Before the age of the dinosaurs, a mass extinction event occurred that destroyed 70 percent of all terrestrial vertebrate species and almost all aquatic species. It took as long as 10 million years for life on earth to recover from what is now known as the end-Permian extinction event.

After that recovery but before the rise of the dinosaurs, the ancestors of modern lizards and snakes emerged.

From the University College London:

Two new fossil jaws discovered in Vellberg, Germany provide the first direct evidence that the ancestors of lizards, snakes and tuatara (known collectively as lepidosaurs), were alive during the Middle Triassic period – around 240 million years ago.

The new fossil finds predate all other lepidosaur records by 12 million years. The findings are published in BMC Evolutionary Biology.

The international team of scientists who dated the fossil jaws have provided evidence that lepidosaurs first appeared after the end-Permian mass extinction event, a period when fauna began to recover and thrive in the more humid climate.



Lead author Dr Marc Jones, who conducted the research at UCL, explained: "The Middle Triassic represents a time when the world has recovered from the Permian mass extinction but is not yet dominated by dinosaurs. This is also when familiar groups, such as frogs and lizards, may have first appeared."

The small teeth and lightly built jaws suggest that the extinct animal preyed on small insects. The new fossils are most closely related to the tuatara, a lizard-like reptile.

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The new fossil jaws can improve molecular dating estimates of when reptiles began to diversify into snakes, lizard and tuatara, and when the first modern lizards inhabited the earth. Previous estimates have varied over a range of 64 million years and the team are keen to help narrow this down.

"Some previous estimates based on molecular data suggested that lizards first evolved 290 million years ago," said second author Cajsa Lisa Anderson, University of Gothenburg. "To a palaeontologist this seems way too old and our revised molecular analysis agrees with the fossils."

Revised molecular dating in light of this new fossil find now suggests lizards began to diversify into most of the modern groups we recognise today, such as geckos and skinks, less than 150 million years ago in the Cretaceous period, following continental fragmentation.

Read more here.

Photos: Marc Jones/UCL