A new pelobatoid frog from the lower Eocene of southern China

作者:Wang, Yuan; Rocek, Zbynek*; Dong, Liping
来源:Palaeobiodiversity and Palaeoenvironments, 2018, 98(2): 225-242.
DOI:10.1007/s12549-017-0304-1

摘要

A new frog with pelobatoid affinities is described from the lower Eocene of southern China based on 11 individuals at different developmental stages. Comparative analysis reveals that this anuran shares osteological characters with the rather diverse family Megophryidae. In particular, intervertebral discs are present between the anterior vertebral centra and the lamella alaris of the squamosal is widely separated from the maxilla, which lacks a zygomaticomaxillar process. The new frog also shares features with the genus Pelodytes and especially with its most primitive extant species, P. caucasicus. Particularly given that Pelodytidae and Megophryidae are grouped in the Pelobatoidea, and that the new fossil frog existed almost 50 Ma ago, these comparisons suggest that the new frog represents a Paleogene member of the Pelobatoidea. Phylogenetic analysis supports this conclusion, but relationships within the superfamily Pelobatoidea remain unstable across different analyses, as do the positions of fossil frogs of similar geological age in Mongolia (Prospea) and USA (Aerugoamnis). Nevertheless, this new discovery represents the first record of a Paleogene frog from China as well as the first fossil anuran from South China, filling the large gap between Chinese Cretaceous and Neogene anurans. The new frog also opens an important window on the early evolutionary history of the Pelobatoidea, which presumably originated in East Asia.