Cryptobranchoidea

The suborder Cryptobranchoidea represents the most primitive group of salamanders. These amphibians are characterized by external fertilization, a separate angular bone in the lower jaw, and the presence of two pairs of limbs. They lack external gills and can be found in aquatic, semiaquatic, and terrestrial environments.1

The suborder includes two families:
* Hynobiidae (Asiatic salamanders): These are generalized, medium-sized salamanders found in northern Asia. They possess lacrimal and septomaxillary bones in their skull.1
* Cryptobranchidae (Asiatic giant salamanders and hellbenders): These are very large, aquatic salamanders found in Japan, China, and the eastern United States. They lack lacrimal or septomaxillary bones in their skull. The genus Cryptobranchus specifically refers to the hellbenders.12