Very little is still known about when the earliest animals left the seas to colonise the land. But new evidence has been unearthed by scientists that give us some clues in the form of the earliest known fossil footprints of four-legged creatures ever found.
The discovery of these fossilised tracks that were left 395 million years ago by animals up to eight feet long has been hailed as a 'missing link' in the transition of life from water to dry land. The discovery has amazed scientists as these unique footprints date to around 18 million years before it was thought that four-limbed vetebrates known as tetrapods were known to have existed.
These fossil footprints were left in the mud in the shallow waters of an ancient marine lagoon, and were discovered by scientists in the Holy Cross Mountains in south-eastern Poland and have 'hand' and 'foot' shapes but show no evidence of a dragging body. Scientists believe that tetrapods evolved from fish through an intermediate type of animal known as elpistostogids that retained many fish-like characteristics such as paired fins instead of feet and hands even though they had evolved tetrapod body and head shapes.
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