First occurrence of the rare middle Jurassic ammonite genus Erymnocerites Jeannet from southern Poland

Abstract

ABSTRACT The genus Erymnocerites Jeannet is recorded for the first time from Poland. A single specimen, assigned to Erymnocerites argoviensis Jeannet is recorded from the Callovian Lamberti Zone from the Ogrodzieniec quarry (southern Poland). It is associated with upper Callovian forms of Peltoceras schroederi, Kosmoceras duncani and Quenstedtoceras lamberti. However, this condensed bed also yielded lowermost Oxfordian species of Peltoceratoides (Peltoceratoides) williamsoni, Peltoceratoides (Parawedekindia) arduennensis, Euaspidoceras subbabeanum, E. babeanum, Bukowskites minax, Cardioceras spp. and Hecticoceras (Putealiceras) punctatum, suggesting a condensation spanning the uppermost Callovian to lowermost Oxfordian for the lower beds at the Ogrodzieniec quarry. The recorded specimen differs from the middle Callovian Coronatum Zone E. argoviensis, which is a much larger (still septate at 188 mm), more depressed, less evolute, and has a rounded whorl section. However, based on the similarities in septal suture line and ribbing pattern, and considering the morphological variations in pachyceratids, the Polish specimen is referred to E. argoviensis. Based on the size difference between the Herznach (Switzerland) holotype of E. argoviensis (phragmocone~188 mm; maximum shell diameter~320 mm) and the Polish specimen (phragmocone 76 mm; maximum shell diameter 133 mm), it is speculated and the latter be the corresponding microconch.