The genus ''Savageoceras'' is a barrandeoceratid first known from the Middle

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 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 shortest period of the Paleozo ...

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolita ...

consisting of rapidly enlarging, depressed cyrtocones with a trapezoidal section; ventral side wider and flatter than dorsal; sides converging on dorsum. Sutures have slight lateral and ventral lobes and

ventrolateral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

saddles. The surface is covered by transverse

striae Stretch marks, also known as striae () or striae distensae, are a form of scarring on the skin with an off-color hue. Over time they may diminish, but will not disappear completely. Striae are caused by tearing of the dermis during periods of r ...

and has rib-like rings that are more prominent at the ventrolateral shoulders but otherwise vaguely defined. The

siphuncle The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and ...

is central; interior unknown.

References

* Sweet, W.C. Nautiloidea - Barrandeocerida. ''

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and co ...

'', Part K. Geological Soc. of America and Univ. of Kansas press. {{Taxonbar, from=Q7427790 Prehistoric nautiloid genera Tarphycerida