The familiar image of kangaroos bounding through the Australian landscape is, as it turns out, perhaps an understatement when considering the Pleistocene era.
Recent research conducted by a collaborative group of scientists from esteemed institutions in the UK – the Universities of Manchester and Bristol – alongside the University of Melbourne in Australia, has yielded fascinating insights. These researchers have determined that colossal kangaroos, conjectured to have possessed more than double the mass of their extant counterparts, were indeed capable of locomotion via bounding, should the circumstances necessitate it.
In a manner consistent with many global fauna from bygone epochs, Australia’s wildlife exhibited significantly greater dimensions in antiquity. Specifically, the most substantial known kangaroo species, identified as Procoptodon goliah, is estimated to have reached a stature of 2 meters (approximately 6.6 feet) and potentially weighed as much as 250 kilograms (around 550 pounds). This remarkable size dwarfs the comparatively modest 90-kilogram frame of contemporary kangaroos.
The prevailing assumption regarding this augmented body mass was that it would have rendered hopping an unviable mode of transport, posing an untenable strain on the Achilles tendons. Consequently, the prevalent theory posited that these ancestral marsupials navigated their environment with a gait that bore an uncanny, and perhaps amusing, resemblance to human locomotion.
However, a contemporary anatomical investigation now proposes that, contrary to prior beliefs, these megafauna were indeed capable of bounding, at least for brief durations.
The investigative team meticulously scrutinized the skeletal elements of the limbs from a diverse collection encompassing 63 species of kangaroos and wallabies, including both extant and extinct varieties. This analysis comprised 94 modern specimens alongside 40 fossilized remains.
Leveraging contemporary species as a comparative framework, the researchers extrapolated the requisite size and robustness of tendons that would have been necessary to withstand the biomechanical stresses imposed by hopping on the pedal extremities of these gargantuan kangaroo lineages. Subsequently, an examination of their calcaneus (heel bones) was conducted to ascertain the presence of appropriate anatomical anchors for tendons of such magnitude.
Furthermore, the researchers meticulously measured the dimensions of the fourth metatarsals – the crucial foot bones susceptible to fracture under torsional forces during a propulsive leaping motion.
The findings were conclusive: all examined ancient species appeared to possess the requisite anatomical adaptations for hopping. The calcanei exhibited sufficiently substantial points of insertion to accommodate robust tendons, and the metatarsals demonstrated the structural integrity to endure the significant forces involved. This structural evidence implies that the remainder of their hindlimb anatomy would have been equally well-equipped.
Nevertheless, the mere possibility of hopping does not equate to its frequent utilization by these prehistoric behemoths as they traversed the open expanses, akin to their more agile modern descendants. Instead, it is probable that their preferred method of ambulation involved a more deliberate, quadrupedal-like gait, reserving bursts of speed for navigating challenging topography or evading predatory threats, drawing parallels to the locomotion of a “furry T. rex.”
“While hopping may not have constituted their primary means of movement, our findings indicate that it could have been integrated into a broader spectrum of locomotive strategies, for instance, enabling short-duration acceleration,” the research team articulated in their publication.
This comprehensive study was formally disseminated within the peer-reviewed journal Scientific Reports.
