A fossil of a new primate species is discovered. Scientists find evidence that members of this species traveled long distances without putting their hands down on the ground and used tools. Which trait would the fossil most likely have?

Traveling long distances without using the hands for support suggests habitual upright, two-legged walking. A curve in the lumbar region helps balance the upper body over the hips during bipedal walking, so the fossil would most likely show this trait. A foramen magnum at the back of the skull and an opposable big toe are more associated with non-bipedal movement, while an inward-angled femur—not an outward-angled one—helps bring the legs beneath the body.

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