Oecoptychius is an extinct genus of fossil ammonite cephalopods.
It is placed into Oecoptychitidae, a family of dwarf ammonites established by Arkell[who?
[citation needed] Oecoptychius 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.
[citation needed] Fossils of the Oecophtychius species have been found in Jurassic sediments of France, Germany and Madagascar.