The fossils were found in a lignite (a type of coal) mine, located in what used to be a swampy and shallow lake deposit. The rocks containing the teeth also hold fossil plants of the Syzygium tree, which produce edible fruits called "champoo" that are still available in southeast Asian fruit markets.
Jaeger believes the fossil ape came to collect these fruits at the lake. Some apes were killed by predators such as crocodiles when they went to drink out of the lake. Others may have been killed by tigers and panthers in the forest.
Syzygium is affiliated with existing East African plant communities, suggesting that a tropical forest belt extended from East Africa to South Asia around 10 to 14 million years ago. "This belt would have allowed free circulation in both directions, at least for tropical forest dwellers," said Jaeger.
Even if the fossil ape is the ancestor to the orangutan, it didn't look like the modern ape. "Evolution basically redesigned apes," said David Pilbeam, professor of anthropology at Harvard University. "Just about every feature of living apestheir torsos, internal organs, ligaments, and jointsis different from their more primitive kin."
The fossil ape probably weighed about 70 pounds (26 kilograms). No known fossil ape is adapted for life in the trees, and Jaeger believes orangutans may therefore be descended from a ground-dweller.
Man and Ape
The discovery could shed new light on the common ancestry of apes and humans. "Very little is known about human evolution in the period 14 to 4 million years ago, during which time the human line split from its more ape-like ancestors and relatives," said Pilbeam.
An international team of medical researchers and anthropologists recently determined that a gene mutation found only in humans and not in our evolutionary cousins, the apes, occurred more than two million years ago, just prior to human brain expansion but after human ancestors stood upright.
"The evolution of early hominines [the ancestors of modern humans] cannot be fully understood as long as the history of extant apes is not clearly situated in time and space," said Jaeger.
A summary of Jaeger's research appears in the current issue of the science journal Nature.
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