A NEW LATE TRIASSIC VERTEBRATE ASSEMBLAGE FROM NORTHWESTERN ARGENTINA

MARTÍNEZ, RICARDO; APALDETTI, GRACIELA CECILIA; CORREA, GUSTAVO ALEJANDRO; COLOMBI, CARINA ESTER; FERNÁNDEZ, ELIANA; SANTI MALNIS, PAULA; PRADERIO, ANGEL; ABELIN, DIEGO; BENEGAS, LAURA G.; AGUILAR-CAMEO, ANDREA; ALCOBER, OSCAR

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Lugar: Buenos Aires; Año: 2015 vol. 54

0002-7014

The Quebrada del Barro Formation (QBF) is part of the continental Marayes-El Carrizal Basin, in NW Argentina. Here we report a diversefaunal assemblage recently discovered in the Quebrada del Barro Formation, along with a preliminary discussion of the taxonomic statusand affinities of numerous vertebrate specimens found at two localities where this unit is exposed. The new vertebrate association includes remainsof at least 12 different new species related to six major vertebrate groups: Cynodontia, Testudinata, Sphenodontia, Pseudosuchia,Pterosauria, and Dinosauromorpha. The most abundant specimens in this faunal assemblage are opisthodontian sphenodonts, tritheledontidcynodonts and basal sauropodomorph dinosaurs, but the assemblage also includes diagnostic remains of lagerpetid dinosauromorphs, theropods,pterosaurs, basal crocodylomorphs, and stem testudinatans. Several of these groups have also been reported for the Los Colorados Formation(LCF), although the two units differ in their taxonomic content at the species level and in the relative abundance of different taxonomic groups.A comparison of these two faunal assemblage suggest the fauna of QBF is younger than that of LCF and we tentatively assess a late Norian?Rhaetian age for the QBF. Some of the specimens reported here are known from well-preserved specimens and yield important new informationfor understanding the evolution of these groups, which underscores the relevance of the QBF fauna for assessing the dynamics of the majorgroups of vertebrates that dominated the terrestrial ecosystems during the early Mesozoic in Pangea