Oreopithecus

Oreopithecus (from the Greek ὄρος, oros and πίθηκος, pithekos, meaning 'hill-ape') is an extinct genus of hominoid primate from the Miocene epoch whose fossils have been found in today's Tuscany and Sardinia in Italy. It existed 9 to 7 million years ago in the Tusco-Sardinian area when this region was an isolated island in a chain of islands stretching from central Europe to northern Africa in what was becoming the Mediterranean Sea. Oreopithecus was one of a large number of European immigrants that settled this area in the Vallesian–Turolian transition and one of few hominoids, together with Sivapithecus in Asia, to survive the so-called Vallesian Crisis. To date, dozens of individuals have been discovered at the Tuscan localities of Montebamboli, Montemassi, Casteani, Ribolla, and, most notably, in the fossil-rich lignite mine in the Baccinello Basin, making it one of the best-represented fossil apes. Oreopithecus bambolii was first described by French paleontologist Paul Gervais in 1872. In the 1950s, Swiss paleontologist Johannes Hürzeler discovered a complete skeleton in Baccinello and claimed it was a true hominin—based on its short jaws and reduced canines, at the time considered diagnostic of the hominin family; and claimed it was a biped—because the short pelvis was closer to those of hominins than those of chimpanzees and gorillas. Hominin affinities claimed for Oreopithecus remained controversial for decades until new analyses in the 1990s reasserted that Oreopithecus was directly related to Dryopithecus. The peculiar cranial and dental features were explained as consequences of insular isolation. This new evidence confirmed that Oreopithecus was bipedal but also revealed that its peculiar form of bipedalism was much different from that of Australopithecus. The hallux formed a 100° angle with the other toes, which enabled the foot to act as a tripod in erect posture, but prevented Oreopithecus from developing a fast bipedal stride. When a land bridge broke the isolation of the Tusco-Sardinian area 6.5 million years ago, large predators such as Machairodus and Metailurus were present among the new generation of European immigrants and Oreopithecus faced quick extinction together with other endemic genera. Known as the 'enigmatic hominoid', Oreopithecus can dramatically rewrite the palaeontological map depending on if it is a descendant from the European ape Dryopithecus or some African anthropoid. Some have suggested the unique locomotory behavior of Oreopithecus requires a revision of the current consensus on the timing of bipedality in human developmental history, but there is limited agreement on this point among paleontologists. Simons (1960) considered Oreopithecus closely related to the early Oligocene Apidium, a small arboreal proto-ape that lived nearly 34 million years ago in Egypt. It shows strong links to modern apes in its postcranium and, in this respect, it is the most modern Miocene ape below the neck with closest similarities to the postcranial elements of Dryopithecus, but its dentition is adapted to a leafy diet and a close link is uncertain. Others claim it to be either the sister taxon to Cercopithecoidea or an even direct human ancestor, but it is usually placed in its own subfamily within Hominidae. It could instead be added to the same subfamily as Dryopithecus, perhaps as a distinct tribe (Oreopithecini). A cladistic analysis of Nyanzapithecus alesi recovers Oreopithecus as a member of the proconsulid subfamily Nyanzapithecinae. Oreopithecus bambolii is estimated to have weighed 30–35 kg (66–77 lb). It possessed a relatively short snout, elevated nasal bones, small and globular neurocranium, vertical orbital plane, and gracile facial bones. The shearing crests on its molars suggest a diet specializing in plant leaves. The very robust lower face, with a large attachment surface for the masseter muscle and a sagittal crest for attachment of the temporal muscle, indicates a heavy masticatory apparatus. Its teeth were small relative to body size. The lack of a diastema (gap) between the second incisor and first premolar of the mandible indicates that Oreopithecus had canines of size comparable to the rest of its dentition. In many primates, small canines correlate with reduced inter-male competition for access to mates and less sexual dimorphism.