This project will study shape variation in the upper ankle bones of primates of modern aspects (Euprimates) and their closest relatives. Ankle bones are commonly well-preserved in the fossil record, and their shape variation is thought to reflect the way the hind limbs are used in locomotion. The major questions being addressed in this research relate to reconstructing the sequence of changes in locomotion that occurred in the evolutionary origin and subsequent radiation of Euprimates, which will help identify patterns of ancestry through time. The project is novel in utilizing digital imagery, experimental methods, and inclusion of a comprehensive sample of extant and extinct primates. The broader impacts include support of a young investigator, training of graduate and undergraduates of typically under-represented minorities in science. The data will be made available in an online digital library.
The project will focus on generating digital models of primate astragali and calcanei using microCT and laser scanning, and optical topography. Travel is planned to visit museums where obscure and important specimens reside in order to image those specimens. Digital data will be quantified using precise linear measurements, geometric morphometrics, and new automated methods being developed by the PI and collaborators. The data will be analyzed using traditional statistical techniques as well as using new methods that take into account potential non-independence of biological data due to differential phylogenetic relatedness. With this project the PIs will evaluate several types of hypotheses: those concerning the 1) correlation between ankle shape and different modes of locomotion, 2) presence (and significance) of similiarities among certain fossil euprimates (i.e., Adapidae, Omomyidae, Eosimiidae, and definitive stem-Anthropoidea) and the rest of the euprimate radiation, and 3) evolutionary pattern and adaptive significance of shape variation in the primate astragalus and calcaneus.