Final answer:
The location of the Foramen Magnum is the best indicator of bipedalism in a fossil for paleoanthropologists.
Step-by-step explanation:
The best indicator of bipedalism in a fossil for paleoanthropologists is the location of the Foramen Magnum. The foramen magnum is the hole at the base of the skull where the spinal cord enters. In bipedal species, such as humans, the foramen magnum is positioned towards the center of the skull, while in quadrupedal species, it is positioned towards the back. This is because the position of the foramen magnum is directly related to the alignment of the spine and the ability to walk upright.