Thu. Jun 30th, 2022

Life restoration of Taytalura in its natural habitat with the extinct conifer Rhexoxylon in Ischigualasto (Argentina) throughout the Late Triassic, hiding from the primitive dinosaur Eodromaeus (in the background) inside the skull of a mammalian forefather. Credit: Original art work developed by scientific illustrator Jorge Blanco
International group of researchers explain a brand-new fossil species representing the ancient forerunner of many contemporary reptiles.
Along with the charismatic tuatara of New Zealand (a “living fossil” represented by a single living types), squamates (all snakes and lizards) make up the Lepidosauria– the biggest group of terrestrial vertebrates in the planet today with roughly 11,000 species, and by far the largest modern group of reptiles. The early phase of lepidosaur evolution 260-150 million years earlier, is marked by very fragmented fossils that do not offer much helpful information to understand their early evolution, leaving the origins of this greatly diverse group of animals embedded in secret for decades.
In a research study released today (August 25, 2021) in Nature an international group of scientists explain a new types that represents the most primitive member of lepidosaurs, Taytalura alcoberi, found in the Late Triassic deposits of Argentina. Discovered by lead author Dr. Ricardo N. Martínez, Universidad Nacional de San Juan, Argentina, and manager at the Instituto y Museo de Ciencias Naturales, Taytalura is the very first three-dimensionally preserved early lepidosaur fossil. It permitted scientists to infer with great self-confidence its placement in the evolutionary tree of reptiles and help in closing the gap of our understanding of the origin and early evolution of lepidosaurs.

Reconstruction of the skull of Taytalura based upon high-resolution CT scans (left) and its placement in the evolutionary tree of reptiles (right). Credit: (Left) Gabriela Sobral, Jorge Blanco, and Ricardo Martínez; (Right) Tiago Simões
Martínez and co-author Dr. Sebastián Apesteguía, Universidad Maimónides, Buenos Aires, Argentina, carried out high-resolution CT scans of Taytalura which provided verification that it was something related to ancient lizards. They then got in touch with co-author Dr. Tiago R. Simões, postdoctoral fellow in The Department of Organismic and Evolutionary Biology, Harvard University, to help identify and analyze the fossil. Simões concentrates on studying these animals and in 2018 released the largest existing dataset to understand the evolution of the significant groups of reptiles (living and extinct) in Nature.
” I understood the age and region of the fossil and could inform by analyzing a few of its external functions that it was carefully related to lizards, however it looked more primitive than a real lizard and that is something quite unique,” stated Simões.
The researchers then got in touch with co-author Dr. Gabriela Sobral, Department of Palaeontology, Staatliches Museum für Naturkunde Stuttgart, Germany, to process the CT scan data. Sobral, an expert in processing CT data, developed a mosaic of colors for each bone of the skull allowing the team to understand the fossils anatomy in high-detail resolution on a scale of only a couple of micrometers– about the same thickness as a human hair.
With Sobrals data, Simões was able to apply a Bayesian evolutionary analysis to identify the proper positioning of the fossil in the reptile dataset. “Its not even a lizard in the evolutionary tree,” said Simões, “but its the extremely next thing there, in between real liizards and tuataras, and all other reptiles.”
” This beautifully 3D maintained fossil is really an important finding. It is the most complete fossil representing the early phases of lepidosaur evolution that we have up until now. All other known fossils are too insufficient, which makes it hard to categorize them for sure, however the total and articulated nature of Taytalura makes its relationships a lot more particular,” said Sobral.
Simões agreed, “Taytalura is a major point in the reptile tree of life that was formerly missing. Because these fossils are so small they are extremely challenging to protect in the fossil record. And what candidate fossils we do have are extremely fragmented and inadequately protected, so they do not supply as much useful data for analysis.”
Even more, it has a special dentition, varying from the teeth found in any living or extinct group of lepidosaurs. “What our analyses informs us, besides some other anatomical traits that we might see on it, in the skull specifically, is that this sphenodontian body type, at least for the skull, is the ancestral pattern for lepidosaurs.
” Taytalura protects a composition of functions that we were not expecting to discover in such an early fossil. It reveals some functions that we thought were special for the tuatara group. On the other hand, it made us question how really “primitive” certain lizard features are, and it will make researchers reassess several points in the evolution of this group,” stated Sobral.
” The almost perfectly preserved Taytalura skull reveals us information of how a extremely successful group of animals, consisting of more than 10,000 types of snakes, tuataras, and lizards, originated,” stated Martínez. “But it likewise highlights the paleontological significance of the paleontological website of Ischigualasto Formation, known for maintaining a few of the most primitive dinosaurs understood in the world. The extraordinary quality of conservation of the fossils at this site permitted something as tiny and delicate as this specimen to be preserved for 231 million years.”
” Contrary to almost all fossils of Triassic lepidosaurs discovered in Europe, this is the first early lepidosaur found in South America, recommending lepidosaurs were able to move throughout greatly remote geographic areas early in their evolutionary history,” concurred Simões.
” We are accustomed to accept that the Mesozoic Era was an age of enormous reptiles, enormous proto-mammals, and huge trees, and hence we frequently search for fossils that show up at human height, simply strolling,” said Apesteguía. “However, the largest part of the ancient ecosystem parts was small, as today. There was a universe of animals sneaking amongst larger, clawed or hoofy paws. Taytalura teaches us that we were missing out on crucial details by looking not just for bigger animals, however for also thinking that the origin of lizards occurred just in the Northern Hemisphere as evidence appeared to support till now.”
While Taytalura is primitive, it is not the earliest lepidosaur. The fossil is 231 million years of ages, but there are likewise fossils of true lizards from 11 million years earlier. The team plans to next check out older websites in hopes of finding similar or different types from the exact same family tree that branch right before the origin of real lizards.
Referral: “A Triassic stem lepidosaur lights up the origin of lizard-like reptiles” 25 August 2021, Nature.DOI: 10.1038/ s41586-021-03834-3.

Along with the charismatic tuatara of New Zealand (a “living fossil” represented by a single living types), squamates (all snakes and lizards) make up the Lepidosauria– the largest group of terrestrial vertebrates in the world today with roughly 11,000 species, and by far the largest contemporary group of reptiles. The early phase of lepidosaur development 260-150 million years ago, is marked by really fragmented fossils that do not offer much helpful data to understand their early evolution, leaving the origins of this greatly varied group of animals embedded in secret for years.
It is the most total fossil representing the early stages of lepidosaur advancement that we have so far. Because these fossils are so small they are extremely difficult to preserve in the fossil record. The fossil is 231 million years old, but there are likewise fossils of real lizards from 11 million years previously.

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