And fossil It has been in the Natural History Museum in London since the 1950s. has shown that modern lizards originated 35 million years agoin the Late Triassic and not in the Middle Jurassic as previously thought.
The fossil had been found, along with others, in a quarry in Gloucestershire, southwest England, in the 1950s. when the necessary technology did not exist to expose its contemporary features.
The head of the team who has now proceeded to study their featuresDavid Whiteside, from the Bristol School of Earth Sciences, UK, recalls that the first time he saw it It was in a closet full of Clevosaurus fossils..
“Our specimen was simply labeled ‘Clevosaurus and other reptile.’ As we investigated the specimen, we became more and more convinced that actually it was more related to the current lizards than with the Tuatara group.
The fossil is a relative of the lizards alive, such as monitor lizards or gila monsters. Being a modern type lizard, affects all estimates of the origin of lizards and snakes, jointly called Squamata.
In addition, it affects assumptions regarding their rates of evolution, and even the key trigger for the origin of the group, said the authors of the study published in Science Advances.
“This is a very special fossil and probably become one of the most important found in recent decades», indicated Whiteside regarding the specimen, which has been baptized as Cryptovaranoides microlanius (small butcher), in homage to its jaws, full of sharp teeth.
The team performed X-ray scans to reconstruct the fossil in three dimensions and see all the little bones that were hidden inside the rock where is it located.
Cryptovaranoides is “clearly” a squamate and there is only one important primitive feature not found in its modern relatives, an opening on one side of the end of the upper humerus bonethrough which an artery and a nerve pass.
“In terms of importance, our fossil displaces the origin and diversification of squamosals from the Middle Jurassic to the Late Triassic,” said Mike Benton, co-author of the study.
That was a time of great restructuring. of terrestrial ecosystems following the mass extinction at the end of the Permian (252 million years ago).
At that time new groups of plants arose, especially modern type conifersas well as new types of insects and some of the first modern groups such as turtles, crocodiles, dinosaurs and mammals.
Cryptovaranoides microlanius probably lived in limestone crevices on small islands that existed around Bristol at the time, feeding on arthropods and small vertebrates.
