Middle–Late Permian tetrapods from the Rio do Rasto Formation, Southern Brazil: a biostratigraphic reassessment

Abstract

Dias-da-Silva, S. 2011: Middle–Late Permian tetrapods from the Rio do Rasto Formation, Southern Brazil: a biostratigraphic reassessment. Lethaia, Vol. 45, pp. 109–120. The Rio do Rasto Formation (Permian of Southern Brazil) was previously regarded as Guadalupian–early Lopingian age. Three tetrapod-based localities are known: the Serra do Cadeado area, Aceguá and Posto Queimado. The latest tetrapod-based biostratigraphic contribution considers that the Posto Queimado and Aceguá faunas are coeval and Wordian (middle Guadalupian) in age, correlated to the Isheevo faunas from Eastern Europe and to the Tapinocephalus Assemblage Zone of South Africa; whereas the Serra do Cadeado fauna is Capitanian (late Guadalupian), correlated to the Kotelnich fauna of Eastern Europe and, from bottom to top, to upper Pristerognathus, Tropidostoma and lower Cistecephalus assemblage zones of South Africa. A re-evaluation of the tetrapods from the Rio do Rasto Formation and new fossil discoveries in the localities of Posto Queimado and Serra do Cadeado area (melosaurine and platyoposaurine temnospondyls, a basal anomodont, a dinocephalian and a basal dicynodont) supports a new tetrapod-based biostratigraphic scheme for the Rio do Rasto Formation. Accordingly, the age of the fauna at Aceguá is late Roadian-early Wordian, whereas the locality of Posto Queimado is late Wordian-Capitanian. The Serra do Cadeado Area is correlated with both southernmost ones (Guadalupian) but also Wuchiapinghian (early Lopingian). □Paraná Basin, Passa Dois Group, tetrapod biostratigraphy, Western Gondwana.