No abstract

Seven new rodent faunas are described from the Pčinja and Babušnica-Koritnica basins of south-east Serbia. The geology of the Tertiary deposits in the Pčinja and Koritnica-Babušnica basins of south-east Serbia is briefly reviewed. The fossil content of the new vertebrate localities is listed, and an inventory of the rodent associations is presented. The rodent associations are late Eocene-early Oligocene in age, interpreted on biostratigraphical grounds. These are the first rodent faunas of that age from the Balkan area, an important palaeogeographic location between Europe and Asia. The Muridae, with the subfamilies Pseudocricetodontinae, Paracricetodontinae, Pappocricetodontinae, Melissiodontinae and ?Spalacinae, are dominant with eight genera, four of which are new. The diversity of the Melissiodontinae and Paracricetodontinae in the faunas suggests that these subfamilies originated in this region. The bi-lophodont cheek teeth occurring in the Oligocene assemblages are identified as the first record of the Diatomyidae outside of Asia. In light of the large amount of new data, the palaeogeographic setting and faunal turnover of the Eocene-Oligocene is discussed.

Two new late Oligocene species of Deperetomys: D. calefactus and D. saltensis, are described and the affinities between the various species are discussed. The new records extend the stratigraphic range of Deperetomys into the Oligocene, making it the first European Miocene murid that can be traced across the "Cricetid vacuum". A single M1 of a large early Oligocene murid that may represent the oldest record of Deperetomys is described. The classification problems that arise as a result of the fast increase of information of the Paleogene Muridae from Asia and the Middle East are addressed and the need to recognise and define clades above the genus level is demonstrated. Our conclusion is that the Deperetomys clade contains at least three different evolutionary lineages.

Isolated teeth of Melissiodontinae from two Eocene and four Oligocene localities in southeastern Serbia are described. One new genus and two new species are named. The study of the derived morphology of the cheek teeth and of the contrastingly primordial microstructure of the tooth enamel of this diverse material provides a glimpse into the early history of the subfamily. The supposedly Asian murid ancestor of the Melissiodontinae seems to have reached the Serbian-Macedonian land area during the early or middle Eocene, which is shortly after the split up of the Muridae and Dipodidae and before the 'Grande Coupure' of central and Western Europe. We interpret the rapid consequent specialisation of the morphology of the chewing apparatus of the Melissiodontinae as an adaptation to feeding on small invertebrates on the floor of the Eocene forest.

A new diatomyid genus and species, Inopinatia balkanica, from the early Oligocene of south-east Serbia is described, and the affinities between the Diatomyidae and Ctenodactylidae are discussed. Inopinatia balkanica nov. gen. nov. sp. seems to have retained its deciduous teeth throughout life just as all other species of the family. The only other diatomyid described from outside south-east Asia which is Pierremus explorator López-Antoñanzas, 2010 is transferred to the thryonomyid species Paraphiomys knolli López-Antoñanzas and Sen, 2005.