Temporal range: 12.5–8.5Ma Miocene
|Sivapithecus indicus skull, Muséum national d'histoire naturelle, Paris|
Sivapithecus is a genus of extinct primates. Fossil remains of animals now assigned to this genus, dated from 12.5 million to 8.5 million years old in the Miocene, have been found since the 19th century in the Siwalik Hills in the Indian Subcontinent. Any one of the species in this genus may have been the ancestor to the modern orangutans.
In 1982, David Pilbeam published a description of a significant fossil find — a large part of the face and jaw of a Sivapithecus. The specimen bore many similarities to the orangutan skull and strengthened the theory (previously suggested by others) that Sivapithecus was closely related to orangutans.
Sivapithecus was about 1.5 metres (4.9 ft) in body length, similar in size to a modern orangutan. In most respects, it would have resembled a chimpanzee, but its face was closer to that of an orangutan. The shape of its wrists and general body proportions suggest that it may have spent a significant amount of its time on the ground, as well as in trees. It had large canine teeth, and heavy molars, suggesting a diet of relatively tough food, such as seeds and savannah grasses.
Currently three species are generally recognized:
- Sivapithecus indicus fossils date from about 12.5 million to 10.5 million years ago.
- Sivapithecus sivalensis lived from 9.5 million to 8.5 million years ago. It was found at the Pothowar plateau in Pakistan as well as in parts of India. The animal was about the size of a chimpanzee but had the facial morphology of an orangutan; it ate soft fruit (detected in the toothwear pattern) and was probably mainly arboreal.
- Sivapithecus parvada described in 1988, this species is significantly larger and dated to about 10 million years ago.
Siwalik specimens once assigned to the genus Ramapithecus are now considered by most researchers to belong to one or more species of Sivapithecus. Ramapithecus is no longer regarded as a likely ancestor of humans.
The first incomplete specimens of Ramapithecus were found in Nepal on the bank of Tinau River western part of the country in 1932. The finder (G. Edward Lewis) claimed that the jaw was more like a human's than any other fossil ape then known. In the 1960s this claim was revived. At that time, it was believed that the ancestors of humans had diverged from other apes 14 million years ago. Biochemical studies upset this view, suggesting that there was an early split between orangutan ancestors and the common ancestors of chimps, gorillas and humans.
Meanwhile, more complete specimens of Ramapithecus were found in 1975 and 1976, which showed that it was less human-like than had been thought. It began to look more and more like Sivapithecus - meaning that the older name must take priority. It could be that Ramapithecus was just the female form of Sivapithecus. They were definitely members of the same genus. It is also likely that they were already separate from the common ancestor of chimps, gorillas and humans, which may be represented by the prehistoric great ape, Nakalipithecus nakayamai.
- History of hominoid taxonomy
- Human evolutionary genetics
- Gibbons, Ann (2006). The first human. Doubleday. ISBN 978-0-385-51226-8.
- Kelley, Jay (2002). "The hominoid radiation in Asia". In Hartwig, W. The Primate Fossil Record. Cambridge University Press. pp. 369–384. ISBN 978-0-521-66315-1.
- Palmer, Douglas (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. pp. 292–293. ISBN 1-84028-152-9.
- Szalay, Frederick S.; Delson, Eric (1979). Evolutionary History of the Primates. New York: Academic Press.
- Photo of the 1982 Sivapithecus skull ("GSP 15000")
- Ramapithecus. (2011). In Encyclopædia Britannica. Retrieved from http://www.britannica.com/EBchecked/topic/490510/Ramapithecus
- Sivapithecus. (2011). In Encyclopædia Britannica. Retrieved from http://www.britannica.com/EBchecked/topic/546964/Sivapithecus