The Permian-Triassic extinction, also known as the "Great Dying" that occurred about 250 million years ago devastated nearly all class of life on Earth.
Up to 96 percent of species died out during the event, but a prehistoric fossil discovered in the Italian alps suggests that a group of reptiles known as squamates, which include lizards and snakes, managed to survive the event.
All life that now exists on Earth is believed to have descended from about 4 percent of the species that survived the Permian-Triassic extinction.
Mother Of All Lizards
Scientists have identified the prehistoric fossil of the "mother of all lizards." They said that the creature was the direct ancestor of about 10,000 species that are alive today.
The tiny reptile, called Megachirella wachtleri, was first described in 2003, but recent scans revealed its fossils have hidden features that suggest the creature is the oldest known ancestor in the squamate group.
The ancient lizard lived 240 million years ago back when the Earth only had one continent and dinosaurs just emerged on the planet.
Study researcher Tiago Simoes, from the University of Alberta in Canada, said that the findings suggest that lizards have been on the planet as early as 240 million years ago, which means that the squamate lineage had already split from other ancient reptiles prior to the Permian-Triassic mass extinction.
The extinction event wiped out up to 95 percent of marine life and 75 percent of terrestrial life, but squamates apparently survived.
"Divergence time estimates using relaxed combined morphological and molecular clocks show that lepidosaurs and most other diapsids originated before the Permian/Triassic extinction event, indicating that the Triassic was a period of radiation, not origin, for several diapsid lineages," the researchers wrote in their study, which was published in the journal Nature on May 30.
75 Million Years Older Than Previously Known Oldest Squamate Fossils
Using CT scanning, researchers found several features that link the Megachirella to squamates. Two of Megachirella's features, a collarbone structure and a part of the braincase, were unique to the squamate group, which allowed scientist to identify Megachirella as the first squamate from the Triassic.
They found that the Megachirella is 75 million years older than the previously known oldest squamate fossils, which fills the fossil gap in the origin of lizards.
"It deserved further attention — especially in the form of CT [computed tomography] scanning — to provide greater anatomical details and an improved data set, to understand its placement in the evolutionary tree of reptiles," Simoes said.