Research by international scientists has discovered fossils of what may be the earliest four-legged backboned animals to walk on land.

The lizard-like creatures lived about 355 million years ago, when the ancestors of modern reptiles, birds and mammals emerged from swamps. The discovery plugs a 15 million-year gap in the fossil record.

There are five complete fossils and many more fragments of bones that have yet to be classified. Some resemble lizards or newts, while others are larger, with almost crocodile-like proportions.

The research was carried out by experts from the University Museum of Zoology Cambridge, the University of Leicester, the National Oceanography Centre University of Southampton, National Museums Scotland, the British Geological Survey, and the School of Life Sciences here at the University of Lincoln.

Dr Marcello Ruta from the School of Life Sciences contributed to the phylogenetic analysis of the fossils.

The team’s scientific paper detailing their findings was published in Nature’s Ecology & Evolution journal.