Scientists once assumed that hopping—a hallmark of kangaroo movement—would break down beyond a certain body size. But new research drawing on fossil remains and anatomical analysis suggests that even enormous Ice Age kangaroos, some weighing up to 250 kilograms, were built to hop after all.
The recent discovery of new examples of prehistoric fossilized kangaroo remains contradicts past long-held beliefs, now suggesting that colossal kangaroo species from Australia’s Ice Age could still bounce across the landscape.
Today, the largest kangaroo on Earth is the red kangaroo, which weighs in at around 90 kilograms. During the Pleistocene epoch, however, some kangaroo species were more than twice that size, with certain individuals weighing up to 250 kilograms. This previously gave rise to the idea that such giants would have abandoned hopping in favor of slower forms of movement, such as walking.
A team of scientists from the University of Manchester, the University of Bristol, and the University of Melbourne published their findings in a study in Scientific Reports, outlining detailed measurements of living kangaroos and direct fossil evidence, revealing that giant kangaroos were built differently from their modern relatives in ways that supported hopping despite their huge size.
“Previous estimates were based on scaling up modern kangaroos, which might overlook crucial anatomical differences,” said lead researcher Megan Jones, a postgraduate researcher at the University of Manchester, in a statement. “Our findings show that these animals weren’t just oversized versions of today’s kangaroos—they were structurally adapted to manage their enormous size.”
Factors Considered
The team examined two major factors that could potentially limit hopping ability. The first involved the strength of the foot bones and the ankle’s ability to anchor the powerful tendons required for hopping. The second focused on fossilized limb evidence, which showed that the foot bones of giant kangaroos were shorter and thicker than those of modern kangaroos, allowing them to withstand the intense forces generated during landing. Similarly, their heel bones were broad enough to support much thicker ankle tendons—an important feature for storing and releasing the energy needed for hopping.
However, the researchers caution that giant kangaroos likely moved differently from today’s red kangaroo. “Thicker tendons are safer but store less elastic energy,” said Dr. Katrina Jones, Royal Society Research Fellow at the University of Bristol. “This likely made giant kangaroos slower and less efficient hoppers. They were probably better suited to short bursts of movement rather than long-distance travel. Hopping still would have been useful for navigating rough terrain or escaping predators.”
Fossil evidence also shows a wide range of transport strategies among extinct kangaroo species. Some may have combined hopping with upright walking or quadrupedal movement, suggesting that hopping was just one component of a broader “movement repertoire.”
The study also sheds light on the ecological diversity of prehistoric Australia. “Kangaroos had a much broader ecological range in the past than today,” said Dr. Robert Nudds, Senior Lecturer in Evolution, Infection, and Genomics at the University of Manchester.
“Some species were grazers like modern kangaroos, while others were browsers, occupying niches not represented among large kangaroos today.”
If nothing else, the research may leave modern Australians feeling relieved that today’s kangaroos are far smaller than their massive, Ice Age ancestors.
Chrissy Newton is a PR professional and the founder of VOCAB Communications. She currently appears on The Discovery Channel and Max and hosts the Rebelliously Curious podcast, which can be found on YouTube and on all audio podcast streaming platforms. Follow her on X: @ChrissyNewton, Instagram: @BeingChrissyNewton, and chrissynewton.com. To contact Chrissy with a story, please email chrissy @ thedebrief.org.