Final answer:
Ardi's form of bipedality involved using palms and feet to navigate tree branches, signifying a dual mode of locomotion both in trees and on the ground, characteristic of Ardipithecus ramidus.
Step-by-step explanation:
Ardi's intermediate form of bipedality included the use of palms and feet to move along tree branches. Ardipithecus ramidus, commonly known as Ardi, is a hominin species which exhibited an interesting combination of traits that suggest bipedality on the ground and quadrupedal locomotion in the trees. Studies of Ardi's morphology, specifically the skeletal structure of the limbs and the grasping big toe resembling those of arboreal primates, support the hypothesis that this species was both capable of walking on two legs and adept at climbing trees. Although Ardi did not have a prehensile tail or the specialized brachiation adaptations such as the very long arms seen in some other primates, its features point to an important stage in hominin evolution. Among these were adaptations for a life spent partly in the trees and partly on the ground, a pivotal ecological shift that has been subject to wide scientific research. The ability to use palms and feet in the trees while walking bipedally on the ground suggests Ardi had a different form of locomotion compared to exclusively ground-dwelling hominins that emerged later.