Article: Electroreceptors in the Lower Permian tetrapod Discosauriscus austriacus
In most ornamented dermal cranial bones of the larvae of the Lower Permian tetrapod Discosauriscus austriacus from Moravia, distinct rounded or oval pits are present. They are situated in, or close to, the sensory grooves and pit-lines. The diameter of each pit is c. 1 mm. The inner surface is sometimes smooth and consists mainly of smaller pits, depressions, or short canals which have small foramina at their bases. Such structures, designated as foraminate pits, have not previously been found in tetrapods. Positionally and structurally, the foraminate pits are comparable with the so-called pore-groups of some rhipidistians, in particular the osteolepids. It is concluded here that these structures are homologous and that the bones which bear them must therefore also be homologous. Thus the bones enclosing the pineal foramen in osteolepiforms are frontals. On the basis of comparisons with Recent urodeles, the foraminate pits are interpreted as structures which may have housed the ampullary electroreceptive organs. If so, Discosauriscus, like the rhipidistians, was an electroreceptive animal.