Thrincoceratidae Ruzhencev & Shimansky, 1954

Family Thrincoceratidae Ruzhencev & Shimansky, 1954

Fig. 9 View Fig

Diagnosis

Family of the superfamily Trigonoceratoidea with discoidal, subevolute to evolute conch; whorl overlap small if present, coiling rate high to extremely high. Whorl profile almost circular in the early juvenile stage. Ornament in the early species with longitudinal, equidistant ridges throughout ontogeny; advanced species with reduction of spiral lines. Suture line with broadly rounded lobes and saddles.

Included genera

Thrincoceras Hyatt, 1893 (Tournaisian to Viséan; 8 species).

Lispoceras Hyatt, 1893 (Tournaisian to Serpukhovian; 5 species).

Diodoceras Hyatt, 1900 (Tournaisian; 1 species).

Neothrincoceras Ruzhencev & Shimansky, 1954 (Artinskian; 3 species).

Remarks

Ruzhencev & Shimansky (1954) established the family Thrincoceratidae for the genera Thrincoceras , Maccoyoceras and Neothrincoceras and had “not the slightest doubt” that this family and the “closely related” family Domatoceratidae Miller & Youngquist, 1949 descended from common ancestors, and not directly from each other ( Ruzhencev & Shimansky 1954: 51). A little later, Shimansky (1962) classified the group only as a subfamily with the genera Discitoceras , Stroboceras , Thrincoceras , Maccoyoceras and Epistroboceras Turner, 1954 , while Neothrincoceras was placed in the family Neothrincoceratidae within the superfamily Centrocerataceae . Another five years later, Shimansky (1967: 168) reduced the subfamily to the genera Thrincoceras and Neothrincoceras .

Kummel (1964: K427) considered both the Thrincoceratidae and the Neothrincoceratidae to be synonyms of the Trigonoceratidae . Histon (1999) also included the genus Thrincoceras in the Trigonoceratidae . Dzik (1984: 172) included Thrincoceras , together with Discitoceras , Pararineceras and Maccoyoceras in Lispoceras within the family Trigonoceratidae .