Classification

Traditionally the amphibians have included all tetrapods that are not amniotes. They are divided into three subclasses:
Subclass Labyrinthodontia (diverse Paleozoic and early Mesozoic group)
Subclass Lepospondyli (small Paleozoic group)
Subclass Lissamphibia (frogs, salamanders, etc

)Of these only the last includes recent species.

With the cladistic revolution, this classification has been modified, and the Labyrinthodontia discarded as being a paraphyletic group without unique defining features apart from shared primitive characteristics. Classification varies according to the preferred phylogeny of the author, and whether they use a stem or node-based classification. Generally amphibians are defined as the group that includes the common ancestors of all living amphibians (frogs, salamanders, etc) and all their descendants. This may also include extinct groups like the temnospondyls (traditionally placed in the disbanded subclass "labyrinthodontia"), and the Lepospondyls. This means that there are a now large number of basal Devonian and Carboniferous tetrapod groups, described as "amphibians" in earlier books, that are no longer placed in the formal Amphibia.

Fire Salamander (Salamandra salamandra)

All recent amphibians are included in the Lissamphibia, which is usually considered a clade (which means that it is thought that all Lissamphibians evolved from a common ancestor apart from other extinct groups), although it has also been suggested also that salamanders arose separately from a temnospondyl-like ancestor (Carroll, 2007).

Authorities also disagree on whether Salientia is a Superorder that includes the order Anura, or whether Anura is a sub-order of the order Salientia. In effect Salientia includes all the Anura plus a single Triassic proto-frog species, Triadobatrachus massinoti. Practical considerations seem to favour using the former arrangement now.

The Lissamphibia are traditionally divided into three orders, but an extinct salamander-like group, the Albanerpetontidae, is now considered in addition to the other three groups.
Family Albanerpetontidae - Jurassic to Miocene (extinct)
Superorder Salientia
Triadobatrachus (Triassic)
Order Anura (frogs and toads) Jurassic to recent - 5,362 recent species
Order Caudata or Urodela (salamanders): Jurassic to recent - 556 recent species
Order Gymnophiona or Apoda (caecilians): Jurassic to recent - 173 recent species