Scientists May Have Been Wrong About Giant Kangaroos

Giant prehistoric kangaroos may have been able to hop after all, despite earlier claims that they were simply too heavy. Researchers found their foot bones and tendons were robust enough to withstand the stress of hopping, based on detailed comparisons with modern species. (Artist’s concept.) Credit: SciTechDaily.com

Despite their enormous size, giant ancient kangaroos may have been capable of hopping in short, powerful bursts.

Ancient relatives of today’s kangaroos, some of which may have weighed as much as 250 kilograms (550 pounds), might not have been as limited in their movement as scientists once believed. New research published today (January 22) in Scientific Reports suggests these massive animals were capable of hopping in short bursts. This conclusion challenges earlier studies that argued kangaroos weighing more than 160 kilograms were simply too heavy for their ankles to handle the forces involved in hopping.

Reconstruction of Sthenurine Hopping. Credit: Megan Jones Fossil Bones Offer New Clues About Movement

To investigate how these giant kangaroos may have moved, Megan Jones and her colleagues analyzed the hindlimbs of 94 modern specimens and 40 fossil specimens representing 63 species of kangaroos and wallabies. The sample included members of the extinct giant kangaroo group Protemnodon, which lived during the Pleistocene (between 2.6 million and 11,700 years ago).

For each species, the researchers relied on previously published body weight estimates and detailed measurements of the fourth metatarsal, an elongated foot bone that plays a crucial role in hopping among modern kangaroos. Using the length and diameter of this bone, the team assessed whether the limbs could withstand the physical stresses produced during hopping.

Sthenurine skeleton in the South Australian Museum. Credit: Megan Jones Testing Tendons and Heel Bones for Strength

The researchers also compared the heel bones of giant kangaroos with those of living kangaroo species. They calculated how large the Achilles tendon would need to be to absorb the forces generated during hopping in much heavier animals. The team then evaluated whether the heel bones of giant kangaroos were large enough to accommodate tendons of that size.

Their analysis indicates that the metatarsals of all known giant kangaroo species were strong enough to tolerate hopping-related stress. The heel bones also appear to have been sufficiently large to support the tendon thickness required for this type of movement.

Heel bone of the largest giant kangaroo species, Procoptodon goliah. Credit: Megan Jone, UCMP, Berkeley Short Bursts, Not Long Journeys

Taken together, the results suggest that the hindlimbs of giant kangaroos were mechanically capable of supporting hopping. However, the researchers caution that hopping was unlikely to be their primary way of getting around. Due to their enormous body size, repeated long-distance hopping would have been inefficient.

Instead, the authors point out that occasional hopping is already seen in many smaller animals today, including hopping rodents and small marsupials. They propose that brief, powerful hops may have given giant kangaroos a survival advantage in specific situations. In particular, these sudden movements could have helped them escape predators such as the extinct marsupial lions known as Thylacoleo.

Reference: “Biomechanical limits of hopping in the hindlimbs of giant extinct kangaroos” 22 January 2026, Scientific Reports.
DOI: 10.1038/s41598-025-29939-7

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