OecoptychiusOecoptychius is an extinct genus of fossil ammonite cephalopods. The species lived during the Middle Jurassic.Taxonomic positionOecophtychius was named by Neumayr in 1878. It is placed into Oecoptychitidae, a family of dwarf ammonites established by Arkell, 1957, that is a part of the superfamily Stephanoceratoidea.DiagnosisOecoptychius is an eccentrically coiled, dwarf ammonite. Inner whorls smooth, spheroidal; outer whorls with fine biplicate ribbing, ventral groove, and an acute elbow at half a whorl before the aperture; peristome contracted, with outwardly directed lappets.DistributionFossils of the Oecophtychius species have been found in Jurassic sediments of France, Germany and Madagascar.