Paper No. 17-15
Presentation Time: 11:30 AM
INFERRING SOCIALITY IN EXTINCT CARNIVORANS FROM DENTAL MICROWEAR TEXTURES: LESSONS FROM BONE CONSUMPTION AND PACK STATUS IN MODERN YELLOWSTONE WOLVES
Cooperative hunting has been observed in at least three families of carnivorans (Candiae, Felidae, and Hyaenidae), which use this tactic to capture larger prey than could be caught alone. The prevalence of cooperative hunting by extinct carnivorans, such as dire wolves and the saber-toothed cat Smilodon, remains debated, with evidence cited from skeletal pathologies, taphonomy (e.g., mass death assemblages), and phylogenetics. Alternate evidence might come from how food is shared within a group based on status, as determined by relatedness, breeding availability, and sex. Higher status may grant individuals access to the more desirable carcass parts, whereas subordinates may be given less desirable gristle and bones. Such discrimination is observed in modern gray wolves, but requires a proxy to apply to the fossil record. Dental microwear texture analysis (DMTA) quantifies microscopic tooth textures in 3D and is a valid proxy of durophagy (e.g., bone consumption). We used DMTA on Yellowstone (YNP) wolves, which are an ideal test population due to extensive field observation of pack/individual behavior, and thorough post-mortem skull collection since reintroduction. Further, stable isotope analysis shows that their most common prey are elk, which are large enough to be shared by a pack. We hypothesized that dominant wolves eat less bone than subordinate pack-mates and that that this difference would be evident from DMTA data. Identifying similar patterns via DMTA in fossils could be used to infer cooperative hunting in extinct carnivorans. Here, we scanned the 2nd lower molar from 33 wolves of 7 packs and dispersers, 15 female and 18 male, that died from 2000-10. DMTA data were not significantly correlated with rank, nor date of death, possibly due to high prey availability since reintroduction. However, we found females had consumed significantly tougher (higher anisotropy) food (e.g., flesh) than males. Mean complexity values were not significantly different between sexes, but males possess significantly greater variance of complexity, suggesting more variable bone processing. Sex is one factor of an individual’s rank, but these results suggest that sex might be a better predictor of durophagy than rank, potentially limiting the applicability of microwear as a proxy for social behavior in extinct carnivorans.