Ontogenetic dental patterns in Pleistocene hyenas (Crocuta crocuta Erxleben, 1777) and their palaeobiological implications

During the Pleistocene, humans and hyenas co-occurred at sites, which included cavities and rock-shelters, accumulating bone assemblages attributable to both the hominids and carnivores. Studies of these co-occurrences have given rise to much debate about the relationships established, suggesting that an interpretation of the nature of the biological activities conducted could be useful for understanding predator behaviour and for reconstructing the palaeobiology of these sites. Dentition analysis is an effective technique, employed in zooarchaeological studies, to interpret the use of shared spaces. However, to date, tooth development studies aimed at determining the age of an archaeological assemblage are scarce. At Pleistocene sites, isolated hyena teeth are typically the most common elements. In Terrasses de la Riera dels Canyars (Gava, Barcelona, NE Iberian Peninsula), a fluvial deposit dated at 39.6 ka cal Before the Present (BP) (Heinrich Stadial 4) with a sizeable record of large mammals and just a few lithic tools (Aurignacian), cranial and postcranial hyena bones are remarkably well-preserved, exhibiting all their ontogenetic stages. Here, we conduct an analysis of dental ontogeny (employing X-ray imaging techniques), wear and replacement, and propose four age categories for hyena juveniles and one category for subadults based on complete (or almost complete) mandibles and maxillae. By employing these five, more detailed, age clusters, the minimum number of individuals is found to increase. Application of the method to the site's isolated teeth confirms its validity. The hyena mortality pattern recorded at Canyars, together with descriptions of extant hyena behaviour, indicate that the site was used primarily as a communal den.