Metrioceras is an extinct genus of prehistoric nautiloids. The nautiloids are a subclass of shelled cephalopods that were once diverse and numerous but are now represented by only a handful of species.
Sepkoski, J.J. Jr. 2002. A compendium of fossil marine animal genera. D.J. Jablonski & M.L. Foote (eds.). Bulletins of American Paleontology363: 1–560. Sepkoski's Online Genus Database (CEPHALOPODA)
