Extinct kangaroos may not have 'hopped'

A new study has found that extinct giant kangaroos may have walked instead of hopping their way.

The "short-faced," large-bodied sthenurine kangaroos, a now extinct relative to modern-day kangaroos, had first appeared in the middle Miocene and became extinct in the late Pleistocene. The largest of these kangaroos had an estimated body mass of 240 kg, almost three times the size of the largest currently living kangaroos.

Scientists speculate that kangaroo of such size may not have been physically able to hop. Analysis of different sthenurine species limb bones when compared to other kangaroos showed a number of anatomical differences, especially in the larger species.

The physical differences suggest that the large kangaroo species lacked many specialized features for rapid hopping, but had anatomy suggesting they supported their body with an upright posture and were able to support their weight on one leg at a time using their larger hips, knees, and stabilized ankle joints.

The authors posit that sthenurines adopted a walking gait on two hind legs, in the smaller and earlier forms, which may have been used as an alternative gait to using the tails as fifth limb at slower speeds. Larger Pleistocene kangaroos may have used this gait exclusively as they evolved larger body sizes, where hopping rapidly was no longer a possible option.

The study is published in the open-access journal PLOS ONE.