A graveyard of pterosaurs has been found in southern Brazil at what had been the bottom of a Cretaceous lake, shedding new light on how these reptiles flew – and lived, which was apparently in families. Also, they had enormous crests that made the adults look rather like flying sailboats. There crest seems to have been common to both sexes, and to have grown larger with age.
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Contrary to common assumptions, pterosaurs were not dinosaurs. They were lizards with crested heads that had the true gift of flight. It is true that pterosaurs, which were found on the coastlines of every prehistoric continent – though rarely inland, go back as far as the dinosaurs. In fact both derive from the same line, the avemetatarsalians, which may go back as far as 250 million years; they also went finally extinct together about 65 million years ago.
The remains found in Cruzeiro do Oeste, Brazil were of an unknown species that lived some 90 million years ago, Caiuajara dobruskii – which was unlike its pterosaur peers in many ways, says the paleontological team headed by Paolo Manzig of Universidade do Contestado in a paper published by Plos One.
For one thing, their crests were gargantuan. For another, while the pterodactyl set liked coastlines, these individuals lived around an oasis in a desert – though, the paleontologists speculate, it could have been migratory.
Birdlike beak features
Pterosaur fossils are rare, and almost all have been incomplete and alone. This is the first concentrated pterosaur graveyard to have been found – and the remains are in decent, three-dimensional condition. Previously found pterosaur remains tended to be shattered and flattened.
The team's primary purpose was to classify the new pterosaur, which they did: it belongs to the toothless pterodactyloid clade Tapejaridae, they wrote, a group of flying lizards that is believed to have lived off fruit.
They also concluded from the pile of bones, which included at least 47 lizards (but possibly hundreds, the authors point out), that these lizards were gregarious, living in colonies – and based on bone development, that the babies could fly from a very young age.
Another interesting factoid is that the beak seems to have been covered in a horny chitinous coating like the keratinized skin layer that covers bird beaks (known as the rhamphoteca).
All in the pterodactyl family
As for their gregariousness, the compelling fact is the discovery of multiple pterosaurs found in close association. Much the same has been suggested for other extinct reptiles, as well as many dinosaurs.
While many pterosaurs are assumed to have been fishers, including based on their habit of living coastally, Caiuajara dobruskii seems to have lived in colonies around a lake situated in a desert, say the scientists.
But did the parents care for their young? While we can't know, and they may have – the researchers postulate that these pterosaurs were precocial, probably developing the ability to fly very young, based on the way their bones developed.
They do not seem to have been particularly large. Most of the bodies found seem to have been of young pterosaurs, say the researchers, making it very difficult to establish the wing span of the adult, but the researchers believed it maxed out at about 2.35 meters, a meter less than a self-respecting albatross. The biggest known pterosaur, the Quetzalcoatlus, boasted a wing-span of 12 meters, giving rise to the surmise that it couldn't get off the ground to save its life, but could glide. We don't know.
Quetzalcoatlus by the way was also a toothless pterosaur, and also may have lived in colonies, judging by the proximity of its rather rare remains. But sadly for the proto-mammals living in prehistoric Texas of the late Cretaceous, 68 million years ago, it apparently ate them, not fruit like its earlier cousin, the Caiuajara.
In June, Chinese scientists said they had unearthed no fewer than 40 adult individuals of another newly identified pterosaur species as well as five pterosaur eggs - very rare indeed - preserved beautifully in three dimensions. No eggs were found in the Brazilian bunch.
With reporting by Reuters