Polish scientists have uncovered the oldest fossilised footprints made by a four-legged creature.
The discovery may lead to a radical change in current theories on when fish first crawled out of the water and onto land.
The footprints were found in the Holy Cross Mountains in south-east Poland and are thought to be some 395-million years old, 18 million years older than previous finds.
The tetrapods tracks have distinctive front and back foot prints and show no evidence of a dragging body, they also indicate that the animal was around 2.5 metres in length.
Researchers claim the prints contradict all accepted theories on the evolution of early four-legged land dwellers.