Vestinautilinae Korn, 2025, subfam. nov.

Subfamily Vestinautilinae subfam. nov. urn:lsid:zoobank.org:act: 10F74235-B3AF-4D2A-A0B8-92DBA57676A4 Fig. 13 Type genus Vestinautilus Ryckholt, 1852. Diagnosis Subfamily of the family Trigonoceratidae with discoidal to pachyconic, subevolute conch. Whorl overlap small. Whorl profile usually rounded triangular or rounded trapezoidal. Venter broadly rounded, flattened or weakly concave. Ornament with longitudinal ridges in most species; younger species show a reduction of the spiral ridges. Suture line with rounded external and lateral lobes, internal lobe shallow. Etymology The subfamily name refers to the type genus. Included genera Vestinautilus Ryckholt, 1852 (Tournaisian to Viséan; 20 species). Edaphoceras Hyatt, 1884 (Viséan; 2 species). Subvestinautilus Turner, 1954 (Tournaisian to Viséan; 7 species). Remarks The Vestinautilinae subfam. nov. are a subfamily that can be easily distinguished from the other subfamilies by their characteristic morphology with a rounded triangular or rounded trapezoidal whorl profile and the presence of coarse longitudinal ridges (Fig. 13). The origin of the Vestinautilinae subfam. nov. is probably to be found in the subfamily Trigonoceratinae. The stratigraphically oldest species of Vestinautilus from the early Late Tournaisian have a conch morphology and shell ornamentation that still closely resemble species from genera such as Triboloceras and Rineceras. The Vestinautilinae show a morphological evolution with a progressive reduction in the number of longitudinal ridges. These are largely restricted to the ventrolateral shoulder in the younger species. At the same time, the venter changes from a concave to a convex shape.