text: Traditionally the amphibians are taken to include all tetrapods that are not amniotes. Recent amphibians all belong to a single subgroup of these, called the Lissamphibia. Recently there has been a tendency to restrict the class Amphibia to the Lissamphibia, i.e. to exclude tetrapods that are not more closely related to modern forms than they are to modern reptiles, birds, and mammals.\n\nThere are two ancient, extinct, subclasses:\n\nSubclass Labyrinthodontia (paraphyletic) \nSubclass Lepospondyli \nOf the remaining modern subclass Lissamphibia there are three orders:\n\nOrder Anura (frogs and toads) (in Superorder Salientia): 5,228 species \nOrder Caudata or Urodela (salamanders): 552 species \nOrder Gymnophiona or Apoda (caecilians): 171 species \nAuthorities 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.