Bortolin site, a new fossiliferous locality in the triassic (Ladinian/carnian) of southern brazil

Abstract

A new fossiliferous site from the Pinheiros-Chiniquá Sequence (Santa Maria Supersequence) with typical tetrapod components of the Dinodontosaurus Assemblage Zone (AZ) is here described. The new site is included in the Faxinal do Soturno Structural Block. The fossil content is characterized by cranial and postcranial material of rauisuchian archosaurs, traversodontid and chiniquodontid cynodonts and dicynodonts, the first occurrence of a large-sized coelacanth fish in the Brazilian Triassic, as well as ichnological material, represented by coprolites. The presence of Luangwa together with Massetognathus raises interesting questions regarding the age of this site included in the Dinodontosaurus AZ when compared with other localities of Southern Brazil, western Argentina and Africa. As in other localities of this AZ, the fossil specimens recovered in Bortolin site exhibit remarkable differences on their fossil preservation: those from the lower portion of the outcrop (distal floodplain) possess a heterogeneous preservation (variable between poor to fairly good) whereas those from the top levels (proximal floodplain) are comparatively better preserved. This new locality, with a large amount of stratigraphically controlled fossils, constitutes a key-locality to study the distribution of Triassic terrestrial tetrapods and to perform comparisons with other sites of this AZ, in which several historical records lack a precise provenance.