engleski

Galeacysta etrusca, its significance in the southern Pannonian Basin

In the Late Miocene, central and eastern Croatia was a part of the southern Pannonian Basin. A greater part of the Basin was filled with brackish water - Lake Pannon that existed from the end of the Middle Miocene to the Early Pliocene. At the end of the Pannonian (ca 8.0 Ma) water levels rose (Magyar et al, 1999) and some new dinocysts appeared: Galeacysta etrusca Corradini & Biffi, 1988, Spiniferites cruciformis Wall et al. 1973. and Pyxidiniopsis psilata (Wall et al. 1973) Head 1994. Galeacysta etrusca is also known from the lago-mare facies of Italian Messinian (Corradini & Biffi, 1988), and two later forms are known from the late Quaternary brackish water sediments of the Black, Marmara and Aegean Sea (Mudie et al., 2001). Question is if those forms evolved in Pannonian Basin or immigrated from the Eastern Paratethys or from the Mediterranean. Galeacysta etrusca could develop from Spiniferites balcanicus because of the adaptation on a new, fresher environment that requires thinner and lighter cyst. In Mediterranean Galeacysta etrusca first appeared in Late Messinian (ca 5.5-5.0 Ma.) in lago-mare facies, while at that time it already disappeared from the Pannonian Basin. Galeacysta etrusca could migrate through the Djerdap (Danube) strait towards the east and through the Marmara Sea in Mediterranean. In Marmara Sea Galeacysta etrusca could adapt on even more freshwater environment in Pleistocene, and evolve in Pterocysta cruciformis Rochon et al, 2002. which could be the same species but with more cruciform body as a result of adaptation on the fresher and colder environment.

dinoflagellate cysts; Pannonian Basin; Pontian; Messinian

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