What is the primary characteristic of Ardipithecus?

Ardipithecus is primarily characterized by being not fully bipedal. This early hominin shows a mix of adaptations for both climbing and walking. The skeletal structure of Ardipithecus, particularly its pelvis and feet, indicates that while it had some capabilities for bipedalism, it was not fully adapted to a completely upright, bipedal locomotion as seen in later hominins like Homo erectus or Homo sapiens. This suggests that Ardipithecus retained significant arboreal characteristics, which were crucial for survival in its environment. Understanding this aspect of its physiology helps in the study of human evolution, particularly in tracing the transition from more ape-like ancestors to fully bipedal human ancestors.