began to take over from the nautiloids.’
    • ‘Other fossil groups include diverse rugose corals, some tabulate corals, nautiloids, gastropods, and trilobites.’
    • ‘Ammonoids reflected changing environmental conditions by changing their fecundity, whereas in nautiloids a strong heritable differential occurred between genotypes.’
    • ‘They may represent a distinct lineage of early nautiloids, perhaps quite different anatomically to the contemporary and superficially similar oncocerids.’
    • ‘Some nautiloids display embryonic shells that match the dimensions of the ammonoids.’
    • ‘More than 500 specimens of embryonic shells of orthocerid nautiloids from the Imo Formation were investigated.’
    • ‘These nautiloids are very similar in form and structure to the tarphycerids, among which they are now generally included as a suborder.’
    • ‘Coiled shells, commonly of ammonoid cephalopods, nautiloids, or gastropods, have been given colloquial names such as rams' horns, snakestones, serpentstones, and conger eels.’
    • ‘Ammonoids are descendants of the extinct, primitive coiled nautiloids and they are extinct relatives of modern squid, octopus, cuttlefish, and nautilus.’


Mid 19th century: from the modern Latin genus name Nautilus (see nautilus).