Recent multidisciplinary studies of the permafrost deposits in Northern Yakutia have greatly improved ourknowledge about the Late Pleistocene environmental history of the region. One of the interesting facts aboutthe past life on the Laptev Sea shelf region is the abundance of fossil mammal bones, found over the coastallowlands and on the shelf land. More than 4000 fossil mammal bones have been collected in the Lena DeltaRegion, on the New Siberian Islands, Oyogos Lowland, Muostakh Island, and in the Anabar-Olenek Region.Our investigations were focused on the study of the ?Mammoth fauna?. All bone findings were collected andregistered. Such an approach combined with radiocarbon dating of bone collagen makes it possible to revealsome important aspects of large animal distribution on the studied area during the Late Quaternary. In totalthe taxonomic composition of the collections from the Laptev Sea Region is close to the Late Pleistocene"Mammoth" fauna from other Arctic Siberia Regions but the relations of large grazing mammal specieswere collected on various localities are different (Table 2.1).Table 2.1: Composition of the big grazing mammals of the ?Mammoth? fauna from the Laptev Sea RegionSpecies LyakhovskyIslandOyogos Yar BykovskyPeninsulaOlenekskyChannelMamontovKlykMammuthus primigenius 26% 40% 37% 42% 9%Equus caballus 25% 16% 18% 15% 30%Rangifer tarandus 18% 12% 15% 16% 39%Bison priscus 20% 22% 13% 5% 5%Ovibos moschatus 7% 3% 1% 1%Possibly, the diversity of mammal associations can be explained by local taphonomic and other randomfactors. But it can also describe the differences in paleoenvironmental conditions of the studied regions.Predominance of horse bones in some collection e.g. marks the regions with environmental conditions thatare more favourable for the horse: hard soil, think snow caver and etc. (for example, Mamontov Klyk).Other sites (e.g. Oyogos Yar, Bykovsky Peninsula, Oleneksky Channel were more favourable for the woollymammoth. The number of bison and muskox bones shows also differences in environment. Unusually highnumbers of reindeer remains from Mamontov Klyk can be explained by the presence of modern bones.The paleoenvironment had changed during Late Pleistocene too. The period of the most unfavourableenvironmental conditions for the woolly mammoth was probably between 22 ka BP and 15 ka BP, whenonly a few dates from woolly mammoth bones were obtained. It is interpreted as an extremely cold and dryperiod during the Late Pleistocene. The last ?mammoth? period from 15 ka BP to 9 ka BP is characterizedby a rapid increase of the number of dates with maximum is around 11 to 10 ka BP. It is also a periodwith the largest number of woolly mammoth dates during the Late Pleistocene. That was a period with themost favourable environmental conditions for the mammoths. Radiocarbon data on horses bone reflect noessential fluctuation during the last 50 ka BP.