Nostoceratidae

Nipponites is an extinct genus of heteromorph ammonites. The shells of Nipponites (primarily N. mirabilis) form "ox-bow" bends, resulting in some of the most bizarre shapes seen among ammonites.

Nostoceras is an extinct genus of ammonites. The genus name comes from Ancient Greek νόστος (nóstos), meaning "return", and κέρας (céras), meaning "horn", named as such by Alpheus Hyatt because the species' shell bends back on itself.

Bostrychoceras is a genus of heteromorph ammonite from the family Nostoceratidae. Fossils have been found in Late Cretaceous sediments in Europe and North America.

Didymoceras is an extinct genus of ammonite cephalopod from the Late Cretaceous epoch (approximately 76 Ma). It is one of the most bizarrely shaped genera, with a shell that spirals upwards into a loose, hooked tip. It is thought to have drifted in the water vertically, moving up and down. The genus name comes from Ancient Greek δίδυμος (dídumos), meaning "twin", and κέρας (céras), meaning "horn".