Biface Trimming Elements as Indicators of Tool Rejuvenation Intensity: The Case of Sibiryachikha, Altai

Biface trimming elements represent an important diagnostic source of information for studying various stages of bifacial tool production. In Middle Paleolithic assemblages, they often constitute a significant portion of the sample, making them particularly useful for identifying specific technological operations such as primary reduction and shaping of bifacial preforms, edge formation and retouching, working edge rejuvenation, and modification of bifacial tools. Here, we present the findings of a systematic typological analysis of biface trimming elements. Through a comprehensive metric and morphological analysis of experimental collections and Middle Paleolithic assemblages representing the Sibiryachikha industries of the Altai, we have developed a refined typology of technical spalls with regard to local archaeological specificity. Our analysis revealed no statistically significant differences either between parameters of type 0 and type 1 spalls or between those of type 2 and type 3, suggesting that these groups correspond to specific technological operations. In contrast, type 4 and type 5 technical spalls, which indicate onsite tool modification, show significant metric differences. The results demonstrate functional and technological distinctions between the assemblages. Materials from Chagyrskaya Cave are especially indicative of primary edge retouching and tool shaping, while the Okladnikov Cave industry mostly evidences maintenance and modification of bifacial tools.