Research found the only kangaroo that doesn’t hop, and it can tell us how Ruth evolved their quirky walking

In the remaining rainforests of coastal far north Queensland, Bushwalkers are fortunate to get a glimpse into the petite marsupials, the last living representative of their family.

The Musky Rat-Kangaroo (Hypsiprymnodon Moschatus) weighs only 500 grams and looks like a potroux. It is part of a lineage that extends before kangaroos evolve their distinctive hopping gait.

Unlike their larger relatives, Musky can be seen during the day. Foraging in forest trash for fruits, fungi and invertebrates.

As the only living macropodoid that does not hop (a group that includes kangaroos, wallaby, potoru and beton), it can provide important insights into how this iconic form of migration has evolved in Australia.

Our study, published in Australian Mammals, aimed to observe muskys in their native habitats to better understand how they move.

Why Kangaroos are special

Looking around the world, hopping animals are extremely rare. Hopping evolved in an extinct group of South American marsupials known once with macropodoids, four times with rodents, and perhaps once as the Argiroraggids.

In animals heavier than 5 kilograms, hopping is a very efficient form of movement. This is a very efficient form as energy is stored in the Achilles tendon behind the heel.

But most of the hop animals are really small. The only hopping animal with a weight of over 500 grams is the kangaroo. And Australia once had more kangaroo species, many of which have grown very large.

We still don’t really know why they evolved hopping gait despite the abundant fossil kangaroos, especially considering how they’ve become really efficient at weights over 5 kilograms. The hypothesis ranges from predator escape to energy conservation and vegetation openings as Australia moves into arid climate.

Researchers looking at the proportion of limbs suggest that fossil kangaroos also flew around. But it probably was much more diverse in the way extinct Lou moved than previously suggested.

Why Musky is important in the evolution of Roo

Musky is the last living member of Hypsiprymnodontidae, a macropodoid family that branched out during the early days of the kangaroo evolution. For this reason, it is believed that muskys may migrate in a similar way to their early kangaroo ancestors.

Research into the evolution of kangaroos often refers to the movement of muskys, but it only passes. And in 1982 only a single, short, direct explanation of Musky’s actually movement behavior was published. The authors observed that Muskees moved the hind limbs together at the boundary, and that all four limbs were also used at high speeds.

So we tried to answer the question: H. Can Moschatus be hop? If not, what form of movement would you use?

High-speed video recordings were used to examine the sequence in which Musky places four feet on the ground, as well as the relative timing and duration of each scaffold.

Through this gait analysis, Musky decided to use what is primarily referred to as “bound” or “halfbound” gait. Boundary walking is characterized by HindFeets moving together in sync, like the Bipedal Kangaroos Hop. In Musky’s case, furf (or “hand”) also generally move together in close sync.

Other marsupials that move on four and four fours are not known to use this distinctive style of movement to the same extent as Musky. Rather, other species tend to use a combination of half-binding and some form of galloping (walking used by horses, cats, and dogs) or hopping.

From all fours to hopping

We also managed to confirm a simple appetite-inducing observation from the 1980s. Even when traveling at high speeds, Musky always used square walking and made sure he didn’t grow just his back.

Therefore, they are the only living kangaroos that do not hop.

Combined with further investigation of anatomy, these observations help us to approach understanding how and why kangaroos adopted unique bipedal hopping behaviors.

These results also show potential pathways to how bipedal hopping evolved in kangaroos. Perhaps it started with animals that moved to everything on fours like other marsupials, such as brushtail possums, then left boundaries like Musky, and finally evolved into the iconic hopping kangaroos found in Australia today.

However, we are not clear how the kangaroo movement’s prominent energy economy evolved, or why hopping kangaroos have become much larger than hopping rodents.

The next part of the study needs to focus on it, informing us by major fossil discoveries early in the evolution of kangaroos.

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