Genus Maccoyoceras Miller, Dunbar & Condra, 1933

Type species

Nautilus (Discites) discors M‘Coy, 1844; original designation.

Diagnosis

Genus of the family Trigonoceratidae with evolute conch; whorls slightly impressed; whorl profile hexagonal or pentagonal with flattened venter and narrowly rounded umbilical margin. Ornament in the adult stage with coarse growth lines, in the preadult stage with fine spiral lines. Suture line with shallow external and lateral lobes. Siphuncle small with subcentral position (after Kummel 1964; emended).

Included species

Nautilus (Trematodiscus) discoidalis Winchell, 1862, Michigan; Nautilus (Discites) discors M‘Coy, 1844, Ireland; Nautilus Leveilleanus de Koninck, 1844, Belgium; Maccoyoceras pentagonum sp. nov., Algeria; Discitoceras wrightii Foord, 1900, Ireland.

Stratigraphic range

Late Tournaisian to Viséan.