Zittelloceras is an extinct genus of nautiloids from the order Oncocerida which are among a large group of once diverse and numerous shelled cephalopods, now represented by only a handful of species.
Zittleoceras, which is included in the family Oncoceratidae, is characterized by subcircular or slightly depressed cyrtoconic shells with ventral, suborthochoanitic empty siphuncles; the shell surface typically with crenulated transverse frills or distinct noncrenulated annulations.
Zittleoceras has been found in middle and upper Ordovician sediments in North America and Scotland.
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