Ancient, Extinct Kangaroos Walked on Two Legs Instead of Hopped

Not all kangaroo families liked to hop. Scientists have discovered an ancient kangaroo that lived 100,000 years ago that walked on two legs like a human rather than hopping or lumbering away on all fours.

The new findings come after researchers further examined Pleistocene members of a now-extinct family of sthenurine kangaroos. The scientists first began their investigations after looking at a sthenurine skeleton that seemed to display a sturdy rather than flexible-looking spine. This seemed to indicate that the ancient species moved differently than modern kangaroos.

That's why the researchers decided to examine the kangaroo a bit closer. The scientists made nearly 100 measurements on more than 140 individual kangaroo and wallaby skeletons from many genera and species. They found that on statistical plots charting trait after trait of hind limb bones, sthenurines stood apart from the modern grey kangaroos.

In fact, it's likely that the anatomy of all sizes of sthenurines would have made them poor hoppers. For especially giant species, one of which probably weighed as much as 550 pounds, hopping would have been especially hard. In fact, it's very likely that these large species walked.

"If it is not possible in terms of biomechanics to hop at very slow speeds, particularly if you are a big animal, and you cannot easily do pentapedal locomotion, then what do you have left?" asked Christine Janis, one of the researchers, in a news release. "You've got to move somehow."

Currently, the researchers are unsure whether this reliance of walking, which isn't as fast as efficient or as suited for long distances as hopping, may explain why sthenurines became extinct 30,000 years ago. However, it's possible that walking made it difficult for the ancient creatures to avoid human hunters.

While the research seems to point to bipedal walking for these animals, the scientists point out that more research should be conducted. For now, though, it appears that these kangaroos were specialized for walking-not hopping.

The findings are published in the journal PLOS One.