Vadim V. Titov

Development of the steppe zone in southern Russia based on the reconstruction from the loess-soil formation in the Don-Azov Region

Herbaceous communities in forest ecosystems on the southern part of the Russian Plain appeared in the Middle Miocene (∼10 Ma BP). In the Late Miocene (∼7 Ma BP), feather-grass steppe associations appeared among them. In the time span of 2.7 to 2.1 Ma BP (i.e., in the Early Quaternary, according to the current chronostratigraphic scale), the steppe zone arose on the southern Russian Plain in the Don-Azov Region. Seven stages of this zone development here have been distinguished throughout the Quaternary. The first one (Eopleistocene-Early Pleistocene) was characterized by savanna-like subtropic ecosystems. Then, in the Middle Pleistocene, the temperate zone ecosystems (tallgrass prairie-like steppes) developed here and were followed by steppe ecosystems close to the modern ones in Central Europe. The ecosystems of rich-species forb steppes developed in the Late Pleistocene. Finally, in the optimum of the modern interglacial (Holocene), steppes became similar to the modern ones here, but with a slightly higher precipitation. The general trend is characterized by reduction in heat and water provision and increase in aridization progressing from earlier to later stages.

Reconstruction of Late Pleistocene events in the periglacial area in the southern part of the East European Plain

An integrated study of the loess–soil sequence in the coastal exposure near the settlement of Beglitsa (Rostov oblast) allowed us, for the first time, to reconstruct the landscape-climatic changes that occurred in the eastern Azov region over the course of the Late Pleistocene. In the south of the periglacial zone, considerable differences between intensity of the loess accumulation in the Early and Late Valdai Cryochrons were revealed. In the Early Valdai Epoch, which corresponds roughly to the end of Marine Isotope Stage (MIS) 5 and MIS 4, loess accumulation occurred after completion of development of the Mezin pedocomplex and before the beginning of the Bryansk stage of soil development, i.e., over more than 20 000 years. In the much shorter Late Valdai Cryochron MIS 2 (10 000–12 000 years), loess accumulation reached 5 m. The data evaluation shows that the loess accumulation rates in the Early Valdai Epoch (~0.07 mm/year) and the Late Valdai Epoch (~0.5 mm/year) differ from each other by an order of magnitude.

Mass burial of Late Pleistocene bisons in the northeastern part of the Sea of Azov area (Port Katon, Rostov Region)

140 Port Katon, a reference section of Quaternary deposits, is located in a coastal cliff on the southern coast of Taganrog Bay of the Sea of Azov. The cliff exposes a section of the sixth (Margaritovo) Terrace from the eastern part of the settlement of Port Katon to the former village Podlyudki. The section has been paleontologically known since 1960s, yielding remains of large and small Early Pleistocene mammals of the Tamanian faunal unit [1–3]. Recent studies have shown that the section of Port Katon represents a bio stratigraphic sequence ranging from the Early Pleis tocene until the end of the Pleistocene [4–7]. In 2003, a mass burial of primeval European bisons Bison priscus [8] was discovered between the settlements of Port Katon and Podlyudki (46°52′ N, 38°43′ E). The site was excavated by a joint team of the Azov Museum Reserve headed by G. Timonina and the archaeological expedition of Rostov State University lead by S.I. Lukyashko. The geology of the section was studied by the team of the Geological Institute of the Russian Academy of Science headed by A.E. Dodonov. The coastal outcrop hosting the burial has a total height of about 30 m. This section does not show paleosols possibly indicating an ancient gully filled by loams. Bone remains occur at a depth of 6.7 m at the base of a 4.8 m thick bed composed of homogeneous finely porous loess like loams. This layer is covered by layers of brownish (0.3 m) and brownish gray loam (0.6 m) containing carbonate nodules. The section is crowned by modern soil (0.8 m), composed of dark gray loam with a strong humus content, and a layer of modern chernozem soil (0.2 m). The bone bed is located at the level of an indistinct chernozem like paleosol (probably of Bryansk age), exposed laterally, on both sides of the studied section [4]. Excavations and surface collecting unearthed more than 1800 fossil remains (collections AMZ, KP 30 053, 30 439). At present, about half of the burial bone mate rial has been obtained. The identical preservation of fossils, spatially restricted localization of the material, age and gender ratios of animals, and the absence of stone tools and signs of bone use by humans likely indicate the simultaneous catastrophic death of a herd of bisons. The minimum number of individuals counted by the posterior left metapodia is 47. Small mammals are presented in the bed only by isolated bones of ground squirrels Spermophilus sp. Age composition. The age structure of the Port Katon bison herd was determined using the wear degree and eruption stage of teeth, and the stages of epiphysal fusion on calcaneus and metapodia. One of the lower jaws with dp2 m1 has a preserved unerupted permanent incisor, which in modern bisons start func tioning only at the age of one year [9]. The second molar (m2) is still unerupted being entirely inside the jaw. Similar tooth wear stage of the milk and perma nent teeth have been found in three other individuals of the sample. A comparison of our data with those of Belan [10] on B. priscus from the Amvrosievka site (Late Palaeolithic, Ukraine), and with modern bisons indicates an age of about eight months for the youngest animals in the Port Katon sample. Thus, taking the birth of calves as occurring in April–June, we con clude that the death of the herd occurred in Decem ber–February. The study of wear degree in 24 m3 of B. priscus from Port Katon has shown that the collection is dominated by bones of young animals. Unlike the large sample of bison remains from kitchen midden in the Amvrosievka site, the Port Katon herd includes more juveniles below 4 years of age, and older animals (older Mass Burial of Late Pleistocene Bisons in the Northeastern Part of the Sea of Azov Area (Port Katon, Rostov Region)