Mesozoic anurans from Liaoning Province, China, and phylogenetic relationships of archaeobatrachian anuran clades

Two Jurassic-Cretaceous anurans are described based on well-preserved speci mens from the lower part of the Yixian Formation, western Liaoning Province , northeastern China. One specimen, from the Heitizigou site, documents a n ew genus and species, and the second, from the Sihetun site, is the holotyp e and only known specimen for the recently named Callobatrachus sanyanensis . Phylogenetic relationships of the major archaeobatrachian anuran clades a re investigated with incorporation into the analysis of selected (well-esta blished) early fossil taxa. The new taxon named and described in this paper is placed as the representative of a distinct archaic anuran clade, and Ca llobatrachus is considered to be an ingroup member of the Discoglossidae, c onstituting the earliest record of the family from Asia. The oldest known f ossil anuran, Prosalirus from the Early Jurassic of Arizona, is grouped wit h Notobatrachus as sister taxa, and the two together form the most basal cl ade of Anura. Contradicting the widely accepted Leiopelmatidae-Discoglossid ae sistergroup relationship, new evidence places the Leiopelmatidae as the most basal extant familial group and the sister group to other archaeobatra chian clades. The relationships and classification of the major archaic anu ran clades are discussed, based on the phylogenetic results of this study.