A Three-Dimensionally Preserved Frog (Amphibia, Anura) from the Lower Cretaceous Kuwajima Formation, Tetori Group, Ishikawa Prefecture, Japan

Abstract

The Early Cretaceous Kuwajima Formation, Tetori Group, Japan has yielded various aquatic and terrestrial vertebrates, but lissamphibian records are limited to albanerpetontids and an isolated longbone of a frog. Here we provide the first report of an associated frog specimen from the Tetori Group. The specimen is composed of a few skull elements and several postcranial bones, including the femur, ilium, and vertebrae. This new Tetori frog is distinguished from the previously reported Early Cretaceous Asian genera, Liaobatrachus from China, and Hyogobatrachus and Tambabatrachus from Japan, in having hatchet-shaped sacral diapophyses and a posteriorly tapering urostyle with a weakly developed dorsal crest. Phylogenetic analysis of this new material places it as a non-neobatrachian frog that may be related to previously described Chinese and Japanese taxa, but more complete material would be needed to establish its affinities with confidence.