Permafrost terrestrial deposits contain rich different records mirroring environmental changes in the Laptev Sea region during Late Pleistocene Holocene. Mammal remains of the ―Mammoth fauna‖ are the most common artifacts in the paleontological collection of the Lena Delta Reserve museum. The collection includes single bones, fragments of skeletons, bones with soft tissues and hair of Late Pleistocene and Holocene animals. In contradiction to the other collections our one is unique by 100% registration of all bone findings. To reconstruct the composition of animal populations and their changes on the Laptev shelf land during the Late Pleistocene and Holocene an extensive program of 14C bone collagen dating was conducted. Unique paleontological material (more 4000 fossil bones) had been collecting during our investigations in the frame of the Russian-German Cooperation ―Laptev Sea System‖ (1998i2008). It allows us to reconstruct terrestrial ecosystems and their changes.Material was collected from four regions: Lena Delta Region, the New Siberian Islands, Olenek-Anabar interrivers and south-west coast of the East Siberian Sea.Lena Delta Region. Collection contains more than 900 samples. At the most part of material was collected at Bykovsky Peninsula (Mamontovay Khayata location). In general, taxonomic composition of the collection is rather typical for ―Mammoth‖ fauna of northeast Siberia. The woolly mammoth, horse, reindeer and bison dominate. Radiocarbon dates of bones confirm geological conclusion sedimentation in the region was continual approximately the last 60 ka BP (Schirrmeister et al., 2002). The age distribution of bones from Bykovsky Peninsula is not homogeneous. The largest amount of dates belongs to the period from 36 to 20.5 ka BP. The other dates concentrate in the period 14.513.1 ka BP. There are also two periods with only few dates: 44.536 and 23.814.5 ka BP. Such an uneven data distribution can be interpreted in two different ways. Firstly, it depends on the geological situation and secondly, on the number of animals in the region. Probably the periods with large amount of date are the favorable environmental conditions. Holocene data of horse and musk ox also prove that these animals lived during the second part of the Holocene at this region.The different quality of the outcrop exposition was reflected in the number of collected bones and the data distribution. The lower part of the outcrop was badly exposed. This explains the small number of bones dated to more than 36 ka BP. The lack of mammoth dates in the period 20.514.5 ka BP in the Bykovsky collection reflects a relative decrease in their numbers, and probably less favorable environmental condition for mammoth life (Kuznetsova et al., 2001). Reindeer bones were dated in this time interval.Principal four species of Mammoth fauna are the same in collections from other localities of the Lena Delta Region but their percentage is different. Collection from Kurungnakh Island contains near 50% of woolly mammoth bones while only 19% of mammoth bones were collected from outcrop of Khardang Islands. Distinguishing feature of Lena Delta collection is high percentage of hares bones (9.2% - Bykovsky Peninsula, 7.4% - Kurungnakh. Island, 23.8% - Khardang Island).The New Siberian Islands. Collection contains more than 1200 bones. Main part was collected at south coast of Bolshoy Lyakhovsky Island (Zimive section). Species composition is typical for the Mammoth fauna but number of woolly mammoth and horse bones are very close 25.8% - woolly mammoth and 25% - horse bones. The largest number of dated bones falls within the period between 44 and 32 ka BP, predominantly between 44 and 20 ka BP with no large temporal gaps. It was the period of the favorable environmental conditions (Andreev et al., 2004). Most of the infinite dated bones probably originate from the lower parts of the outcrops, which are older than 45 ka BP.At the Zimove section was identified gap of sedimentation between 30 and 12 ka BP, but we found bones with dates of this interval Mammuthus primigenius, Coelodonta antiquitatis, Equus sp. and Ovibos moschatus. The youngest mammoth bone is 14C dated to 12.03±0.06 ka BP and the youngest horse bone to 2.2±0.05 ka BP. This horse bone date is currently the youngest horse age from the Arctic and supports the results of our studies (Schirrmeister et al. 2002) suggesting that horses lived in the east Siberian Arctic during the late Holocene.A single find of a saiga bone was dated to 46.79±1.18 ka BP. This antelope is a good indicator of typical cold steppe conditions - firm and dry soil surface in summer and very thin snow cover in winter.Finds from other New Siberian Islands are not abundant. The most interesting samples from these locations are two Late Holocene bones from Kotelny Island: 3.0±0.045 and 2.8±0.12 ka BP. It reveals palaeoenvironmental conditions, which are suitable for horses.