Researchers found a tooth from the newfound species Nsungwepithecus gunnelli, the oldest member of the primate group that contains Old World monkeys (cercopithecoids). The team also found a jawbone from the newfound species Rukwapithecus 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.
DNA evidence has long suggested that apes and Old World monkeys 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.
The age of the new specimens extends the origin of apes and Old World monkeys into the Oligocene Epoch, which lasted from 34 million to 23 million years ago. Previously, only three primate species were known from the late Oligocene globally, Stevens said.
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