Introduction

During the nineteenth century and the first half of the twentieth century, a great number of papers on Cenozoic fossil European non-marine molluscs were published. After the Second World War the number of publications dealing with fossils of this group decreased and among the relatively limited number of papers published since then the majority regards malacological assemblages of the Quaternary period. Many faunas must be revised and consequently their utility for paleoclimatical, paleoecological or paleogeographical purposes is very limited.

The potentiality of non-marine mollusc fossil assemblages to the reconstruction of paleoclimates has been clearly evidenced by many works of many malacologists working on the Quaternary (Lozek, 1964; Puisségur, 1976). The majority of the species recorded in sediments of this period (especially of middle and late Pleistocene and Holocene) are still living and a quantitative analysis of the composition of the fossil assemblages gives very accurate information about the local climatic conditions. This fact is strictly linked to the onset of the main glaciations just at the beginning of the middle Pleistocene. Unfortunately this situation is not the same for older periods in which the climatic changes were not so sharp and the majority of the fossils belong to extinct species. Since the shell morphology of land species generally is not affected by climatic variations, the information about environmental changes is inferred indirectly considering other factors: the occurrence or disappearance of the taxa, their geographic distribution (also in connection with the latitude and elevation, for example, of living species of the same genus), the degree of the species diversity of the assemblages.