Proterosaurus

Proterosaurus (Gr. proteros, 'first,' sauros, 'reptile'), a genus of fossil reptiles occurring in the Permian system, which is the lowest horizon at which reptilian remains have as yet been detected. It is of a primitive type, and belongs to a highly generalised group of reptiles. The skull is imperfectly known, but the teeth appear to have been anchyllosed to the bone, and not implanted in distinct sockets, as was at one time supposed.