Paleontologists have discovered in Argentina the most primitive representative of the lepidosaur group, which includes lizards and snakes. He lived about 231 million years ago. The find allows for a fresh look at the evolution of this most numerous modern group of vertebrates. The research is published in the journal Nature.
Reptiles have come a very long evolutionary path and today occupy a very important place in most terrestrial ecosystems. The largest group is Lepidosauria, which includes all lizards and snakes. Today, there are 11,000 species of lepidosaurs, making them the largest group not only among reptiles, but among all modern vertebrates.
However, the early history of lepidosaurs (260-150 million years ago) is very sketchy. The reason for this is typical - a lack of fossils. But a new find could close the gaps. Scientists have discovered the most primitive Lepidosaurus ever discovered in the Argentine Ischigualasto Formation. The new species that lived in the Late Triassic period 231 million years ago was named Taytalura alcoberi.
Paleontologists have analyzed the fossil using high-resolution computed tomography. So they confirmed that the found animal belongs to lepidosaurs. Further processing of the data allowed the team to understand the anatomy of the fossil in high resolution at a scale of just a few micrometers.
Using all the information obtained from CT, the scientists applied Bayesian evolutionary analysis. With his help, they determined the location of the taitalura on the evolutionary tree. It turned out that the reptile was the most primitive representative of the genus, from which all lizards and snakes descended.
Simoes agreed: “Taitalura is an important point in the reptile tree of life that did not exist before. Since these fossils are very small, they are very poorly preserved. And the candidate fossils we have are very fragmented and poorly preserved, so they don't provide as much useful data for analysis,”said Thiago Simois of Harvard University.
The skull of the taitalura showed that the first lepidosaurs were more Tuatara than scaly ones. In addition, the teeth of the taitalura were different from those of any living or extinct group of lepidosaurs. According to scientists, the features of the taitalura force us to take a fresh look at the evolution of lepidosaurs.
Equally important, the taitalura was the earliest lepidosaur found in South America. Before that, representatives of the group were found mainly in Europe. Therefore, the find may indicate that at the dawn of their evolutionary history, lepidosaurs could migrate over great distances.