Artist concept of Dearc sgiathanach. Image: Natalia Jagielska
Paleontologists have discovered the biggest flying animal known from the Jurassic period: a pterosaur with an eight-foot wingspan that lived 160 million years ago on what is now a picturesque Scottish island, reports a new study.Pterosaurs are an iconic dinosaur family, with perhaps the best-known being the pterodactyl. Later pterosaurs eventually grew to gargantuan sizes on par with fighter jets, but the new species, which is named Dearc sgiathanach, confirms years of speculation that these fliers were already getting big roughly 100 million years before their entire family was wiped out by the cataclysmic asteroid impact that capped off the age of dinosaurs.
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The remains of the pterosaur, which was a juvenile that was likely still growing, are unusually intact for a pterosaur. It was first spotted during a 2017 expedition to Scotland’s Isle of Skye, a region that has already yielded tantalizing glimpses of the Jurassic period, such as sauropod footprints and the remains of ancient sea predators. The discovery of the “spectacularly preserved three-dimensional skeleton” fills “a frustrating gap in the pterosaur record,” according to a study published on Tuesday in Current Biology. “For some reason, in our location, we have a pterosaur that is preserved in three dimensions,” said Natalia Jagielska, a Ph.D. student in paleontology at the University at Edinburgh who led the new study, in a call. “That’s super, super rare. That doesn’t really happen.”“It's a little miracle,” she added. “But it might be an indication that something interesting is going on in Scotland, on a taphonomic level, that we should be looking for, because if this can preserve well, what else can?” Pterosaurs were the first vertebrates to evolve powered flight, an ability that allowed them to dominate the skies during the age of dinosaurs, even as birds began to emerge as their airborne rivals. Much like birds, pterosaurs had hollow, lightweight bones that enabled them to take to the air, but which are also the reason they remain so scarce in the fossil record.
“When we are talking about something from the Middle Jurassic, we're talking about 166 million years and that's a lot of time,” Jagielska said. “Imagine something like a pterosaur: It is a flying reptile, an animal that has to be able to survive in flight. "To do it, it developed very thin bone-holes—they are about a millimeter thick—which is excellent for the animal, but when it comes to preservation, it isn’t really good for us.”Over large timescales, “those bones start being crushed or flattened into two dimensions” by the surrounding rock, she explained.Scientists have long suspected that Jurassic pterosaurs grew to sizes that are comparable to the largest modern birds, but these assumptions were based on occasionally fragmentary fossils that did not provide conclusive sizes. That all changed in May 2017, when Amelia Penny, a study co-author who was then a PhD student at the University of Edinburgh, noticed an exquisitely preserved skull bulging out of the limestone rock at Rubha nam Brathairean, also known as Brothers’ Point, which is a peninsula on the northeast coast of the Isle of Skye.The expedition team had to rush to extract the specimen from the limestone using diamond-tipped saws as the tide rushed in over the peninsula. But the effort was worth it: The specimen is nearly complete and includes important portions of the brain vault, tail, and wings, which stretched about 2.5 meters (eight feet) from tip to tip.
Strikingly, some enamel is even preserved on its teeth, a detail that sheds light on its pescatarian lifestyle. In addition, visible growth patterns inside a fractured bone allowed the scientists to estimate that the animal was about two years old when it died, which means it was likely still growing into an even larger adult size. As a result, Dearc sgiathanach—which is a name derived from Scottish Gaelic that means both “winged reptile” and “reptile from Skye”—at last validates the paleontological hunch that pterosaurs reached large sizes much earlier than was previously known. Though the animal is the largest pterosaur ever found from the Jurassic period, it’s likely that it shared the skies with contemporaries that were as big or possibly bigger, but that did not leave behind such an intact skeleton. “It's the biggest [pterosaur] we have currently, so it proves that around the middle early Jurassic pterosaurs were much more diverse and bigger than previously anticipated,'' Jagielska said. “They would already have global distribution as north of Scotland and as south as Latin America and Chile.” The discovery has major implications for understanding the long reign of pterosaurs, while also shedding light on the emergence of early birds. Now that the species has been officially introduced to the world in the new study, Jagielska intends to examine the specimen further and scour museum archives to learn more about its behavior, its possible relatives, and the long-lost world that it once inhabited. “It's wonderfully preserved, so it’s like a treasure trove of things we can be doing,” she concluded.