Courtship dating instrumental
Although the fossils of several older proto-frogs with primitive characteristics are known, the oldest "true frog" is Prosalirus bitis, from the Early Jurassic Kayenta Formation of Arizona. Authorities disagree as to whether Salientia is a superorder that includes the order Anura, or whether Anura is a sub-order of the order Salientia.The Lissamphibia are traditionally divided into three orders, but an extinct salamander-like family, the Albanerpetontidae, is now considered part of Lissamphibia alongside the superorder Salientia.Some fish had developed primitive lungs to help them breathe air when the stagnant pools of the Devonian swamps were low in oxygen.They could also use their strong fins to hoist themselves out of the water and onto dry land if circumstances so required.
The phylogeny of Paleozoic amphibians is uncertain, and Lissamphibia may possibly fall within extinct groups, like the Temnospondyli (traditionally placed in the subclass Labyrinthodontia) or the Lepospondyli, and in some analyses even in the amniotes.
Amphibians evolved adaptations that allowed them to stay out of the water for longer periods.
Their lungs improved and their skeletons became heavier and stronger, better able to support the weight of their bodies on land.
The young generally undergo metamorphosis from larva with gills to an adult air-breathing form with lungs.
Amphibians use their skin as a secondary respiratory surface and some small terrestrial salamanders and frogs lack lungs and rely entirely on their skin.