Stenopoceratidae, Korn, 2025

Family Stenopoceratidae fam. nov.

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Figs 18C View Fig , 20 View Fig

Type genus

Stenopoceras Hyatt, 1893 .

Diagnosis

Family of the superfamily Grypoceratoidea with an extremely discoidal to thinly discoidal, involute conch. Whorl profile in the adult stage compressed with very narrow venter. Ornament consisting of fine growth lines. Suture line always with rounded and small external lobe and broadly rounded lateral lobe separated by a subacute saddle, without annular process.

Etymology

The family name refers to the type genus.

Included genera

Stenopoceras Hyatt, 1893 (Bashkirian to Roadian; 9 species).

Parastenopoceras Ruzhencev & Shimansky, 1954 (Artinskian; 1 species).

Leptodomatoceras Leonova & Shchedukhin, 2023 (Asselian or Sakmarian; 1 species).

Remarks

The genera of the family Stenopoceratidae were previously placed in the family Domatoceratidae ( Miller & Youngquist 1949; Ruzhencev & Shimansky 1954), in the family Grypoceratidae ( Kummel 1953, 1964; Shimansky 1967, 1979), in the subfamily Domatoceratinae ( Shimansky 1962) or in the family Phacoceratidae ( Dzik 1984) . However, Ruzhencev & Shimansky (1954: 51) proposed an evolutionary lineage with Stenopoceras as the terminal genus. This separate lineage is used here to name a separate family characterised by increasing compression of the whorl profile, closure of the umbilicus and narrowing of the venter.