Maccoyoceras Miller, Dunbar & Condra, 1933

Korn, Dieter & Klug, Christian, 2023, Early Carboniferous coiled nautiloids from the Anti-Atlas (Morocco), European Journal of Taxonomy 885, pp. 156-194 : 169-170

Genus Maccoyoceras Miller, Dunbar & Condra, 1933

Type species

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

Diagnosis

Genus of the family Trigonoceratidae with discoidal, usually evolute conch; whorls slightly impressed; whorl profile hexagonal or pentagonal with flattened or slightly concave venter and narrowly rounded umbilical margin. Conch moderately increasing in height with a high coiling rate (WER usually higher than 2.00). 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

North America ( Winchell 1862): Nautilus (Trematodiscus) discoidalis Winchell, 1862 , Michigan.

Northern and Central Europe ( de Koninck 1844; M‘Coy 1844; Foord 1900): Nautilus (Discites) discors M‘Coy, 1844 , Ireland; Nautilus Leveilleanus de Koninck, 1844 , Belgium; Discitoceras Wrightii Foord, 1900 , Ireland.

North Africa( Korn & Bockwinkel2022; Korn et al. 2022): Maccoyoceras concavum Korn &Bockwinkel, 2022 , Algeria; Maccoyoceras habadraense Korn & Bockwinkel, 2022 , Algeria; Maccoyoceras pentagonum Korn, Miao & Bockwinkel, 2022 , Algeria; Maccoyoceras saharensis Korn & Bockwinkel, 2022 , Algeria.

Remarks

For a discussion of the composition and limits of the genus, seeKorn et al. (2022) andKorn & Bockwinkel (2022).