Recently , the theory that temnospondyls were the ancestors of all lissamphibians has gained wide support . The skull morphology of some small temnospondyls has been compared to those of modern frogs and salamanders , but the presence of bicuspid , pedicellate teeth in small , paedomorphic or immature temnospondyls has been cited as the most convincing argument in favor of the temnospondyl origin of lissamphibians . Seen in lissamphibians and many dissorophoid temnospondyls , pedicellate teeth have calcified tips and bases . During the development of most tetrapods , teeth begin to calcify at their tips . Calcification normally proceeds downward to the base of the tooth , but calcification from the tip stops abruptly in pedicellate teeth . Calcification resumes at the base , leaving an area in the center of the tooth uncalcified . This pattern is seen in living amphibians and fossils .