Scientists uncover a mysterious Jurassic lizard with snake-like jaws

A "False Snake" From Scotland

The new species was named Breugnathair elgolensis, meaning "false snake of Elgol" in Gaelic, after the region on Scotland's Isle of Skye where it was unearthed. Breugnathair had snake-like jaws and sharply curved teeth similar to those of modern pythons, yet its body remained short and equipped with well-developed limbs like a typical lizard.

"Snakes are remarkable animals that evolved long, limbless bodies from lizard-like ancestors," said the study's lead author Roger Benson, Macaulay Curator in the American Museum of Natural History's Division of Paleontology. "Breugnathair has snake-like features of the teeth and jaws, but in other ways, it is surprisingly primitive. This might be telling us that snake ancestors were very different to what we expected, or it could instead be evidence that snake-like predatory habits evolved separately in a primitive, extinct group."

Rewriting the Squamate Family Tree

Snakes and lizards together make up the reptile group known as squamates. The researchers placed Breugnathair in a newly defined branch of extinct predatory squamates called Parviraptoridae, which was previously known only from incomplete fossils. Earlier finds had suggested that bones with snake-like teeth and others with gecko-like features came from different animals. However, the new analysis of Breugnathair shows that both sets of features existed in the same species, uniting them in one unexpected creature.

The fossil was first discovered in 2016 by Stig Walsh from the National Museums Scotland during an expedition with Benson and colleagues on the Isle of Skye. Since then, the team has spent nearly a decade studying it, using advanced imaging techniques such as computed tomography and powerful X-rays at the European Synchrotron Radiation Facility in Grenoble, France.

A Window Into Early Reptile Evolution

"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," said Susan Evans from University College London, who co-led the study. "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 specialized features we find in parviraptorids, as demonstrated by this new specimen, is an important reminder that evolutionary paths can be unpredictable."

Nearly 16 inches 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. But is it a lizard-like ancestor of snakes? Because it has such an unusual mixture of features, and because other fossils that shed light on early squamate evolution are rare, the researchers did not arrive at a conclusive answer. Another possibility is that Breugnathair could be a stem-squamate, a predecessor of all lizards and snakes, that independently evolved snake-like teeth and jaws.

"This fossil gets us quite far, but it doesn't get us all of the way," Benson said. "However, it makes us even more excited about the possibility of figuring out where snakes come from."

Other study authors include Zoe Kulik from the American Museum of Natural History, Elizabeth Griffiths Jason Head from the University of Cambridge, Jennifer Botha from the University of the Witwatersrand, South Africa, and Vincent Fernandez from the European Synchrotron Radiation Facility.

Funding was provided, in part, by the National Research Foundation, Genus: DSTI-NRF Centre of Excellence in Palaeosciences, and the Palaeontological Scientific Trust.