World's oldest lizard dating back 205 million years discovered preserved in UK quarry

After much debate between scientists, a small skeleton found in a quarry near Bristol has been identified as the world’s oldest lizard.

In the initial study, the reptile skeleton was named Cryptovaranoides microlanius (meaning ‘hidden lizard, small butcher due to its sharp teeth) and is estimated to be around 205 million years old - and the fossil is so old that pushed back the origins of the whole lizard-snake group, called Squamata by 35 million years.

It was originally studied in 2022 and the findings were released in Science Advances, written by Dr David Whiteside, Dr Sofia Chambi-Trowell and Professor Mike Benton from The University of Bristol, who recently published a follow-up paper in Royal Society Open Science and concluded the reptile is the world's oldest modern-type lizard.

“We knew our paper would be controversial,” explained Dr Whiteside about the original study. “But we were confident that we had looked at every possible feature and compared it with everything we could.”

Professor Benton noted how the team were "surprised, perhaps even shocked" when last year another team of academics weren't convinced the skeleton was a lizard and didn't even think it was part of the lizard family, but rather "an archosauromorph, more closely related to crocodilians and dinosaurs".

The world's earliest lizard, Cryptovaranoides microlanius.David Whiteside/University of Bristol

And so the trio reviewed their initial findings, the rival paper, and all the data including the original specimen as well as the X-ray scans that show the details hidden within the rock.

Dr Chambi-Trowell recalled looking at the "marvellous images from those CT scans" and additional access to the fossil which led the team to conclude "most of the concerns raised were wrong”.

In fact, all the details of the skull which included the jaws, the teeth, and the limb bones proved that Cryptovaranoides is a lizard.

“In our new paper, we provide great detail of every criticism made and we provide more photographs of the specimen and 3D images from the scans, so everyone can check the detail," Professor Benton said.

Dr Whiteside concluded: “The result of all this had to be tested by a phylogenetic analysis.

"This is where we code hundreds of anatomical features in Cryptovaranoides and other modern and fossil lizards, as well as various archosauromorphs.

After running the analysis, it provided the original result and so concluded that "the little Bristol reptile is indeed the world’s oldest modern-type lizard".

These finding were published in Royal Society Open Science.

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