209 million-year-old flying dinosaur finally unearthed

By Stephen Beech

The fossilized remains of North America’s oldest known flying dinosaur, dating back more than 200 million years, have been unearthed.

Researchers say the "seagull-sized" pterosaur would have been small enough to comfortably perch on a person’s shoulder.

Pterosaurs lived alongside other dinosaurs, as well as frogs and turtles, and were the first vertebrates to evolve powered flight.

The jawbone of the new pterosaur species was discovered alongside hundreds of other fossils, including one of the world’s oldest turtle fossils, at a remote bonebed in Petrified Forest National Park, Arizona.

Researchers say it would have been small enough to comfortably perch on a person’s shoulder.

They explained that the fossils, dating to the late Triassic period around 209 million years ago, preserve a "snapshot" of a dynamic ecosystem where older groups of animals, including giant amphibians and armored crocodile relatives, lived alongside evolutionary "upstarts" such as frogs, turtles and pterosaurs.

The new species of winged reptile the team discovered is one of the oldest species of pterosaur found outside of Europe.

The "remarkable" fossil was unearthed by preparatory Suzanne McIntire, who volunteered in the Smithsonian’s National Museum of Natural History FossiLab for 18 years.

She said: “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."

The tooth-studded jaw revealed vital clues about how the earliest pterosaurs lived.

Because the tips of the teeth were worn down, the researchers concluded that the pterosaur likely fed on the site’s fish, many of which were encased in armor-like scales.

The team named the new pterosaur species Eotephradactylus mcintireae.

The generic name means "ash-winged dawn goddess" and references the site’s volcanic ash and the animals’ position near the base of the pterosaur evolutionary tree.

The species name references its discoverer, McIntire, who retired last year.

Study leader Dr. Ben Kligman, of the Smithsonian’s National Museum of Natural History, said: "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.

“Fossil beds like these enable us to establish that all of these animals actually lived together.”

The new site helps fill a gap in the fossil record that predates the end-Triassic extinction (ETE), according to the findings published in the journal Proceedings of the National Academy of Sciences.

Dr. Kligman says that around 201.5 million years ago, volcanic eruptions associated with the break-up of the supercontinent Pangaea dramatically altered global climates and wiped out roughly 75% of the species on Earth.

That cleared the way for newer groups, such as dinosaurs, to diversify and dominate ecosystems worldwide.

But direct evidence of the transition on land is difficult to find due to a lack of terrestrial fossil outcrops from right before the ETE.

However, Dr. Kligman says there are few better places to look than Petrified Forest National Park, which is famed for its Triassic fossil beds and colorful deposits of petrified wood.

One of the park’s geologic outcrops, the Owl Rock Member, is rich in volcanic ash.

Minerals within the ash have allowed researchers to date the Owl Rock layer to around 209 million years old, making them among the park’s youngest rocks.

The exposures of the Owl Rock Member at the park are found in very remote areas and so have not received the same attention as other geological features in the park.

In 2011, a team co-led by research geologist Kay Behrensmeyer were searching for fossils of prehistoric precursors to mammals and ended up discovering a bonebed containing an entire Triassic ecosystem.

Dr Kligman, who began working on the site in 2018, said: “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."

He said the creatures whose remains have been preserved in the bonebed were likely buried in a flood.

The site is so rich in small fossils that excavating them all in the field was impossible, according to the researchers.

The team encased large pieces of the surrounding sediment in plaster and brought them back to prepare in the lab.

Many of the sediment blocks ended up at the museum’s FossiLab, where a team of volunteers spent thousands of hours, often in view of curious museum visitors, carefully chiselling rock away from bones under the microscope.

In total, the team has uncovered more than 1,200 individual fossils - including bones, teeth, fish scales and coprolites, or fossilized poo.

The collection contains 16 different groups of vertebrate animals that once inhabited a diverse ecosystem.

Dr. Kligman says the region’s rivers were filled with fish - such as freshwater sharks and coelacanths - as well as ancient amphibians, some of which grew up to six feet long.

He said the surrounding environment was home to fearsome reptiles that evolved earlier in the Triassic, including armored herbivores and toothy predators that resembled giant crocodiles.

Dr. Kligman says some of the fossils are from an ancient turtle with spike-like armor and a shell that could fit inside a shoebox.

He says the tortoise-like animal lived around the same time as the oldest known turtle, whose fossils were previously uncovered in Germany.

Dr. Kligman added: “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."