Final answer:
Deinonychus and other dromaeosaurs walked on the third and fourth toes of each hind foot, and this bipedal stance allowed for agile movement and balance facilitated by their long tails.
Step-by-step explanation:
Deinonychus and other dromaeosaurs walked on the third and fourth toes of each hind foot. This type of locomotion is part of what places Deinonychus in the group of dinosaurs called theropods, which are known for their bipedal stance and were the ancestors of modern birds. Deinonychus in particular shared many traits with birds, such as feathers, wings, and strong leg muscles for its size, indicating a close evolutionary relationship.
Theropods like Deinonychus utilized their bipedal stance to facilitate quick and agile movement, which was likely useful for hunting and evasion. Their long tails balanced their bodies, especially if they had long necks, to help maintain their center of gravity when running or changing direction rapidly. The skeletal structure, including the positioning of the legs directly under the pelvis, provided support for this dynamic mode of locomotion.