Rhynchorthoceras

Rhynchorthoceras Temporal range: MOrdovician
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	Nautiloidea
Order:	Tarphycerida
Family:	Lituitidae
Genus:	Rhynchorthoceras

Rhynchorthoceras is a Middle Ordovician genus characterized by a rapidly expanded, weakly annulate orthocone, like the orthoconic section of Ancistroceras, but with only a curved, cyrtoconic apex instead of juvenile whorls.

Rhynchorthoceras is probably derived from Ancistroceras by a loss of the tarphycerid type apex, although it has been included with the orthocerid Sinoceratidae.

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