A new protocol to differentiate trampling marks from butchery cut marks

Microscopic signatures have previously been used to emphasize the similarities of butchery and trampling marks. The experimental background applied to differentiate both types of marks has been rather limited and authors have sometimes reached conflicting conclusions. This is partly due to methodological reasons: some authors have used very high magnification to examine microscopic features, whereas others have relied on more reduced magnification. Likewise, some experiments have exposed bones to trampling for reduced periods (minutes) whereas others have used longer time periods (hours). The present study stresses that the use of a scanning electronic microscope is not practical for identifying the impact of butchery and trampling marks in complete bone assemblages. It also emphasizes that previous studies have not addressed all the possible variables that could potentially be used to discriminate these marks, nor have they quantified the morphological patterns of each type of mark. Here we present a multivariate analysis of more than a dozen variables and show that butchery and trampling marks have very distinctive microscopic morphology. We advocate the use of a low magnification approach (≤40×), which can enable the analysis of complete assemblages using either hand lenses or binocular lenses. We also show the morphological criteria that differentiate butchery cut marks made with simple and retouched tools. We show that whereas complete discrimination of marks is impossible due to some degree of overlap, the list of criteria derived through multivariate analyses can be confidently used to correctly differentiate butchery and trampling marks in more than 90% of cases.