''Chicagooceras'' is a genus of

orthocerid Orthocerida, from Ancient Greek ὀρθός (''orthós''), meaning "straight", and κέρας (''kéras''), meaning "horn", also known as the Michelinocerida, is an order of extinct orthoceratoid cephalopods that lived from the Early Ordovician ...

s from the

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 ...

of North America. Shells are short, breviconic, and faintly curved. Sutures are fairly wide spaced and though straight, slope slightly, dorso-ventrally, to the rear. Siphuncle: small, slightly ventral of the center, thought to be orthochoanitic (straight septal necks) and cylindrical (tubular connecting rings).

References

* Walter c. Sweet, 1964. Nautiloidea -Orthocerida.

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. Geological Society of America.
''Chicagooceras''
in Fossilworks. Prehistoric nautiloid genera Silurian animals {{paleo-nautiloidea-stub