Trocholitidae

Systematic Paleontology Class Cephalopoda Subclass Nautiloidea Order Tarphycerida Family Trocholitidae

Trocholitids (family Trocholitidae) are tarphycerids with a subcentral to marginal dorsal siphuncle, in contrast with the ventral siphuncle found in the Tarphyceratidae and Estonioceratidae. As with all nautiloids the siphuncle is retrochoanitic, with septal necks pointing to the rear, toward the apex of the shell.

Trocholitid shells are evolute, with all whorls showing and vary from smooth to strongly ribbed. Whorls are in close contact, as with the Tarphyceratidae. The dorsum (dorsal site) has a longitudinal impression formed as it overlaps the ventral side of the previous whorl. At maturity the body, or living, chamber diverges from the earlier whorls.

Genera include Trocholites, Graftonoceras, Curtoceras, and Discoceras.

References W.M Furnish and Brian F. Glenister, 1964. Nautiloidea - Tarphycerida. Treatise on Invertebrate Paleontology. Part K.