Here's a fact you should know about the world you live in: it is home to more types of scaly reptiles than all mammal families combined. The order of Squamata reptiles, which includes snakes, lizards and creatures resembling the legless worms known as amphisbaenians, is the largest terrestrial vertebrate order on the planet.
And yet, scientists know very little about where all those geckos, snakes and iguanas are and pythons came. Genetic evidence suggests that the order originated in the Permian period, more than 250 million years ago. But the oldest known scaly fossil was about 70 million years younger than that.
"It's longer than the time between us and the dinosaurs, and we had no idea what was going on," said Tiago Simoes, a paleontologist at the University of Alberta.
Enter Megachirella wachtleri, a 7.5 cm fossil, 240 million years old, and a new and exciting track in this evolutionary mystery.
According to the research of Simoes and his colleagues that was published on Thursday in the journal Nature, megachirella is the "mother of all lizards", the oldest known ancestor of all squamates. Its existence helps explain the transition from more primitive reptiles to the large and diverse order that now slides, crawls and digs on all continents except Antarctica.
In a video for Muse Science Museum in Trento, Italy, co-author Michael Caldwell called the fossil a "perfect example." "It's almost a Rosetta virtual stone in terms of the information it gives us about the evolution of snakes and lizards," said Caldwell, also a paleontologist at the University of Alberta.
The partial skeleton of Megachirella was discovered by an amateur fossil hunter in the Dolomite mountains of northern Italy and first described by scientists in 2003. But, limited by the technology of the time and an incomplete understanding of the order of Scales, the researchers were not quite sure how the new species fitted into the reptiles' family tree. 19659008] The Megachirella wachtleri lived in the middle Tribadic period. "src =" data: image / png; base64, R0lGODlhAQABAPAAAOrq6v /// yH5BAAAAAAALAAAAAABAAEAAAICRAEAOw == "data-srcset =" // www.nzherald.co.nz/resizer/ovGXwelCLqK-boI6AksTDhr64Rk=/320×418/smart/filters:quality ( 70) /arc-anglerfish-syd-prod-nzme.s3.amazonaws.com/public/CGJLG2QONNH75KPL36Z5QWSWPA.jpg 320w, // www.nzherald.co.nz/resizer/0-Zgesg5s6ETV5JmTPzapiwG85k=/375×490/smart/filters:quality (70) /arc-anglerfish-syd-prod-nzme.s3.amazonaws.com/public/CGJLG2QONNH75KPL36Z5QWSWPA.jpg 375w, // www.nzherald.co.nz/resizer/ri3Q6R5_w9C8ORVq_9iUa7cA9Rw=/620×810/smart/filters:quality ( 70) /arc-anglerfish-syd-prod-nzme.s3.amazonaws.com/public/CGJLG2QONNH75KPL36Z5QWSWPA.jpg 620w "/>
Fifteen years later, the High-resolution micro-scan of the CT allowed us to look inside the rock that held the fossil and identify the hidden features inside.
In a synchrotron installation, Simoes and his colleagues identified the therstics in the brain's box of the animal, bone necklace and dolls that are uni that lizards. They also found evidence of vestigial traits that the more modern squamates have lost since then: a small cheek bone called the flat and primitive quadrant bones called gastralia (which are also found in many dinosaurs).
Simoes dedicated his doctorate to the understanding of the family Tree of life and extinct squamates.
"For the first time, having that information with this highly expanded data set, it was now possible to really evaluate the relationship of not only this species but also of other reptile species," Simoes said.
When megachirella walked the Earth, in the Middle Tribadic period, the land mbades of the world were crushed together in a supercontinent called Pangea. The flowers had not evolved, and the soil was dominated by primitive plants called lycopods (ancestors of club mosses and quillworts). The conditions under which the fossil was found, in marine sediments but surrounded by fossilized terrestrial plants, suggest that a powerful storm hit the coast where the megachirella lived and dragged the small creature into the sea.
Simoes and his colleagues are still looking for evidence of megachirella behavior. And they still have to complete the tens of millions of years between megachirella and the next oldest fossil fossil. Many early Cretaceous fossil lizards (more than 100 million years ago) do not seem to fit perfectly into any known lineage, and megachirella could help explain these oddities.
"Confirm that we have no idea", Simoes said of the new species. "But on the positive side, we also have all this additional information in terms of the transition from more general reptile features to more lizard features."