''Oocerina'' is an extinct genus of

nautiloid Nautiloids are a group of cephalopods (Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and ''Allonautilus''. Fossil nautiloids are diverse and species rich, with over 2,500 recorded species. Th ...

cephalopods that lived during the Late

Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

of Europe, Russia, and North America. ''Oocerina'', included in the oncoerid family Oncoceratidae and arbitrarily within the Slender Oncoceratidae, is characterized by a moderately slender, elongate shell with an exogastric curvature, such that the lower side with the siphuncle is convex in profile and the opposite, upper, side is concave in profile. Shells are laterally compressed, curvature is gentle to almost straight. Chambers are short, septa close spaced, sutures typically straight. The siphuncle is nummuloidal, containing actinosiphonate deposits within. '' Oonoceras'' is similar except for having a generally stronger curvature and a simpler, non-actinosiphonate siphuncle.

References

* Dinosaurs to Dodos: An Encyclopedia of Extinct Animals by Don Lessem and Jan Sovak * Walter C.Sweet, Nautiloidea-Oncocerida, in the

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology,'' published from 1953–2007 by the Geological Society of America and the University of Kansas, then 2009–present by the University of Kansas Paleontological Institute, is a definitive multi-authore ...

, Part K, Teichert C and Moore R.C Eds, Geological Society of America and University of Kansas press, 1964 (K283-K290) Silurian animals Silurian animals of Europe Silurian animals of North America Prehistoric nautiloid genera {{paleo-cephalopod-stub