A little creature, known as Megachirella wachtleri was found in the Italian Alps in 2003. The newly studied fossil is being hailed by scientists as the “mother of all lizards.” It is thought this animal washed out to sea 240 million years ago off the coast of what’s now Italy turns out to be the oldest known fossil of a lizard.
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The fossilized remains of a small lizard discovered in rock from the Italian Alps have shaken up the evolutionary family tree of reptiles and shed new light on the survivors of the most devastating mass extinction the world ever faced, researchers say.
Thought to have lived in the Triassic period, about 240 million years ago, has been unveiled as the oldest known member of a group of reptiles known as squamates. Squamates include lizards, snakes and peculiar legless creatures known as worm lizards.
“All lizards and snakes are descendants from Megachirella or a Megachirella-like lizard,” said Dr. Massimo Bernardi, co-author of the study from the University of Bristol.
According to the journal Nature, the finding not only sheds light on what the last common ancestor of such creatures would likely have looked like, but reveals that squamates probably appeared far earlier than previously thought, and survived one of the planet’s greatest catastrophes.
Using an x-ray technique known as CT-scanning, the team were able to examine in 3D previously hidden features of the fossil. In addition, they spent about 400 days visiting and examining some 150 specimens of ancient lizard-like creatures held in collections around the world and analyzed both skeletal and molecular data, which included DNA from living squamates.
The results reveal that Megachirella is a squamate, pushing back the earliest known member of the group by 75 million years and backing up some previous molecular studies that had proposed squamates existed in the Triassic period.
A further result of the new family tree, the team says, is that it settles a long-standing debate, revealing that geckoes evolved earlier than iguanas.
And there’s more. Combining both the molecular data and observations of skeletal features, the team were able to estimate when the earliest squamates appeared. Thus revealing they probably originated just before a catastrophic mass extinction event 252 million years ago when more than 90% of the marine creatures and 70% of land vertebrates died. This event is known as the “Great Dying”.
Team researcher Bernardi said the discovery overturns current theories that they arose after the disaster and reveals that many different species appeared in the wake of the catastrophe due to factors such as a lack of competitors.
“It is like the other side of extinctions,” he said. “Squamates, for example, were actually there before the extinction, they went through in some way, and they took the opportunities that opened up just after the extinction,” he said.
Bernardi says Megachirella probably lived along shorelines, and that the specimen found in the Dolomites met with a watery end amid a thunderstorm.
“At that time geological reconstructions show us very clearly that the Dolomites were a series of islands with rich vegetation and fine sand beaches, and probably Megachirella was walking along one of those beaches,” he said. “it was taken by the thunderstorm because in the very same layers you see a lot of plants and debris and things that were coming from land into the sea.
David Martill, professor of palaeobiology at the University of Portsmouth who was not involved in the study, said the revelation that squamates arose before the Great Dying casts the creatures in a new light. “This means squamates are real survivors,” he said. “The Permo-Triassic extinction event was a dangerous time to be alive. Not much escaped its deathly touch.”
Looking at its features, they inferred that it followed the evolutionary path of early reptiles, but crucially, it arose before the eventual split between lizards and snakes.
Researchers could never figure out where the small, lizard-like reptile fit in the evolutionary tree. According to a press release for the study in the journal Nature, paleontologists have now taken a fresh look at the three-inch creature using CT scans to create 3D images of the rock-encased animal.
Sarah Kaplan at The Washington Post reports that those scans revealed details of the brain case, collar bone and wrists unique to squamate lizards, as well as bones that survive today in modern lizards as reduced vestigial structures.
Ruth Shuster at Haaretz reports that the data settle a long-simmering debate in reptile evolution, by showing that geckoes split from the common ancestor of all lizards before iguanas. Snakes split off from burrowing lizards likely sometime in the Jurassic period.
