'Teeth were still in the bone': A Smithsonian team found North America’s oldest pterosaur in Arizona. Photo / the Washington Post
At a remote bone bed in Arizona, dense with fossils dating back around 209 million years, a Smithsonian-led team of researchers has discovered North America’s oldest known pterosaur, according to a news release.
Pterosaurs were the first vertebrates to develop powered flight, soaring above dinosaurs and other surreal creatures that called the prehistoric world home.
The finding, detailed in an article in PNAS published on Tuesday, offers clues to the evolution of the winged reptiles, which have more than 150 named species, including the Hollywood favourite – the pterodactyl.
Before the study, there were only two known Triassic pterosaurs from North America, Ben Kligman, a palaeontologist at the Smithsonian’s National Museum of Natural History and an author on the study, said in an email.
This is the only early pterosaur globally whose precise age has been determined – 209.2 million years old – information that is crucial to understanding “how a fossil animal fits into patterns of evolutionary and environmental change”, he said.
Suzanne McIntire, formerly a volunteer with the museum, unearthed the fossil. “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,” she said in a statement.
The pterosaur’s jaw holds worn-down teeth, suggesting it ate fish with armoured scales, and the creature “would have been small enough to comfortably perch on a person’s shoulder”, according to the release.
Call the new species the “ash-winged dawn goddess”, as the team has named it, or a small nightmare, as anyone imagining a winged reptile on their shoulder might.
Regardless, it’s a noteworthy discovery from the Petrified Forest National Park site, from which teams at the museum have uncovered more than 1200 individual fossils, including fish scales, teeth and fossilised poop.
The fossils offer a window into a vibrant, bygone ecosystem, where animals such as giant amphibians, some up to 2m-long, and armoured crocodile relatives lived among “evolutionary upstarts” such as frogs, turtles and pterosaurs.
“Fossil beds like these enable us to establish that all of these animals actually lived together,” Kligman said.
Among the findings was an ancient turtle “with spike-like armour and a shell that could fit inside a shoebox”, the news release says.
It’s believed to have lived around the same time as the oldest known turtle, suggesting the creatures spread across the supercontinent Pangaea quickly.
“Surprising for an animal that is not very large and is likely walking at a slow pace,” Kligman noted.
Contrary to common belief, pterosaurs are not dinosaurs – their name comes from “winged lizard” in Greek. Some were the size of paper airplanes, while others were as big as fighter jets and feasted on baby dinosaurs. They went extinct around 66 million years ago.
The early evolution of pterosaurs is something of a mystery as they appeared in the fossil record some 215 million years ago with fully evolved wings, Kligman noted.
Bones of pterosaurs from the Triassic era, about 251.9 to 201.3 million years ago, are also small, thin, and often hollow, so they are easily destroyed before fossilisation.
Scientists have named the newly discovered pterosaur Eotephradactylus mcintireae. The genus name, Eotephradactylus, refers to Eos, the goddess of dawn; tephra translates to ash, and dactyl refers to the fingerlike wings, referencing volcanic ash at the site of its discovery and the animals’ position near the base of the pterosaur’s evolutionary tree. The species name is a callback to its discoverer, McIntire.
The unearthed fossil is “one of the only early pterosaurs whose anatomy can be observed in a detailed way in three dimensions”, Kligman said.
Its teeth are especially noteworthy as they’re fused into the socket, a feature shared with small, slender Triassic reptiles known as lagerpetids, a group which some hypothesise may be closely related to pterosaurs.
Kligman called the setting of the finding, which he described as “a river system flowing through the arid sub-tropical floodplains of central Pangaea”, unusual for early pterosaurs, and said there may be similar river deposits from other Triassic rocks that can also preserve pterosaur bones.
He said they hope “this creates a new search image for filling gaps in the early evolution of pterosaurs”.