''Selkirkoceras'' is a genus of armonoceratid cephalopods similar to ''

Kochoceras ''Kochoceras'' is an extinct nautiloid genus from the later Ordovician belonging to the family Actinoceratidae and found in North America. Morphology ''Kochoceras'' is relatively short, breviconic, and grew to be fairly large with a shell more ...

'' of the

Actinoceratidae The Actinoceriatidae are a family of actinocerids named by Saemann in 1853 for those that grew to have large shells with blunt apices and large siphuncles with widely expanded segments and a generally arcuate endosiphucular canal system.Teicher ...

, but with recumbent septal necks. The first siphuncular segment is large, broad, and blunt. ''Selkirkoceras'', which is known from the Middle Ordovician of western North America, is included in the '' Nybyoceras'' branch of the

Armenoceratidae The Armenoceratidae are a family of early Paleozoic nautiloid cephalopods belonging to the order Actinocerida.Flower 1957.Studies of the Actinoceratida.; Memoir 2; New Mexico Bureau of Mines and Mineral Resources, Socorro, NM Teichert 1964. Act ...

(Teichert, 1964), which also includes ''Nybyoceras'' and '' Megadisocosorus''.

References

* Curt Teichert, 1964. Actinoceratoidea, Treatise on Invertebrate Paleontology, Part K. Geological Society of America and University of Kansas Press. Prehistoric nautiloid genera Actinocerida {{paleo-nautiloidea-stub