The giant, bipedal kangaroos that walked like humans instead of hopping across Australia

Nature · Published 3 October 2026 Swipe more like this →

In short: Sthenurus, a genus of extinct kangaroos, were massive creatures reaching 240 kilograms. Unlike their modern, hopping relatives, these giants possessed a robust, monodactyl skeletal structure that suggests they moved by walking bipedally. They navigated ancient Australian landscapes alongside early humans, yet their rigid dietary habits likely sealed their fate.

Sthenurus, meaning strong tail, represented a significant departure from the kangaroos we recognize today. While modern species are defined by their hopping locomotion, the largest Sthenurus species were likely too heavy for such movement. Instead, their anatomy—featuring a broad pelvis and powerful hind limbs—suggests they walked on two legs in a manner reminiscent of hominids. This gait was likely reserved for slow travel, as hopping would have been inefficient for animals that could grow to three meters in length.

The genus displayed remarkable cranial and dental specializations. Their short, deep skulls provided stereoscopic vision, granting them superior depth perception compared to living macropodids. Their teeth were heavily enamelled and featured distinct striations, allowing them to process tough vegetation. Interestingly, while their environments shifted from lush, browse-heavy landscapes to drier, grass-dominated plains over thousands of years, the genus showed little anatomical or dental flexibility to accommodate these dietary transitions.

The extinction of Sthenurus remains a subject of investigation. Evidence from sites like Cuddie Springs confirms that they shared habitats with early Native Australians. While some researchers have explored the possibility that human interaction contributed to their decline, the absence of specialized hunting tools and the presence of butchery marks suggest a complex relationship. Ultimately, many experts point toward the significant climate shifts of the era as a primary driver of extinction. Because these herbivores failed to adjust their feeding behaviors as the continent dried and vegetation changed, they were left vulnerable to the environmental pressures that reshaped the Australian megafauna.

The diversity within the genus was substantial, with multiple species often coexisting in the same regions. At Lake Callabonna, for instance, three distinct species—S. stirlingi, S. tindalei, and S. andersoni—were found together. These fossils reveal a unique evolutionary path, marked by monodactyl feet and reduced lateral digits, which set them apart from the Macropodinae subfamily. These adaptations highlight a specialized lineage that thrived for millions of years before disappearing from the fossil record.

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