A professor of Ecology and Evolutionary Biology at Brown University, Christine Janis, together with her colleagues has stated that ancient kangaroos never hopped like their modern brethren, and that they actually walked almost like humans do. Skeletons of ancient kangaroos indicate that they were much bigger in size and couldn’t have hopped given their sheer weight, they would have walked but then, they also stood on one foot to support their weight.
The extinct kangaroos had larger hips, knee joints, broader and flared pelvis, and more big-boned than their modern relatives, and their larger gluteal muscles indicated they were able to stand on one leg at any particular point in time to support their full body weight. There are various species of kangaroos today, and most of the ancient ones would have weighed 220 kilos, which was almost thrice the size of modern kangaroos.
Given their estimated weights and size, hopping would have nearly been impossible for the ancient kangaroos. Although modern kangaroos hop when they want to run for speed, and they support their weight with their tails if they ever need to stand upright – like a third leg, ancient kangaroos would not have been capable of this feat seen in modern ones today.
According to Janis, “at best, they’d have been really clumsy hoppers. They would have had to do something else to get around slowly. Hopping is a tricky gait, and modern kangaroos are near the limit, in terms of size. All of the differences we found were suggestive of putting weight on one foot at a time.” Ancient kangaroos were short-faced and known as sthenurine kangaroos.