Fossils reveal that monkeys were in Asia 6.4 million years ago

Fossils that were recovered from a lignite mine in China indicate that monkeys existed in Asia at the same time as apes 6.4 million years ago. According to an international team of researchers, the remains most likely belong to ancestors of monkeys that exist in the same region today. 

Study lead author Nina G. Jablonski is a professor of Anthropology at Penn State.

“This is significant because they are some of the very oldest fossils of monkeys outside of Africa,” said Professor Jablonski. “It is close to or actually the ancestor of many of the living monkeys of East Asia. One of the interesting things from the perspective of paleontology is that this monkey occurs at the same place and same time as ancient apes in Asia.”

The fossils were linked to an extinct genus of Old World monkeys called Mesopithecus pentelicus. The team studied a jawbone and a proximal femur bone, as well as a calcaneus, or heel bone.

“The significance of the calcaneus is that it reveals the monkey was well adapted for moving nimbly and powerfully both on the ground and in the trees,” said Professor Jablonski. “This locomotor versatility no doubt contributed to the success of the species in dispersing across woodland corridors from Europe to Asia.”

The lower jawbone and proximal femur bone indicate that the individual was a female, explained the researchers. They theorize that M. pentelicus was probably a “jack of all trades” who was able to navigate in the trees and on land. The analysis of the teeth revealed that the monkeys could eat a wide variety of fruits and flowers.

“The thing that is fascinating about this monkey, that we know from molecular anthropology, is that, like other colobines (Old World monkeys), it had the ability to ferment cellulose,” said Professor Jablonski. “It had a gut similar to that of a cow.”These monkeys can eat low-quality food that is high in cellulose and obtain sufficient energy by fermenting the food and using the fatty acids that are made available from the bacteria. A similar pathway is used by other animals, including cows, goats, and deer.

“Monkeys and apes would have been eating fundamentally different things,” said Professor Jablonski. “Apes eat fruits, flowers, things easy to digest, while monkeys eat leaves, seeds and even more mature leaves if they have to. Because of this different digestion, they don’t need to drink free water, getting all their water from vegetation.”

“These monkeys are the same as those found in Greece during the same time period. Suggesting they spread out from a center somewhere in central Europe and they did it fairly quickly. That is impressive when you think of how long it takes for an animal to disperse tens of thousands of kilometers through forest and woodlands.”

While there is evidence to suggest that the species emerged in Eastern Europe and spread out from there, the researchers say the exact patterns are unknown. What they do know, however, is that the dispersal was rapid in evolutionary terms. 

At the end of the Miocene when these monkeys were leaving Eastern Europe, apes were vanishing from everywhere except in Africa and parts of Southeast Asia.

“The late Miocene was a period of dramatic environmental change,” said Professor Jablonski. “What we have at this site is a fascinating snapshot of the end of the Miocene – complete with one of the last apes and one of the new order of monkeys. This is an interesting case in primate evolution because it testifies to the value of versatility and adaptability in diverse and changing environments. It shows that once a highly adaptable form sets out, it is successful and can become the ancestral stock of many other species.”

The study is published in the Journal of Human Evolution.

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By Chrissy Sexton, Earth.com Staff Writer