Liroceratoidea Miller & Youngquist 1949

Superfamily Liroceratoidea Miller & Youngquist, 1949 Diagnosis Superfamily of the suborder Liroceratina with a pachyconic and rarely discoidal or globular, subinvolute to involute conch. Whorl profile usually circular or depressed oval without distinct ventrolateral shoulder; in some species with a pronounced but rounded ventrolateral shoulder. Dorsal whorl zone usually small to moderately deep. Juvenile sculpture in the early species with spiral lines that may be restricted to the umbilical area; derived species are often smooth. Suture line very simple, almost straight across flanks and venter. Included families Liroceratidae Miller & Youngquist, 1949 (Early Carboniferous to Late Permian; 17 Palaeozoic genera, 118 Palaeozoic species). Coloceratidae Hyatt, 1893 [homonym; synonym of Liroceratidae Miller & Youngquist, 1949]. Paranautilidae Kummel in Flower & Kummel, 1950 (Early to Late Triassic). Permonautilidae Barskov & Shilovsky, 2014 (Middle to Late Permian; 1 genus, 10 species). Planetoceratidae fam. nov. (Early to Late Carboniferous; 1 genus, 9 species). New family to be described by Korn & Ghaderi (in press) (Late Permian; 3 genera, 5 species). Remarks The species of the Liroceratoidea can easily be distinguished from the species of the other superfamilies of the Liroceratina by the simple septal shape and thus the very simple, almost straight suture line. The Palaeozoic families are characterised as follows: Liroceratidae Miller & Youngquist, 1949 – Ancestral forms with involute or subinvolute conch, umbilical wall usually rounded (Fig. 32). Planetoceratidae fam. nov. – Ancestral forms, in which the terminal whorl detaches from the preceding whorl (Fig. 33). Permonautilidae Barskov & Shilovsky, 2014 – Advanced forms, which possess a prominent thorn-like umbilical process in the adult stage (Fig. 34). New family to be described by Korn & Ghaderi (in press) – Ancestral forms with a pronounced umbilical margin and a flattened umbilical wall; the venter has the tendency to become flattened or weakly concave (Fig. 35).