Oldest Ever Lizard Dates Back 240 Million Years And Rewrites Reptile History

Some 15 years ago a fossilized lizard the size of a chameleon was uncovered deep in Italy's Dolomites mountain range. Buried for hundreds of millions of years under sand and clay, Megachirella wachtleri is rewriting reptile history today.

Initially mislabeled as a member of a broader reptile group, scientists writing in the journal Nature have finally discovered that not only is Megachirella a lizard, but that it's the world's oldest known lizard.

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Preserved specimen of Megachirella wachtleri housed in a museum. MUSE - Science Museum, Trento, Italy

At 240 million years old, the animal pushes back the history of squamates—a group of scaly animals including all lizards and snakes—by some 75 million years.

"When I first saw the fossil I realised it had important features that could link it to the early evolution of lizards," study co-author Tiago Simões of the University of Alberta in Canada told the AFP.

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Simões and his team scanned the fossil and discovered it had a tiny lower-jaw bone characteristic of squamates, and squamates alone, among other distinguishing features. They put together the biggest ever reptile dataset to pinpoint Megachirella's place in the family tree.

"I spent nearly 400 days visiting over 50 museums and university collections across 17 countries to collect data on fossil and living species of reptiles to understand the early evolution of reptiles and lizards," Simões explained to the AFP.

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Megachirella wachtleri walks through plants in this artist's impression of the Italian Dolomites region, about 240 million years ago. Davide Bonadonna

The discovery sheds light on the weird and wonderful squamate family. An incredibly diverse group of land vertebrates, scientists had struggled to match up a 70 million-year gap between the fossil record and DNA-based evolutionary history predictions.

The new evidence suggests these creatures split off from other reptiles before a mass extinction 252 million years ago. Hardy squamates survived this Permian/Triassic extinction, which wiped out more than 70 percent of life on our planet. The group diversified shortly after, eventually becoming the rich group of creatures we know today.

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This particular fossil, study co-author Michael Caldwell of the University of Alberta told AFP, is something of a Rosetta stone for the evolution of snakes and lizards. The original Rosetta stone helped scientists translate Ancient Egyptian hieroglyphics.

Before this work, he added, "[We] really had no real understanding of where they came from in terms of their evolutionary history."

This latest discovery still leaves another large gap in the fossil record, Simões told LiveScience. "What we are discovering is the tip of the iceberg, and much further work needs to be done to understand the early evolution of squamates," he said.