Reconstructed individuals of Actinoceras bigsbyi, from here.

Belongs within: Actinoceratida.

Actinoceras was a Middle Ordovician to Lower Silurian genus of large actinocerid cephalopods.

Characters (from Teichert 1964): Large, straight, somewhat fusiform shells, with tendency to decrease in diameter from anterior part of phragmocone toward aperture; cross-section circular to subcircular. Siphuncle large, usually somewhat off-centre, tending to decrease in diameter towards adult part of phragmocone; septal necks long, brims relatively short; narrow endosiphuncular canal in mature stage with simple radial canals. Cameral deposits common, usually episeptal and hyposeptal; circulus sometimes present.

<==Actinoceras Bronn 1835T64 (see below for synonymy)
    |--*A. bigsbyi Bronn 1835T64
    |--A. adnatum Foerste & Teichert 1930P68
    |--A. altopontense Foerste & Teichert 1930P68
    |--A. amundsoni Foerste 1921P68
    |--A. arcanum Foerste & Teichert 1930P68
    |--A. bellefontense Foerste & Teichert 1930P68
    |--A. beloitenseT64
    |--A. caneyense Foerste & Teichert 1930P68
    |--A. capitolinumP68
    |--A. centraleP68
    |--A. cinctum Foerste & Teichert 1930P68
    |--A. circulare Foerste & Teichert 1930P68
    |--A. cloueiH84
    |--A. cochleatumH84
    |--A. concavum Endo 1932P68
    |--A. crebiseptumP68
    |--A. curdsvillense Foerste & Teichert 1930P68
    |--A. giganteum [=Orthoceras giganteum]H84
    |--A. glencoense Foerste & Teichert 1930P68
    |--A. glenni Foerste & Teichert 1930P68
    |--A. imbricatumH84
    |--A. infelix [=Orthoceras infelix]H84
    |--A. jessaminense Foerste & Teichert 1930P68
    |--A. kentuckiense Foerste & Teichert 1930P68
    |--A. latonummulatum [=Orthoceras (Actinoceras) latonummulatum]P68
    |--A. lentiexpandum Foerste & Teichert 1930P68
    |--A. libanum Foerste & Teichert 1930P68
    |--A. lindenense Foerste & Teichert 1930P68
    |--A. pohli Foerste & Teichert 1930P68
    |--A. ruedemanni Foerste & Teichert 1930P68
    |    |--A. r. ruedemanniP68
    |    `--A. r. clarkeiP68
    |--A. saffordi Foerste & Teichert 1930P68
    |--A. tennesseense Foerste & Teichert 1930P68
    |--A. tenuifilum (Hall 1843)KE19
    |    |--A. t. tenuifilumP68
    |    `--A. t. centrale Foerste 1921P68
    |--A. turgidonummulatum [=Orthoceras (Actinoceras) turgidonummulatum]P68
    |--A. vaughanianum Girty 1909P68
    |--A. vertebratumH84
    `--A. youngi [=Orthoceras (Actinoceras) youngi]P68

Actinoceras Bronn 1835T64 [=Actinoceratites Bronn 1834 (n. n.) non Schrammen 1928T64, Arctinoceras (l. c.)T64; incl. Conotubularia Troost 1838T64, Conotabularia (l. c.)T64]

*Type species of generic name indicated


[H84] Hyatt, A. 1883–1884. Genera of fossil cephalopods. Boston Soc. Nat. History, Proc. 22: 253–338.

[KE19] King, A. H., & D. H. Evans. 2019. High-level classification of the nautiloid cephalopods: a proposal for the revision of the Treatise Part K. Swiss Journal of Palaeontology 138: 65–85.

[P68] Purnell, L. R. 1968. Catalog of the type specimens of invertebrate fossils. Part I: Paleozoic Cephalopoda. United States National Museum Bulletin 262: 1–198.

[T64] Teichert, C. 1964. Actinoceratoidea. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt K. Mollusca 3. CephalopodaGeneral FeaturesEndoceratoideaActinoceratoideaNautiloideaBactritoidea pp. K190–K216. The Geological Society of America and the University of Kansas Press.

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