This ammonite was found in association with Tmaegoceras nudaries and Coroniceras luningense, indicative of the Mullerense Subzone of the Involutum Zone of the early Sinemurian. The venter is compressed and rounded on early whorls but becomes subquadrate on the outermost preserved whorl, with the strong ribs extending completely over it.
Any suggestions as to its genus are most welcome!