Tiny Ancient Skeleton Redefines the Split Between Monkeys and Apes

The mother of all apes may not look like researchers would have expected. Based on modern apes—gorillas, chimpanzees and humans—many have assumed that our ancient ancestors were sturdy-bodied and rather large. But a new find unearthed in Spain challenges this assumption.

Researchers discovered part of an 11.6-million-year old skeleton that carries some ape-like characteristics, including a large braincase, but a muzzle like that of a lesser ape such as a tree-swinging gibbon, reports Ann Gibbons for Science. 

This mix of features and the specimen’s age puts the creature, named Pliobates cataloniae, at the base of the ape family tree. Pliobates had eye sockets that telescope out, like a gibbon’s, but elbow and wrist bones that would have allowed the creature to clamber in trees, like great apes and humans do, rather than swing like a gibbon or a monkey.​

But the ancient ape would have weighed only about 8 to 11 pounds, according to the recent study published in Science. That means this ancient ancestor was tiny.

Apes, including the lineages that would become present-day humans, great apes, and lesser apes, diverged from monkeys about 25 million years ago. Previously, scientists had suspected that an animal like Proconsul, a large-bodied ape that lived 23- to 5-million years ago, was the last common ancestor of all apes. Though the new specimen isn’t old enough to be the mother of all apes, Pliobates's tiny stature suggests this ancient ancestor may too be small.

Primate paleontologists may also need to rethink some other assumptions. “For decades, the small stuff was thought to be related to gibbons and the big stuff was thought to be related to great apes," paleoanthropologist John Fleagle, who was not involved in the new research, tells Gibbons for Science. But these new results show that researchers searching for the origin of apes can’t discount these small fossils.

Researchers discovered Pliobates northwest of Barcelona, Spain, buried in sediment beneath a landfill. And though it may seem odd to some to find a primate outside of Africa, it isn’t. Europe attracted it’s fair share of ancient ape species during the Miocene epoch, when subtropical forests grew on the Northern continent. This actually makes Europe an excellent candidate for the home of the last common ancestor of all apes.

The shake-up of the ape family tree could have been anticipated. Evolution is a complex process, study author David Alba tells Eva Botkin-Kowacki for The Christian Science Monitor. The ape’s evolutionary tree is bushy, rather than linear. 

While the Miocene epoch hosted more that 30 different apes of various sizes and appearance, only a few lineages survive today, according to Alba.

Though the question of the last common ancestor for apes persists, this little ape skeleton has opened new and tiny possibilities.

Maris Fessenden | | READ MORE

Maris Fessenden is a freelance science writer and artist who appreciates small things and wide open spaces.