Alejandra Ortiz Rivarola

ALEJANDRA ORTIZ RIVAROLA, Arizona State University, Tempe, Arizona, was awarded fundin in October 2016 to aid research on ‘A Comprehensive Analysis of the Deciduous Dentition of Plio-Pleistocene Hominins.’ Dental features figure prominently in species diagnoses, dietary inferences, and phylogenetic reconstructions of hominoids (humans, apes, and their fossil relatives). However, this work has focused almost exclusively on the permanent dentition. Comparatively little research has been devoted to the characterization of the different anatomical aspects of primary (deciduous) teeth. To fill these gaps, a large-scale study conducted since 2016 examines the internal and external dental anatomy to address key aspects of human origins, including species diversity, patterns of growth and development, and life history strategies by means of deciduous teeth. Collected data include more than 450 high-resolution scans, representing at least 11 species of extinct and extant hominoids. While several aspects of the project are still in progress, initial analysis of an important feature of dental tissue anatomy ‘enamel thickness’ reveals that, unlike the pattern found in permanent molars, orangutans do not stand out as having relatively thick-enameled teeth compared to chimpanzees and gorillas. In contrast, humans have a significantly thicker enamel in their dentitions than both Asian and African great apes. By documenting deciduous enamel and its distribution, this project will also provide insights into the factors influencing rates of dental wear and their utility in life history reconstructions.