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- North America’s earliest known flying reptile discovered.
- Fossils excavated at Petrified Forest National Park.
- Dating back 209 million years to the Triassic Period.
Researchers have uncovered fossils in Arizona, including North America’s oldest flying reptile, shedding light on a period of transition when ancient species preparing to go extinct coexisted with new arrivals at the dawn of the dinosaur era.
The remains of a pterosaur, approximately the size of a small seagull, along with other species, were found in Petrified Forest National Park, renowned for its Triassic fossils, including enormous tree trunks. The newly discovered fossils are 209 million years old and comprise at least 16 different vertebrate species, seven of which were previously unknown.
The Triassic Period followed the planet’s largest mass extinction event, which occurred around 252 million years ago, and concluded with another extinction about 201 million years ago that eliminated many of the major competitors to the dinosaurs, which would later dominate during the Jurassic period. Both catastrophes are believed to have been triggered by severe volcanic activity.
The fossils, encased in rock laden with volcanic ash, offer a glimpse into a vibrant tropical ecosystem marked by rivers on the edge of a vast desert.
In addition to the pterosaur, researchers discovered primitive frogs, lizard-like reptiles, and one of the earliest-known turtles— all sharing similarities with their modern relatives. The ecosystem’s largest predators and herbivores belonged to reptile lineages that were thriving at that time but went extinct relatively quickly thereafter.
Despite the onset of the era of dinosaurs, no actual dinosaurs were found in this ecosystem, indicating that they had not yet become the dominant species.
“Although dinosaurs can be found in contemporary rock layers in Arizona and New Mexico, they were absent from the ecosystem we’re studying,” stated paleontologist Ben Kligman from the Smithsonian Institution’s National Museum of Natural History in Washington, who led the study published in the journal *Proceedings of the National Academy of Sciences*.
“This is unusual and may relate to dinosaurs favoring different habitats,” Kligman added.
This ecosystem existed just north of the equator in the ancient supercontinent Pangaea, which later fragmented and formed today’s continents.
Pterosaurs, relatives of dinosaurs, were the first vertebrates to achieve powered flight, a feat later accomplished by birds and bats. Pterosaurs are believed to have emerged about 230 million years ago, around the same time as the earliest dinosaurs, but the oldest known pterosaur fossils date to approximately 215 million years ago in Europe.
The recently identified pterosaur, dubbed *Eotephradactylus mcintireae*, is thought to have hunted fish in local rivers. Its partial skeleton features parts of a toothy lower jaw, several isolated teeth, and bones of its elongated fingers, which made up its wing structure.
*Eotephradactylus* had a wingspan of about three feet (one meter) and a skull measuring about four inches (10 cm) long. It possessed curved fangs at the front of its mouth for catching fish while flying over rivers and blade-like teeth for slicing prey in the back. Researchers believe that *Eotephradactylus* had a tail, a common feature of early pterosaurs.
The name *Eotephradactylus* translates to “ash-winged dawn goddess,” reflecting the nature of the rock where it was discovered and the species’ position near the beginning of the pterosaur lineage. The species name *mcintireae* honors Suzanne McIntire, the former Smithsonian fossil preparator who discovered it.
The turtle found was a terrestrial species, while the lizard-like reptile was related to New Zealand’s modern-day Tuatara. Additional reptiles discovered include armored plant-eaters, a large fish-eating amphibian, and various fish, including freshwater sharks.
The ecosystem’s largest predators were relatives of crocodiles, potentially reaching lengths of 20 feet (six meters), outsize compared to the carnivorous dinosaurs in that region at the time. Additionally, a four-legged carnivorous reptile from the rauisuchian group roamed the land, while a semi-aquatic carnivore from the phytosaur group inhabited the rivers, resembling crocodiles yet differing in features such as nostrils located on the top of the head rather than at the end of the snout.
Many species represented in the fossils, including rauisuchians and phytosaurs, became extinct during the end-Triassic extinction event. Frogs and turtles endure to this day, while pterosaurs ruled the skies until the asteroid impact 66 million years ago brought an end to the age of dinosaurs.
“This site marks a pivotal shift toward more modern terrestrial vertebrate communities,” Kligman noted.
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