Geometric morphometrics reveal relationship between cut-mark morphology and cutting tools

The analysis of bone-surface modifications (BSM), such as butchering marks, is necessary to better understand how the exploitation of animal resources by past hominins influenced their biological and cultural evolution. In this paper, we try to quantify to what extent the depth of the cut marks influences the shape of their cross sections. This is of crucial importance for a valid interpretation of the shape data collected on archaeological BSMs. Two groups of slicing cut-mark cross sections were experimentally produced with two flint burins on a defleshed cattle innominate, and a set of butchering marks were produced with an unretouched flint flake. These were analysed by means of 3D microscopy and geometric morphometrics. The resulting sets of striae show different depths and different cross-sectional shapes. Shallower cross sections display less steep walls and, consequently, a wider opening angle. When the characteristics of the burin cutting edges were investigated, it was clear that the difference in shape between the two groups of striations was probably a function of the way in which the tool penetrated the bone. These results are taphonomically relevant since similar differences in cross-sectional shapes have been found in marks produced with different tools.