Huge Extinct Kangaroo Wasn't a Hopper

Huge, now extinct, kangaroos that roamed the Australian outback 100,000 years ago weren't hoppers, despite the popular connotation, but had bones made for walking instead, a new study shows.

These "short-faced" sthenurine kangaroos, three times the size of today's modern marsupials, in fact lumbered along on two legs just like they were humans. Weighing in at more than 500 pounds, it's no wonder researchers thought it unlikely that these beasts had the biological hardware needed for hopping around.

Christine Janis, professor of ecology and evolutionary biology at Brown University, led a team that analyzed the limb bones of the rabbit-faced kangaroos, and compared them with the anatomy of their modern relatives. The team discovered that the extinct species had hind limbs and spines different from the red and grey kangaroos of today, which suggested that they didn't have the leg power to support its giant body during hopping.

So, the researchers believe that its bones were made for walking instead. The anatomy of the ancient kangaroo indicates that it maintained an upright posture and its body could support one leg at a time, thanks to its larger hips and knees and its stabilizing ankles. A bipedal stride was likely the only way they could handle their own weight.

"I don't think they could have gotten that large unless they were walking," Janis said in a press release. "We need to consider that extinct animals may have been doing something different from any of the living forms, and the bony anatomy provides great clues."

Not to mention that sthenurines were also different in that they had teeth for browsing for food, rather than grazing, like the large kangaroos of today.

Whether any of the sthenurines still hopped to attain fast speeds, Janis said, remains to be seen, but they at least used bipedal walking for moving at a slower pace.

It's also quite possible that their poor hopping skills even led to their demise some 30,000 years ago. By gently plodding along, the giant animals may have made themselves easy targets for hunters who could easily out-maneuver them.

The team's findings can be found in the journal PLOS ONE.