Palaeobiogeographical significance of some Pliensbachian gastropods from north-eastern Sicily (Italy)

Starting from the study of two Pliensbachian gastropod species, the palaeobiogeographical significance of the gastropod faunas of north-eastern Sicily was investigated. The species [Muricotrochus (Laeviconulus) epuloides (Szabó, 1981) and Anoptychia crenata (Stoliczka, 1861)] stem from pelagic sediments cropping out on the eastern side of Monte Ziretto, near Taormina. Their palaeogeographical distribution is limited to the western Tethyan areas that were characterized by pelagic sedimentation since the Late Sinemurian or Early Pliensbachian. In order to ascertain how this information reflects features of the whole palaeogeographical domain, the Pliensbachian gastropod fauna from Rocche Rosse (Galati Mamertino, W of Messina, Sicily), published by M. Gemmellaro in 1911, was preliminarily studied. This is the most diversified and richest Early Jurassic gastropod fauna known from the Peloritani Mountains. From the palaeogeographical point of view, three stocks characterize the fauna. The most important consists of species occurring exclusively in areas characterized by pelagic sedimentation. The other two stocks, which are composed, respectively, by ubiquitous species and species known exclusively from Rocche Rosse, are not useful for paleobiogeographical comparisons. Then, the distribution of the two species analysed, which is restricted to the western Tethyan areas characterized by pelagic sedimentation, is in accordance with the results of the study of a diversified fauna and seems to reflect a peculiar feature of the Pliensbachian gastropod faunas of Peloritani Mountains.