for National Geographic News
Researchers have unearthed a fossil ape that dates back 10 to 13.5 million years and could be an ancestor to the orangutan. The species, Lufengpithecus chiangmuanensis, was found in Thailand. It's the first fossil ape that has been discovered in the region where orangutans live today.
The fossils were found during a six-year survey of a coal mine in northern Thailand. They consist of 22 isolated teeth from both the upper and lower jaws of several apes.
"It's the first time an ancestor of an extant ape has been identified in the old fossil record [more than 10 million years]," said Jean-Jacques Jaeger, professor of paleontology at France's University of Montpellier, whose research team made the discovery.
Apes have a poor fossil record. Anthropologists hope the new find will lead to additional discoveries, which could help piece together the evolutionary puzzle of apes and even shed new light on human evolution.
Modern orangutans hail from the Pleistocene era, 2 million to 100,000 years ago. Their geographic distribution once included much of Southeast Asia. However, they became extinct from many areas because of deforestation and hunting. Today, the orangutan can only be found in Borneo and Sumatra.
The orangutan is the only great ape with a fossil record. (Strangely, no African fossil has ever been found that is related to chimpanzees or gorillas.) But determining the ancestry of the orangutan has proven extremely difficult.
Previous discoveries of the orangutan's extinct relatives have been dismissed as possible ancestors. Sivapithecus, which lived in Pakistan 8 to 12.8 million years ago, had a face like an orangutan but its teeth and lower jaw are different. Its skeleton shows it to have walked on all fours, like a baboon. Lufengpithecus, which lived in southern China 8 to 9 million years ago, had a dental structure with no analog among apes living today.
"The new Thai fossil ape shares many dental characters with that Lufengpithecus, but it has a less specialized anterior dentition, similar to that of orangutan," said Jaeger. "It appears to be the best candidate to represent the ancestor or a species closely related to the ancestor of orangutan."
Some experts warn against establishing ancestry by comparing teeth because animals can have similar dental structures and still be very different. The new fossil could be a close relative of the orangutan, but perhaps not an ancestor.
Researchers don't know how the different relatives were related to each other. "Maybe they evolved in another place, like Arabia for instance, which is not well documented," said Jaeger.
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