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The fossil found in the drawer was found to be the oldest known modern lizard | Fossils

The fossil found in the drawer was found to be the oldest known modern lizard | Fossils

The fossilized remains of a small, sharp-toothed lizard, left in a closet for more than half a century, have pushed back the origin of the group that includes modern snakes and lizards by tens of millions of years.

The specimen was collected from a quarry near Tortworth in Gloucestershire in the 1950s by the late fossil hunter Pamela L Robinson. But its true identity was not appreciated because the creature was mislabeled and stored, until recently when it was found at the Natural History Museum in London.

Now researchers say advances in technology have allowed them to take another look, revealing that the creature holds a key position in the reptile family tree.

An artist’s impression of Cryptovaranoides when he was alive. Photo: Lavinia Gandolfi

“It’s partly a story of neglected fossils [a] a drawer, and partly a story [that] without CT scanning, you would not have been able to do the work we did,” said prof. Michael Benton, paleontologist from the University of Bristol and co-author of the study.

The long-tailed creature – about 25 cm long – is believed to have lived around 202 million years ago. Cryptovaranoides microlanius. First mandate denotes a hidden lizard-like animal, referring to the time it spent unrecognized and probably hiding in rock crevices during its lifetime. Another term, which translates as microbutcher, is a nod to the curved teeth of a blade-like creature.

Using CT scans, Benton and colleagues were able to view the fossil in fine detail and study the bones trapped within the rock. Benson said the animal’s skull was 3 cm long. “The fossil is tiny, the ribs are just tiny,” he said.

The results reveal that the animal was a pangolins – one of a group of scaly reptiles that includes creatures such as lizards and snakes. “They start out as lizards — snakes evolve later in the Cretaceous,” Benton said.

The creature has key features of modern lizards, such as modified bones at the back of the skull to allow extra flexibility when opening the jaw, making it the oldest such reptile yet found.

Lizard head modeling.
Lizard head modeling. Photo: David Whiteside, Sophie Chambi-Trowell, Mike Benton and Natural History Museum UK

“It’s an angimorph lizard, which today includes 350 species, including everything from the gila monster of North America to the Komodo monitor, the giant predatory lizard of Indonesia,” Benton said.

The team says the discovery pushes back the origin of modern squamates by at least 34 million years. The oldest known modern lizard was previously thought to have lived about 168 million years ago.

The team adds that the discovery has important implications for understanding the rate of evolution within the tree of life, the timescale and drivers of biodiversity in modern squamates – the latter of which may help conserve living species.

“Previously, the common ancestor of all these living forms was dated to the Middle Jurassic, but now we’re pushing it back to the Late Triassic,” Benton said.

He said that while Cryptovaranoides microlanius was the closest scientists now have to the last common ancestor of modern squamates, its advanced features mean the title likely belongs to another, perhaps even older, creature.

Professor Steve Brusatte, a paleontologist at the University of Edinburgh who was not involved in the work, said that while scientists had made great strides in understanding the origins of mammals, birds and crocodiles, the origins of lizards and snakes were more of a mystery.

Illustration of a skeleton showing the spine, lower jaw and limbs
Illustration of a skeleton showing the spine, lower jaw and limbs. Photo: David Whiteside, Sophie Chambi-Trowell, Mike Benton and Natural History Museum UK

“Few skeletons of these delicate animals have been preserved as fossils, and many of them are so fragile that they have proved very difficult to study,” he said.

“If its identification as a modern-style lizard is correct, it would mean that lizards began to diversify during the Triassic period, along with some of the earliest dinosaurs and mammals. It also proves that there are astonishingly important British fossils still lurking, either in the field waiting to be discovered, or in museum collections waiting to be properly studied.”



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