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