Procoptodon Goria: The 2-Meter Tall Kangaroo Credit: Michael Long/Science Photo Library
New bone analysis suggests even the colossal kangaroos of ancient Australia might have been capable of jumping.
During the Pleistocene, some kangaroos weighed over twice as much as today’s species. One subset, the Stenurines, reached such enormous sizes that their ability to jump was doubted, leading researchers to believe they primarily walked on their hind legs.
“When discussing giant kangaroos, the stenurines are a frequent topic,” says Megan Jones from the University of Manchester, UK. “These unique kangaroos feature very short, box-shaped skulls and one toe on each foot. The largest male red kangaroos today average around 90 kilograms, while the biggest stenulin weighed nearly 250 kilograms.”
Among these giants is Procoptodon Goria, the most significant kangaroo species, standing approximately 2 meters tall and going extinct around 40,000 years ago.
Debate has persisted regarding the stress on their feet, prompting Jones and her team to analyze bone measurements from 67 macropod species—encompassing modern kangaroos, wallabies, potoroos, beetongs, rat kangaroos, and extinct giant kangaroos.
They measured leg bones (including the femur, tibia, and calcaneus) and gathered body weight data to estimate tendon sizes and their endurance under stress.
“The kangaroo’s Achilles tendon is on the brink of rupture but serves a vital role,” states Jones. “It enables kangaroos to store elastic energy for the next jump. Simply scaling today’s kangaroo would present challenges.”
Yet, ancient kangaroos weren’t merely massive. With shorter legs and wider calcaneus bones, their structure mitigated bending influences during hopping, allowing for larger tendons capable of withstanding the corresponding forces.
“This evidence indicates they weren’t mechanically restricted from jumping,” asserts Jones. “Whether they actually jumped, however, is a different question.”
While hopping likely wasn’t their primary locomotion mode, it might have been used sporadically for rapid movement, Jones explains.
This study reinforces the view that the iconic kangaroo hop is likely an adaptable feature within a surprisingly varied locomotor repertoire, according to Benjamin Kia from Uppsala University, Sweden. Over millions of years, this versatility has contributed to the ecological triumph of macropods.
The flexibility remains clear today; red kangaroos, often perceived as constant hoppers, can also utilize their tails as a fifth limb for walking. “Tree kangaroos exhibit diverse locomotion styles—they walk, jump, bounce, and can even move on two legs,” adds Jones.
Topics:
- Evolution/
- Animal Behavior
Source: www.newscientist.com
