New osteological criteria for the identification of domestic horses, donkeys and their hybrids in archaeological contexts

The identification of domestic equid remains is a recurrent issue and an intense subject of discussion in zooarchaeological studies. Indeed, despite historical sources describing the key role of equids in numerous past societies, their accurate identification on archaeological sites is still problematic, and only few methods have been developed in order to distinguish the bones of horses, donkeys and their hybrids. Moreover, some of the extant published visual macroscopic criteria are considered as possibly unreliable, partly because of the absence of preliminary test on a large sample of modern specimens. In this work, we try to solve these issues by testing a set of macroscopic visual criteria, collected in the literature or newly described, on a comparative sample of 107 modern skeletons of domestic equids. We quantified the reliability of these criteria and found evidence of 26 osteological characters allowing for the identification of between 90% and 100% of the horses and donkeys of our comparative sample. A method to identify the complete or sub-complete skeletons of hybrids is also proposed using combinations of characters observed on several bones. Finally, the defined osteological criteria are observed on a set of archaeological skeletons, coming from antique to modern sites, in order to demonstrate the applicability of our approach to archaeological remains. The use of our methodology on zooarchaeological samples could allow for a better assessment of the presence of donkeys and hybrids in archaeological sites, and thus, could help improve the knowledge of their respective importance and use by human past societies