New research challenges the idea that massive Ice Age kangaroos were too heavy to hop. Scientists found that these animals, weighing up to 250 kilograms, had leg bones and tendons capable of supporting short bursts of hopping. This ability likely helped them evade predators.
A study published in Scientific Reports indicates that extinct giant kangaroos from the Pleistocene epoch, which spanned from 2.6 million to 11,700 years ago, possessed the biomechanical capacity for hopping despite their enormous size. Researchers Megan E. Jones, Katrina Jones, and Robert L. Nudds analyzed hindlimbs from 94 modern kangaroo and wallaby specimens alongside 40 fossils from 63 species, including the genus Protemnodon.
The team focused on the fourth metatarsal, a crucial foot bone for hopping in contemporary kangaroos. By measuring its length and diameter against body weight estimates, they determined that these bones could endure the stresses of hopping. Additionally, comparisons of heel bones suggested that the Achilles tendons in giant kangaroos were sufficiently robust to handle the forces involved.
Previous studies had claimed that kangaroos exceeding 160 kilograms lacked the ankle strength for such movement, portraying them as slow and grounded. However, this new evidence shows their hindlimbs were mechanically equipped for occasional hopping, though not for sustained travel, which would have been inefficient for such large bodies.
The authors propose that brief hopping bursts served a defensive purpose, allowing these animals to flee from threats like the extinct marsupial lion Thylacoleo. Observations of hopping in smaller modern species, such as rodents and marsupials, support the plausibility of this behavior in giants. This finding reframes our understanding of how these Pleistocene megafauna navigated their environment, highlighting adaptability in locomotion amid a changing Ice Age landscape.
The research underscores the importance of fossil analysis in uncovering lost behaviors, offering insights into the evolutionary pressures on ancient marsupials.
