''Sactorthceras'' is an

orthoceratoid Orthoceratoidea is a major subclass of nautiloid cephalopods. Members of this subclass usually have orthoconic (straight) to slightly cyrtoconic (curved) shells, and central to subcentral siphuncles which may bear internal deposits. Orthoceratoi ...

genus (subclass Nautiloidea s.l.) known from the Middle Ordovician of eastern North America (NY), Norway and Korea and is the type genus of the Sactorthoceratidae. ''Sactorthceras'' was named by Kobayashi in 1934 to include smooth or striated, straight or slightly curved longicones with short camerae and slender, subcentral, suborthochoanitic siphuncles with segments slightly inflated and no cameral deposits. ''Sactorthocras'' has also been recognized in the

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 ...

Racine Formation The Hunton Megagroup also Hunton Super Group, Hunton Group, Hunton Formation and Hunton Limestone is predominantly composed of carbonate rock, deposited between the Silurian and early to mid Devonian periods. In many States it acts as a reservoir ...

of Wisconsin, and from the Ordovician of China and Iran. Related genera include ''

Centroonoceras ''Centroonoceras'' is a middle Ordovician cyrtoconic nautiloid cephalopod, otherwise similar to the orthoconic '' Sactorthoceras'' and also included in the Sactorthoceratidae. It was named by Kobayashi, 1934, and has been found in Korea and in ...

'' and '' Sigmocycloceras''

-References-

*Sweet, Walter C. 1964. Nautiloidea -Orthocerida. Treatise on Invertebrate Paleontology, Part K. Geological Soc. of America and Univ of Kansas press.
Sactorthoceras ref Paleodb
{{Taxonbar, from=Q7397401 Orthocerida Middle Ordovician first appearances Silurian extinctions Prehistoric cephalopod genera