Primate skeletons. Historical artwork of various primate skeletons, showing their evolutionary similarity. The skeletons are (from left to right): an orangutan (Pongo pygmaeus), a chimpanzee (Pan troglodytes), a gorilla (Gorilla gorilla) and man (Homo sapiens). All primates display certain physical characteristics such as opposable thumbs, big toes and frontaly-directed eyes with binocular vision. Man has a larger skull capacity than other primates as well as shorter arms and smaller feet and hands. The other primates are essentially four-footed. The gorilla is by far the most physically powerful primate, with a bigger frame and larger pelvis.