ON THE ORIGIN AND COMPOSITION OF EARLY CHOKRAKIAN (MIDDLE MIOCENE) GASTROPODS OF THE EASTERN PARATETHYS

Abstract

The systematic composition and diversity of Early Chokrakian gastropods, represented by 85 species, are discussed. Twenty species are presumed to be endemic to the Eastern Paratethys, since they are not known for the Middle Miocene basins of the Mediterranean. It is supposed that some representatives of the families Diastomatidae, Potamididae, Pyramidellidae, Aclididae, and some others, which are phylogenetically related to some Indo-Pacific species, migrated to the Early Chokrakian Sea (about 16 Ma) through a system of straits between the Eastern Paratethys, Eastern Mediterranean, and Mesopotamia. Obtortio praeroxolanica, Cerithidium agibelicum, Potamides cicur, Aclis (Murchisonella) caucasica, Bacteridium elegans, etc. are probably of Indo-Pacific origin.