About 385 million years ago, a primitive vertebrate walked through the muddy coastline of Ireland's Valentia Island, dragging its lizard-like tail behind it as it climbed ashore. Incredibly, the tracks it left behind were preserved and can still be seen today, a snapshot of one of the very first transitions of life from the sea to the land.
These prehistoric footprints were preserved by silt and turned to rock over the years, and today the petrified Tetrapod Trackway is among the oldest evidence in the world of four-legged vertebrates—animals with backbones—walking on land. These early amphibians, of course, eventually evolved into mammals, and ultimately into humans.
The Tetrapod Trackway on Valentia Island have been dated to the Devonian Period and are between 350 million and 370 million years old. It is one of four similar trackways currently existing in the world: There are others in Tarbet Ness, Scotland; Genoa River, NSW Australia; and Glen Isla, Victoria Australia.