The three types of animals popularly known as amphibians are newts and salamanders (Order Urodela), frogs and toads (Order Anura), and caecilians (Order Gymnophiona), all belonging to the Class Lissamphibia. They have moist skin, no claws, and a layer of fibrous tissue that separates the base and crown of their teeth. Each goes through a primarily aquatic larval stage before metamorphosing into an adult. The earliest modern amphibians arose more than 210 million years ago in the Triassic from an earlier group of amphibians known as lepospondyls.
The largest living amphibian is the Chinese giant salamander (Andrias Davidianus); one specimen caught in Guizhou Province, China, in 1923 measured 5 feet 9 inches along the curve of its body. The largest frog is the rare Goliath frog (Conraua goliath) from Central Africa, which has been measured to an overall length, with legs extended, of 34.5 inches.
Of the six mystery amphibians listed here, three are frogs, one is a salamander, and two are possible caecilians (wormlike, legless animals that burrow into the soil in the tropics)