Globimitoceras Korn, 1993

Korn, Dieter & Weyer, Dieter, 2023, The ammonoids from the Gattendorfia Limestone of Oberrödinghausen (Early Carboniferous; Rhenish Mountains, Germany), European Journal of Taxonomy 882, pp. 1-230 : 28-29

Genus Globimitoceras Korn, 1993

Type species

Globimitoceras globiforme Vöhringer, 1960 ; original designation.

Diagnosis

Genus of the subfamily Prionoceratinae with globular conch in the juvenile and adult stage. Umbilicus almost closed throughout ontogeny. Growth lines fine and straight, without shell constrictions but with internal shell thickenings. Suture line with very narrow external and adventive lobes.

Genus composition

Central Europe ( Vöhringer 1960): Imitoceras globiforme Vöhringer, 1960 .

South Europe ( Korn & Feist 2007): Globimitoceras albaillei Korn & Feist, 2007 .

North Africa ( Ebbighausen & Bockwinkel 2007): Globimitoceras rharrhizense Ebbighausen & Bockwinkel, 2007 .

South China ( Sun & Shen 1965): Imitoceras sphericum Sun & Shen, 1965 .

Remarks

Globimitoceras contains prionoceratid ammonoids that possess a spherical, subinvolute or involute conch throughout ontogeny but, unlike Mimimitoceras , do not possess shell constrictions. The aperture is very low at all stages; the whorl expansion rate rarely exceeds a value of 1.50.

Kullmann (2009) did not accept Globimitoceras as a valid genus and placed it in the synonymy of Paragattendorfia . He justified this by stating that Globimitoceras was introduced for species that only differ in the narrow umbilicus throughout almost the entire ontogeny. However, the genus is not only separated from Paragattendorfia by the width of the umbilicus alone but also by differences in the suture line. While Globimitoceras has very narrow external and adventive lobes, these are broader and V-shaped in Paragattendorfia ; furthermore, the ventrolateral saddle is broadly rounded in Globimitoceras but narrow in Paragattendorfia .