Scientists have unearthed two ancient fossils that could better help explain how the split between apes and monkeys occurred. The discoveries, dating back 25 million years ago, are the oldest of their kind.
Apes and monkeys can be easily confused, but the two groups are actually different and believed to have diverged from a common ancestor between 34 and 23 million years ago. Apes include chimpanzees, gorillas, and rather popular human, while monkeys (or cercopithecoids) consist of species like baboons and macaques.
"These discoveries are important because they offer the earliest fossil evidence for either of these primate groups," said Nancy Stevens, lead author of the study published in the journal Nature and an anthropologist at Ohio University. "These finds can help us to further refine hypotheses about the timing of diversification of major primate groups."
Both the fossils were identified as belonging to their respective ape-monkey groups through dental identification. The new hominid was named Rukwapithecus fleaglei, and the new cercopithecoid was dubbed Nsungwepithecus gunnelli.
The fossils were discovered in a riverbed in the Rukwa Rift in Tanzania, which lies along the border of the East African tectonic plate. The region is believed to have undergone major terrestrial changes, some of which could account for the two groups parting evolutionary ways.
"The rift setting provides an advantage in that it preserves datable materials together with these important primate fossils," said geologist Eric Roberts from James Cook University in Australia.
Previously, the oldest fossils from both groups stemmed from 20 million years ago. Geneticists, however, placed the time frame for the split between apes and monkeys between 25 million and 30 million years ago. The new findings help bridge the gap between the fossil record and DNA evidence.
You can read the full published study in the journal Nature.