A juvenile anuran from the Lower Cretaceous Jiufotang Formation, Liaoning, China

Abstract

A disarticulated partial skeleton of a juvenile anuran is reported from the Lower Cretaceous Jiufotang Formation, Jehol Group, in Liaoning Province, China. The individual has a premaxilla with a tall, wide bifurcate alary process and a well-defined palatine process; a maxilla without pre- or postorbital processes; and no contact between the squamosal and the maxilla. The centra of the presacral vertebrae are notochordal. The urostyle (with transverse processes) and the pelvic girdle are proportionally short, and the hind limbs are long (including proportionally long femur, tibiofibula, and proximal tarsals), and the tibiofibula is considerably longer than the femur. Comparison with other frogs suggests the hindlimb proportions of the Jiufotang frog are similar to those of anurans that are primarily saltatory. Although body proportions and other osteological features distinguish the Jiufotang anuran from other Jehol taxa, its immaturity and fragmentary preservation preclude detailed discussion of its systematic position. Nonetheless, this frog documents not only the first fossil anuran from the Aptian Jiufotang Formation of China, but also the most recent Mesozoic anuran currently known from China.