Actinoceras is the principal and root genus of the Actinoceratidae, a major family in the Actinocerida, that lived during the Middle and Late Ordovician.
Lambeoceras is a genus of rather large actinocerids with a convexly lenticular cross section from the Upper Ordovician of North America and the sole representative of the family Lambeoceratidae.
Paraloxoceras is a genus of straight shelled, orthoconic nautiloid cephalopods, now extinct, that lived during the Early Carboniferous. Fossils have been found in Europe and central Asia; the type, P. konincki, named by Flower, came from Belgium.
Spyroceras is a genus of pseudorthocerids from the Devonian of North America and Europe, defined by Hyatt in 1884. Pseudorthocerids are a kind of orthocertaoid, a taxonomic group within the Nautiloidea. Specifically Spyroceras belongs to the pseudorthocerid family, Spyroceratidae.
Pseudactinoceras is an extinct nautiloid cephalopod included in the order Pseudorthocerida and the namesake of the family Pseudactinoceratidae.
Wardoceras is an extinct nautiloid genus from the late Early Ordovician of Western Utah, assigned to the orthocerid family, Michelinoceratidae
Metabaltoceras, first described by Rousseau Flower in 1964, is a fossil cephalopod genus in the family Baltoceratidae, with a small, slender, fairly fusiform shell, and a large empty siphuncle in contact with the ventral surface. The siphuncle is achoanitic, having virtually no septal necks, segments formed all but entirely by connecting rings. Shells are generally straight, beginning with a subcircular cross section in the adapical portion but becoming faintly depressed adorally. Sutures are straight and transverse except ventrally, where they produce deep, prominent lobes.
Sactoceras is an extinct nautiloid cephalopod that lived during the Ordovician and Silurian in what would become North America, Europe, and Asia.
Carbactinoceratidae is a family of extinct cephalopods with external shells that lived around 325 million years ago, during the Carboniferous period. They were the last group of orthocones to attain sizes exceeding one meter in length. One specimen of the carbactinoceratid species Rayonnoceras solidiforme, recently found in Arkansas, was measured at 2.5 metres (8.2 ft) long.
The Actinoceriatidae are a family of actinocerids named by Saemann in 1853 for those that grew to have large shells with blunt apecies and large siphuncles with widely expanded segments and a generally arcuate endosiphucular canal system. Their range is from the upper Middle Ordovician to the Lower Silurian. Actinocerids are generally straight-shelled nautiloid cephalopods with a siphuncle composed of expanded segments, typically with thin connecting rings, in which the internal deposits are penetrated by a system of canals
The Armenoceratidae are a family of early Paleozoic nautiloid cephalopods belonging to the order Actinocerida.
Nybyoceras is an actinocerid genus assigned to the Armenoceratidae and similar to Armenoceras except for having a siphuncle close to the ventral side of the shell.
Pseudactinoceraidae is a family in the nautiloid cephalopod order, Pseudorthocerida, known from the Upper Devonian and Lower Carboniferous (Mississippian).
Mandaloceratidae is a family in the nautiloid cephalopod order Discosorida, from the Middle and Upper(?) Silurian characterized by short, essentially straight shells referred to as breviconic, typically with a faintly exogastric shape produced by the profile of the body chamber. Apertures vary from round to T-shaped, with a long narrow, ventral, hyponomic sinus for the maneuvering funnel. Siphuncles are commonly central or subcentral with generally broad, expanded, segments and usually thin connecting rings.
Veneficoceras is a genus of the rod-bearing Baltoceratidae, an extinct cephalopod family with characteristics of the orthoceratoid Dissidocerida, found in Cassinianage, Lower Ordovician, limestone in western Utah.
Kobyashiceras is an extinct genus in the cephalopod order Actinocerida, from Lower Devonian marine sediments in Japan. The type and sole included species is Kobayashiceras gifuense. The generic name honors the late Dr. Teiichi Kobayashi who contributed greatly to the study of Paleozoic cephalopods. The specific name is derived from Gifu, the name of the prefecture in which the type locality is found.
The Sactorthoceratidae comprise Orthocerataceaen genera with a subcentral suborthochoanitic siphuncle composed of slightly expanded segments and free of organic deposits. The camerae (chambers) of the phragmocone likewise have organic deposits that are typically retarded or sparse.
Adnatoceras is a genus of mid Devonian to Pennsylvanian orthoconic nautiloid cephalopods included in the pseudorthocerid family Spyroceratidae, characterized by tubular, straight-sided, siphuncle segments that expand abruptly at the septal foremena. In some species the siphuncle segments become more ovoid in the later grow stages. The name Adnatoceas comes from the wide area of contact, or adnation, between the connecting ring and flared out brim of the cyrtochaoanitic septal neck.
Discosoridae comprise a family of endogastric discosorids,, with endocones in the siphuncle, ranging from the Middle Silurian to Middle Devonian.
Dolorthoceras is a nautiloid cephalopod from the upper Paleozoic found in Lower Devonian to Lower Permian strata in North America, Europe, Asia, and Australia.
