The subclass Lissamphibia includes all recent amphibians and means smooth amphibia.
Extant amphibians fall into one of three orders — the Anura (frogs and toads), the Caudata or Urodela (salamanders and newts), and the Gymnophiona or Apoda (the limbless caecilians).
Although the ancestry of each group is still unclear, all share certain common characteristics, which indicates they evolved from a common ancestor and so form a clade. The publication of a Permian-period stem form Gerobatr achus hottoni showed the frogs and salamanders had a common ancestor more recently (ca 290 Ma) than had been thought by using the molecular clock alone.