Brisbane, AustraliaWhen an inferno razed the former palace that housed Brazil’s Museu Nacional in 2018, it damaged millions of valuable artifacts, including many globally significant fossils. But now, a 70-million-year-old bone retrieved from the rubble is offering scientists a ray of hope.
Together with a second bone that was in a building unaffected by the fire, this fossil represents the first evidence that pterosaurs ruled the skies above Antarctica as the age of dinosaurs drew to a close.
“It's terrific to hear that at least some of the pterosaur collection is not only being salvaged, but is in good enough condition, and with sufficient records, that it can continue to inform science,” says Mark Witton, a pterosaur expert at the University of Portsmouth in the U.K. who was not involved in the research.
Collected from Vega Island in the Antarctic Peninsula, the rescued fossil belonged to either an azhdarchid or pteranodontian pterosaur, two varieties that were common during the late Cretaceous period. But while Antarctica was then much warmer, and covered with lush conifer forests that were seemingly ideal pterosaur habitat, evidence of these reptilian fliers on the southern landmass has been tough to track down. Pterosaur bones have incredibly thin walls and are full of air pockets that make them instantly recognizable, but that are also very delicate and unlikely to stand the test of time as fossils.
With the recovered bones in hand, paleontologists have at last made a convincing case that that impressively large pterosaurs once soared over the region: The bone that survived the museum fire is believed to come from a creature with a 16-foot wingspan. (Find out about a similarly large “frozen dragon” pterosaur found in Canada.)
“There are many important fossils and other items recovered from the palace, but the blackened bone is the first of any kind to be studied after the fire,” says paleontologist and Museu Nacional director Alexander Kellner, who revealed the find late last week at a meeting of the Society of Vertebrate Paleontologyin Brisbane, Australia.
“Any story about fossils or specimens that survived is great,” comments Liz Martin-Silverstone, who works on pterosaurs at the University of Bristol in the U.K. “It doesn’t counter the immense sadness and devastation of all that was lost, but at least we know some things survived.”
Of ice and fire
Until now, the only evidence of pterosaurs known from Antarctica was the tiny upper arm bone of a crow-size creature found in the 1990s. That bone showed pterosaurs had been present in what are now the Transantarctic Mountains about 190 million years ago, in the early Jurassic.
The new discoveries are among hundreds of diverse fossils recovered by a Brazilian team that visited the Antarctic Peninsula on four expeditions between 2006 and 2019. This region of the continent, which juts toward South America, is the only part of Antarctica that the Brazilian navy can get them to safely, Kellner says. Even then, each expedition involves many weeks of often fruitless hunting for fossils in very trying conditions.
“Antarctica is one of those places where the climate changes very abruptly,” Kellner says. “You can have this really gorgeous day, and in less than one hour, it can turn into a very big nightmare where you can be confined for a week or more in the tent.”
The team discovered their first pterosaur remains there on James Ross Island in 2016, unearthing two parts of a wing bone from a pterosaur that likely had a 10- to 13-foot wingspan. They then found the Vega Island fossil, from an even larger pterosaur, in 2017. Both sets of fossils date back 70 to 80 million years, in the late Cretaceous.
Following the expeditions, the fossils were taken into the collections of the Museu Nacional in Rio de Janeiro. Thankfully, at least half the specimen from James Ross Island was in a separate laboratory in 2018 and escaped the fire, while the location of the other half is yet to be determined.
“The finds are particularly significant, as there has been very little material described from Antarctica, primarily due to it being largely covered in ice and snow,” says Adele Pentland, a palaeontologist at Swinburne University in Melbourne who recently described a late Cretaceous pterosaur from Australia.
Ray of hope
Australia was still connected to Antarctica back then, as the last remaining vestige of the southern supercontinent of Gondwana. The newly described fossils augment a very patchy record of pterosaurs from both these regions, helping us to understand when and why pterosaurs went extinct, Witton says.
It’s been unclear whether pterosaurs were already declining in the late Cretaceous and were simply finished off by the Chicxulub asteroid impact 66 million years ago, or if “they were a healthy, relatively successful group right until the end,” he says. These new records from Antarctica indicate that pterosaurs were present across the planet in the dying days of the Cretaceous, a sign in support of the latter case.
“We're seeing lots of hints that pterosaurs were in better shape as they approached the end-Mesozoic extinction than previously realized,” Witton says.
With the latest finds described, the researchers hope to secure funding for ongoing expeditions to Antarctica to find more pterosaur fossils that will flesh out the final chapter of their story.
“Now that we know that they are there,” Kellner says, “it is just a matter of time until more specimens will come to light.”