A fossil discovered in Scotland has revealed a new species and family of Jurassic reptile linked to the origins of lizards and snakes, reports a study co-led by a UCL researcher.
Published in Nature by an international team including researchers at UCL, the American Museum of Natural History, National Museums Scotland and colleagues in the UK, France and South Africa, the study describes a previously unknown Jurassic reptile that lived around 167 million years ago. The species has been given the Gaelic name Breugnathair elgolensis, meaning 'false snake of Elgol', referencing the area of the Isle of Skye where it was discovered.
Breugnathair had snake-like jaws and highly curved teeth, similar to those of modern-day pythons. Unlike living snakes, it had the proportions and limbs of lizards such as a gecko. The fossil is among the oldest and most complete Jurassic lizards known to science.
Lizards and snakes together form a group called squamates. Breugnathair has been categorised in a group of extinct, predatory squamates called Parviraptoridae, which was previously known only from more fragmentary fossils initially described by UCL Professor Susan Evans.
Earlier fossil studies reported snake-like tooth-bearing bones that were found in close proximity with bones that had gecko-like features. But because these seemed so drastically different, some researchers believed they belonged to two different animals. The new work on Breugnathair rejects those earlier findings, showing that both snake-like and gecko-like features exist together in a single animal.
Breugnathair might therefore provide evidence of the lizard-like ancestors of snakes, but it also has primitive anatomical traits suggesting that parviraptorids were stem-squamates, the predecessors of all lizards and snakes.
Professor Susan Evans, Director of the UCL Centre for Integrative Anatomy, UCL Division of Biosciences and co-lead author of the Nature paper, said: "The Jurassic fossil deposits on the Isle of Skye are of world importance for our understanding of the early evolution of many living groups, including lizards which were beginning their diversification at around this time.
"I first described parviraptorids some 30 years ago based on more fragmentary material, so it's a bit like finding the top of the jigsaw box many years after you puzzled out the original picture from a handful of pieces. The mosaic of primitive and specialised features we find in parviraptorids, as demonstrated by this new specimen, is an important reminder that evolutionary paths can be unpredictable."
Co-lead author Dr Roger Benson, Curator of Paleontology at the American Museum of Natural History, said: "Snakes are remarkable animals that evolved long, limbless bodies from lizard-like ancestors. Breugnathair has snake-like feature of the teeth and jaws, but in other ways is surprisingly primitive. This might be telling us that snake ancestors were very different to what we expected, or it could instead be evidence for evolution of predatory habits in a primitive, extinct group."
Close to 40cm long from head to tail, Breugnathair was one of the largest lizards in its ecosystem, where it likely preyed on smaller lizards, early mammals, and other vertebrates, like young dinosaurs.
The fossil was discovered in 2016 near Elgol, on the Isle of Skye, by National Museums Scotland curator Dr Stig Walsh, and it is now part of the Museum's collection. The researchers have spent almost 10 years since then preparing the specimen, imaging it with computed tomography as well as with high-powered x-rays at the European Synchrotron Radiation Facility in Grenoble, France, and analysing the results.
Co-author Dr Stig Walsh, Senior Curator of Vertebrate Palaeobiology at National Museums Scotland, said: "The Isle of Skye is one of the most important Middle Jurassic sites in the world. Breugnathair elgolensis is a remarkable addition to the fossil record, helping to rewrite our understanding of the evolution of snakes and lizards. We're delighted to add it to the other amazing finds in the National Collection that were discovered in Skye, truly Scotland's Jurassic Isle."
