In 1992 off the coast of Ireland, a Swiss geology student accidentally discovered the longest set of footprints made by the first four-legged animals to walk on earth.

They pointed to a new date for the key milestone in evolution when the first amphibians left the water 385 million years ago. The salamander-type animal which was the size of a basset hound lived when County Kerry was semi-arid, long before dinosaurs, as Iwan Stössel explains to Josephine McDermott.

(Picture: Artwork of a primitive tetrapod. Credit: Christian Jegou/Science Photo Library)