An ancestor's face
In 1979, a team of paleontologists on the Potwar Plateau of Pakistan uncovered part of a fossil skull that rearranged the family tree of great apes. The specimen, cataloged as GSP 15000, belonged to an extinct ape genus called Sivapithecus. Dated to the Miocene epoch, around 12.2 million years ago, the fossil presented a face strikingly similar to that of a modern orangutan (Pongo).
The discovery, published in 1982 by paleoanthropologist David Pilbeam, demonstrated a close evolutionary link between Sivapithecus and orangutans. The facial anatomy of GSP 15000 shows several shared, specialized features: tall, oval-shaped eye sockets, a narrow region between the eyes, and a dished, concave profile. These details confirmed that the orangutan lineage had diverged from the other great apes—the ancestors of gorillas, chimpanzees and humans—much earlier than previously thought. The find solidified the idea that the ancestors of orangutans evolved in Asia, not Africa.
Life in the Miocene Siwaliks
Sivapithecus fossils are found in the Siwalik Hills, a region of the outer Himalayas known for its many deposits of Neogene mammal fossils. During the Miocene, this area was not the rugged terrain it is today but a subtropical woodland and forest environment. Sivapithecus was about 1.5 meters long, comparable in size to a modern chimpanzee or orangutan.
Analysis of its anatomy shows of its lifestyle. The ape's large canine teeth and heavy molars with thick enamel suggest a diet of relatively tough foods, such as seeds, tough-rinded fruits or grasses. While its face was decidedly orangutan-like, its body was different. The shape of its wrist and body proportions indicate it spent significant time on the ground, likely moving in a pronograde (four-limbed, above-branch) fashion similar to a monkey. It also had adaptations for powerful grasping and climbing in trees, but it likely did not practice the same kind of below-branch suspension seen in modern orangutans. Three distinct species are generally recognized: S. indicus, S. sivalensis, and the much larger S. parvada.