Rodent gnawing over fresh, dry and thermo altered bones: an experimental study with archaeological implications at El Mirador Cave (Atapuerca, Spain)

Rodents gnaw bones to wear down their upper and lower incisors, which grow continuously. These gnawing marks are conspicuous and have long been identified in the fossil record. Archaeological taphonomy studies link modifications made by rodents to weathered and dried bones, while forensic taphonomy indicate that rodents also act on fresh corpses, consuming flesh and other tissues as well as fresh bones. Although these two approaches are complementary, there is a lack of information on how rodents modify bones in states other than dry or fresh. This experimental study aims to fill this gap in the research, describing modifications left by rodents (Mus musculus) to fresh, boiled, carbonised, calcined, and dry bones. Our results indicate that rodents modify bones regardless of their state, and that the most intense gnawing occurs on bones containing fat. During the study, the pedestalling phenomena emerged as a characteristic modification produced only on fresh and boiled samples. We applied our results to the study of the human remains from El Mirador Cave (Atapuerca, Spain) and identified pedestalling for the first time in the archaeological record. This modification may have been favoured by the presence of fatty bones laying exposed on the surface of the site.