Prehistoric nautiloid genera

Cameroceras, from Ancient Greek καμάρα (kamára), meaning "chamber", and κέρας (kéras), meaning "horn", is an extinct genus of endocerid cephalopod which lived in equatorial oceans during the entire Ordovician period. Like other endocerids, it was an orthocone, meaning that its shell was fairly straight and pointed. It was particularly abundant and widespread in the Late Ordovician, inhabiting the shallow tropical seas in and around Laurentia, Baltica and Siberia (equivalent to modern North America, Europe, and Asia).

Cymatoceras is a wide-ranging extinct genus from the nautilitacean cephalopod family, Cymatoceratidae. They lived from the Late Jurassic to Late Oligocene, roughly from 155 to 23 Ma.

Aturia is an extinct genus of Paleocene to Miocene nautilids within Aturiidae, a monotypic family, established by Campman in 1857 for Aturia Bronn, 1838, and is included in the superfamily Nautilaceae in Kümmel 1964.

thumb|Eutrephoceras dorbignyanum thumb|Eutrephoceras dekayi from the [[Coon Creek Formation]]

Plectronoceras is the earliest known shelled cephalopod, dating to the Late Cambrian. None of the fossils are complete, and none show the apex or aperture of the shell. Approximately half of its shell was filled with septa; 7 were recorded in a shell. Its shell contains transverse septa separated by about half a millimetre, with a siphuncle on its concave side. Its morphology matches closely to that hypothesised for the last common ancestor of all cephalopods.