When early terrestrial animals began moving about on mud and sand 360 million years ago, the powerful tails they used as fish may have been more important than scientists previously realized. That’s one conclusion from a new study of African mudskipper fish and a robotic model inspired by the animal. Animals analogous to the mudskipper would have used modified fins to move around on flat surfaces, but for climbing sandy slopes, the animals needed to use their tails to propel themselves forward, the research