Two types of completely new structures for tetrapods — pit-lines and foraminal pits — are present in the exocranial bones of Lower Permian Discosauriscus austriacus. The morphology and position of these sensory structures are basically identical with thase in the exocranial bones of osteolepiform fishes. These structures as well as the bones which bear them are considered to be homologous both in Discosauriscus and osteolepiforms. These conditions indicate that bones enclosing the pineal foramen in osteolepiforms are frontals.