Final answer:
A straight spine is NOT considered an adaptation for bipedalism; instead, an S-shaped spine helps in weight distribution and shock absorption necessary for upright walking.
Step-by-step explanation:
The correct answer to the question of which is NOT considered to be an adaptation for bipedalism is a straight spine. The adaptations that are conducive to bipedalism include a valgus knee, which allows hominins to walk with their feet under the center of their pelvis, a bowl-shaped pelvis that supports the organs and allows for more efficient walking, and a forward positioned foramen magnum, which enables the skull to balance on the vertical spine. Our spines are actually S-shaped, not straight, and this curvature helps to distribute weight, absorb shock, and maintain balance while walking or running upright.