Researchers describe a new fossil species that represents the ancient pioneers of the most modern reptiles

Reconstruction of Taytalura’s life in its natural habitat by the extinct conifer Rhexoxylon of the Late Triassic Ischigualast (Argentina), hiding from the primitive dinosaur Eodromaeus (background) in the skull of the mammalian ancestor.Credit: Scientific illustrator Jorge Blanco

Lizards and snakes are important elements of most terrestrial ecosystems on Earth today. Scaled reptiles (all lizards and snakes), along with New Zealand’s charismatic tuatara (“living fossils” represented by a single living species), make up lepidosauria. By far the largest modern group of reptiles. Both Squamata and Tuatara have a very long evolutionary history. Their lineage is older than the divergent dinosaurs that originated from each other at some point about 260 million years ago. However, the early stages of lepidosauria evolution 260-150 million years ago are characterized by highly fragmented fossils and do not provide much useful data to understand the early evolution. Without providing, the origins of this highly diverse group of animals have been embedded in the mystery for decades.

In a study published on August 25 Nature An international team of researchers describes a new species that represents the most primitive members of the lepidosauria. Taytalura alcoberiFound in Late Triassic deposits in Argentina. Discovered by lead author Dr. Ricardo N. Martinez, curator at San Juan National University in Argentina, and the Museum of Natural Sciences. Taytalura Is the first three-dimensionally preserved early lepidosauria fossil. This allows scientists to confidently infer that they are located in the evolutionary tree of reptiles, helping to bridge the gap in knowledge of their origin. Early evolution Of lepidosauria.

Martinez and co-authors Dr. Sebastián Apesteguía, Universidad Maimónides, Buenos Aires, Argentina, Taytalura It provided confirmation that it was related to ancient lizards. Next, I contacted co-author Dr. Tiago R. Simes, a postdoctoral fellow at the Department of Bioevolutionary Biology, Harvard University, to help identify and analyze fossils. Simões specializes in the study of these creatures, and in 2018 published the largest existing dataset to understand the evolution of the major groups of reptiles (living and extinct). Nature..

“I knew the age and origin of the fossil, and by examining some of its external features, I was able to find out that it was closely related to the lizard, but it was better than the real lizard. Also looks primitive and it’s very special, “Simões said.

The researchers then contacted Dr. Gabriella Sobral, co-author of the Paleontology Department at the Stuttgart National Museum in Germany, to process the CT scan data. Sobral, a specialist in the processing of CT data, created a mosaic of the colors of each bone in the skull. This allows the team to understand the anatomy of fossils in high resolution on a scale of just a few micrometers, about the same thickness as human hair. ..

Using Sobral data, Simões was able to apply Bayesian evolutionary analysis to determine the proper placement of fossils in the reptile dataset. Simões recently applied the Bayesian method, which applies the method first developed in epidemiology to study how viruses like COVID-19 evolve. Time and rate of anatomical evolution during the rise of the tetrapod. Statistical analysis confirmed their suspicions Taytalura In fact, it was the most primitive member of the lineage that ultimately produced all the lizards and snakes. “It’s not even an evolutionary tree lizard, but it’s the next thing that’s there among true lizards and tuatara, and all other reptiles,” Simes said.

“This beautifully preserved fossil in 3D is a truly important discovery. It is the most complete fossil that represents the early stages of lepidosauria evolution to date. All other known fossils are too incomplete and are certain. Difficult to classify into, but the complete and clear nature of Taytalura We will make that relationship more secure. “

The dawn of modern reptiles

Reconstruction of Taytalura’s skull based on high-resolution CT scans (left) and placement of reptiles in the evolutionary tree (right). Credits: Left) Gabriella Sobral, Jorge Blanco, Ricardo Martinez.Right) Tiago Simes

Simes agreed, “Taytalura It is the main point of the previously missing reptile tree of life. These fossils are so small that they are very difficult to keep in their fossil records. And the candidate fossils we have are very fragmented and poorly preserved, so there is not much data useful for analysis. “

Taytalura The skull reveals that the first lepidosauria are much more like tuatara than scaled reptiles, so scaled reptiles represent a major deviation from this ancestral pattern. Moreover, it has a unique dentition, unlike the teeth found in living or extinct groups of lepidosauria. “Our analysis shows that, in addition to other anatomical features found in the skull, at least in the skull, this tuatara body shape is a pattern of lepidosauria ancestors. It’s more like a lepidosauria. “

“”Taytalura It retains a composition of features not found in these early fossils. For example, you’ll see some features that you thought were exclusive to the tuatara group. On the other hand, we will be wondering if certain lizard features are really “primitive” and scientists will reconsider some points in the evolution of this group, “Sobral said. Says.

“Almost completely preserved Taytalura The skull details how a highly successful group of animals was born, including over 10,000 species of snakes, lizards, and tuatara. Save some of the most primitive dinosaurs known in the world. The extraordinary quality of fossil preservation at this location allowed small, as fragile specimens as this specimen, to be preserved for 231 million years. “

“In contrast to almost all Triassic lepidosauria fossils found in Europe, this is the first early lepidosauria found in South America, and lepidosauria are early in evolutionary history. It suggests that we were able to move to a very remote geographical area, “Simões agreed.

“We are accustomed to accepting that the Mesozoic was an era of giant reptiles, giant proto-mammals, and giant trees. Therefore, we are usually fossils that are visible at human height just by walking. Look for, “said Apestegia. “But most of the components of the ancient ecosystem were as small as they are today. The fauna universe was creeping between the larger, clawed, or hoofy’s feet. Taytalura Not only looking for large animals, but as evidence has been supported so far, thinking that the origin of lizards originated only in the Northern Hemisphere tells us that there is a lack of important information. “

in the meantime Taytalura It is primitive and not the oldest lepidosauria. The fossils are 231 million years old, but there are also real lizard fossils 11 million years old.The team then plans to explore older sites in the hope of finding similar or different species from the same strain that diverges just before their true origin. Lizards..

Rapid Evolution: Sustained Fast Evolution Explains how Tetrapods Evolved from Fish

For more information:
Triassic-stem lepidosauria illuminate the origin of reptiles such as lizards. Nature (2021). DOI: 10.1038 / s41586-021-03834-3 ,

Provided by
Harvard University

Quote: Researchers found the most modern reptiles (August 25, 2021) obtained from on August 25, 2021. Describes a new fossil species that represents the ancient pioneers of the day). html

This document is subject to copyright. No part may be reproduced without written permission, except for fair transactions for personal investigation or research purposes. The content is provided for informational purposes only.

Researchers describe a new fossil species that represents the ancient pioneers of the most modern reptiles

Source link Researchers describe a new fossil species that represents the ancient pioneers of the most modern reptiles

Related Articles

Back to top button