Many spectacular fossil finds have revealed how humans evolved from the common ancestors of chimpanzees 6 to 7 million years ago. However, little was known about the previous common ancestor, who lived at least 10 million years ago. Up to now. A complete skull found in Kenya of a baby ape that lived 13 million years ago reveals how all living apes and humans could have been the common ancestor.
The finding, announced in the journal Nature , was made by an international team led by Isaiah Nengo from Stony Brook University-affiliated Turkana Basin Institute and De Anza College, USA; and it allows answering questions that, with previously available fossils, were difficult to answer: did the common ancestor of living apes and humans originate in Africa? What were these ancestors like?
The newly discovered ape fossil, nicknamed Alesi by its discoverers and known by its museum number KNM-NP 59050, comes from a critical time period in the African past. In 2014, it was discovered by Kenyan fossil hunter John Ekusi in 13-million-year-old rock layers in the Napudet area, west of Lake Turkana, in northern Kenya.
“The town of Napudet offers us a rare glimpse of an African landscape 13 million years ago,” says Craig S. Feibel of Rutgers University-New Brunswick. ” A nearby volcano buried the forest where the baby monkey lived, preserving the fossils and countless trees, and it also provided us with the critical volcanic minerals with which we were able to date the fossil .”
The fossil belonged to an infant, and is the most complete extinct ape skull known in the fossil record. Many of the most informative parts of the skull are preserved within the fossil, and to make them visible, the team used an extremely sensitive form of 3D X-ray imaging at the synchrotron facility in Grenoble, France.
“We were able to reveal the brain cavity, inner ears and still hidden adult teeth with their daily record of growth lines,” says Paul Tafforeau, a member of the European institution. “The quality of our images is so good that we were able to establish from the teeth that the baby was around 1 year and 4 months old when he died.”
Adult teeth still hidden within the infant monkey’s skull also indicate that the specimen belonged to a new species, Nyanzapithecus alesi . Until now, all the Nyanzapithecus species were only known through the teeth and it was an open question whether or not they were monkeys, “says John Fleagle of Stony Brook University.” Importantly, the skull has fully developed bony tubes. skeletal, an important characteristic that links it to living apes, “adds Ellen Miller of Wake Forest University.
Alesi’s skull is about the size of a lemon , and with its remarkably small snout it looks more like a baby gibbon. “It gives the initial impression that it is an extinct gibbon ,” observes Chris Gilbert of Hunter College, New York. “However, our analyzes show that this appearance is not found exclusively in gibbons, but evolved several times among extinct monkeys, monkeys and their relatives.”
The key to confirming that the new species is not a gibbon is in its inner ear. “Gibbons are known for their fast, acrobatic behavior in trees,” says Fred Spoor of University College London and the Max Planck Institute for Evolutionary Anthropology, “but Alesi’s inner ears show that he would have had a much more cautious way of moving. Over there.”
” Nyanzapithecus alesi was part of a group of primates that existed in Africa for more than 10 million years,” concludes lead author Isaiah Nengo. “What Alesi’s discovery shows is that this group was close to the origin of living apes and humans and that this origin was African.”
References:
Nengo, I., Tafforeau, P., Gilbert, CC, Fleagle, JG, Miller, ER, Feibel, C., Fox, D., Feinberg, J., Pugh, KD, Berruyer, C., Mana, S. , Engle, Z. and Spoor, F. “New infant cranium from the African Miocene sheds light on ape evolution”. Nature. August 10, 2017. https://www.nature.com/doifinder/10.1038/nature23456
Image: Fred Spoor.
