Modern day kangaroos are a diverse bunch of species, however, we recognize them by their tendency to hop. Recently, a study has been published in the PLOS One journal stating, the ancient relatives of kangaroos possibly had a gait, which will seem strange to us: They actually walked upright on two legs, like humans.
Researchers claimed that, now extinct sub-family of sthenurine kangaroos had legs made for walking. Some species of the giant were short-faced, weighed more than 220 kilos, which is roughly 3 times the weight of their contemporary relatives. With such size, hopping would have become heavy.
Christine Janis (study author), who is a professor of ecology and evolutionary biology at Brown University stated that, “At best, they’d have been really clumsy hoppers. Though, she along with her colleagues believed that sthenurine was more than just awkward.”
Current species of kangaroos hop for speed. They actually use a particular type of stroll when they need to move slowly: They use their tails as a third leg.
Some former studies revealed that sthenurine cannot actually manage that movement. These kangaroos had rigid spines and their tails are not springy and flexible that support their colossal weight.
Professor Janis stated that, “They would have had to do something else to move around slowly.”
Professor Janis and her colleagues examined the various components of sthenurine skeletons and identified some differences between these and modern day kangaroos. Sthenurine kangaroos had larger hip and knee joints along with the broad, flared pelvis, which enable for larger gluteal muscles that support their body weight even on one leg most of the times as compared to the modern kangaroos possess.
Janis and her colleagues think that sthenurines firstly used this walking gait for slow locomotion , though they also hopped at high speed similar to other kangaroos. With the passage of time, the differences in their gait enabled them to evolve into a huge-size and those kangaroos had to give up hopping for good.
She further stated that, “Hopping is a thorny gait, and current kangaroos are near the limit, in terms of size. This is just one case of humans thinking that extinct animals must have moved and acted like their modern-day relatives. In most of the cases, the truth is a lot more alien.”