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A group of researchers led by the Smithsonian has found the oldest pterosaur ever discovered in North America, the flying reptiles that coexisted with dinosaurs and were the first vertebrates to develop active flight.
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In a paper published in the Proceedings of the National Academy of SciencesResearchers, including paleontologist Ben Kligman, a Peter Buck Postdoctoral Fellow at the Smithsonian's National Museum of Natural History, have revealed the fossilized jawbone of a new species and provided details about the seagull-sized pterosaur, along with hundreds of other fossils—such as one of the oldest turtle fossils—discovered at a remote site in Petrified Forest National Park in Arizona.
These remains, from the late Triassic era approximately 209 million years ago, offer a glimpse into a thriving environment where older species of creatures, such as large amphibians and armored crocodile-like animals, coexisted with newer developments like frogs, turtles, and pterosaurs.
The site illustrates the shift toward more modern land vertebrate communities, where we begin to see groups that would flourish later during the Mesozoic era coexisting with older animals that do not survive past the Triassic," Kligman stated. "Fossil deposits such as these help us confirm that all of these creatures actually lived together.
The updated website aids in filling a void in the fossil record that occurs before the end-Triassic extinction (ETE). Approximately 201.5 million years ago, volcanic activity linked to the splitting of the supercontinent Pangaea significantly changed global climates and caused the extinction of about 75% of Earth's species. This created opportunities for new groups, such as dinosaurs, to evolve and become dominant across ecosystems.
Concrete proof of this change on land is challenging to locate because there are few land-based fossil exposures from just prior to the ETE. Nevertheless, Petrified Forest National Park offers one of the best locations to search, known for its Triassic fossil layers and vibrant collections of petrified wood.
One of the park's geological exposures, known as the Owl Rock Member, contains a significant amount of volcanic ash. The minerals found in the ash have enabled scientists to determine that the Owl Rock layer is approximately 209 million years old, placing it among the park's youngest rock formations.
These rocks are also some of the least explored within the park, as stated by William Parker, a paleontologist from Petrified Forest National Park and co-researcher on the recent study. The outcrops of the Owl Rock Member in the park are located in highly secluded regions and thus have not garnered the same level of focus as other geological layers in the area.
In 2011, a group led by research geologist Kay Behrensmeyer, who serves as the National Museum of Natural History's curator of vertebrate paleontology, explored the region's challenging badlands, known for housing rattlesnakes and wild horses. Their goal was to find fossils of early ancestors of mammals, but they instead uncovered a bonebed that held a complete Triassic ecosystem.
"That's the exciting part of paleontology: you start searching for one thing, but then you discover something amazing that you didn't anticipate," said Kligman, who started working at this site as part of his doctoral studies in 2018.
This section of northeastern Arizona was located in the center of Pangaea and was situated just north of the equator 209 million years ago. The region's semi-arid climate featured small river channels that crisscrossed the landscape and were probably subject to seasonal flooding. These floods carried sediment and volcanic ash into the channels.
One of these floods probably covered the animals whose remains are found in the bonebed. The location has an abundance of tiny fossils, making it impractical to collect them all during fieldwork.
The group wrapped big sections of the nearby sediment in plaster and transported them back for preparation in the laboratory. A number of these sediment blocks were sent to the museum's FossiLab, where a group of volunteers spent thousands of hours, frequently visible to inquisitive museum guests, methodically removing rock from bones using a microscope.
The team has discovered over 1,200 separate fossils, such as bones, teeth, fish scales, and fossilized waste. This collection includes 16 distinct types of vertebrate creatures that once lived in a rich environment.
The area's interwoven rivers teemed with fish, such as freshwater sharks and coelacanths, along with ancient amphibians that could reach lengths of up to 6 feet. The nearby landscape hosted dangerous reptiles that developed during the earlier Triassic period, including armored plant-eaters and fierce predators that looked like large crocodiles.
Coexisting with these unusual animals were several more common creatures, such as relatives of tuataras and primitive frogs. The scientists also detailed the fossils of an ancient turtle featuring spiky armor and a shell that could fit in a shoebox. This turtle-like creature existed during the same period as the oldest known turtle, whose remains had been previously discovered in Germany.
"This implies that turtles quickly spread throughout Pangaea, which is unexpected for an animal that isn't very big and is probably moving at a slow speed," Kligman stated.
The turtle was not the only new species to emerge in this area. The pterosaur species the team uncovered is among the earliest known pterosaurs found beyond Europe. This flying reptile would have been tiny enough to easily rest on someone's shoulder.
The extraordinary fossil was discovered by preparator Suzanne McIntire, who dedicated 18 years to volunteering in the museum's FossiLab.
"What was thrilling about discovering this specimen was that the teeth remained in the bone, which meant the animal would be simpler to recognize," McIntire stated.
The jaw filled with teeth provided important insights into the lifestyle of the first pterosaurs. Since the ends of the teeth were worn, the researchers determined that the pterosaur probably hunted fish found in the area, most of which had tough, scale-covered bodies.
The team has named the new pterosaur species Eotephradactylus mcintireae. The genus name translates to "ash-winged dawn goddess" and alludes to the location's volcanic ash as well as the creature's place near the beginning of the pterosaur evolutionary lineage. The specific name honors its finder, McIntire, who stepped down last year.
The site is the most recent research partnership between the National Museum of Natural History and Petrified Forest National Park. Scientists from the Smithsonian have been gathering petrified wood, fossils, and archaeological items from the area since the early 1900s.
Besides Kligman and Behrensmeyer, the new paper features input from Adam Fitch, who is also connected to the National Museum of Natural History. The research also involves authors associated with Columbia College Chicago, Massachusetts Institute of Technology, Denver Museum of Nature & Science, and Petrified Forest National Park.
More information:Kligman, Ben T., An unusual bone bed provides insight into a vertebrate community containing pterosaurs and turtles in equatorial Pangaea prior to the end-Triassic extinction,Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2505513122. doi.org/10.1073/pnas.2505513122
Provided by Smithsonian
This narrative was first released onTech Bytes Lab.
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