Flake morphology and maintenance of core flaking surface convexity in lithic industries of late middle and early stages of Upper Paleolithic in Southern Siberia and Central Asia

This research reveals possible diachronic tendencies and varieties of methods designed to maintain longitudinal and transverse convexity of core flaking surfaces based on comparison of metric and morphological parameters of laminar spalls. The study collections derive from various regions of southern Siberia and Central Asia, where assemblages of Late Middle Paleolithic and early stages of Upper Paleolithic are widespread. Blade oblongness (the ratio of length to width) and cross-section height reflect metric parameters. An additional criterion was examined: the system of guiding ridges that determine the degree of flake transverse convexity. We took into account the initial shape of stone raw material: rectangular nodule, rounded pebble, or a combination thereof. We used lithic assemblages of the late stages of Middle Paleolithic, initial stages of Upper Paleolithic, and Early Upper Paleolithic of southern Siberia and Central Asia. We reconstructed technical approaches designed to establish and maintain core flaking surface convexity in the form of subprismatic knapping present in the industries of the initial stages of Early Upper Paleolithic in their complete and typical form. Lithic industries of the initial stages of PUP and the final stages of Middle Paleolithic exhibit the most significant differences in spall morphology. We conclude that flaking approaches characteristic of the early stages of PUP were maintained through the late PUP and into the beginning of the Early Upper Paleolithic, even if spall morphology does not distinguish the boundary parameters of the earlier industries with elongated blades and deep cross-sections.