In human pelvis the wings of the ilium extended from either side of the pelvis , in chimpanzee pelvis the wings are extend from the back because chimpanzee is tall.
Lucy and other species could walk well because their hip and knee joints were similar to humans." like human's,like chimp's".Her small skull with long arms and conical rib cage are like an ape's but she has a more human for example- spine, pelvis and knee due to walking upright.
According to Johnson - Lucy was either a small member of genus homo or small Australopithecus. When comparing Lucy , its shows an intermediate curvature between those of modern human and chimpanzees.
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