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Could Ardipithecus walk upright on the ground?

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skeleton of “Ardi” — Ardipithecus Reconstructed frontal view of the skeleton of “Ardi,” a specimen belonging to the early hominid species *Ardipithecus ramidus*.

Yes, Ardipithecus ramidus was capable of walking upright on the ground.12

While Ardipithecus was not as well-adapted for the efficient, striding bipedalism seen in later hominids, it possessed several anatomical features that indicate it was capable of two-legged walking to a degree not found in living or fossil apes. Key evidence for this includes:1

Skull: The foramen magnum—the opening where the spinal cord enters the skull—is positioned centrally under the skull, which helps balance the head atop the spinal column for an upright posture.3
Pelvis: The pelvis featured a short, broad upper blade (ilium) and muscle-attachment sites similar to those of later bipedal hominids, which are markers of bipedal locomotion.43
Foot: The foot structure included a rigid midfoot and lateral foot that functioned as a lever during walking.4

Despite these terrestrial adaptations, Ardipithecus retained a fully opposable great toe and other features suited for climbing, suggesting it lived in a woodland environment and maintained a partially arboreal existence.412