Timing of the Mimomys–Arvicola transition on the Russian Plain

An important problem for understanding the history of the small mammal communities of Eurasia is the time of final disappearance of ancient voles of the genus Mimomys and appearance of recent water voles of the genus Arvicola. The new material from the Mastyuzhenka section of Don basin shows that, in the Mimomys–Arvicola evolutionary lineage, the roots of the cheek teeth were lost and, hence, the genus Arvicola appeared in the pre-Okian (pre-Elsterian = pre-Anglian) time, that is, in the final phase of the Cromerian. This brings the timing of this transition in Russia closer to that in Central and Western Europe, and therefore provides better support for inter-regional biochronological correlations.