North America's oldest known pterosaur discovered in a petrified forest

In the arid, fossil-rich landscape of Arizona’s Petrified Forest National Park, a team of paleontologists stumbled across something unexpected. The experts found the fossilized jawbone of a pterosaur that may be the oldest ever found in North America.

The discovery came from a remote site that revealed not just one remarkable creature, but a whole ecosystem preserved in stone.

The study was led by scientists from the Smithsonian’s National Museum of Natural History and Petrified Forest National Park. The research introduces a new pterosaur species alongside more than 1,000 other fossils.

Some of these include one of the world’s oldest turtle specimens. Together, the fossils paint a vivid picture of life just before one of Earth’s biggest mass extinctions.

Life before mass extinction

The pterosaur fossils come from rock layers that date back to the Late Triassic period. During this time, ancient amphibians and crocodile-like reptiles lived side by side with animals that would go on to shape the future of the planet, including early turtles, frogs, and flying reptiles.

“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,” said study lead author Ben Kligman.

This glimpse into prehistoric life is especially valuable because it dates to just before the end-Triassic extinction – about 201.5 million years ago – when massive volcanic eruptions dramatically altered Earth’s climate.

The event wiped out roughly 75% of all species, paving the way for dinosaurs to rise to dominance.

Fossils hidden by ash

Direct fossil evidence from just before this extinction is hard to come by. Few fossil-rich outcrops from this time exist, but Petrified Forest National Park is one of the rare exceptions.

Known for its colorful layers of petrified wood and Triassic fossils, the park has long been a treasure trove for paleontologists.

One rock layer, called the Owl Rock Member, has proven especially important. It’s full of volcanic ash, which helped scientists date it precisely to around 209 million years ago. These are some of the park’s youngest rocks – but also among its least explored.

Study co-author William Parker explained that the Owl Rock exposures are tucked away in extremely remote areas. Few teams have been able to study them in detail.

In 2011, a research group led by Kay Behrensmeyer decided to take on the challenge. Braving the rugged terrain – complete with rattlesnakes and wild horses – they went in search of mammal-like fossils.

What they found instead was a densely packed bonebed, full of life from a vanished world.

“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,” said Kligman, who started working at the site during his PhD studies in 2018.

Ancient life buried by floods

Back in the Triassic, this part of Arizona was located near the equator and sat in the center of the supercontinent Pangaea.

The land was semi-arid, with winding river channels and a seasonal flood cycle. One of those floods likely buried the animals that are now preserved in the bonebed.

The fossil layer was so dense with tiny remains that collecting them onsite was impossible. Instead, researchers carved out large blocks of sediment, wrapped them in plaster, and brought them back to the lab.

Many of these blocks were sent to the Smithsonian’s FossiLab, where volunteers spent thousands of hours carefully exposing the bones.

Small fossils, major clues

The rivers teemed with fish like coelacanths and freshwater sharks. Giant amphibians – some stretching over six feet long – swam through the streams. On land, armored herbivores and crocodile-like predators ruled.

At the same time, smaller creatures were starting to make their mark. The team identified early frogs, relatives of today’s tuataras, and a turtle with spike-like armor that could fit in a shoebox.

The remains of a small pterosaur were also hidden among the layers – just one part of a fossil record that shows how quickly new groups were emerging and spreading across Pangaea.

“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,” said Kligman.

Pterosaur that perched like a bird

One of the most exciting finds was a jawbone with teeth still in place. It belonged to a small pterosaur, one of the first vertebrates capable of powered flight. This early flier could have perched on a person’s shoulder.

The pterosaur fossil was uncovered by Suzanne McIntire, a volunteer who spent 18 years working in the FossiLab.

“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 wear on the teeth gave scientists a clue about the pterosaur’s diet. It likely fed on armored fish that were common in the area.

The new species was named Eotephradactylus mcintireae, which translates to “ash-winged dawn goddess.” This title honors McIntire, who retired last year.

What exactly is a pterosaur?

Pterosaurs were flying reptiles that existed during the time of dinosaurs. They were the first animals with backbones to evolve powered flight, well before birds or bats came on the scene.

Powered by skin stretched across an extended fourth finger, they ranged in size and shape from something no larger than a crow to giants with wings up to 30 feet or more.

Pterosaurs were not dinosaurs. They formed their own group of reptiles and possessed special adaptations for flight. Some flew above coastlines, while others preyed on fish or small land animals inland.

The new fossil contributes to what is known about those early birds and how they expanded around the globe.

The full study was published in the journal Proceedings of the National Academy of Sciences.

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