New Ape Species Named After 13-Million-Year-Old Skull Discovery

Infant ape's tiny skull could have a big impact on ape evolution

Infant ape's tiny skull could have a big impact on ape evolution

Researchers believe a 13 million-year-old skull recovered in Kenya belongs to the earliest common ancestor of humans and all living apes.

According to Price at Science, placing N. alesi in the ape-ancestor camp helps answer a big question in paleontology: whether the common ancestor of hominins and apes evolved in Africa or somewhere in Eurasia.

A paper detailing their findings was published Wednesday in the journal Nature.

Much remains unknown about the common ancestors of living apes and humans from the critical time when these branches diverged. "So, as you can imagine, there are numerous possibilities for how that distribution came to be, and different researchers have suggested different hypotheses for where the common ancestor of the living apes and humans might be found".

"Nyanzapithecus alesi was part of a group of primates that existed in Africa for over 10 million years", lead study author Isaiah Nengo, of Stony Brook University in NY, said in the statement.

Co-author Craig Feibel, Professor of Geology and Anthropology at of Rutgers University, New Brunswick, added: "The Napudet locality offers us a rare glimpse of an African landscape 13 million years ago". The only way to finally settle this debate once and for all is to find more fossil evidence, which, based on precedence, won't be easy. However, the size of the skull and teeth do suggest that if Alesi had reached adulthood, it would have weighed about 24.9 lbs.

Comparisons with other African ape fossils indicate that the infant's skull belongs to a new species that the researchers named Nyanzapithecus alesi. "It also provided us with the critical volcanic minerals by which we were able to date the fossil". But we know far less about the ancestors that we share with modern apes - which lived more than 10 million years ago.

It is extremely uncommon to find fossil primate skulls, especially those belonging to apes.

Scientists think the skull was from an infant ape that died in a forest and was subsequently covered by ash from a nearby erupting volcano.

Among living primates, humans are most closely related to the apes, including chimpanzees, gorillas, orangutans and gibbons. The skull had been nicknamed "Alesi" after the local Turkana word for "ancestor".

"We were able to reveal the brain cavity, the inner ears and the unerupted adult teeth with their daily record of growth lines", Paul Tafforeau of the European Synchrotron Radiation Facility in Grenoble, France. The three-dimensional X-ray images taken of these adult teeth were so detailed that researchers could count their enamel layers, which were laid down over time like rings inside a tree, helping the scientists estimate that the baby primate was 16 months old when it died.

We can't definitively say that modern apes and humans evolved directly from this newly discovered species - many more specimens from different eras would be needed to create that clear a picture.

The new skull has a noticeably small snout, like a gibbon, but scans of the inside of the cranium reveal that it had ear tubes which are closer to chimpanzees and humans. "This gives the initial impression that it is an extinct gibbon", observes Chris Gilbert of Hunter College, New York. In gibbons, a part of the inner ear called the semicircular canals, which coordinates balance, is large relative to body size. Gibbons are known for their fast and acrobatic behaviors in trees, so the inner ears of Alesi show that it had a more cautious way of moving around. Members of a team led by paleoanthropologist Isaiah Nengo estimated the fossil's age by assessing radioactive forms of the element argon in surrounding rock, which decay at a known rate.

The work was supported by the Leakey Foundation and trustee Gordon Getty, the Foothill-De Anza Foundation, the Fulbright Scholars Program, The National Geographic Society, The European Synchrotron Radiation Facility, and the Max Planck Society.

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