Along with their two front and hind legs, kangaroos often use their tail as a 'fifth leg' which helps them maintain their gait, a new study reveals.
According to the study by researchers at Simon Fraser University showed that the animals move with a "pentapedal" gait, which provides new insight into the diversity of biological movement, and specific insight into why humans walk the way they do.
Lead researcher Max Donelan of SFU's Locomotion Laboratory said that they measured the forces the tail exerts on the ground and calculated the mechanical power it generates, and found that the tail is responsible for more propulsive force than the front and hind legs combined.
Donelan said that the tail also generates almost exclusively positive mechanical power, performing as much mechanical work as a human leg when walking at the same speed. Their muscular tail is used to propel and power their motion-just like a leg.
The researchers also said that one of the central findings of our human walking research is that it is very important to time the push-off of your back leg to make walking less effortful.
The study found that the tail is anatomically quite different, being made up of more than 20 vertebrae taking on the roles of our feet, calves and thigh bones.
The study was published in the Royal Society journal Biology Letters.