Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 89. (Budapest 1997)

Hír, J.: Cricetus runtonensis solymarensis ssp. n. (Mammalia, Rodentia) from the Late Middle Pleistocene fauna of Solymár

The subspecies of Solymár is different from the Lower Pleistocene C. runtonensis in the more complicated morphology of the M2, m2, m3 molars. During the study of the Early Pleistocene C. praeglacialis and Recent C. cricetus HÍR (1997) has found a contrary trend: the simplification in the morphology. This fact confirms the supposition of the author, that the C. praeglacialis -C. cricetus group and the C. runtonensis group are two independent evolutionary lines of the Middle European Pleistocene hamsters. After the Late Middle Pleistocene C. runtonensis completely disappeared from the Carpathian Basin. In this moment we can not give an unambiguous explanation of the disappearence and returning of the species. The paleoecological preferences of C. runtonensis are not clear. The composition of the fauna Somssich-hegy 2 suggests a mainly continental steppe environment (JÁNOSSY 1990). The material of Solymár reflects a forest ecosystem and mild climate, but the above mentioned other Late Middle Pleistocene faunas (Pongor Hole and Lök-völgyi Cave) are dominated by steppe elements as well. In the chronological evaluation of the Solymár fauna VÖRÖS (1988) published his opinion, that on the basis of the specific composition of the macromammals the fauna can be put into the Upper Biharian (Early Middle Pleistocene) substage. This is a remarkable contradiction to the relative age determination refers to the micromammals, especially on the Arvicola with undifferentiated enamel structure, which establishes the Late Middle Pleistocene age (HEINRICH 1982). After the detailed study of the hamsters we can confirm the chronological determination based on the micromammals, because in the Hungarian Late Biharian faunas the species Cricetus runtonensis is missing. In the faunas of Vértesszőlős and Tarkő 1 the C. cricetus is found. In the lower layers (2-16) of Tarkő an extra large sized hamster was collected. It was determinated as "C. c. runtonensis" by JÁNOSSY (1976b, 1986), but this determination is erroneous, because the dimensions are much larger than the studied C. runtonensis populations and refer to the C. major species after FAHLBUSCH (1976). Acknowledgements - The author would like to express his sincere thanks to the staff of the Department of Paleontology of the Hungarian Natural History Museum for the kindness in offering the material investigated. The research activity was supported by the Hungarian Scientific Research Fund (OTKA No. 144117). REFERENCES FAHLBUSCH, V. (1976): Cricetus major WOLDRICH (Mammalia, Rodentia) aus der mittelpleistozänen spaltenflung Petersbuch I.-Mitt. BayerStaatssamml. Pal. Hist. Geol. 16: 71-81. FEJFAR, O. & HEINRICH, W. (1981): Zur biostratigraphischen Untergliederung des kontinentalen Quartärs in Europa anhand von Arvicoliden (Rodentia, Mammalia). - Eclogae geol. Helv. 74 (3): 997-1006. FEJFAR, O. & HEINRICH, W. (1986): Biostratigraphic subdivision of the European Late Cenozoic based on muroid rodents (Mammalia). - Mem. Sac. Geol. Ital. 31: 185-190. FEJFAR, O. & HEINRICH, W. (1990): Proposed biochronological division of the European continental Neogene and Quaternary based on Muroid rodents (Rodentia, Mammalia). - In: FEJFAR, O. & HEINRICH, W. (eds): International Symposium Evolution Phytogeny and Biostratigraphy of Arvicolids (Rodentia.Mammalia). Geol. Survey, Praha, pp. 115-124.