The Karnian bivalves (Mollusca) from Lesno brdo, Slovenia, NW Yugoslavia and their paleobiological significance

Abstract

The performed biostratinomic investigation indicated that the locality Lesno brdo should be considered and studied as a locality of fossil biocoenosis. The investigation was carried out according to schemes of the composition and of functioning of the community. For establishing the taxonomical and quantitative composition of the community descriptive and numerical methods were used by the author. The influences on the composition of the community were studied by geochemical, sedimentological and paleoecological methods. To establish and understand the functioning of the community in ones existing ecosystem fossils were investigated by the methodology of adaptive functional morphology as the relations between the shape of the organism, environment, living habit and evolution. The origin of new species and subspecies in the Lesno brdo locality is not placed into the selective, but into the fast sympatric adaptive speciation and subspeciation. Also the influence of topographical and hydrographical conditions on speciation and subspeciation, as well as on the evolutional convergence of genera Trigonodus and Myophoria was established. The paleobiogeographical differences and similarities in the region of the Southern Alps have an ecological reason. Insight into biofacies and biochronology of the southem alpine localities drew attention to ecostratigraphy and diacronicity, two notions to which in this country until recently hardly any attention was dedicated.