Petrified Forest National Park, Arizona, July 7, 2025 – A Smithsonian-led research team has discovered the oldest known pterosaur in North America, a sea gull-sized winged reptile that lived 209 million years ago during the late Triassic period.
The fossilized jawbone of the new species, named Eotephradactylus mcintireae, was unearthed alongside hundreds of other fossils, including one of the world’s oldest turtle fossils, at a remote bonebed in Arizona’s Petrified Forest National Park. The findings, published today in Proceedings of the National Academy of Sciences, provide a rare glimpse into a dynamic ecosystem just before the end-Triassic extinction.
A Snapshot of a Triassic Ecosystem
Led by paleontologist Ben Kligman, a Peter Buck Postdoctoral Fellow at the Smithsonian’s National Museum of Natural History, the team uncovered over 1,200 fossils, including bones, teeth, fish scales, and coprolites, representing 16 vertebrate groups. The bonebed, located in the park’s Owl Rock Member, captures a transitional moment when older animals, such as giant amphibians and armored crocodile relatives, coexisted with emerging groups like frogs, turtles, and pterosaurs.
“The site captures the transition to more modern terrestrial vertebrate communities where we start seeing groups that thrive later in the Mesozoic living alongside these older animals that don’t make it past the Triassic,” Kligman said. “Fossil beds like these enable us to establish that all of these animals actually lived together.”
The fossils date to 209 million years ago, predating the end-Triassic extinction (ETE) around 201.5 million years ago, when volcanic eruptions tied to the breakup of Pangaea caused global climate shifts, eliminating about 75% of Earth’s species. This event allowed newer groups, like dinosaurs, to dominate. The Owl Rock Member’s volcanic ash enabled precise dating, making it one of the park’s youngest and least-studied geological layers.
Discovery in the Badlands
In 2011, a team co-led by Kay Behrensmeyer, curator of vertebrate paleontology at the National Museum of Natural History, explored the park’s rugged badlands, home to rattlesnakes and wild horses. Initially searching for mammal precursors, they stumbled upon the bonebed, which preserved an entire Triassic ecosystem.
“That’s the fun thing about paleontology: you go looking for one thing, and then you find something else that’s incredible that you weren’t expecting,” Kligman said.
The site’s semi-arid environment, positioned just above the equator in Pangaea, featured braided rivers and seasonal floods. One such flood likely buried the creatures in sediment and volcanic ash, preserving them. Due to the abundance of small fossils, the team encased sediment blocks in plaster for lab preparation. Volunteers at the museum’s FossiLab spent thousands of hours chiseling rock under microscopes, often in view of visitors.
A New Pterosaur and Ancient Turtle
The new pterosaur, Eotephradactylus mcintireae, was discovered by volunteer preparator Suzanne McIntire, who worked at FossiLab for 18 years. The tooth-studded jawbone, with worn teeth, suggests the pterosaur fed on armored fish. Its generic name, meaning “ash-winged dawn goddess,” reflects the site’s volcanic ash and its early place in pterosaur evolution. The species name honors McIntire, who retired in 2024.
“What was exciting about uncovering this specimen was that the teeth were still in the bone, so I knew the animal would be much easier to identify,” McIntire said.
The team also found a turtle fossil with spike-like armor and a shell small enough to fit in a shoebox, dating to the same period as the oldest known turtle from Germany. “This suggests that turtles rapidly dispersed across Pangaea, which is surprising for an animal that is not very large and is likely walking at a slow pace,” Kligman said.
A Diverse Prehistoric World
The bonebed revealed a diverse ecosystem. Rivers teemed with freshwater sharks, coelacanths, and amphibians up to six feet long. The landscape hosted armored herbivores, crocodile-like predators, tuatara relatives, and early frogs. The findings highlight Petrified Forest National Park’s significance for studying the Triassic, a period underrepresented in terrestrial fossil records.
Ongoing Research and Collaboration
The study, supported by the Peter Buck Postdoctoral Fellowship Program, the Smithsonian, and others, involved researchers from Columbia College Chicago, MIT, Denver Museum of Nature & Science, and Petrified Forest National Park. The National Museum of Natural History has studied the region’s fossils since the early 20th century, and this discovery strengthens its collaboration with the park.
William Parker, a park paleontologist and study co-author, noted the Owl Rock Member’s remoteness limited prior research. The bonebed’s discovery opens new avenues for understanding the Triassic’s ecological transitions.
