A breed of kangaroos that walked the earth 30 million years ago were too heavy to hop, a new study has revealed.
The sthenurines branch of mega-fauna grew up to 2.7m high and tipped the scales at a whopping 240kg — too big to jump around, a report published in PLoS One claims.
Instead the giant kangaroos moved their hind-limbs one at a time like a human, with a more rigid body structure thanks to larger hips and knees.
"People often interpret the behaviour of extinct animals as resembling that of the ones known today but how would we interpret a giraffe or an elephant known only from the fossil record?" Brown University academic Christine Janis said.
"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."
The giant kangaroos also had shorter snouts than their modern miniatures.
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