Source: BBC

About seven million years ago, human evolution was just getting started in east Africa. But thousands of kilometres to the north, another ape empire was in its death throes.

Europe had been home to several species of ape since about 17 million years ago. Some researchers even think important events in ape evolution happened in Europe. But by seven million years ago all but one of these apes had vanished.

An Italian ape called Oreopithecus was the last species standing from Europe’s golden age of apes. Arguably, it was the strangest of the lot.

Oreopithecus has been puzzling researchers ever since its discovery in the rocks of Tuscany and Sardinia late in the 19th Century. Its fossil bones tell the story of an animal that did not look or act like its European ape ancestors.

Instead, Oreopithecus seems to have been oddly like an early member of our human lineage, even though it does not belong on our branch of the ape evolutionary tree.

Oreopithecus once roamed Tuscany (Credit: Inge Johnsson/Alamy Stock Photo)

The latest evidence for this comes from an analysis ofOreopithecus’s diet. Sherry Nelson at the University of New Mexico in Albuquerque and Lorenzo Rook at the University of Florence, Italy, looked at oxygen and carbon isotopes in the teeth of Oreopithecus.

The exact balance of carbon isotopes locked away in fossil teeth can give researchers a sense for the kind of vegetation an extinct animal ate. A “low” balance, meaning a relatively high level of carbon-12, is typical of vegetation from trees and shrubs. A “high” balance, with relatively more carbon-13, indicates a diet rich in grasses and sedges.

Oreopithecus has been puzzling researchers ever since its discovery

Meanwhile, the oxygen isotopes can reveal the sort of environment in which that vegetation grew. This is because the oxygen isotope balance in teeth reflects the oxygen balance in the dietary vegetation, which in turn is strongly affected by how much water that vegetation routinely lost through evaporation.

“When both [carbon and oxygen ratios] are low it means a closed, wet system, probably forest floor,” says Nelson. “Where both are high it means an evaporative system like a grassland.”

However, the values locked in the Oreopithecus teeth did not fit into either of these categories. The carbon ratios were unusually high but the oxygen ratios were low.

This suggests Oreopithecus was unlike almost all apes.

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