New robot shows how first land animals moved 360 mln years ago

Scientists have developed a robot that shows how early terrestrial animals began moving about on mud and sand 360 million years ago.
Animals would have used modified fins to move around on flat surfaces, but for climbing sandy slopes, the animals could have benefited from using their tails to propel themselves forward, the researchers found.
The findings may help designers create amphibious robots able to move across granular surfaces more efficiently - and with less likelihood of getting stuck in the mud.
Scientists from the Georgia Institute of Technology, Clemson University and Carnegie Mellon University in the US studied the African mudskipper fish and developed of a robot model that used the animal's locomotion techniques.

The study also examined flow and drag conditions in representative granular materials, and applied a mathematical model incorporating new physics based on the drag research.
"Most robots have trouble moving on terrain that includes sandy slopes," said Dan Goldman, an associate professor in the Georgia Tech School of Physics.

"We noted that not only did the mudskippers use their limbs to propel themselves in a kind of crutching motion on sand and sandy slopes, but that when the going got tough, they used their tails in concert with limb propulsion to ascend a slope," Goldman said.
"Our robot model was only able to climb sandy slopes when it similarly used its tail in coordination with its appendages," he said.

Based on fossil records, scientists have long studied how early land animals may have gotten around, and the new study suggests their tails - which played a key role in swimming as fish - may have helped supplement the work of fins, especially on sloping granular surfaces such as beaches and mudflats.
"We were interested in examining one of the most important evolutionary events in our history as animals: the transition from living in water to living on land," said Richard Blob, from Clemson University.
Researchers recorded how the mudskippers (Periopthalmus barbaratus) moved on a variety of loose surfaces.
The small fish, which uses its front fins and tail to move on land, live in tidal areas near shore, spending time in the water and on sandy and muddy surfaces.

Researchers applied the principles to a robot model known as MuddyBot that has two limbs and a powerful tail, with motion provided by electric motors.
Information from both the mudskipper and robotic studies were also factored into a mathematical model provided by researchers at Carnegie Mellon University.
Using their "fins" alone, both the mudskippers and the robot struggled to climb slopes and often slid backward if they didn't use their tails, researchers said.
Early land animals likely did not have precise control over their limbs, and the tail may have compensated for that limitation, helping the animals ascend sandy slopes.

The study was published in the journal Science.