Published: Fri, August 11, 2017
Research | By Jo Caldwell

South Bay Professor Finds 13 Million Year Old Ape Skull

South Bay Professor Finds 13 Million Year Old Ape Skull

The lemon-sized skull was discovered in Kenya by an global team of researchers, and was dated to the middle of the Miocene era, a little-understood time when many species of ape arose in Africa, including common ancestors of both modern apes and humans. They first appear in the fossil record during the end of the Oligocene geological epoch in Africa (from about 33.9 million to 23 million years ago) and persisted until perhaps the late Miocene.

Alesi's skull is the most complete ape cranium fossil from an extinct species ever found, the researchers wrote in an article announcing the new discovery published Wednesday in the journal Nature.

Paleontologists have found bits of teeth and jaws from apes that lived during the Miocene, but traces of their skulls and limbs are exceptionally rare.

The tiny Alesi skull is 13 million years old.

While a lot is known about human evolution since we split from chimps about seven million years ago, little was known about common ancestors from before 10 million years ago.

The team used an extremely sensitive form of 3-D X-ray to peek inside the skull, revealing information that led them to conclude the skull belonged to an infant one to four months old when it died. As such, researchers were not sure what the last common ancestors of living apes and humans might have looked like, and even whether they originated in Africa or Eurasia. "What the discovery of Alesi shows is that this group was close to the origin of living apes and humans and that this origin was African".

The shape of the unerupted adult teeth revealed that Alesi belonged to a genus, or group of species, known as Nyanzapithecus, a sister group to the hominoids that was discovered about 30 years ago.

"More fossil prospecting at the Napudet site is well worth it since the chances of finding really exciting stuff there are very high", he added. Modern gibbons are smaller apes and somewhat resemble monkeys, but they are tailless like other apes.

The dating of the skull was done by analyzing the rock layer from which the fossil was pulled, and by measuring the argon isotopes. Numerous most informative parts of the skull are preserved inside the fossil, and to make these visible the team used an extremely sensitive form of 3D X-ray imaging at the synchrotron facility in Grenoble, France. The researchers established this age by counting the layers within the fossilized dental structures, a process akin to counting tree rings. "It has therefore been hard to find answers to two fundamental questions: Did the common ancestor of living apes and humans originate in Africa, and what did these early ancestors look like?" "This complete skull - it is now forever going to be a touchstone for all future studies in primate evolution and growth and development in the apes, so it's fantastic in that way". However, the size of the skull and teeth do suggest that if Alesi had reached adulthood, it would have weighed about 24.9 lbs.

However, gibbons swing through trees and launch themselves from one branch to another.

The research team believes the ape's cranium suggests that it was slower and less agile than the more acrobatic, arm-swinging apes like the gibbon.

"The living apes are found all across Africa and Asia-chimps and gorillas in Africa, orangutans and gibbons in Asia-and there are many fossil apes found on both continents, and Europe as well", Christopher Gilbert, paleoanthropologist at Hunter College in NY and co-author of the paper, tells Choi. Gibbon ancestors are thought to have diverged from precursors of living great apes and humans between 20 million and 15 million years ago, Alba says.

"The authors claim that Nyanzapithecus is the closest thing we know to the last common ancestor of all living apes", Begun told Gizmodo. He tells Dvorsky that he believes other ape specimens, including Proconsul and Ekembo are also good candidates for being the last common ancestor. It is about the size of a lemon, and the species is named Nyanzapithecus alesi.

It's always been known that apes and humans share a common ancestor, but not a lot is known about what that ancestor was and where it came from.

So the debate continues, as does the paleontology.

Here's ESRF's video about the discovery of Nyanzapithecus alesi. "It was much older than that".

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