Fig. 2: Metric comparison of the breadth of flake removal scars relative to the dimension of the bone tools, and the size and weight of the notched bone tools compared with the lithic artefacts found in the same assemblage.

a–d, Scatterplot of the breadth for the most invasive (a,b) and all (c,d) removal scars present on the FLK T69 Complex bone tools and on bone fragments produced during experimental (Exp) bone fracturing to expose the marrow of horse⁹ and elephant⁴ limb bones compared with the cortical thickness (a,c) and the shaft fragment size index (b,d). The maximum breadth of the largest flake removal scars on the bone tools and on fragments of limb bones fractured for marrow extraction demonstrates that the former are considerably larger irrespective of the cortical thickness or the shaft fragment size index. The difference in trend observed when considering all flake removal scars is probably due to the production of numerous small contiguous retouch flakes to shape the bone tool edges. e,f, Length and width (e) and length and weight (f) comparisons between the T69 Complex bone tools and the lithic assemblage found in the same horizon are shown. Bone tools are more elongated than the LCT, but their current weight falls within the range of variation recorded for the LCT found at the T69 Complex. Trend lines and grey bands indicate the linear regression method and the 90% confidence interval, respectively (a–d), and the ellipses denote the 90% confidence interval (e,f).