A new toothless pterosaur (Pterodactyloidea) from Southern Brazil with insights into the paleoecology of a Cretaceous desert

The first pterosaur bone bed from Brazil was reported in 2014 at the outskirts of the town Cruzeiro do Oeste, Paraná State, in the Southern region of the country. Here named 'cemitério dos pterossauros' site, these outcrops were referred to the Goio-Erê Formation (Turonian-Campanian) of the Caiuá Group (Bauru Basin) and revealed the presence of hundreds of isolated or partially articulated elements of the tapejarine pterosaur Caiuajara and fewer amounts of a theropod dinosaur. Here we present a new tapejaromorph flying reptile from this site, Keresdrakon vilsoni gen. et sp. nov., which shows a unique blunt ridge on the dorsal surface of the posterior end of the dentary. Morphological and osteohistological features indicate that all recovered individuals represent late juveniles or sub-adults. This site shows the first direct evidence of sympatry in Pterosauria. The two distinct flying reptiles coexisted with a theropod dinosaur, providing a rare glimpse of a paleobiological community from a Cretaceous desert

Picture of skulls belonging to several specimens of <i>Caiuajara dobruskii</i>.

(A) specimen CP.V 1449 (holotype) in right lateral view; (B) specimen CP.V 1005; (C) specimen CP.V 1050–1; (D) inverted specimen CP.V 8171 in left lateral view; (E) inverted specimen CP.V 1448; (F) inverted specimen CP.V 5703. Bold arrows indicate the slight dorsal expansion of the premaxillary posterior process. Scale bar equals 50 mm.</p

<i>Caiuajara dobruskii</i> analysed specimens with listed content.

Caiuajara dobruskii analysed specimens with listed content.</p

Comparison of both morphology of the parietal crest and contact of the premaxilla with the dorsal margin of the skull in the Tapejarinae specimens discussed in this work.

The specimens compared are those Tapejarinae with at least preserved one of those features analysed.</p

Picture of the whole block of specimen CP.V 8175.

(TIF)</p

The mandibular symphysis of <i>Caiuajara dobruskii</i>.

(A) Picture in posterodorsal view; (B) schematic drawing in posterodorsal view; (C) picture in posterior view; (D) schematic drawing in posterior view. Shaded patches are marking concavities as a result of the suture processes of the symphyseal shelf. Scale bar equals 50 mm.</p

Schematic drawing of CP.V 8175 in right lateral view, a new specimen identified as <i>Caiuajara dobruskii</i>.

The interpretation of the covered free nasal process is pointed out in detail. Scale bar equals 50 mm.</p

Schematic drawing of specimen CP.V 8175 skull and lower jaw with their respective measures.

Scale bar equals 50 mm.</p

Comparison of the identified ontogenetic stages in the Tapejarinae specimens discussed in this work.

Comparison of the identified ontogenetic stages in the Tapejarinae specimens discussed in this work.</p

Isolated postcranial elements of the specimen CP.V 8175.

(A) pteroid; (B) isolated manual phalanx; (C) ungueal phalanx; (D) proximal carpals; (E) left IV metacarpal in anterior view; (F) left IV metacarpal in posterior view. (TIF)</p