Fossil found in closet shows lizards are millions of years older than previously thought

The fossil showing the skull and skeleton of the specimen (David Whiteside, Sophie Chambi-Trowell, Mike Benton and Natural History Museum UK)

A fossil found in a cupboard at the Natural History Museum in London has pushed the origins of lizards back millions of years.

The specimen demonstrated that modern lizards originated in the Late Triassic and not the Middle Jurassic as previously thought.

This fossilized relative of living lizards — such as monitor lizards, gila monsters, and slowworms — was identified in a museum collection preserved in the 1950s.

It included specimens from a quarry near Tortworth in Gloucestershire. The technology did not exist then to exhibit its contemporary characteristics.

As a modern-type lizard, the new fossil impacts “all estimates” of the origin of lizards and snakes, collectively called Squamata.

It affects hypotheses about their rates of evolution and even the key trigger for the group’s origin, the scientists said.

The research team named their discovery Cryptovaranoides microlanius which means “little butcher” in homage to its jaws filled with sharp teeth.

Dr David Whiteside, from the University of Bristol’s School of Earth Sciences, and leader of the study, said: ‘I first spotted the specimen in a cupboard full of Clevosaurus fossils in the warehouses of the Natural History Museum in London where I am Scientific Associate.

“This was a fairly common fossil reptile, a close relative of the New Zealand Tuatara which is the sole survivor of the group, Rhynchocephalia, which split from the squamates over 240 million years ago.

‘Our specimen was simply tagged’Clevosaurus and another reptile.’ As we continued to investigate the specimen, we became more and more convinced that it was actually more closely related to modern lizards than the Tuatara group.

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

He said that Cryptovaranoides is clearly a squamate as it differs from Rhynchocephalia in the braincase, neck vertebrae, shoulder region, and the presence of an upper median tooth in the anterior part of the mouth, the way the teeth are set on a shelf in the jaws.

Co-author Professor Mike Benton said: ‘In terms of significance, our fossil shifts the origin and diversification of squamates from the Middle Jurassic to the Late Triassic.

“This was a period of great restructuring of terrestrial ecosystems, with the origin of new groups of plants, especially conifers of the modern type, as well as new types of insects, and some of the first modern groups such as turtles, crocodiles, dinosaurs, and mammals.

“The addition of the older modern squamates then completes the picture. It appears that these new plants and animals entered the scene as part of a major reconstruction of life on Earth after the end-Permian mass extinction 252 million years ago, and specifically the Carnian Pluvial Episode, 232 million years ago, when climates swung between wet and dry and caused great disturbance to life.”

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