Data from: Atolchelys lepida, a new side-necked turtle from the Early Cretaceous of Brazil and the age of crown Pleurodira

We report a new pleurodiran found in the Morro do Chaves Formation, Barremian of the Sergipe-Alagoas Basin (Brazil). We tested the phylogenetic position of Atolchelys lepida gen. et sp. nov. by including it in a cladistic analysis along with all representatives clades of Pleurodira. The new species is a basal member of the family Bothremydidae and represents the oldest unambiguous Eupleurodira. The biogeographical and chronostratigraphic significance of the finding have implications to the calibration of molecular clocks of side-necked turtles, extending the minimal age of the origin Eupleurodira back to more than 12 Ma earlier than previously designed (ca 125 Ma). The reanalyzes of Pelomedusoides relationships also provides evidence that the earlier evolution and relationships among main lineages of side-necked turtles can be explain, at least partially, by a sequence of vicariance events.