Ladinian ammonoids from the Balaton Highland (Hungary) I. Nemesvámos

Abstract

Recent collecting from the classic fossil site of Katrabóca at Nemesvámos (northeastern part of the Balaton High- land) yielded a well-preserved Ladinian (Longobardian) fossil assemblage from the red nodular limestone of the Buchen- stein Formation. The ammonite material consists of about 450 specimens; of these, 117 specimens could be identified as species; 68 of them are presented in this paper. A special phenomenon is the lenticular bivalve and gastropod coquina in Bed 13, which may have been formed by submarine redeposition and rapid cementation of the shells. The sedimentary structures of Beds 11 and 12 also indicate redeposition; most parts of the rich Arpadites assemblage contain fragmented shells and the specimens have a chaotic orientation. The richest ammonite assemblage was found in Bed 9 where the bedding-parallel arrangement of the large Protrachyceras shells and their iron-manganese oxide coating indicate low sedimentation rate and related condensation. The new collection significantly expands the taxonomic composition of the Katrabóca ammonoid fauna; within the 23 briefly described taxa of this paper nine are new at the locality.