Beijing: Scientists have found that the fossil samples unearthed in a lignite mine in China belong to a monkey species that lived about 6.4 million years ago, a discovery which indicates that they existed in Asia at the same time as apes, and are probably the ancestors of some of the modern primates in the area.
According to the researchers, including Nina G. Jablonski from the Pennsylvania State University in the US, the samples collected from a mine in southeastern Yunan Province in China are "some of the very oldest fossils of monkeys outside of Africa”. "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," Jablonski noted.
The study, published in the Journal of Human Evolution, noted that the unearthed jaw and thigh bones were found in close proximity, "and are probably of the same individual." The scientists also uncovered a left calcaneus -- heel bone -- that belongs to the same species of monkey, Mesopithecus pentelicus.
"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," Jablonski said. "This locomotor versatility no doubt contributed to the success of the species in dispersing across woodland corridors from Europe to Asia," she added.
According to the researchers, the lower jawbone and upper portion of the leg bone indicate that the individual was female.
The scientists believe these monkeys were probably "jacks of all trades" able to navigate in the trees and on land, and their teeth indicated they could eat a wide variety of plants, fruits and flowers, while apes eat mostly fruit. "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. It had a gut similar to that of a cow," said Jablonski.
The monkeys were successful, according to the scientists, since they could eat low-quality food high in cellulose and obtain sufficient energy by fermenting the food and using the subsequent fatty acids then available from the bacteria.
They said a similar pathway is used by animals like cows, deer, and goats. "Monkeys and apes would have been eating fundamentally different things. Apes eat fruits, flowers, things easy to digest, while monkeys eat leaves, seeds, and even more mature leaves if they have to," Jablonski said. "Because of this different digestion, they don't need to drink free water, getting all their water from vegetation," she added.
The study noted that these monkeys are the same as those found in Greece during the same time period. Based on the evidence obtained so far, the researchers believe these monkeys did not have to live near bodies of water, and could survive periods of dramatic climatic change.
"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 kilometres through forest and woodlands." While there is evidence that the species began in Eastern Europe and moved out from there, Jablonski and her team noted that the exact patterns are unknown.
However, they said the dispersal of the species was rapid. "It shows that once a highly adaptable form sets out, it is successful and can become the ancestral stock of many other species," Jablonski said.