Cross references: Amphibians Sauropsids Therapsids
Permian Discontinuity Subcortical Brain
http://en.wikipedia.org/wiki/Labyrinthodont"There is today a general consensus that all modern amphibians, the Lissamphibia, have their origin in Labyrinthodont stock, but this is where consensus ends. The fragile bones of the Lissamphibians are extremely rare as fossils, and the modern amphibians are highly derived, making comparison with fossil Labyrinthodonts difficult."
"Labyrinthodontia (Greek, "maze-toothed") is an older term for any member of the extinct subclass of amphibians, which constituted some of the dominant animals of Late Paleozoic and Early Mesozoic times (about 390 to 210 million years ago). The group is ancestral to all extant landliving vertebrates, and as such constitutes an evolutionary grade (a paraphyletic group) rather than a clade."
"The Labyrintodonts have their origin in the early middle Devonian or possibly earlier. They evolved from a bony fish group: the fleshy-finned Rhipidistia. The only other living group of Rhipidistans alive today are the lungfish, the sister group of the landliving vertebrates."