In Paramesotriton caudopunctatus, Ambystoma mexicanum and Bombina orientalis two auditory papillae are present, the amphibian and basilar papillae. The amphibian papilla of P. caudopunctatus and A. mexicanum is an oval structure comprising two cell areas of approximately equal size, with oppositely oriented bundles of cilia. In B. orientalis the sensory epithelium of the amphibian papilla is composed of an anterior region, which is comparable to the entire sensory epithelium in the Caudata, and an appreciably longer, posterior section. This posterior patch is clearly sinusoidal in shape, similar to those of evolutionary advanced anurans. There is evidently a coevolution of the auditory system and complex vocal communication.