Fossil found in London museum cupboard moves lizard origins back 35 million years

Discovery at Natural History Museum shows the reptiles were living during the Late Triassic period

A CT scan showing the fossilised lizard's head, next to the Cryptovaranoides microlanius fossil itself. Photo: Natural History Museum UK

A fossil found hidden in a cupboard at London's Natural History Museum has shifted the origins of the modern lizard back 35 million years.

The scientist behind the discovery believes it is one of the most important finds in this field in the past few decades.

The fossilised relative of living lizards — such as monitors, the gila monster and slow worms — was identified in a stored museum collection originally discovered in the 1950s in a quarry near the village of Tortworth, in Gloucestershire, south-west England.

It had previously been thought that lizards originated in the Middle Jurassic period, between about 174.1 million and 163.5 million years ago.

But the Tortworth fossil indicates they were already around in the Late Triassic period — between about 237 million and 201.3 million years ago.

“This is a very special fossil and likely to become one of the most important found in the last few decades,” David Whiteside, research associate at the University of Bristol’s School of Earth Sciences, said.

“It is fortunate to be held in a national collection, in this case the Natural History Museum, London.

Mr Whiteside paid tribute to the palaeontologist who uncovered the fossil in the mid-20th century.

“We would like to thank the late Pamela L Robinson who recovered the fossils from the quarry and did a lot of preparation work on the type specimen and associated bones.

“It was such a pity she did not have access to CAT scanning technology to help her observe all the detail of the specimen.”

The discovery now means all estimates of the origin of lizards and snakes, together called the Squamata order of reptiles, will be affected, as will assumptions about their rates of evolution.

The team, led by Mr Whiteside, has named their discovery Cryptovaranoides microlanius, meaning "small butcher" in tribute to its jaws that were filled with sharp-edged slicing teeth.

“I first spotted the specimen in a cupboard full of Clevosaurus fossils in the storerooms of the Natural History Museum in London, where I am a scientific associate,” Mr Whiteside said.

“[Clevosaurus] was a common enough fossil reptile, a close relative of the New Zealand tuatara that is the only survivor of the group, the Rhynchocephalia, that split from the squamates over 240 million years ago.

“Our specimen was simply labelled 'Clevosaurus and one other reptile'.

"As we continued to investigate the specimen, we became more and more convinced that it was actually more closely related to modern day lizards than the tuatara group.

“We made X-ray scans of the fossils at the university, and this enabled us to reconstruct the fossil in three dimensions, and to see all the tiny bones that were hidden inside the rock.”

Co-author Prof Mike Benton, also of the University of Bristol’s School of Earth Sciences, said the lizard would have lived at a time when major restructuring of ecosystems was taking place.

“In terms of significance, our fossil shifts the origin and diversification of squamates back from the Middle Jurassic to the Late Triassic,” he said.

“This was a time of major restructuring of ecosystems on land, with origins of new plant groups, especially modern-type conifers, as well as new kinds of insects, and some of the first of modern groups, such as turtles, crocodilians, dinosaurs and mammals.

“Adding the oldest modern squamates then completes the picture.”

“It seems these new plants and animals came on the scene as part of a major rebuilding of life on Earth after the end-Permian mass extinction 252 million years ago.”