Orthonychiidae Bandel & Fryda , 1999, 1843

Nuetzel, Alexander, Ebbestad, Jan Ove, Seuss, Barbara, Munnecke, Axel, Mapes, Royal H. & Cook, Alex G., 2023, On Paleozoic platycerate gastropods, Zitteliana 97, pp. 29-51 : 29

Family Orthonychiidae Bandel & Fryda, 1999

Remarks.

Bandel and Frýda (1999) erected this family for limpet-shaped Paleozoic gastropods formerly included in Platyceratidae . Based on the openly coiled fishhook-like protoconch of the Pennsylvanian limpet-shaped species Orthonychia parva (Swallow, 1858 in Shumard and Swallow), they placed Orthonychiidae in their new order Cyrtoneritimorpha . However, the protoconch of the Devonian type species of Orthonychia is yet unknown (see Knight 1941). The Ordovician family Pollicinidae resembles some members of Orthonychiidae but these shells are bilaterally symmetrical and their early ontogeny is largely unknown (see Peel 2020a, b).