Descrição morfológica e relações filogenéticas de novos materiais de pterosauria da formação Romualdo, Brasil

Abstract

Pterosaurs are extinct reptiles, constituting the first group of vertebrates to raise active flight. They are found on all continents, being well represented in Brazil by the findings of the Araripe Basin. In this record, the Anhangueria clade is especially well documented in Romualdo Formation (Aptian/Albian of Araripe Basin). The present work presents two specimens of Anhangueria (MPSC R1057 and MPSC R990) of Romualdo Formation. MPSC R1057 is represented for a isolated mandible belonging to Brasileodactylus araripensis. This specimen permit the observation of new characteristics present in other specimens, but never described. The new information results in a new diagnosis for B. araripensis, amongst them: (i) a proeminent palatal keel, which becomes higher in relation to the alveolar margin from the 3º pair of alveoli; (ii) mandibular keel between the alveoli, narrow in the rostrum, and which extends caudally in direction the mandibular fossa, with a accentuated medial groove; (iii) from the 2º–3º pairs of alveoli, the dental line is arcuate in elliptical form to the ventral direction, with its lowest point in the 5º alveoli; (iv) from the 4º pair, the alveoli have a alternated disposition, with the alveoli (left and right) not paired from each other. The phylogenetic analyses confirmed a terminal grouping of MPSC R1057 with Brasileodactylus, within Anhangueria. MN 4797-V originally denominated as Brasileodactylus cf. araripensis, is reallocated as cf. Anhangueria. The second specimen, MPSC R990, presents has partially preserved skull and skull bones, premaxilla without crest and a heterodont dentition. Morphological comparisons with other pterosaur groups demonstrated that MPSC R990 has exclusive characteristics, such as: (i) presence of the sulcus between the premaxilla and maxilla in a well-defined convex form, between 6º–10º pairs of alveoli; (ii) 1º and 2º pairs of teeth smaller than the 6º e 7º pairs; (iii) 1º e 2º pairs of maxillary teeth with roots projected forward, being these anteriorly oriented, and the remaining of the teeth oriented laterally. The phylogenetic analyses classified it as a close relationship with Guidraco venator, within the Anhangueria clade. This specimen represents a new species of pterosaur, with close relationship with Guidraco.