''Karoceras'' is a genus of oncocerid

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 ...

s that lived during the Silurian and possibly Early Devonian, type genus for the

Karoceratidae Karoceratidae is a family of nautiloids within the order Oncocerida, characterized by straight or curved, laterally narrow, shells and slender, ventral siphuncles that are empty except in '' Karoceras''. Siphuncle segments are inflated ventrally ...

. The shell is a compressed, exogastric cyrtocone, section sub ovoid. The siphuncle is ventral, near the outer, externally convex curvature. Septal necks flair outwardly, segments are inflated ventrally and are straight dorsally, a character of the family. ''Karoceras'' is the only member of the Karoceratidae that is actinosiphonate, a character produced by lamellae projecting radially inward toward the middle of the siphuncle from the connecting rings. This genus has been found in central Europe in the region of the Czech Republic and on Novaya Zemlya.

References

* Walter C. Sweet, 1964. Nautiloidea -Oncocerida,

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. Geological Society of America.
''Karoceras''
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Fossilworks
Mar.5,2015 Prehistoric nautiloid genera Oncocerida {{paleo-nautiloidea-stub