Researchers from a major British university have revisited the fossil record of Australia’s Pleistocene megafauna, focusing on the giant kangaroos and their close relatives that inhabited Australia and nearby islands between about 2.5 million and 10,000 years ago. The team’s findings challenge the long-held assumption that the earliest ancestors of modern kangaroos and wallabies possessed an inherent talent for hopping. Their conclusions come from a careful analysis of skeletal remains across multiple sites, shedding light on how these ancient creatures moved and what their bodies could endure during life in diverse ancient landscapes.
Among the most striking discoveries is the size and mass of these giants. Protemnodons, as they are known, could reach roughly two meters in height and tipped the scales at about 170 kilograms. That body plan is roughly double the mass of today’s living kangaroos and wallabies, yet the bones tell a story about different mechanical demands placed on movement and balance. The researchers emphasize that such heft would have demanded unique musculoskeletal arrangements to support stability, energy efficiency, and locomotor control in a world without the same plant resources or predator dynamics seen in modern ecosystems.
Earlier investigations had already suggested that the ankle joints of Protemnodon bore strain patterns inconsistent with hopping. The latest work extends this view by comparing ankle and leg structures with broader limb proportions, revealing patterns that diverge significantly from those of contemporary kangaroo species. This mismatch implies that hopping, as known today, did not evolve in the same way for these ancient giants and may not have been a primary mode of locomotion for them in their environment.
In place of a hopping-centric design, the fossil record reveals a suite of proportions that point to a different locomotor strategy. Protemnodon limbs show a distinctive distribution of muscle leverage and joint angles that would have supported more stable, ground-dominant movement. The giant kangaroos appear to have integrated a heavier, more robust limb framework, allowing for steady ambulation and powerful strides while navigating the varied terrains of their era. This interpretation aligns with the observed fossil cues that leg bones did not optimize for repeated, high-impact leaps but rather for controlled, consistent support over long distances.
A close look at other extinct relatives, such as the stenurines, adds another layer to the narrative. These creatures, while also standing upright on their hind limbs, seem to have favored two-footed gaits that were more about walking than hopping. This diversity within the same broad family underscores a landscape where multiple modes of travel coexisted, likely reflecting a mosaic of habitats—from open plains to denser scrub and rocky outcrops—that demanded different physical adaptations to exploit available food sources and evade threats.
Experts interpret this variety as evidence that prehistoric Australia presented a range of environmental conditions that shaped locomotive decisions among large marsupials. Instead of a single, uniform hopping tactic emerging for all big kangaroos, the record suggests a broader experimentation with movement. Such differences would have been advantageous in a setting characterized by shifting climate patterns, patchy vegetation, and a patchwork of ecological niches that rewarded flexible bodies and adaptable gaits. This nuanced view helps explain why modern kangaroos and wallabies, with their familiar hopping rhythm, occupy a different niche in today’s ecosystems.
As paleontologists expand their search for new subterranean forms, discoveries continue to reshape how scientists understand Australia’s ancient fauna. The study of underground-dwelling species that dug holes and tunnels adds to the broader context of how ancient creatures adapted to living underground and exploiting the subsurface environment. By comparing these lineages, researchers gain a clearer picture of the evolutionary pressures that guided limb design, posture, and locomotion in a continent known for its remarkable assortment of large marsupials and its complex array of habitats.