Um novo arquegossauróide (tetrapoda: temnospondyli) para a formação rio do rasto (permiano da bacia do paraná)

Abstract

A partially complete skull of a Temnospondyli amphibian was found in the Posto Queimado locality in 2008, at the municipality of São Gabriel, central region of the Rio Grande do Sul, Brazil. The outcrops of this locality belong to the Rio do Rasto Formation, corresponding to a package of rocks from the Middle and Upper Permian (Wordian to Changhsingian). The material was reported as belonging to the superfamily Archegosauroidea, family Archegosauridae e subfamily Melosaurinae. After the mechanical preparation of the specimen, it was phylogenetically analyzed and included in the less inclusive archegosaurid clade Melosaurinae, as a sister taxon of the Russian Melosaurinae Konzhukovia. The material exhibits a combination of distinctive features which indicate it is a distinguished and new species of the genus Konzhukovia. Previously, a single species of archegosauroid had been described in the Rio Grande do Sul State, based upon a long mandible fragment: the long-snouted Bageherpeton longignathus. Besides B. longignathus, archegossauroids are represented by two other records in South America: undetermined platyoposaurine fragments from the Serra do Cadeado, Paraná State, and Prionosuchus plummeri from the southern limit of the Maranhão State. This new species supports the hypothesis that archegosauroids had been widely distributed and diverse in both Gondwana and Laurasia during Permian. It also adds useful information for biostratigraphic correlation between the locality Posto Queimado with Eastern Europe, dating this location within the range Wordian- Capitanian.