A new Lower Coniacian fauna from the Jerzmanice Zdrój region of the North Sudetic Basin, SW Poland

Abstract

This paper describes and interprets a newly discovered Lower Coniacian (lower Upper Cretaceous) macro- and micro- fossil fauna (vertebrate and invertebrate remains) from sedimentary rocks of the Jerzmanice Zdrój region of the North Sudetic Basin of SW Poland. Several inoceramid bivalve taxa that previously were only known from other parts of the North Sudetic Basin were recovered from light grey, marly sandstones of Early Coniacian age. A fragment of ammonite was also discovered, as was a shark's tooth from the family Cretoxyrhinidae: this may be ?Cretoxyrhina mantelli Agassiz, 1843, a species not hitherto known from the Lower Coniacian (Emscherian sensu Scupin (1912-13)) of the North Sudetic Basin. Abundant foraminifers were observed in thin sections. The newly discovered inoceramid bivalves - Cremnoceramus deformis erectus Meek, 1877, Cremnoceramus waltersdorfensis waltersdorfensis Andert, 1911 and Inoceramus lusatiae Andert, 1911 - fit into the current biostratigraphic scheme for the region. The inoceramids can all be assigned to the Cremnoceramus deformis erectus Zone, which correlates with the Gavelinella moniliformis foraminiferal Zone and thereby confirms an Early Coniacian age. The Turonian-Coniacian boundary in the North Sudetic Basin can now be placed between the respective inoceramid zones of Inoceramus costellatus Woods, 1912 (actually Mytiloides costellatus Woods, 1912) and Inoceramus schloenbachi Böhm, 1911 (actually Cremnoceramus crassus crassus Petrascheck, 1903). The macrofossils found in the Jerzmanice section suggest that the host sediments were laid down in a Late Cretaceous epicontinental basin, under the North Sudetic Sea, that had deepened during the Early Coniacian. This interpretation agrees with the global bathymetric curve for the Late Cretaceous in Europe.