''Oocerina'' is an extinct genus of

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

cephalopods that lived during the Late

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 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 shortest period of the Paleozo ...

of Europe, Russia, and North America. ''Oocerina'', included in the oncoerid family

Oncoceratidae Oncoceratidae is a family of nauatiloid cephalopods in the order Oncocerida established by Hyatt, 1884, that range from the Middle Ordovician to the Upper Silurian. Diagnosis Oncoceratidae are characterized by generally compressed, cyrtocon ...

and arbitrarily within the

Slender Oncoceratidae {{Taxobox , name = Slender Oncoceratidae , fossil_range = M Ord- U Sil , image = Oocerina plebeia.JPG , image_caption = ''Oonocerina plebeia'', Barrande from Slivenec, Prague, (Czech Republic) at the National Museum (Prague) , regnum = Anima ...

, 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 ''Oonoceras'' is an extinct genus of fossil cephalopods included in the nautiloid order Oncocerida and the family Oncoceratidae from the Middle Ordovician to Middle Silurian of North America and Europe, arbitrarily included in the Slender Oncoc ...

'' is similar except for having a generally stronger curvature and a simpler, non-actinosiphonate siphuncle. Oocerina plebeia-001

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, 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 {{silurian-animal-stub