The Faxinal do Soturno local fauna, late Triassic of Rio Grande do Sul, Brazil

Abstract

The rich assemblage of small size tetrapods recorded in a fine sandstone package from the locality of Faxinal do Soturno, Rio Grande do Sul, Brazil, provides the opportunity to know several synchronous taxa that would integrate a real faunistic association. The non-mammalian cynodonts are the most taxonomically diverse group, being represented by the ictidosaur Riograndia guaibensis, the tritheledontid Irajatherium hernandezi and the brasilodontids Brasilodon quadrangularis and Brasilitherium riograndensis. Beyond these little cynodonts, a new one was discovered, Minicynodon maieri gen. et sp. nov., that is still closest related to mammaliformes than the brasilodontids cited. The parareptilia are represented by Soturnia caliodon, a procolophonid vinculated to Hypsognathus. Sphenodontia is represented by Clevosaurus brasiliensis wich represents the oldest record of the group for South America. A new Lepidosauria non-rhynchocephalian, Cargninia enigmatica gen. et sp. nov., was also discovered in this locality. The basal saurischia dinosaur Guaibasaurus candelariensis is the biggest animal from this fossil association. The study of the fauna of Faxinal do Soturno has brought relevant information about anatomic and evolutionary implications concerning the represented groups, as well biochronological, paleoecological and paleobiogeographic aspects. © 2010 by the Sociedade Brasileira de Paleontologia.