New research suggests giant flying pterosaurs roamed the air all over the world 60 million years ago in the Late Cretaceous Period.

According to Live Science, the researchers, who published a new study in the journal ZooKeys, said the ancient dinosaurs had wingspans as large as 39 feet. Dubbed Azhdarchidae, the pterosaur "dragons" also apparently had no teeth.

"This shift in dominance from toothed to toothless pterodactyloids apparently reflects some fundamental changes in Cretaceous ecosystems, which we still poorly understand," the study's author Dr. Alexander Averianov, of the Zoological Institute of the Russian Academy of Sciences, said in a press release.

Pterosaurs belonged to the same family of dinosaurs as the pterodactyl and some were so large they may have needed to build up momentum on the ground before taking flight. Previous fossil analysis also showed the pterosaur was likely the first vertebrates to fly, some 220 million years ago.

"Azhdarchidae currently represent a real nightmare for paleontologists: most taxa are known from few fragmentary bones, which often do not overlap between named taxa, the few articulated skeletons are poorly preserved, and some of the best available material has remained undescribed for forty years," Averianov said.

In general, pterosaurs' evolutionary history is incomplete because their bones were delicate and their fossils rare, Live Science reported. Before this research was published, the majority of Azhdarchidae fossil analyses were based on fragments of bones or incomplete skeletons.

Scientists discovered a rare pterosaur whose fossil was unearthed in Brazil with a unique bony ridge on its head that resembled a butterfly wing. Perhaps the most unique thing about the discovery was that there were 47 identifiable individuals at the site.

Most were juveniles, but the researchers believed the bone fragments could have belonged to hundreds more than just the identifiable ones. Unlike Azhdarchidae, these C. dobruskii did not grow so big.