A study led by University of Texas at Austin anthropologists suggests Oreopithecus, an ape that lived 9 million to 7 million years ago, did not, in fact, walk habitually on two legs.
The study confirms anatomical features related to habitual upright, two-legged walking remain exclusively associated with humans and their fossil ancestors, a UT Austin release said Thursday.
"Our findings offer new insight into the Oreopithecus locomotor debate," anthropologist Gabrielle Russo said of the study published in the Journal of Human Evolution. "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."
The lower spine anatomy of Oreopithecus is not consistent with bipedal walking, the researchers said, and is more similar to that of apes, indicating it is incompatible with the functional demands of walking upright as a human does.
"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," researchers Liza Shapiro said.