Homologues of most of the bones of temnospondyls are also seen in other early tetrapods , aside from a few bones in the skull , such as interfrontals , internasals , and interparietals , that have developed in some temnospondyl taxa . Most temnospondyls have tabular horns in the backs of their skulls , rounded projections of bone separated from the rest of the skull by indentations called otic notches ; in some temnospondyls , such as Zatrachys , they are pointed and very prominent . Among the most distinguishing features of temnospondyls are the interpterygoid vacuities , two large holes in the back of the palate . Another pair of holes , choanae , are present in front of these vacuities , and connect the nasal passage with the mouth . Temnospondyls often have teeth on their palates , as well as in their jaws . Some of these teeth are so large , they are referred to as tusks . In some temnospondyls , such as Nigerpeton , tusks in the lower jaw pierce the palate and emerge through openings in the top of the skull .