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Temporal range: Ordovician-Permian
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: Nautiloidea
Order: Orthocerida
Genus: Cycloceras
McCoy (1844)

Cycloceras is an extinct nautiloid cephalopod genus from the Carboniferous of Western Europe, (Ireland and Scotland) of unknown affinity with the orthocerida (Sweet 1964 in) [1]


Cycloceras was named by McCoy (1844 and assigned to the Michelinoceratida by Flower (1962)and to the Orthocerida by Sweet in Teichert et al. (1964);[2] Cycloceras is possibly a member of the Cycloceratidae and may be synonymous with Perigrammoceras Foerste


The type species of Cycloceras, C. annularis, is based in an internal mold of a body chamber on which the position of the siphuncle is indiscernible (Sweet 1964,) Species referred to Cycloceras are annulated, subcylindrical orthocones with no longitudinal ornamentation . Fig 186, p K258 Teichert et al. (1964) shows Cycloceras as narrow, gently expanding, annulated othocone with a narrow subcentral siphuncle. Annuli (circular transverse bands or costae) are thick and close spaced, giving a corrugated appearance.


  1. ^ C. Teichert et al 1964. Treatise on Invertebrate Paleontology K(3)Nautiloidea:1-519
  2. ^ PaleoBiology Database:Cycloceras,basic info