Caiuajara dobruskii is an extinct genus of tapejarid pterosaur that lived in Brazil during the Late Cretaceous period around 94-72 million years ago.
Discovery and naming[]
In 1971, the laborers Alexandre Dobruski and his son João Gustavo Dobruski found a pterosaur fossils in a near Cruzeiro do Oeste in the south of Brazil, in the state of Paraná.
Description[]
The largest individuals of Caiuajara had an estimated wingspan of 2.35 meters. The species had a large toothless head with, in adult individuals, an enormous shark fin-shaped crest on the snout. Mandibles The describing authors established several distinguishing unique traits, autapomorphies. The tip of the snout is strongly oriented to below, at 142 to 149°, relative to the edge of the upper jaw.
The rear ascending branches of the premaxillae on their midline form an elongated bony rim projecting to below into the nasoantorbital fenestra, the large skull opening in the side of the snout. In the concave upper rear of the symphysis, the fronts of the lower jaws grown together, a rounded depression is present. The front outer edge of the quadrate shows a longitudinal groove. Below the front part of the nasoantorbital fenestra, a depression is present in the upper jaw edge.
Additionally, Caiuajara shows a unique combination of traits that are themselves not unique. The lower edge of the eye socket is rounded. At a maximal occlusion, the gap between the upper and lower jaw is wider than with other tapejarines. The pteroid on its bottom surface shows a conspicuous depression lacking a pneumatic opening.
Paleobiology[]
The habitat of Caiuajara was a desert with dunes. The layers in which the fossils were found had been deposited in a lake in the desert; probably the bones had been exposed at the surface around the lake for a time and were then by storms blown into it, eventually sinking to the bottom.
Possibly the same storms caused many individuals to die together; this could also have been the result of droughts. A succession of layers shows that the lake was likely inhabited by the pterosaurs for a great length of time, although it is also possible they visited the lake during regular migrations. Fossil plants — tapejarids are often assumed to have been herbivores — have not been found, so there are no direct indications about the food source. Likewise, remains of invertebrates have not been discovered.
The large concentrations of fossils, among pterosaurs very rare and only equaled by those found of the Argentine form Pterodaustro, were by the describers seen as proof of a gregarious lifestyle, Caiuajara living in colonies. The many specimens also allowed to determine a growth series, the first such an ontogenetic sequence for pterosaurs of which it is nearly certain that it really represented a single species.