New biostratigraphic evidence (texanitid ammonites, inoceramids and calcareous nannofossils) for the Upper and the uppermost Coniacian in the Bohemian Cretaceous Basin
Abstrakt
The re-discovered original specimen of the texanitid ammonite Texanites pseudotexanus, described as Mortoniceras texanus by Hibsch (1929) and illustrated as Mortoniceras pseudotexanus by Storm (1931), as well as three fragments of Paratexanites serratomarginatus documented (and one illustrated) by Fritsch (in Fritsch & Schlönbach 1872) as Ammonites Texanus, all from the Bohemian Cretaceous Basin (BCB), were systematically re-evaluated. The occurrence of these two zonal markers confirms the presence of Upper and uppermost Coniacian strata in the BCB.
Sediment samples from the specimen of T. pseudotexanus provided calcareous nannofossils, including Lucianorhabdus cayeuxii and Lithastrinus grillii, documenting the uppermost Coniacian, lower part of the UC11c Subzone. These data are in accordance with the occurrence of the inoceramid bivalves Magadiceramus subquadratus, M. crenelatus and M. complicatus.
Sediment samples from the specimen of P. serratomarginatus provided calcareous nannofossils, including Lithastrinus grillii and Lithastrinus septenarius, documenting the Upper Coniacian (UC11 nannofossil Zone).