Discoceras

Discoceras Temporal range: M-U Ordovician
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	Nautiloidea
Order:	Tarphycerida
Family:	Trocholitidae
Genus:	Discoceras Barrande, 1867

Discoceras, a member of the Trocholitidae in the Tarphycerida, not to be confused with Discosorus.

Discoceras is characterized by closely coiled, gradually expanding shells with a subquadrate cross section, that may be ribbed or smooth. The sides are broadly rounded; the venter wide and slightly rounded. The maximum width is slightly dorsal of the middle. The dorsum has a slight to moderate impression. The siphuncle starts off central for the first half whorl then becomes marginodorsal in the succeeding 1.5 to 2 whorls, then subdorsal at maturity. As with Trocholites the dorsal siphuncle in Discoceras probably indicates an orientation during life that places the back of the living chamber high in the shell.

Discoceras has been found in Middle and Upper Ordovician sediments in Northern Europe, Baffin Island in Canada, Yunnan and Hubei provinces in China, and in Punjab, India.

See also

• List of nautiloids

References

• Discoceras, p K360 in Vol K of the Treatise on Invertebrate Paleontology in the section on the Trocholitidae,ppK359-K362, in the Chapter on the Tarphycerida by Furnish and Glenister starting with page K343.