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International audience; The issue of using chariots in the culture of the Bronze Age population of Central Mongolia was studied on the materials of archaeological sites from one micro-region in the Khoid Tamir river valley, drawing primarily from images on rocks and stone stelae. Systematic analysis of rock art styles and burial traditions based on radiocarbon dates of burials and ritual deposits of bone enabled us to distinguish two periods of chariots’ usage here: 1)prior to ca. 1200 BCE, in the Sagsai culture; 2) after ca. 1200 BCE, with the DSK culture. The study of the chariot image, its parts, and attributes of charioteers in visual compositions allowed us to reconstruct its role in the life and beliefs of herders. On deer stones, a charioteer’s attributes (belt plates with a pair of hooks) are always adjacent to individual sets of weapons, which indicates the use of chariots by warriors. At the same time, images of the chariot and chariot draught teams on rocks and stelae of both periods appear connected with burial rites and ideas about the posthumous path to the afterlife. An important role in this transition was performed by a male deer, which led the deceased and his horses to the sky. Veneration of the deer image increased significantly during the second period, which is reflected in the composition of deer stones of the Mongol-Transbaikal type.

International audience; This study introduces the engravings on a mammoth tusk from the lower reaches of the Tom River in WestSiberia. The tusk was found in 1988 during construction works and was later transferred to the Tomsk StateUniversity, but it remained almost unknown to specialists until now. Radiocarbon dating by AMS reported theage of the tusk as 13,100–13,005 Сal BP (95% confidence level). The surface of the tusk is engraved with imagesof two-humped camels arranged in two pairs. In addition, arrows and wounds within the contours of the animalscan be seen. The comparative analysis of the stylistic features of the camel figures shows that they correspond tothe age of the tusk itself, making them, at present, the oldest camel images in Asia. The discovery of the en-gravings in this region is consistent with the theory of mobile population groups moving to western Siberia fromthe periglacial steppe to the south in the Late Upper Paleolithic.

11 pages; International audience; The present study proposes a workflow to extract from orthomosaics the enormous amount of dry stones used by past societies to construct funeral complexes in the Mongolian steppes. Several different machine learning algorithms for binary pixel classification (i.e. stone vs non-stone) were evaluated. Input features were extracted from high-resolution orthomosaics and digital elevation models (both derived from aerial imaging). Comparative analysis used two colour spaces (RGB and HSV), texture features (contrast, homogeneity and entropy raster maps), and the topographic position index, combined with nine supervised learning algorithms (nearest centroid, naive Bayes, k-nearest neighbours, logistic regression, linear and quadratic discriminant analyses, support vector machine, random forest, and artificial neural network). When features are processed together, excellent output maps, very close to or outperforming current standards in archaeology, are observed for almost all classifiers. The size of the training set can be drastically reduced (to ca. 300 samples) by majority voting, while maintaining performance at the highest level (about 99.5% for all performance scores). Note, however, that if the training set is inadequate or not fully representative, the classification results are poor. That said, the methods applied and tested here are extremely rapid. Extensive mapping, which would have been difficult with traditional, manual, or semi-automatic delineation of stones using a vector graphics editor, now becomes possible. This workflow generally surpasses pedestrian surveys using differential GPS or a total station.

Rock art studies are facing major technical challenges for extensive documentation. Nowadays, recording is essentially obtained from time-consuming tracing and rubbing, techniques that also require a high level of expertise. Recent advances in 3D modelling of natural objects and computational treatment of the modelled surfaces may provide an alternative, and reduce the current documentation bottleneck. The aim of this study is to examine the extent to which such treatments can be applied. The case study presented here concerns the famous deer stones erected by ancient Mongolian nomad populations. The 3D acquisition workflow is based on structure-from-motion, a versatile photogrammetric technique, well adapted to various field conditions. From the 3D geometry of objects of interest, elevation raster maps are produced by projection on four sides of the stela. These digital elevation models are then tested using algorithms based on differential geometry, sky visibility and local morphology, the general principles of which are briefly exposed. All these approaches may be appropriate with essentially planar surfaces. However, in the case of irregular carved surfaces, such as those of deer stones, the most efficient algorithm appears to be positive openness. In favourable cases, the incisions can be automatically delineated, facilitating the final drawing. Results obtained at the end of the process are comparable to the best drawings available in the literature, and can also include archaeological information about rock surface conditions. The procedure considerably accelerates the workflow in comparison with traditional techniques, reduces the level of expertise required, and provides 3D models, which can easily be shared, or further analysed by morphometric methods, for instance. (C) 2018 Elsevier Masson SAS. All rights reserved.