A new study focussing on a 240 million-year-old lizard fossil has provided a better understanding of early lizards and rewritten part of reptile history.
The fossilised lizard-like creature, dubbed Megachirella wachtleri, has been determined to be the oldest known squamate – a group of reptiles including snakes, lizards and legless lizards – and suggests these animals appeared earlier than previously thought.
The specimen was found by an amateur fossil hunter in the Dolomites, part of the Italian Alps, in the early 2000s, but scientists could not figure out exactly where the ancient reptile fit in evolutionary history. Although scientists believed the creature to be related to modern squamates, there was not sufficient evidence to classify it as a direct ancestor, reports National Geographic.
In a new analysis, published on Wednesday in the journal Nature, an international team of palaeontologists reanalysed the fossil using data from high-resolution CT scans. The CT scans provided 3D images of the fossil, allowing scientists to view previously hidden details of the rock-encased animal. The scans revealed several features that are unique to lizards, including parts of the creature’s collarbone, brain case and wrists, reports The Washington Post.
Over the course of 400 days, researchers examined 150 fossil specimens of lizard-like animals held in collections across the globe. The team also gathered molecular data, including DNA, and skeletal data from modern squamates and concluded that Megachirella was an ancient squamate, making it the oldest ever discovered.
“All lizards and snakes are descendants from Megachirella or a Megachirella-like lizard,” study co-author Dr Massimo Bernardi, from the University of Bristol, told The Guardian. Bernardi added that Megachirella would likely have been around 25-30 centimetres long.
“The specimen is 75 million years older than what we thought were the oldest fossil lizards in the entire world and provides valuable information for understanding the evolution of both living and extinct squamates,” lead author Tiago Simões, from the University of Alberta, said in a press release accompanying the study.
The new data – which the team says is the largest reptile dataset ever compiled – also allowed researchers to estimate when the first squamates appeared on Earth. The data showed that squamates likely appeared right before a mass extinction event 252 million years ago known as the “Great Dying,” reports The Guardian. The findings contradict theories that the first squamates appeared after the mass extinction, which marked the death of 70% of land vertebrates and 90% of marine creatures.
David Martill, professor of palaeobiology at the University of Portsmouth in the UK, told The Guardian that the discovery changes the perception of squamates. “This means squamates are real survivors,” said Martill, who was not involved in the study. “The Permo-Triassic extinction event was a dangerous time to be alive. Not much escaped its deathly touch.”