Australia’s Oldest Pterosaur Bones Prove They Soared Below The Antarctic Circle

Bones from Dinosaur Cove, Australia, prove the presence of flying reptiles at the location 107 million years ago. The importance of this find lies in the fact that at the time the Cove lay inside the Antarctic Circle, meaning the Sun did not rise for weeks on end. This certainly tells us something important about pterosaur behavior – either they migrated, hibernated or could hunt in near-total darkness – but we don’t yet know which.

During the Cretaceous, Australia lay far to the south of its current location. Northern Australia, home to giant sauropods such as Australotitan cooperensis and most of Australia’s known pterosaurs, was at temperate latitudes but the southern coastline initially lay south of the Antarctic Circle. The discovery by Dr Thomas Rich and Dr Pat Vickers-Rich of the presence of big-eyed dinosaur bones along this coastline caused a revolution in how dinosaurs more generally were seen. The so-called dinosaurs of darkness proved the capacity of some terrible lizards to survive long periods without sunlight, reshaping questions such as whether dinosaurs were warm-blooded.

After tunneling 60 meters (200 feet) into a seaside cliff the same digs also turned up three bones that were identified as being from pterosaurs, but were then neglected for more than 30 years. Now there is finally someone investigating Australia’s pterosaurs. Now, Curtin University PhD student Adele Pentland and the original finders have published their analysis in a new paper. 

“In 2019 I was working on a bone labelled as a pterosaur, but it was actually a new kind of theropod,” Pentland told IFLScience. For most people, a new dinosaur might be the peak of excitement, but Pentland loves her chosen field, “So I was relieved to work on these and confirm they really were pterosaurs.”

The bones turn out to be the pelvic bones of an adult and juvenile pterosaur, as well as a crushed section of a juvenile’s wing. These are the first juvenile pterosaur bones found in Australia, as well as the continent’s oldest known pterosaur remains. All are small, and look like they might come from a modest-sized bird. However, through comparison with a pelvis of a Brazilian pterosaur Pentland concluded the adult would still have had a 2-meter (7 foot) wingspan, reflecting these creatures’ capacity to drive immense wings with relatively small bodies.

Pentland told IFLScience the bones are insufficient to tell if these were from a new species or an already known one. Indeed, she said, “I couldn’t even work out which family they belonged to.” Without a skull, identifying diet is probably also impossible.

The important feature of the discovery, however, is the location and age. Buried in 107-million-year-old rocks the flying reptiles died below the Antarctic Circle, raising the question of how they coped with winter. The planet may have been warmer then, but the winters would have been just as dark, and almost as cold. 

“I’m not sure if hibernation is realistic for pterosaurs as they had a high metabolic rate,” Pentland told IFLScience. “No paper I’ve read has proposed hibernation, but then few have been found at polar latitudes, just three bones from Antarctica.”

Migration is a more plausible option for the pterosaurs than for the terrestrial dinosaurs of darkness. “Previous research suggests they could fly quite well from a young age,” Pentland told IFLScience. 

Nevertheless, “It will only be a matter of time until we are able to determine whether pterosaurs migrated north during the harsh winters to breed, or whether they adapted to polar conditions,” Pentland said in a statement. “Finding the answer to this question will help researchers better understand these mysterious flying reptiles,”

The study is published in Historical Biology.

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