Small 11.6-million-year old ape fossil redefines evolution by bringing to light a mosaic of traits common to both great and lesser apes.

Humans, gorillas or chimpanzees are part of the great apes family. Approximately 17 million years ago it is believed that great apes and lesser diverged and formed two distinct groups. Lesser apes include small apes, typically living in trees. Among them, siamangs and gibbons are the most recognizable. The 11.6 million-year-old ape fossil offers evolutionary clues bound to make researchers reimagine how the ancestor of all apes might have looked like.

This ancient primate discovered in Catalonia, Spain is estimated to have weighed approximately 5 kilograms. The genus is described as similar to a gibbon, with 3D computer models rendering telescopic eyes like those of the gibbon and a very similar muzzle.

25 million years ago, apes and monkeys became two different groups. Approximately 17 million years ago, apes also diverged. How is it possible then that an 11-year-old ape fossil presents traits characteristic to both lesser apes and great apes? Pliobates cataloniae as the ancient ape is named has been recreated based on the unearthed bony fragments. Its cranium, the muzzle and pieces of the upper jaw, as well as hind bone fragments, one arm and a hand allowed scientists to extract valuable information.

David Alba, paleobiologist with the Institut Català de Paleontologia Miquel Crusafont in Sabadell and colleagues established that Pliobates cataloniae’s brain was similar in size to that of a monkey. Its sharp cusps and small teeth also remind more of a monkey. Still, its wide yet short cranium bring the ancient ape closer to greater apes. Bones in the fossilized arm indicate that Pliobates cataloniae would have been able to rotate its elbow and wrist and climb trees. While great apes present these features, lesser apes don’t.

While Pliobates cataloniae certainly isn’t the common ancestor of all apes, the small 11.6-million-year old ape fossil redefines evolution. Until its discovery, scientists believed that the common ancestor of all apes would have been more like a great ape.

Lesser apes would then shrink on the evolutionary scale, reaching the sizes we are familiar with nowadays. Pliobates cataloniae is here to contradict this thesis, now occupying an important space at the base of the ape family tree.

The genus is described in a paper authored by David Alba and colleagues and featuring in the journal Science.

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