Sexing isolated hominoid canines with special reference to the Middle Miocene specimens from Paşalar, Turkey

Species recognition within fossil hominoids is often complicated by high levels of sexual dimorphism; high levels of variation within fossil samples may indicate the presence of more than one species, or the presence of a single sexually dimorphic species. Questions of species recognition are addressed in this study by controlling for the sex of fossil specimens, specifically isolated canines. The present study examines the question of species recognition for the Middle Miocene site of Paşalar, Turkey. Measurements taken on known sex specimens of Pan troglodytes, Pongo pygmaeus, and Gorilla gorilla are used to calculate indices of canine shape. A stepwise discrimination procedure is used to select variables that are then employed to derive a discriminant function for assigning sex to isolated canines, regardless of the species to which the specimen belongs. The resulting function is then used to assign sex to isolated maxillary and mandibular canines from Paşalar. Results of this analysis reveal two discrete size groupings within the mandibular female canines at Paşalar. The discontinuity between the small and large female canines indicates that these specimens represent the norms of two different species, rather than the maximum and minimum size range of a highly variable species. Results support the hypothesis of two hominoid species at Paşalar previously suggested by Martin & Andrews (1993).