A Rupelian mangrove swamp mollusc fauna from the Thrace Basin in Turkey
Harzhauser, Mathias; Mandic, Oleg; Büyükmeriç, Yeşim; Neubauer, Thomas A.; Kadolsky, Dietrich; Landau, Bernard M.
A Rupelian mollusc fauna from a lignitic coquina overlying the main seam in the Pullukçu lignite mine in the Turkish part of the Thrace Basin is described. The low diversity assemblage comprises twelve gastropods and four bivalve species and is dominated in specimen numbers by Cyrenidae, Dreissenidae, Rissoidae, Thiaridae, Potamididae and Melanopsidae. Ecologically, the taxa indicate mesohaline to polyhaline water conditions and suggest a position far within the mangrove swamp at some distance from the shoreline. In terms of biogeography, the fauna represents a typical Rupelian coastal swamp assemblage, which was rather homogenous at the genus level along all European coasts. Nevertheless, two new thiarid and rissoid genera, represented by numerous specimens, document some biogeographic differentiation from the well-known Rupelian faunas of the North Sea and Eastern Atlantic. For the first time, the enigmatic planorbiform genus Anomalorbina Paul 1996 is also recorded from the Thrace Basin. For the Oligocene, it has been known so far only from the North Sea Basin, emphasizing the current state of poor knowledge of micromolluscs in the Paratethys and Western Tethys. This lack of information on small-sized taxa renders difficult a comparison with other Oligocene faunas of the Paratethys and Western Tethys and documents the limits of paleobiogeographic analyses. Sengoeria and Koskinakra are described as new genera and Vitta rumeliana, Sengoeria thracica, Koskinakra thracica and Sphenia praepusilla are introduced as new species.