What adaptations for bipedal locomotion are found in the legs?

The special arrangement of the foot's bones and muscles, which enables the vital balancing functions, is the primary characteristic that sets bipedal animals apart from other types of animals.

For four-limb locomotion, simpler foot structures and even masses like hoofs are sufficient. The ankle/foot connection, the extended forward foot with a slight backward heel, and most importantly, the flexible toes that provide fine motor control for stability, meet the peculiar requirements of dynamic balance on only two appendages.

While they might increase efficiency, other traits like muscle and leg bone orientation are not necessary to distinguish between quadrupedal and bipedal motion.

Humans have very robust heels and great toes that are permanently aligned with the four smaller lateral toes; as a result, the feet must sustain and propel the entire body on their own, rather than sharing the load with the forelimbs.

Human footprints are distinct from those of other animals because, in contrast to the feet of other primates, which have a mobile midfoot, the human foot has (if not requires) a stable arch to give it strength.

This site, https://tutor.hix.ai has some excellent discussion and graphics.

ScienceDirect.com/science/article/pii/S0021929002004190 has been accessed.

Adaptations for bipedal locomotion found in the legs include:

1. Longer legs compared to other mammals.
2. The presence of an S-shaped curve in the spine to support the body's weight.
3. Alignment of the legs directly beneath the body's center of gravity.
4. Development of a stable and arched foot structure to absorb shock and propel the body forward.
5. Efficient musculature, including well-developed gluteal and thigh muscles, for stability and propulsion.
6. A specialized knee joint that locks during weight-bearing to provide stability and conserve energy.