Anatomic and sistematic analysis of Rhinobatiformes (Chondrichthyes: Batoidea) from Araripe (Santana Group, Romualdo Formation, Lower Cretaceous)

Abstract

The Chondrichthyes are common aquatic fauna components since the Paleozoic. However, the Chondrichthyan paleontological register is composite, basically, by the mineralized parts, like teeth, dermal denticles and spines. Articulated or partial skeletons are rare; the Iansan beurleni is a exception. There are many well preserved specimens of this specie collected already, but the only few publications about that are superficial and inconclusive. In view of these, the complete description of the Inansan beurleni parcial skeletons, collected in Lower Cretaceous rocks of the Chapada do Araripe area in northeast, Brazil, in the lithostratigraphic context of the Romualdo Formation (Araripe Basin) is the principal aim of this project. Specimens of Iansan beurleni deposited in national and international paleontological collections will be used for the morphological comparison, as well as other taxa of fossil and recent Rhinobatiformes. The morphological study will be complete by images of the internal structures of recent and fossil specimens reconstructed in 3D using a CTscan System. Additionally, a phylogenetic analysis is proposed to place phylogenetically the studied specimens between Rhinobatiformes and Batoidea. These results can be help to understand the Batoid evolution, in view that the relationship between rays is poorly resolved and one of the principal problems is the Rhinobatiformes monophyly and its relation with other Batoidea taxa.