Comparisons of impact flakes derived from hyena and hammerstone long bone breakage

Archaeological interpretations of the agent of bone breakage are important for reconstructing site formation. Impact flakes, or bone flakes created during bone breakage that exhibit features analogous to flakes produced during lithic reduction, are often used as evidence of hominin marrow acquisition. However, it has long been acknowledged that carnivores, mainly hyenas, also create flakes with these features, but the body of literature on these flakes is virtually non-existent. Here, we present and analyze impact flakes from hammerstone- and hyena-created assemblages and compare them to published research on hammerstone-generated flakes in experimental and archaeological contexts. Impact flake frequencies in the experimental hyena assemblage occur at half the rate as found in the hammerstone created assemblages. However, hyena created flakes do display typical impact flake features at similar rates to those found in the hammerstone-created assemblage. Finally, we compare some frequencies of impact flakes found in other experiments and at archaeological sites. Due to equifinality, impact flakes can only be used as supporting evidence rather than central evidence for understanding hominin marrow access, especially when multiple agents of bone accumulation are present.