Clydonautilids are characterized by generally smooth, involute, globular to compressed shells with a very small to occluded (hidden) umbilicus and sutures with prominent lobes and saddles.
The Liroceratidae are characterized by generally smooth shells with broadly rounded, depressed whorls, occluded umbilicus, slightly sinuous sutures, and a siphuncle that is usually more or less central.
The Gonionautilidae, named by Kummel in 1950 to contain the Upper Triassic genus Gonionautilus, have a smooth, involute, compressed shell with narrow flattened venter and a suture like that of Clydonautilus, but with a more highly developed median saddle and double-pointed annular lobes.
The Siberionautilidae, named by Popov in 1951 for the Upper Triassic Siberionautilus, have an involute, finely ribbed, globular shell with flattened flanks that converge toward a rounded venter and a highly differentiated goniatitic suture.
The Liroceratidae were the only clydonautilaceans living at the end of the Permian, when a significant number of nautilid genera perished, but enough survived to carry the family, and by inference the superfamily into the Triassic.