Archaeologists Uncover Oldest Lizard-like Fossil: Evolutionary Origins of Lizards

Archaeologists have uncovered the oldest lizard-like fossil yet. The ancient remains reveal a little bit more about the evolutionary origins of lizards and show exactly what sort of species emerged in the distant past.

The new fossil is of a lepidosaur, an ancient creature that was the ancestor of lizards, snakes and tuatara. These lepidosaurs lived during the Middle Triassic period, which occurred around 240 million years ago. What makes this new fossil so interesting, though, is the fact that it's the earliest one ever discovered. In fact, it shows that lepidosaurs first appeared after the end-Permian mass extinction event.

"The Middle Triassic represents a time when the world has recovered from the Permian mass extinction but is not yet dominated by dinosaurs," said Marc Jones, lead author of the new paper, in a news release. "This is also when familiar groups, such as frogs and lizards may have first appeared."

The finding consists of fossil jaws possessing small teeth. It's likely that this now-extinct species probably preyed on small insects. In addition, the creature was most closely related to the tuatara, a lizard-like reptile. Today, tuatara can be found on 35 islands lying off the coast of New Zealand; they are the sole survivors of a group that was once as globally widespread as lizards are today.

This particular fossil is crucial for understanding the evolutionary history of lizards, snakes and tuatara. Knowing when the common ancestor of this grouping first appeared is important for learning about the ecological context of its diversification. In fact, the new fossil helps narrow down when the first modern lizards began to appear.

"Some previous estimates based on molecular data suggested that lizards first evolved 290 million years ago," said Ajsa Lisa Anderson, one of the researchers, in a news release. "To a paleontologist this seems way too old and our revised molecular analysis agrees with the fossils."

The research reveals that lizards probably began to diversify into most of the modern groups we recognize today less than 150 million years ago during the Cretaceous period. That's when animals such as geckos and skinks first began to emerge.

The findings show a little bit more about the evolutionary history of lizards, snakes and tuatara. In addition, it shows that these animals evolved far more rapidly than at first thought.

The findings are published in the journal BMC Evolutionary Biology.