Tanya Lewis, LiveScience Staff Writer
Date: 15 May 2013 Time: 01:00 PM ET

The oldest ape and Old World monkey fossils have been unearthed in a riverbed in Tanzania, a new study reports.

Researchers found a tooth from the newfound speciesNsungwepithecus gunnelli, the oldest member of the primate group that contains Old World monkeys (cercopithecoids). The team also found a jawbone from the newfound speciesRukwapithecus fleaglei, an early member of the hominoids, the group containing the great apes (gorillas, chimpanzees, bonobos, orangutans and humans) and lesser apes (gibbons).

The fossil remnants of these two primate species date back to 25 million years ago, filling a gap in the fossil record that reveals when apes and monkeys first diverged. [In Photos: A Game-Changing Primate Discovery]

“These discoveries are important because they offer the earliest fossil evidence for either of these primate groups,” said lead study author Nancy Stevens, an anthropologist at Ohio University in Athens, Ohio.

This jaw fragment is from the oldest known ape, the genus Rukwapithecus.
CREDIT: Nancy J. Stevens

DNA evidence has long suggested that apes and Old Worldmonkeys diverged from a common ancestor between 25 million and 30 million years ago. But until now, no fossils older than 20 million years had been found.

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