Original presentation: Ammonites catillus d’Orbigny, 1841; Ammonites geslinianus d’Orbigny, 1850
Original publication: d’Orbigny. 1841. [p. 325, pl. 97, figs 1, 2]; d’Orbigny. 1850 [p. 146].
Types: MNHP 6110.
Type locality: “Lamennais near Vibraye, Sarthe, France” (Kennedy, 1988, p. 58).
PaleoDB taxon number: 145853.
Synonyms: Cobban and Scott (1973) considered Metoicoceras gibbosum Hyatt, 1903 a synonym of Metoicoceras whitei Hyatt, 1903. Cooper (1978) agreed that the two taxa are equivalent, but stated that “the name gibbosum has page priority over whitei, and is thus the valid name” (p. 114). This is not correct: the valid name is whitei because Cobban and Scott (1973) were the first revisers (for more on page priority, see this ICZN webpage). Later, it was recognized that Metoicoceras whitei is a synonym of Metoicoceras geslinianum (Cobban et al., 2006). Thus, the species that Cooper (1978) considered to be synonymous with Metoicoceras gibbosum should all be assigned to Metoicoceras geslinianum. These include: Metoicoceras whitei Hyatt, 1903; Metoicoceras kanabense Hyatt, 1903, Metoicoceras acceleratum Hyatt, 1903; and Metoicoceras ornatum Moreman, 1942.
References: Kennedy (1988), Cobban et al. (2006).