We here describe new remains of amphibians and reptiles from the early Miocene (MN 4) of two different Greek localities, Aliveri and Karydia. The newly described material consists of urodelans, alytids, indeterminate anurans, turtles, crocodylians, lacertids, indeterminate scincomorphs, anguids, colubrids, viperids, and indeterminate snakes. The presence of the frog Latonia cf. gigantea in Greece is documented for the first time. Additionally, the presence of viperids in Aliveri implies a much wider distribution for these snakes during the early Miocene of Europe. Of special interest is the presence of a peculiar colubrid that seems to possess a hitherto unknown vertebral structure, which is herein defined as the 'paracentral ridge' . Although incomplete, the new material has important taxonomic and biogeographic implications, as it enhances our understanding of southeastern European herpetofaunas from the early Miocene, a time period that was characterised by major dispersal and extinction events and climatic change that affected the whole continent. Materials and methodsThe majority of specimens described herein belongs to the collection of the UU, whereas the remaining of the described material belongs to the AMPG. Comparative material includes multiple skeletons of extant frogs, salamanders, turtles, lizards, and snakes held in HNHM, MDHC, MNCN, MNHN, NHMW, NMP, and ZZSiD.

Over the last half a century, a massive amount of data has been gathered on Neogene rodents of Europe. Using the NOW database, we analysed changes in generic diversity during the Neogene and the beginning of the Quaternary. Studies as the present are useful for exploring major changes in diversity, but the pitfalls are many and varied. Whereas the quality of the fossil record is good, there are notable exceptions. Within our dataset, MN 1, MN 12 and MN 17 stand out for the limited number of localities available and the record of the eastern Mediterranean is clearly as yet poorer than that from central Europe and the Iberian Peninsula. The record can be influenced by incomplete faunal lists, outdated literature and unresolved taxonomies. In addition, the use of the MN system presumably obscures patterns, as it often does not allow for a co-eval comparison between various regions. Reconstruction of major patterns starts with the understanding of basic data. Despite all these limitations the results of this work indicate that the record for central Europe consistently shows higher diversity than lower latitudes. The highest peak in diversity is found in MN 15, but the record of the Iberian Peninsula shows no increase at that time. The rodent diversity is surprisingly constant during most part of the Neogene, the stronger variations being related to the diversification of the murinae and arvicolinae groups and decline of the cricetine.

Cricetodon is present in the early Miocene of Greece in six assemblages, Cricetodon aliveriensis Klein Hofmeijer and de Bruijn, 1988 in Aliveri and Karydia (both MN4) and Cricetodon meini Freudenthal, 1963 in the MN5 localities of Thymiana A and C, Antonios and Komotini. The two MN4 small mammal assemblages in Aliveri (Euboea island) and Karydia (Northern Greece) have several species in common and Cricetodon aliveriensis is one of them. The aim of this paper is to record and describe this species, the most abundant rodent in the Karydia assemblage, to compare the morphological variation and to discuss the differences in size between the material of Karydia and Aliveri. The results of this study indicate that we deal with one Cricetodon species in Karydia, although more advanced than Cricetodon aliveriensis from Aliveri. This study highlights the importance of a detailed morphological description to the size range of a species. The Karydia material shows a large range in length and width measurements that may indicate heterogeneity of samples. However, the morphological similarity and the normal distribution of the Cricetodon values support the assignment to only one species.

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