A rare stash of thousands of ancient bones found in Brazil has turned in a magnificent find: over 47 skeletons of a single, new species of Upper Cretaceous pterosaur.

Discovered in an old lake deposit on the outskirts of Cruzeiro do Oeste in the southern state of Parana, the bones are unusual for two reasons: firstly, that pterosaur bones had never been found in the southern part of Brazil, with all other pterosaur material found in the northeast.

As for how the grave came to be, evidence suggests that the site — an oasis — was a habitat for the pterosaurs for a very long time, and they did not all die simultaneously.

“Episodic events (e.g., desert storms) likely carried the disarticulated and partially articulated skeletons to the bottom of the lake where they got eventually preserved. The presence of three main levels of accumulation in a section of less than one meter suggests that this region was home to pterosaur populations for an extended period of time,” the paper reads.

“It is also plausible that Caiuajara was a migratory pterosaur that visited this area from time to time, although the first possibility is favoured here. The causes of death remain unknown, although similarities with dinosaur drought-related mortality are striking. However, it is also possible that desert storms could have been responsible for the occasional demise of these pterosaurs.”

Secondly, the size of the cache, found over a space of about 20 square metres, is deeply impressive. Pterosaurs seem to have lived on the coast, and recovered remains are usually limited to fragments of a single specimen. Although the researchers confirmed 47 individuals, they estimate the actual number to be well into the hundreds.

“Most pterosaurs are known from ancient coastal or shallow marine deposits and the number of species that lived deep inside the continents is limited, particularly from desert environments,” the research paper, published in the journal PLOS One, reads.

The new species has been named Caiuajara dobruskii, and the cache contained bones from several stages of development, from young to adult, with wingspans ranging from 0.65 metres to 2.35 metres. The pterosaurs’ heads are also adorned with a large crest, which grew in prominence as the animals matured. The size of the grave suggests that they were a social species, living and flying in colonies, developing flight from a very young age.

As for how the grave came to be, evidence suggests that the site — an oasis — was a habitat for the pterosaurs for a very long time, and they did not all die simultaneously.

“Episodic events (e.g., desert storms) likely carried the disarticulated and partially articulated skeletons to the bottom of the lake where they got eventually preserved. The presence of three main levels of accumulation in a section of less than one meter suggests that this region was home to pterosaur populations for an extended period of time,” the paper reads.

“It is also plausible that Caiuajara was a migratory pterosaur that visited this area from time to time, although the first possibility is favoured here. The causes of death remain unknown, although similarities with dinosaur drought-related mortality are striking. However, it is also possible that desert storms could have been responsible for the occasional demise of these pterosaurs.”