Dr. Fűköh Levente szerk.: Malakológiai Tájékoztató 11. (Eger, 1992.)

A. Dávid: Distribution of Molluscs of the Molluscan Clay of Two Localities According to Habitats and Feeding Habits

Distribution of Molluscs of the Molluscan Clay of Two Localities According to Habitats and Feeding Habits (Wind Brickyard, Eger and Nyárjas Hill. Novaj; Hungary) A. Dávid Abstract: Among the Egerian Age exposures of North-east Hungary the Molluscan Clay of Wind Brickyard (Eger) and Nyárjas Hill (Novaj) contain fossils in exceptional richness. Distribution of molluscs of the Molluscan Clay of these two outcrops according to habitats and feeding habits is examined and compared. There are definite differences between the two localities. Introduction Among the several Upper-Oligocene outrops of North-Hungary the Molluscan Clay layers «f _Wind Brickyard, Eger and Nyárjas Hill, Novaj is compared (Fig.l.). These layers contain well-preserved „micro-mollusc" fossils abudantly. The bivalves, gastropods and schaphopods which were living here during the Egerian stage have belonged into the Hinia — Cadulus fossil community. It refers to similar paleoenvironments in case of both localities. The sea was deeper than 120 metres and the bottom was covered by fine-grained, clayey sediments. The aim of the investigation was to examine the distribution of the molluscs according to habitats and feeding habits in the collected materials. Methods Fifteen kilograms of clay was taken from both localities. After drying the samples were treated with hot water and peroxide of hydrogen. This material was washed out through a 0,5 nun sieve. At the end the molluscan remains were assorted from among the other fossils (e.gJ^oraminifera, Decapoda, Echinoidea, Osteichthyes). Most of the molluscan remains were fragmentary, but there were a lot of complete tests and stone-kernels, too. Only the complete tests and determinable fragments were examined. Because in case of stone-kernels the exact determination of species is often doubtful. Description Wind Brickyard The washed out and assorted material consists of mainly fragments and complete tests. The molluscs from this sample contist of 486 individuals representing 41 species. (Table VA). Most of the species are infaunal (87,8 percent). While takint feeding habits into con-