Actinoceras

Reconstructed individuals of Actinoceras bigsbyi. Image from here.

Belongs within: Actinocerida.

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 1835 (see below for synonymy) T64
    |--*A. bigsbyi Bronn 1835 T64
    |--A. adnatum Foerste & Teichert 1930 P68
    |--A. altopontense Foerste & Teichert 1930 P68
    |--A. amundsoni Foerste 1921 P68
    |--A. arcanum Foerste & Teichert 1930 P68
    |--A. bellefontense Foerste & Teichert 1930 P68
    |--A. beloitense T64
    |--A. caneyense Foerste & Teichert 1930 P68
    |--A. capitolinum P68
    |--A. centrale P68
    |--A. cinctum Foerste & Teichert 1930 P68
    |--A. circulare Foerste & Teichert 1930 P68
    |--A. concavum Endo 1932 P68
    |--A. crebiseptum P68
    |--A. curdsvillense Foerste & Teichert 1930 P68
    |--A. glencoense Foerste & Teichert 1930 P68
    |--A. glenni Foerste & Teichert 1930 P68
    |--A. jessaminense Foerste & Teichert 1930 P68
    |--A. kentuckiense Foerste & Teichert 1930 P68
    |--A. latonummulatum [=Orthoceras (Actinoceras) latonummulatum] P68
    |--A. lentiexpandum Foerste & Teichert 1930 P68
    |--A. libanum Foerste & Teichert 1930 P68
    |--A. lindenense Foerste & Teichert 1930 P68
    |--A. pohli Foerste & Teichert 1930 P68
    |--A. ruedemanni Foerste & Teichert 1930 P68
    |    |--A. r. ruedemanni P68
    |    `--A. r. clarkei P68
    |--A. saffordi Foerste & Teichert 1930 P68
    |--A. tennesseense Foerste & Teichert 1930 P68
    |--A. tenuifilum P68
    |    |--A. t. tenuifilum P68
    |    `--A. t. centrale Foerste 1921 P68
    |--A. turgidonummulatum [=Orthoceras (Actinoceras) turgidonummulatum] P68
    |--A. vaughanianum Girty 1909 P68
    `--A. youngi [=Orthoceras (Actinoceras) youngi] P68

Actinoceras Bronn 1835 [=Actinoceratites Bronn 1834 (n. n.), Arctinoceras (l. c.); incl. Conotubularia Troost 1838, Conotabularia (l. c.), Metactinoceras Zhuravleva 1957] T64

*Type species of generic name indicated

REFERENCES

[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 Treatise on Invertebrate Paleontology pt. K. Mollusca 3. Cephalopoda – General Features – Endoceratoidea – Actinoceratoidea – Nautiloidea – Bactritoidea (R. C. Moore, ed.) pp. K190-K216. The Geological Society of America and the University of Kansas Press.