Ancient kangaroos could not hop

An artist's rendering shows a big-bodied, short-faced kangaroo called a sthenurine that lived in Australia from about 13 million years ago until about 30,000 years ago, in this undated handout. Scientists said on October 15, 2014, that a biomechanical and statistical analysis of fossil bones of a group of huge extinct kangaroos showed that the largest of the bunch in all likelihood could not hop as well as their modern-day relatives. REUTERS/Brian Regal/Brown University/Handout via Reuters (UNITED STATES - Tags: SCIENCE TECHNOLOGY ANIMALS) ATTENTION EDITORS - NO SALES. NO ARCHIVES. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS

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

Scientists said on Wednesday that a biomechanical and statistical 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, disappearing after the first humans arrived on the continent.

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

The study found important anatomical differences in sthenurines’ limb bones compared with other kangaroos.

They likely walked in an upright bipedal stance — putting one foot in front of the other, just like people — in a way modern kangaroos cannot, the study found. This was facilitated by larger hips and knee joints as well as stabilized ankle joints. They also had a relatively inflexible spine not conducive for hopping.

Brown University palaeontologist Christine Janis led the study, published in the scientific journal PLOS ONE. She said she suspected smaller sthenurines used bipedal walking at slow speeds and may have switched to hopping at faster speeds.