PALAEONTOLOGICAL STUDY OF THE ORDER LAMNIFORMES IN THE MIOCENE MEDITERRANEAN BASIN

A palaeontological study of the lamniform assemblage of the Miocene Mediterranean Sea, based on systematic, statistical and of palaeopathological approaches, is proposed. The systematic revision is mainly based on the important deposits of the area of Montpellier (South-Eastern France), of Malta, of the Salentine area (Italy) and of the Tertiary Piedmont Basin (Italy). The systematic analysis is integrated by the contribution of the multivariate statistical investigation: in particular some preliminary results, based on the Principal Component Analysis, are given.The Miocene Mediterranean deposits result characterized by a rich Lamniform population. The analysed material has allowed to identify 5 families, 10 genera and 14 species of sharks belonging to the order. The new data support the similarities of the taxonomic composition among coeval assemblages of the Mediterranean area and the close relationship between the Atlantic and the Mesogea populations, especially in the pelagic species of the order Lamniformes. The low differentiation of the lamniform Mediterranean assemblages and the similarity with the Atlantic faunas are supported by the paleogeographic situation of the Miocene Mediterranean which sees open passages between the basins.The presence of a population of big sharks, with tropical and temperate habits and a prevailing Mediterranean-Atlantic characteristic, from the early to the late Miocene, at least to the Tortonian, perfectly fits the Paleomediterranean fauna first advocated by Arambourg (1927) and the picture given by Cappetta & Ledoux (1970). The palaeopathological analysis of the skeletons of Neogene preys confirms the fact that this assemblage was sustained by a conspicuous alimentary biomass and underlines strict trophic interactions among big sharks, mainly belonging to the ord. Lamniformes, cetaceans and sirenians.