A prehistoric creature that clambered across mud near a watering hole millions of years ago has provided the earliest known evidence of reptiles.

The ancient lizard left a trail of footprints in soft mud that quickly became covered in sediment, preserving its imprints for 315 million years.

It was the first creature with a backbone to develop the ability to breed out of water and paved the way for reptiles to inhabit dry environments and take over from amphibians.

“We are seeing the dawn of the exploration of the continent. These were the first pioneers,” said Howard Falcon-Lang, of the University of Bristol, who found the footprints. “The evolution of reptiles is one of the most important events in the history of life. By acquiring the reptile egg you free yourself from the reproductive necessity of returning to a pond to spawn.”

Hundreds of prints were found in rocks in New Brunswick, Canada. Analysis showed that most were left by amphibians but some were created by the reptile Pseudobradypus. The discovery, reported in the Journal of the Geological Society of London, predates that of the earliest known reptile by up to five million years. Pseudobradypus is thought to be the same as Hylonomus – previously the oldest known species. Until the prints can be linked to fossil skeletons they are officially regarded as two species.

The prints were distinct from those of amphibians because of faint impressions of horny scales in the rock. Professor Mike Benton, also of the University of Bristol, said: “There were only a few species capable of making prints like this. However, the prints showed that the hands had five fingers and scales, sure evidence that they were made by reptiles.”

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