Quantitative Analysis of the Semicircular Canals of Fossil Primates: A Test of Hypotheses About Locomotion in Extinct Species

Pennsylvania State Univ University Park, University Park PA

Investigators

Abstract

Humans are primates - animals with a long history of adaptation to life in trees. As the link between animals and their environment, locomotion is one of the most important animal behaviors. Researchers have made hypotheses about the evolution of locomotion in primates by studying fossil limb bones. These ideas have been based on biomechanical analyses and comparative anatomy. Here, the researchers intend to test hypotheses regarding this association by studying a part of primate anatomy that is intimately linked to locomotion but independent from the limbs. Primate semicircular canals, which are part of the inner ear, are tuned to the demands of locomotion. Their sensitivity, surrogates for which can be measured, is increased in fast moving species and decreased in slower ones. In this research the investigators will study the details of the canals in skulls of modern species and a series of fossil primates by using the non-destructive method of ultra-high-resolution computed tomography. This X-ray technique does not harm rare museum specimens of species that are now endangered in the wild nor irreplaceable fossil skulls. The scientists shall make X-ray slices of skulls and reconstruct their details by computer. These computer images then become the raw data for the study. The details of the canals of modern species, in which the locomotion is known from field observations, will be used as a yardstick by which to infer the locomotion of the ancient ancestral and extinct species.