''Cummingsoceras'' is a genus of barrandeoceroids within the

Tarphycerida The Tarphycerida were the first of the coiled cephalopods, found in marine sediments from the Lower Ordovician (middle and upper Canad) to the Middle Devonian. Some, such as '' Aphetoceras'' and '' Estonioceras'', are loosely coiled and gyroconi ...

, included in the family

Uranoceratidae The Uranoceratidae is a family of Silurian barrandeoceroids that tend to become uncoiled with age and in which siphuncle segments tend to be expanded into the camerae.Flower, R.H. & Kummel, B. 1950. A Classification of the Nautiloidea. Journal ...

. Its shell is a rapidly expanding gyrocone of about 1.5 narrowly separated whorls. The surface is faintly cancellated by slight longitudinal lines that cross growth lines which define a deep hyponomic sinus. The siphuncle is small, subcentral, and with recumbent necks. ''Cummingsoceras'' is known from the middle

Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

Indiana Indiana ( ) is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Lake Michigan to the northwest, Michigan to the north and northeast, Ohio to the east, the Ohio River and Kentucky to the s ...

and

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. It borders on Lake Michigan to its northeast, the Mississippi River to its west, and the Wabash River, Wabash and Ohio River, Ohio rivers to its ...

References

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

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. Geol Soc of America and Univ Kansas Press. Prehistoric nautiloid genera {{paleo-nautiloid-stub