The tiny skeleton discovered on the Isle of Skye, called Bellairsia gracilis, is only 6 cm long and dates from the Middle Jurassic, 166 million years ago. The exceptional new fossil comprises a near-complete skeleton in life-like articulation, missing only the snout and tail. This makes it the most complete fossil lizard of this age anywhere in the world. Bellairsia has a mixture of ancestral and modern features in its skeleton, providing evidence of what the ancestor of today’s lizards (which are part of the wider animal group known as 'squamates') might have looked like.

The research, a joint project between researchers at the universities of Warsaw, Oxford and UCL. First author Dr Mateusz Talanda (University of Warsaw and UCL) said: “This little fossil lets us see evolution in action. In palaeontology you rarely have the opportunity to work with such complete, well-preserved fossils coming from a time about which we know so little.” Analysing the new fossil alongside living and extinct fossil squamates confirms Bellairsia belongs to the 'stem' of the squamate family tree. This means that it split from other lizards just before the origin of modern groups. The research also supports the finding that geckos are a very early branching lineage, and that the enigmatic fossil Oculudentavis, previously suggested to be a dinosaur, is also a stem squamate.