Fossils unearthed in Germany of a remarkable ape that lived about 11.6 million years ago may dramatically alter the understanding of the evolutionary origins of a fundamental human trait - walking upright on two legs.

Scientists said the ape, called Danuvius guggenmosi, combined attributes of humans - straight lower limbs adapted for bipedalism - with those of apes, long arms able to stretch out to grasp tree branches. That indicates Danuvius was able to walk upright on two legs and also use all four limbs while clambering through trees.

It is the oldest-known example of upright walking in apes. The discovery suggests that bipedalism originated in a common ancestor of humans and the great apes - a group that

includes chimpanzees, bonobos, gorillas and orangutans - that inhabited Europe rather than an ancestor from Africa, the continent where our species Homo sapiens first appeared roughly 300,000 years ago, researchers said.

Until now, the oldest fossil evidence of bipedalism in humankind’s evolutionary tree dated to about 6 million years ago: fossils from Kenya of an extinct member of the human lineage called Orrorin tugenensis as well as footprints on the Mediterranean island of Crete.

What are the specialities of Danuvius?

Danuvius was smaller than today’s great apes, though males were close in size to male chimpanzees and bonobos -  perhaps 30 kg - while females were smaller, perhaps 20 kg. Danuvius was just over 1 m tall.

The vertebrae and leg bones in particular suggest that Danuvius moved around on two feet. For instance, the shapes of some of the vertebrae suggest that the ancient ape had a long and flexible lower back, a feature that allows modern humans to stay balanced while walking upright by pulling the weight of the torso over the hips. Danuvius also has several weight-bearing adaptations in its knees and ankles, which would make sense if the ape routinely supported its full body weight on its legs.

But, Danuvius’s strong arms, and hands and feet that would have been able to grip branches tightly, led the researchers to conclude that it probably lived in trees, and had a unique way of moving around: a combination of walking on two feet and hanging on its powerful arms that they dub “extended limb clambering”.

Danuvius lived in what was then a hot climate on a flat landscape with forests and meandering rivers. The emerging picture of its locomotion differs from any known living creature.

If Danuvius turns out to be ancestral to humans, that would mean that some of its descendants at some point made their way to Africa.

“Danuvius changes the why, when and where of evolution of bipedality dramatically,” said paleoanthropologist Madelaine Bhme of the University of Tubingen in Germany, who led the research published in the journal Nature.

The discovery of Danuvius may shatter the prevailing notion of how bipedalism evolved: that perhaps 6 million years ago in East Africa a chimpanzee-like ancestor started to walk on two legs after environmental changes created open landscapes and savannahs where forests once dominated. “This paradigm is now declining, or in other words, is shown by us to be wrong,” Bhme said.

Danuvius indicates that upright walking originated in the trees, not on the ground, and that humankind’s last common ancestor with apes did not go through a stage of hunched knuckle-walking, as previously thought, Bhme added.

“Our last common ancestor with great apes doesn’t look like a chimp, or any living great ape. He may have looked like Danuvius,” Bhme said.

“Danuvius offers a new way of looking at the evolution of bipedalism. Before Danuvius, we did not have a model of the evolution of bipedalism that included key elements of both ape and human posture and locomotion,” said University of Toronto paleoanthropologist and study co-author David Begun.

Fossils of at least four Danuvius individuals were found in the Allgau region of Bavaria, including many key elements but no complete skull. The completely preserved limb bones, vertebra, finger and toe bones enabled the researchers to reconstruct the way the creature moved about in its environment. They were also able to study functionally important joints including the elbow, wrist, hip, knee and ankle.

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