The rich early Miocene small mammal assemblage from Montalvos2, collected from lacustrine deposits directly overlying the basement, is unique within the Teruel Basin, a basin that is otherwise well known for its late Miocene/ Pliocene mammal faunas. The presence of Democricetodon decipiens, Megacricetodon primitivus, Eumyarion and Ligerimys ellipticus enables correlation with the local biozone Ca (approx. 16.3 Ma, MN4). The high percentage of ochotonids in Montalvos2 is remarkable, a phenomenon that is known to occur in older assemblages from the adjacent Calatayud-Montalbán Basin. The association in Montalvos2 includes species indicative of an arid biotope, such as the ochotonid Lagopsis penai and the rodents Simplomys simplicidens, Armantomys aragonensis, Melissiodon dominans and the xerine squirrel Heteroxerus, and species that are supposed to have lived in a more humid forested biotope, such as the Talpidae and the flying squirrel Albanensia. This wide range of species indicates that the environment in the Teruel Basin was highly diverse during the early Miocene.

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The reconstruction of the evolutionary history of the Rhizomyinae and the Spalacinae based on the fossil record strongly suggests that these do not share the same murid ancestor and developed separately since the early Oligocene. This conclusion is supported by the difference in evolutionary dynamics between these groups during the Miocene and Pliocene. Molecular genetic studies of extant representatives of the Rhizomyinae, Spalacinae and Myospalacinae, however, suggest that these subfamilies share similarities that distinguish them from all other Muridae. As a result, geneticists unite these subfamilies into the family Spalacidae and consider the Spalacidae and the Muridae to be sister lineages. Until the conflict between the two disciplines is resolved we prefer to maintain the Rhizomyinae and the Spalacinae as two subfamilies within the family Muridae (superfamily Muroidea).

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.