Kornia Ebbighausen & Bockwinkel, 2007

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 : 37-38

Genus Kornia Ebbighausen & Bockwinkel, 2007

Type species

Kornia citrus Ebbighausen & Bockwinkel, 2007: 143 ; original designation.

Diagnosis

Genus of the subfamily Prionoceratinae with a spindle-shaped conch in the juvenile stage and globular conch in the adult stage. Umbilicus almost closed in stages larger than 7 mm diameter, in the juvenile stage with raised umbilical edge. Growth lines strongly curved back from the umbilical margin, forming broad and deep ventral sinus.

Genus composition

Central Europe ( Vöhringer 1960): Imitoceras sphaeroidale Vöhringer, 1960 ; Kornia fibula sp. nov.; Kornia acia sp. nov.

North Africa ( Ebbighausen & Bockwinkel 2007): Kornia citrus Ebbighausen & Bockwinkel, 2007 .

Remarks

The genus Kornia was introduced by Ebbighausen & Bockwinkel (2007) for very small specimens which are characterised by their spindle-shaped conch and conspicuous umbilical shape, thus differing strongly from all other known early Tournaisian ammonoids. Juvenile ammonoids with such a shape, however, occur repeatedly in the fossil record, as shown for the Late Viséan genera Goniatites de Haan, 1825 ( Klug et al. 2016; Korn 2017) and Hibernicoceras Moore & Hodson, 1958 ( Schmidt 1925; Korn 1988a).

Kornia differs from Globimitoceras , apart from the juvenile conch morphology, in the course of the growth lines, which are almost straight in Globimitoceras are, but in Kornia they have a very broad and deep ventral sinus.