Pterosaur Discoveries Filling the Gap in Early Evolutionary History

The high-flying Pteranodon is a genus of pterosaur that includes some of the largest flying reptiles known. Courtesy of Ilen Elenarts / Adobe Stock. Credit: Elenarts

Here it is original flight story Sorry, Wright Brothers, but this story started before your time – the time of the dinosaurs.

Pterosaurs were the first reptiles to dominate the sky and develop flight, 150 million years before they became extinct 66 million years ago.

However, the basic details of the origin of evolution and how they acquired the ability to fly remained a mystery; one that paleontologists have been trying to crack for the last 200 years. The closest relatives had to be identified in order to learn more about their evolution and to fill in some of the gaps in the fossil record.

With the help of newly discovered skulls and skeletons unearthed in North America, Brazil, Argentina and Madagascar in recent years, Virginia Tech researchers Sterling Nesbitt and Michelle Stocker, from the Department of Geology at the College of Science. The “dinosaur predecessors” called Lagerpetid are the closest relatives of pterosaurs.

Dromomeron

Artistic depiction of Ghost Ranch, Dromomeron (foreground) based on the remains of New Mexico, and related dinosaurs and relatives. Courtesy of Donna Braginetz. Credit: Donna Braginetz

“Where did the pterosaurs come from?” is one of the most important questions in the evolution of reptiles; We think we have the answer now, “he said. Nesbitt is an associate professor of geocenters and an associate professor at the Fralin Institute of Life Sciences and the Center for Global Change.

Their findings were published Nature.

Remains Gregory Dromomeron, a type of lagerpetid, was first collected in Texas in the 1930s and 1940s, but was not properly identified until 2009. Partially preserved in this excavation were partial skulls and skulls, which, after further research, found that reptiles had a good sense of balance and were most likely agile animals.

Lagerpeton

Lagerpeton (hips, legs and vertebrae) is a partial skeleton since Argentina ~ 235 million years ago. Further study of this sample helped to link the properties of lagerpetids with pterosaurs. Photo courtesy of Sterling Nesbitt. Credit: Virginia Tech

After finding more lagerpetid species in South America, paleontologists were able to create a very good picture of what lagerpetids are; were mostly small, wingless reptiles living in Pangea Trias 237 to 210 million years ago.

And in the last 15 years, five research teams from six different countries and three continents have come together to correct some mistakes in the evolutionary history of pterosaur after the recent discovery of many lagpetpetid skulls, forelegs and vertebrae in the United States, Brazil, Argentina and Madagascar.

What gave paleontologists the idea of ​​taking a closer look at lagerpetids as the closest relatives of pterosaurs? Paleontologists have been studying the bones of lagerpetids for some time and have noticed that the length and shape of their bones resemble the bones of pterosaurs and dinosaurs. However, with the few fossils they have previously found, it is only possible to assume that the lagerpetids were somewhat close to the dinosaurs.

What really causes a change in the family tree can be attributed to the lagerpetid skull and forelegs, which exhibit more pterosaur-like features than dinosaurs. And with the help of new technological advances, researchers have found that pterosaurs and lagerpetids share many similarities compared to the eye.

Paleontologists have used microcomputed tomography (µCT) scans to reconstruct the brain and sensory systems within recently discovered skulls, and have found that the brager and sensory systems of lagerpetids are very similar to those of pterosaurs.

“CT data has been revolutionary for paleontology,” said Stocker, an associate professor of vertebrate paleontology and an associate professor at the Fralin Institute of Life Sciences and the Center for Global Change.

“Instead of cutting off this first known skull, some of these fine fossils were collected about 80 years ago and destroyed,” he said. Dromomeron, we were able to use this technology to carefully reconstruct the anatomy of the brain and inner ear of these small fossils to help identify early relatives of pterosaurs. ”

A strange and impressive finding was the development of some neuroanatomical features that allowed flightless lagpetpetids and pterosaurs to fly, which led to more information about the origin of flight.

“This work is the result of international efforts that apply both traditional and advanced techniques,” said Martin D. Ezcurra, lead author of the Museo Argentino de Ciencias Naturales study in Buenos Aires, Argentina. “This is an example of how modern science and collaboration can shed light on the long-standing questions that have plagued paleontologists for more than a century.”

As a result, research will help bridge the anatomical and evolutionary gaps between pterosaurs and other reptiles. The new evolutionary connections that emerge from this work will create a whole new paradigm that will provide a completely new framework for studying the origins and flight capabilities of these reptiles.

With the little information that paleontologists have learned about early pterosaurs, they have often explained an extremely rapid evolution in order to obtain unique body plans. However, since lagerpetids are now considered the predecessors of pterosaurs, paleontologists can say that thanks to the newly discovered “middle man”, pterosaurs developed at the same rate as other major reptile groups.

“Flight is such an attractive behavior and has evolved many times throughout Earth’s history,” said Serjoscha W. Evers of the University of Friborg. “Putting forward a new hypothesis about their relationship with other extinct animals is a step forward in understanding the origin of pterosaur flight.”

Some questions still remain a mystery in this evolution. Now that lagerpetids are the closest relatives of pterosaurs, why do they lack some key features of pterosaurs, including the most prominent of these wings?

“We’re still losing a lot of information about the first pterosaurs, and we still don’t know how their skeletons turned into a flying animal,” Nesbitt said.

A group of Nesbitt, Stocker, and Virginia Tech alumni and undergraduate students will continue to study animals that emerged during the Triassic – a time when there were dinosaurs, turtles, relatives of mammals, and many familiar vertebrate groups on earth. first land-dwellers appeared When conditions were safe and they planned to go to the field to collect more fossils from the Triassic period.

Maybe soon we will have more information to bring the final touches to the original flight story.

Reference: “Mysterious dinosaurs create Pterosauria” written by Martin D. Ezcurra, Sterling J. Nesbitt, Mario Bronzati, Fabio Marco Dalla Vecchia, Federico L. Agnolin, Roger BJ Benson, Federico Brissón Egli, Sergio F. Cabreira, Serjoscha W. Evers, Adriel R. Gentil, Randall B. Irmis, Agustín G. Martinelli, Fernando E. Novas, Lúcio Roberto da Silva, Nathan D. Smith, Michelle R. Stocker, Alan H. Turner and Max C. Langer, December 9, 2020, Nature.
DOI: 10.1038 / s41586-020-3011-4

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