Nautilaceae in the context of Paracenoceratidae

A nautilus (from Latin nautilus 'sails like a vessel'; from Ancient Greek ναυτίλος (nautílos) 'seaman, sailor') is any of the various species within the cephalopod family Nautilidae. This is the sole extant family of the infraorder Nautilaceae and the suborder Nautilina.

It comprises nine living species in two genera, the type of which is the genus Nautilus. Though it more specifically refers to the species Nautilus pompilius, the name chambered nautilus is also used for any of the Nautilidae. All are protected under CITES Appendix II. Depending on species, adult shell diameter is between 10 and 25 cm (4 and 10 inches).

The Nautilina is the last suborder of the Nautilida and the only nautiloids living since the end of the Triassic. The Nautilina, proposed by Shimanskiy, is basically the Nautilaceae of Kummel, 1964, defined by Furnish and Glenister, but differs in omitting two families, the Paracenoceratidae and Pseudonautilidae which instead are placed in the Liroceratina.

The Nautilina are derived from the Syringonautilidae, a family in the Centroceratina (Trigonocerataceae), in the Late Triassic and consists of four families, the Nautilidae, Cymatoceratidae, Herocoglossidae, and Aturiidae. The Nautilidae, which is the root stock of the suborder, includes the living Nautilus.