Discovery Of Ancient Skull Sheds Light On Ape Ancestry

Pablo Tucker
August 11, 2017

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.

Its unerupted teeth placed the skull in the genus Nyanzapithecus as the first member of a brand-new species: Nyanzapithecus alesi.

As well as dating to the "dark ages" of human origins, it is also the most complete extinct ape skull in the fossil record. The skull is also so well-preserved that scientists were able to estimate that the creature died at about 16 months of age. The Kenyan fossil hunter John Ekusi found Alesi's skull in ancient rock layers in the Napudet area, west of Lake Turkana.

Alesi, the skull of the new extinct ape species Nyanzapithecus alesi. A local fossil hunter spotted the almost complete skull in rock layers located near Kenya's Lake Turkana.

The discovery of the infant ape skull - nicknamed "Alesi" after the local Turkana word for "ancestor" - helps bridge some of those gaps, not only because of how intact the outside of the skull is but for what was preserved on the inside. Reconstructing the history of that branch, however, has been hard, mainly because the forests those common ancestors once lived weren't great at preserving fossils.

"We were able to reveal the brain cavity, the inner ears, and the unerupted adult teeth with their daily record of growth lines", says Paul Tafforeau of the European Synchrotron Radiation Facility.

More than 13-million years ago an Infant dead in lush forest.

"We have a lovely ape cranium [skull] from a period that we knew virtually nothing about and this is one of those wonderful cases where discovery leads to all sorts of new and interesting perspectives", Craig Feibel, who chairs Rutgers' Department of Anthropology and is a professor of geology and anthropology, said in a statement.

The species likely persisted until the late Miocene.

N. alesi's tiny mouth and nose, along with several other facial characteristics, make it look much like small-bodied apes called gibbons. Until the discovery, scientists weren't sure if the Nyanzapithecus species were apes or if they had originated in Asia.

"Importantly, the cranium has fully developed bony ear tubes, an important feature linking it with living apes", says Ellen Miller of Wake Forest University.

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. "However, our analyses show that this appearance is not exclusively found in gibbons, and it evolved multiple times among extinct apes, monkeys, and their relatives". But a tiny semicircular canal in the skull suggests was markedly different from gibbons, reports Dvorsky. The research was done by an worldwide team led by Isaiah Nengo of Stony Brook University-affiliated Turkana Basin Institute and De Anza College, U.S.A. This newly-described species of ape, dubbed Nyanzapithecus alesi (or just Alesi for short), lived long before modern apes and humans diverged along separate evolutionary paths (humans split from apes around six to seven million years ago), but the discovery hints at what the earliest true apes must have looked like.

"One of the fun things about this field is that it is so discovery driven", Feibel said. "One new fossil can totally change your perspective on things, and they frequently do".

The scientific journal Nature has published Dr. Nengo's findings in detail.

The study was sponsored 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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