Strewth! Kangaroos that walked like Bruce

Kangaroos hop, right? Well, not all of them.

Scientists said on Wednesday that analysis of fossil bones of a group of huge extinct kangaroos shows that the largest of the bunch in all likelihood could not hop as their modern-day relatives do.

The study focused on a group of big-bodied, short-faced kangaroos called sthenurines that lived in Australia from about 13-million years ago until about 30 000 years ago.

These kangaroos were more heavily built than modern ones and had faces reminiscent of a rabbit. The largest, a species called Procoptodon goliah, weighed about 240kg, stood 2m tall and was 3m long.

The study found important differences in sthenurines' limb bones compared with other kangaroos, making their anatomy ill-suited for hopping.

They likely walked in an upright bipedal stance - putting one foot in front of the other, just like people, the study found.

This was facilitated by larger hips and knee joints as well as stabilised ankle joints. They also had a relatively inflexible spine not conducive to hopping.

Brown University palaeontologist Christine Janis, who led the study, said she suspected smaller sthenurines used bipedal walking at slow speeds and may have switched to hopping at faster speeds.

"But the largest ones may have walked rather than hopped most if not all of the time."