Metacoceratidae Korn 2025

Family Metacoceratidae Korn, 2025 Diagnosis Family of the superfamily Pleuronautiloidea with an equidimensional or more commonly weakly depressed, trapezoidal to inverted trapezoidal whorl profile. Venter usually flattened, but ranging from slightly convex to slightly concave. Ventrolateral shoulder often prominent, ranging from broadly rounded to subangular. Flanks weakly convergent, parallel or weakly divergent, usually flattened and ranging from weakly convex to weakly concave. Umbilical margin usually pronounced, usually subangular in the intermediate growth stage. Sculpture with ventrolateral conical nodes, often with dorsolateral nodes and low ribs on the flank. Suture line with shallow lobes and low saddles. Internal lobe very shallow, without annular process (from Korn 2025). Included genera Metacoceras Hyatt, 1883 (Carboniferous to Triassic); Mojsvaroceras Hyatt, 1883 (Triassic); Huanghoceras Yin, 1933 (Permian);? Shansinautilus Yabe & Mabuti, 1935 (Permian;); Cooperoceras Miller, 1945 (Permian); Epimetacoceras Librovitch, 1946 (Carboniferous) (nomen nudum); Pseudofoordiceras Ruzhencev & Shimansky, 1954 (Permian); Pseudotemnocheilus Ruzhencev & Shimansky, 1954 (Permian); Tanchiashanites Zhao, 1954 (Permian); Mahoningoceras Murphy, 1974 (Carboniferous); Lichuanoceras Xu, 1977 (Permian); Sinotitanoceras Pan, 1983 (Permian); Anthodiscoceras Qin, 1986 (Permian); Serometacoceras gen. nov. (Permian). Remarks A detailed account of the research history of Metacoceras and genera with similar morphology has been given by Korn (2025). Therefore, only the differences between the new genus Serometacoceras gen. nov. and Metacoceras will be discussed here.