The first reconnaissance expedition to the basin of the middle reaches of Kolyma River was conducted in July-August 2013. In 2014 the International Complex expedition “Searching the last giant of the Arctic” was organized; it was conducted in the upper and middle Kolyma region from July 21 to August 16. This expedition, which was organized by the Russian geographical Society and financially supported by Evraz, was the first (after many years) complex paleontological research of kolyma basin. Among newly discovered localities of mammoth fauna, the most important is the locality of Ireleah-Siene (verkhnekolymsky district). In addition to collected in 2013 and identified representatives of the mammoth fauna [1] (m. trogontherii; mammuthus intermedius; m. pimigenius fraasi (=an early form of mammoth); mammuthus primigenius primigenius (=a later form of mammoth); mammuthus sp.; Equus sp.; Cervus elaphus; ovibos sp.; bison sp.; rangifer tarandus; Coelodonta aniquitatis), the list of fauna was added by two carnivore species, ursus arctos and Canis lupus. In 2013 in Ireleah-Siene the tusk of woolly mammoth with pathological anomalies was found. This was the third record of this type in the world. Two mammoth tusks with similar anomalies have been found before, both from yakutia: the tusk from the Bolshoy lyahovsky Island (ZIn, nr. 30), and the tusk found on 16.02.1916 by v. v. Artamonov on kotelny Island which is exhibited in the yaroslavsky yakutsk State Museum of the History and Culture of northern Peoples (Myar, nr. kP 7433, P 167). Only the latter one has been briefly described. There was a tusk fragment with polishing traces among the fauna remains found in 2013: a palaeolithic site was suggested to be in this locality. Field research and additional materials taken in 2014 confirmed this suggestion. Taphonomical and biostratigraphical study of the alluvial deposits of the ancient river, once a tributary of the kolyma River, was conducted, and a few horizons of different age with the mammoth fauna and flora remains were discovered. The samples were taken for the radiocarbon dating, pollen and mineral composition. Bones and tusks of mammoths and other large mammals were collected in situ with clear chopping marks and other evidences of human impact. Some bones were used as tools: borers and polishers. There was also a collection of stone tools: axs, chippers, cutters, burnishers, flakes and other tools made of sandstone, quartzite, carnelian and other minerals.