Dryopithecus

Dryopithecus was a genus of apes that is known from from Eastern Africa into Eurasia. It lived during the Upper Miocene period, from 12 to 9 million years ago, and probably includes the common ancestor of the lesser apes (gibbons and siamangs) and the great apes.

The first species of Dryopithecus discovered was found in France in 1856. The five-cusp and fissure pattern of its molar teeth, known as the Y-5 arrangement, is typical of the dryopithecids and of hominoids in general. Other dryopithecids have been found in Hungary, Spain, and China.

Description
Dryopithecus was about 60 cm in body length, and more closely resembled a monkey than a modern ape. The structure of its limbs and wrists show that it walked in a similar way to modern chimpanzees, but that it used the flat of its hands, like a monkey, rather than knuckle-walking, like modern apes. Its face exhibited klinorhynchy, with its face being tilted downwards in profile.

It likely spent most of its life in trees, and was probably a brachiator, similar to modern orangutans and gibbons. Its molars had relatively little enamel, suggesting that it ate soft leaves and fruit, an ideal food for a tree-dwelling animal.

Morphology
Dryopithecus fontani had a dental formula of 2:1:2:3 on both the upper and lower jaw. The incisors of this species were relatively narrow and less spatulate compared to other genera such as Proconsul. The upper molars of this species had a partly developed lingual cingulum. Dryopithecus fontani had relatively long upper premolars and relatively broad lower premolars. The lower molars had the Y5 pattern, which is also called the Dryopithecus pattern. The cheek had a thin layer of enamel on them and there were low, rounded cusps. This species had gracile canines and a short premaxilla. The mandible of Dryopithecus fontani had an inferior transverse torus but lacked a superior transverse torus. The forelimbs of this species had a reduced olecranon process, a deep humeral trochlea, and the loss of the entepicondylar foramen. Dryopithecus fontani had an average body mass of around 35.0 kilograms.