Unlike semiaquatic temnospondyls , terrestrial temnospondyls have skulls that are adapted for biting land @-@ living prey . The sutures between the bones of the skull in the dissorophoid Phonerpeton are able to withstand a high degree of compression . Compressive forces would have been experienced when biting down on prey . Earlier aquatic tetrapods and tetrapod ancestors differ from temnospondyls like Phonerpeton in that their skulls were also built to withstand tension . This tension would have been experienced during suction feeding underwater . Temnospondyls like Phonerpeton were among the first tetrapods that were almost exclusively terrestrial and fed by biting .