Scientists may now have a better understanding of what the world's first lizards looked like.
A newly studied fossil specimen is being hailed by researchers as the “mother of all lizards” because it's thought to be an early species from which all of today's squamates—lizards and snakes—eventually evolved. Dubbed Megachirella wachtleri, the fossil creature dates back 240 million years, according to a study describing it this week in the journal Nature.
Where was the lizard fossil found?
The Magechirella fossil was found in the Italian Alps 20 years ago. At the time, scientists thought it might be related to squamates, but they didn't have enough evidence to formally describe it as a direct ancestor. Megachirella's detailed features weren't completely discernible, and scientists didn't have a comprehensive understanding of the evolutionary timeline for squamates.
As part of the more recent reanalysis, scientists took the fossil specimen to a research facility in northern Italy where it underwent micro-CT scans. The resulting images showed the animal in greater detail, even allowing scientists to see within the rock the fossil is still nestled within. They scans revealed unique features that finally identified Megachirella as an ancient squamate.
How did scientists find its place in the lizard family tree?
Lead study author Tiago Simões spent more than four years piecing together the squamate lineage. Together with his advisor Michael Caldwell, a University of Alberta paleontologist, he assembled what the team says is the largest reptile dataset ever compiled. It contains phylogenetic data from 130 living and extinct lizard and snake species.
"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 told the AFP.
Then, using data from the micro-CT scans, the team was able to construct a 3-D model of the ancient lizard's physiology. 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.
Why does this discovery matter?
Squamates are among the most diverse and widespread groups of creatures on the planet, but scientists know surprisingly little about their early evolutionary origins. The new discovery is already helping paleontologists better understand how lizards and snakes survived in prehistoric times and eventually gave rise to the scaly animals we see today.
“The specimen is 75 million years older than what we thought were the oldest fossil lizards in the entire world,” Simões says in a press release. Caldwell adds that for paleontologists, Megachirella is akin to the Rosetta Stone, in the way that the fossil is helping them decode the reptile family tree.