A team of researchers led by Smithsonian has discovered the oldest known pterosourium in North America, winged reptiles who lived next to dinosaurs and were the first vertebrates in evolving the driven flight. In an article published on July 7 in Proceedings of the National Academy of SciencesResearchers led by the paleontologist Ben Kigman, a postdoctoral fellow of Peter Buck in the National Museum of Natural History of Smithsonian, present the fossilized jaw of the new species and describe the pterosaur of the size of the seagyt a National Fossils Park in the world.
These fossils, which date back to the period of the late Triassic about 209 million years ago, preserve a snapshot of a dynamic ecosystem where major animals of animals, including giant amphibians and armored crocodile relatives, lived along with evolutionary advenions such as frogs, turtles and pterosaurs.
“The site captures the transition to communities of more modern terrestrial vertebrates where we begin to see groups that prosper later in the Mesozoic that lives with these older animals that do not pass the Triassic,” Kigman said. “The fossil beds like these allow us to establish that all these animals really lived together.”
The new site helps fill a vacuum in the fossil record that is prior to the extinction of the final Triassic (ETE). Around 201.5 million years ago, volcanic eruptions associated with the rupture of the supercontinent Pangea drastically altered global climates and eliminated approximately 75% of species on Earth. This cleared the way for the newer groups, such as dinosaurs, to diversify and master ecosystems around the world.
The direct evidence of this transition on Earth is difficult to find due to the lack of terrestrial fossil outcrops from just before the ETE. However, there are few better places to look than the Forest Petrified National Park, which is famous for its triassic fossil beds and colorful petrified wood deposits.
One of the geological outcrops of the park, the member of the Owl Rock, is rich in volcanic ashes. Minerals within the ashes have allowed researchers to date the OWL rock layer to around 209 million years, which makes them the youngest rocks in the park.
These rocks are also among the least studied of the park according to William Parker, paleontologist of the Petrified Forest Park and co -author of the new study. The exhibitions of the Owl rock member in the park are found in very remote areas and, therefore, have not received the same attention as other geological members in the park.
In 2011, a team was co-dried by research geologist Kay Behrensmeyer, the vertebrate paleontology curator of the National Museum of Natural History, challenged the bad and steep lands of the area, which house rattlesnakes and wild horses. They were looking for prehistoric precursors fossils to mammals and ended up discovering a bed of bones containing a complete Triassic ecosystem.
“That is the fun of paleontology: you are going to look for one thing, and then you find something more incredible you did not expect,” said Kigman, who began working on this site as part of his doctorate in 2018.
This part of Arizona’s northeast was placed in the middle of Pangea and sat down just above Ecuador 209 million years ago. The semi -arid environment of the area was cross -linked by small river channels and probably prone to seasonal floods. These floods washed sediments and volcanic ashes in the channels.
One of these floods probably buried the creatures preserved in the bed of the bones. The site is so rich in small fossils that excavating them all in the field was impossible. Then, the team locked large pieces of the surrounding sediment and brought them back to prepare in the laboratory. Many of these sediment blocks ended up in the museum’s Fosilab, where a volunteer team spent thousands of hours, often in view of the curious visitors of the museum, carefully chiseling bones rocks under the microscope.
In total, the team has discovered more than 1,200 individual fossils, including bones, teeth, fish scales and coprolites, or fossilized peanut. This set contains 16 different groups of vertebrate animals that once inhabited a diverse ecosystem. The braided rivers of the region were full of fish, such as fresh water and celestial sharks, as well as ancient amphibians, some of which grew up to 6 feet long. The surrounding environment was the home of fearsome reptiles that previously evolved in the Triassic, including armored herbivores and teeth predators that looked like giant crocodiles.
Living together with these strange creatures there was a variety of more familiar creatures, including relatives of tuateras and early frogs. The researchers also described the fossils of an old turtle with armor similar to a spike and a shell that could fit inside a shoe box. This turtle animal lived at the same time as the oldest known turtle, whose fossils were previously discovered in Germany.
“This suggests that the turtles are quickly dispersed through Pangea, which is surprising for an animal that is not very large and probably walks at a slow pace,” Kigman said.
The turtle was not the only evolutionary newcomer on this site. The new species of pterosourium that the team discovered is one of the oldest species of pterosourium that is outside Europe. Winged reptile would have been small enough to perch comfortably on a person’s shoulder.
The remarkable fossil was unearthed by the preparator Suzanne McIntire, who offered as a volunteer in the Fosilab of the museum for 18 years.
“The exciting thing about discovering this specimen was that the teeth were still in the bone, so he knew that the animal would be much easier to identify,” McIntire said.
The jaw full of teeth revealed crucial clues about how the earliest first. Because the tips of the teeth were worn, the team concluded that the pterosour probably fed on the fish of the site, many of which were locked in armor scales.
The team called the new species of pterosour Eotephradactylus mcintiree. The generic name means ‘goddess of dawn of the wing of ashes’ and refers to the volcanic ashes of the site and the position of the animals near the base of the evolutionary tree of the pterosour. The name of the species refers to its discoverer, McIntire, who retired last year.
The Bonebed is the latest research collaboration between the National Museum of Natural History and the Forest Petrified National Park. Smithsonian scientists have collected petrified wood, fossils and archaeological objects in the region since the change of the twentieth century.
In addition to Kigman and Behrensmeyer, the new article included contributions from Adam Fitch, who is also affiliated with the National Museum of Natural History. The study also includes authors affiliated with Columbia College Chicago, the Massachusetts Institute of Technology, the Denver Nature and Science Museum and Forest Petrified National Park.
The investigation was supported by the Peter Buck Postdoctoral Scholarship program, the Smithsonian Association, Petrified Forest Museum, the National Parks Service, Columbia College Chicago and the National Foundation of Sciences of the United States.
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