This paper presents analytical results of the study of adaptatiogenesis within the family Arvicolidae (Mammalia, Rodentia) based of morphological changes of the most functional characters of their masticatory apparatus — dental system — through time. The main directions of the morphological differentiation in parallel evolution of the arvicolid tooth type within the Cricetidae and Arvicolidae during late Miocene and Pliocene were identified and substantiated. It is shown that such unique morphological structure as the arvicolid tooth type has provided a relatively high rate of evolution of voles and a wide range of their adaptive radiation, as well as has determined their taxonomic and ecological diversity. The optimality of the current state of this group and evaluation of evolutionary prospects of Arvicolidae were presented and substantiated here as a phenomenon in their evolution.
Beavers of the Genus Trogontherium (Castoridae, Rodentia) from the Late Miocene of Ukraine. Apoltsev, D. A., Rekovets, L. I. - The description of teeth and cranial fragments of extinct beavers, belonging to the genus Trogontherium Fischer von Waldheim, 1809 from Late Miocene strata of Ukraine, is presented in this paper. Their comparison with contemporaneous remains from localities in Europe and Asia is conducted. New data on systematics and paleogeography of Trogontherium (Euroxenomys) minutum minutum Meyer, 1938 and T. (Euroxenomys) minutum rhenanum Franzen, Storch, 1975, and also аbout their possible phylogenetic connections with the most ancient representatives of the family Castoridae are presented.