Early Pleistocene faunas of small mammals in eastern Europe

Materials from many lower Pleistocene localities of small mammal remains el ucidate principal stages of the fauna evolution in eastern Europe and enabl e the biostratigraphic subdivision of host deposits on the basis of evoluti onary changes in small mammal communities and their coordination with geolo gical and geochronological data. Several assemblages and evolutionary phase s of early Pleistocene mammals are distinguished. The first occurrence leve ls of new taxa (mostly of genera and species of Arvicolidae) are used to de tect boundaries between assemblages, The established geochronological subdi visions of the Pleistocene are coordinated with those of West European scal es. The initial period of the early Pleistocene and an early phase of the O dessa fauna of small mammals correspond to the first occurrence level of ar hizodont vole Allophaiomys deucalion. Later faunas of the Odessa assemblage are characterized by the appearance of arhizodont vole genera Prolagurus ( P. ternopolitanus) and Lagurodon (L. arankae), who had teeth lacking cement um. These taxa coexisted with Allophaiomys deucalion. The more progressive Nogaisk faunas of small mammals (Topachevskii, 1965) included the evolved s pecies Allophaiomys pliocaenicus, which coexisted with Prolagurus ternopoli tanus and Lagurodon arankae. The next stage of evolution was marked by orig in of first small lemmings Prolagurus pannonicus. The term Kairy faunas is suggested to be appropriate for assemblages of this stratigraphic level (de rived from the Zapadnye Kairy stratotype locality in the Dnieper River lowe r courses). The Kairy faunas also include voles Allophaiomys pliocaenicus, Mimomys savini, and Mimomys pusillus. These faunas are correlative in age w ith the paleomagnetic Jaramillo Subchron. More progressive assemblages with first Microtus (Terricola) and Microtus (Stenocranius?) hintoni have been already described as the Morozovka faunas (Aleksandrova, 1976). Advanced Mi momys forms, Allophaiomys pliocaenicus nutiensis, and Prolagurus pannonicus are characteristic of this stratigraphic level. Successive Petropavlovka f aunas of small mammals correspond in time to the end of the early Pleistoce ne and to the Matuyama Chron. Their index forms are first voles Microtus ex gr. oeconomus. The advanced Mimomys species (M. savini, M. pusillus) of th e Petropavlovka faunas coexisted with dominant Prolagurus pannonicus, Eolag urus argyropuloi, and Microtus (Stenocranius) hintoni, The early Tiraspol f aunas correlative with the uppermost level of the Matuyama Chronozone are d istinct because of newcomers Microtus arvalinus and Prolagurus posterius.