title: Atolchelys lepida, a new side-necked turtle from the Early Cretaceous of Brazil and the age of crown Pleurodira.
abstract: We report a new pleurodiran turtle from the Barremian Morro do Chaves Formation, Sergipe-Alagoas Basin, Brazil. We tested the phylogenetic position of Atolchelys lepida gen. et sp. nov. by including it in a comprehensive cladistic analysis of pleurodires. The new species is a basal member of Bothremydidae and simultaneously the oldest unambiguous crown Pleurodira. The biogeographic and chronostratigraphic significance of the finding has implications for the calibration of molecular clocks studies by pushing back the minimum age of crown Pleurodira by more than 12 Ma (ca 125 Ma). The reanalysis of Pelomedusoides relationships provides evidence that the early evolution and relationships among the main lineages of side-necked turtles can be explained, at least partially, by a sequence of vicariance events.
authors: Departamento de Biologia Animal, Universidade Federal de Viçosa, Viçosa, Minas Gerais CEP 36570-900, Brazil psrromano@gmail.com.
authors: Pedro S R
authors: PS
authors: Romano
authors: Departamento de Zoologia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro CEP 20550-013, Brazil.
authors: Valéria
authors: V
authors: Gallo
authors: Museu Nacional, Departamento de Geologia e Paleontologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro CEP 20940-040, Brazil.
authors: Renato R C
authors: RR
authors: Ramos
authors: Departamento de Estratigrafia e Paleontologia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro CEP 20550-013, Brazil.
authors: Luzia
authors: L
authors: Antonioli
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001938:Brazil; D005580:Fossils; D010802:Phylogeny; D014426:Turtles / Q000033:anatomy & histology / Q000145:classification*
keywords: Barremian; Morro do Chaves Formation; Testudines; northeastern Brazil; phylogeny