Orthoceratoidea, from Ancient Greek ὀρθός, meaning "straight", and κέρας, meaning "horn", is a major subclass of nautiloid cephalopods. Members of this subclass usually have orthoconic to slightly cyr

Paraphragmitidae is an extinct family of actively mobile aquatic carnivorous cephalopods belonging to the subclass Orthoceratoidea endemic to what would be Asia and Europe during the Silurian living f