A latest study challenges the previous studies by claiming that extinct ancient apes did not walk on two legs like humans. The new study confirms that the features of bipedalism (ability to walk on two legs) were strictly limited to the human and their ancestors.

Till date it was doubtful whether Oeropithecus habitually stood erect. But the new study led by researchers at the University of Texas at Austin, have refuted the previous finding which claims Oreopithecus the 9-7 million year old ape from Italy had the ability to walk on two legs. The study was led by anthropologists Gabrielle A. Russo and Liza Shapiro.

The extinct primate Oreopithecus belonged to the Miocene epoch. Its fossil were discovered in present times Tuscany and Sardinia in Italy. It was one of the larger numbers of immigrants from Europe. They had a short snout and weighed 30-35 kg, reports Wikipedia.

"Our findings offer new insight into the Oreopithecus locomotor debate. While it's certainly possible that Oreopithecus walked on two legs to some extent, as apes are known to employ short bouts of this activity, an increasing amount of anatomical evidence clearly demonstrates that it didn't do so habitually," Russo the lead authors of the study said in a press statement.

For this study, the researchers examined of fossil ape to check if it had possessed lower spine anatomy that could support bipedal walking. They compared the measurements of the lumbar vertebrae (lower back) along with the sacrum (the triangular bone at the base of the spine) to those of the present day human beings, ancient apes and a few others like sloths and the extinct lemur.

Ruso found the lower spine as a good basis to test whether the ancient ape did walk on two legs as the human lumbar vertebrae and sacra have different features that support habitual bipedal walking.

They found that the Oeropithecus lumbar vertebrae and sacrum was different from humans and matched that of the apes hinting that is does not match the functional demands of bipedal walking like humans.

"The lower spine of humans is highly specialized for habitual bipedalism, and is therefore a key region for assessing whether this uniquely human form of locomotion was present in Oreopithecus. Previous debate on the locomotor behavior of Oreopithecus had focused on the anatomy of the limbs and pelvis, but no one had reassessed the controversial claim that its lower back was human-like," Liza Shapiro, also from University of Texas at Austin, according to a news release.

The researchers documented their finding in the Journal of Human Evolution.