A wide variety of biological evidence, ranging from fossils to DNA, indicates that living monkeys, apes, and humans share a common ancestry that excludes all other organisms, including other primates. Known collectively as anthropoids, these “higher” primates differ from their living prosimian relatives (lemurs, lorises, bushbabies, and tarsiers) in many key features of anatomy, physiology, and behavior. Until recently, the fossil record has only weakly illuminated the wide gulf separating living anthropoids and prosimians.

As a result, one of the largest remaining gaps in knowledge of primate evolution concerns the origin and early diversification of anthropoids. Novel paleontological discoveries are finally beginning to resolve the long-standing issue of exactly how anthropoids fit on the primate evolutionary tree. Newly discovered fossils are also leading to unexpected insights regarding the paleobiology of the earliest anthropoids. These new findings are threatening to overturn an earlier consensus about when and where anthropoids originated.