Caiuajara

Caiuajara is an extinct genus of tapejarid pterosaur from the Late Cretaceous of Brazil. It is known from a single type species, Caiuajara dobruskii.

Discovery and naming
In 1971, the labourers Alexandre Dobruski and his son João Gustavo Dobruski found pterosaur fossils in a field near Cruzeiro do Oeste in the south of Brazil, in the state of Paraná.[1] The finds were in 2011 brought to the attention of paleontologists Paulo C. Manzig and Luiz C. Weinschütz.

In 2014, the type species Caiuajara dobruskii was named and described by Paulo Manzig, Alexander Kellner, Luiz Weinschütz, Carlos Fragoso, Cristina Vega, Gilson Guimarães, Luiz Godoy, Antonio Liccardo, João Ricetti and Camila de Moura. The generic name refers to the geological Caiuá Group and the related genus Tapejara. The specific name honours the discoverers.[1]

The holotype, CP.V 1449, was found in a sandstone layer of the Goio-Erê Formation, the age of which is uncertain; it is perhaps dating from the Coniacian-Campanian, very roughly about eighty-five million years old. It consists of a partial skeleton including the skull, lower jaws, neck vertebrae and wing elements. Many hundreds of bones have been discovered, concentrated in several bone beds, and representing at least forty-seven individuals but probably many more. In the total assembly, all elements of the skeleton are present. The bones have been three-dimensionally preserved, not compressed, but are only rarely articulated. The individuals found are often juveniles; adult animals are much rarer, only represented by two skulls and three humeri. Good specimens have been assigned as paratypes, the more fragmentary ones have been referred.

The paratypes are: CP.V 865: a snout, rear of the mandibula, right jugal, vertebrae, ribs and metatarsals; CP.V 867: a snout and limb bones; CP.V 868: a snout, wing elements and other postcrania; CP.V 869: a vertebral column, right arm, coracoid, breastbone, wing phalanges, belly ribs, pelvic elements and a right tighbone; CP.V 870: a shoulder girdle with the humeri; CP.V 871: a right shoulder girdle with right arm elements; CP.V 872: s partial skeleton including the skull, lower jaws, right arm, neck vertebrae and additional limb elements; CP.V 873: a snout and finger phalanges; CP.V 999: a partial skull; CP.V 1001: a slab with a partial skull, lower jaws and postcrania of at least three individuals; CP.V 1003: a partial skull and symphysis; CP.V 1004: a snout; CP.V 1005: a partial crested skull with the complete mandibula; CP.V 1006: a partial crested skull lacking the snout combined with postcrania; CP.V 1023: a snout and postcrania; CP.V 1024: a skull and postcrania of at least three juveniles; CP.V 1025: a thighbone; CP.V 1026: a thighbone; CP.V 1450: a slab containing at least fourteen juveniles; CP.V 2003: a skull with lower jaws and articulated wing elements; UEPG/DEGEO/MP-4151: a slab with two skulls and postcrania; and UEPG/DEGEO/MP-4152: a snout with postcrania.[1]

Most specimens are part of the collection of the Centro Paleontológico of the Universidade do Contestado.

Description
The largest individuals of Caiuajara had an estimated wingspan of 2.35 metres. The species had a large toothless head with, in adult individuals, an enormous shark fin-shaped crest on the snout.

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 praemaxillae 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.[1]

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.