Voronin Grotto (Middle Urals, Russia): Analysis of vertebrate assemblage with taphonomic remarks and reconstruction of the Late Bronze Age and Early Iron Age human environment in the east end of Europe based on small mammals

We present the Voronin Grotto as a new site where numerous remains of vertebrates (total NISP = 12574) and artefacts (N = 46) were found. The grotto is located in Serga River valley at the foot of the western slope of the Middle Urals, i.e., in the east end of continental Europe. The deposits have been accumulating during the last 3310 years. The AMS dates and artefacts indicate that the grotto was periodically visited by human population in the period between 3310 cal BP (the Late Bronze Age) and 1899 cal BP (the Early Iron Age). Recovered vertebrate assemblage included 49 species belonging to 5 classes (Actinopterygii, Amphibia, Reptilia, Aves, and Mammalia). The bones of fish and amphibians were collected by either otters or minks. Prevailing fish sizes between 10 and 15 cm reconstructed by means of bones confirm this. The bones of small mammals accumulated due to the predation of the owls and mustelids. Most identified vertebrate species currently inhabit the vicinity of the grotto, except for the steppe pika. Steppe pika is now disjointed from the Voronin Grotto by approximately 200–300 km to the south. Perhaps between 3310 and 1899 cal BP, steppe pika inhabited the vicinity of the grotto as the Late Pleistocene and Early Holocene relic. Palaeoenvironmental analysis of small mammal assemblage showed the predominance of woodlands with a significant proportion of open mesophytic meadows around the grotto during the last 3310 years. The landscape did not change significantly during this time. This is consistent with high values of the Simpson evenness index (1–D). Between 3310 and 1899 cal BP, the ratio of forests decreased, while the ratio of open meadows increased. Perhaps this was due to anthropic activity. After 1899 cal BP, the relative abundances of taiga small mammal species increased among forest dwellers, which is consistent with palynological data for the Middle Urals. At approximately 3310 cal BP, the climate of area around the grotto was slightly milder, and the winters were warmer than in the present day. At approximately 1899 cal BP, the climate was similar to the modern climate of the region and was cold, without a dry season, and with warm summers (Dfb type according to the Köppen–Geiger classification) as well as that of the previous period. Towards the recent time, the climate became colder and was possibly cold, without a dry season, but with a cold summer (type Dfc).