Tainoceratina Shimansky 1957

Suborder Tainoceratina Shimansky, 1957 Diagnosis Suborder of the order Nautilida, in which a ventrolateral shoulder and an umbilical margin are formed early in ontogeny in the advanced species. Conch usually discoidal, subinvolute to evolute. Juvenile whorl profile depressed oval or circular. Adult whorl profile depressed oval or reniform in the early species, showing numerous modifications during evolution (inverted trapezoidal, trapezoidal or polygonal whorl profiles or with ventral depression). Dorsal whorl zone always present, but usually very small. Juvenile sculpture with radial ribs on the flank; adult sculpture with radial ribs on the flank, ventrolateral nodes or several rows of nodes in derived species. Septa simply domed; with dorsal inflexion in advanced species. Suture line depending on the whorl profile, with shallow lobes and low saddles (from Korn 2025). Included superfamilies Tainoceratoidea Hyatt, 1883 (Carboniferous to Triassic); Pleuronautiloidea Hyatt, 1900 (Carboniferous to Triassic). Remarks A detailed discussion of the suborder Tainoceratina has been given by Korn (2025).