Az Eszterházy Károly Tanárképző Főiskola Tudományos Közleményei. 1994. Sectio Geographiae.(Acta Academiae Paedagogicae Agriensis : Nova series ; Tom. 21)

Dávid Árpád: Contribution to the knowledge of the trace fossils found on the molluscs in the molluscan clay of Nyárjas hill /Novaj, Hungary

Most of the molluscs were fragmentary, but also many complete specimens and specimens in cast preservation were found. The complete shells and identifiable fragments were inspected for the presence of trace fossils. In the case of cast recognition of trace fossils is often uncertain and doubtful. DESCRIPTION: The molluscan remains of the sample consist of 275 individuals representing 32 species /Table 1/. Trace fossils can be seen on the tests of 13 individuals of 8 species. 4.7 percent of individuals and 25 percent of species bear trace fossils in the collected material. 87.5 percent of the species bearing trace fossils were the member of the infauna. Distribution of trace fossils according to feeding habits of mollusc spccies is the following: suspension feeders: 62.5 percent scavengers and predators: 12.5 percent parasites: 25.0 percent The 15 pieces of trace fossils can be assigned to four types /Table 2/. A fragmentary specimen of Caduhts graeilin

a bears characteristic traces of fungal boring /Plate I, Fig. 1/. Cresentic shape of a presumably bite trace is observable on the margine of a Crassatella bosqueti minor valve. There is a fragment of a Fhtbellipecten burdigalensi

s right valve with a complete muricid boring. The characteristic cylindrical borehole can be seen between two furrows at the margin /Plate I, Fig.2/. 12 naticid boreholes can be found in the shells of 10 specimens of six species. The number of complete boreholes is eight. While the number of incomplete boreholes is four. There are five Crassatella hosqueti mino

r valves which bear a single naticid boring. Among the incomplete boreholes two can be seen is the right valve of a Corhula gihha /Fig.3/, /Plate II, Fig. 1. 2./. A specimen of IViso min

or bears traces of multiple predation, too /Plate III. Fig. 1. 2. /. A complete and an incomplete boreholes can be seen on its test /Fig. 4./. 22