The incrassatio frontoparietalis is a clearly delimited part ofthe frontoparietal, covering the gap or gaps in the dorsal wall of the endocranium. In frogs, this structure originates in very early ontogenetic stages, and keeps its shape without considerable changes till maturity. Therefore, it is probably a good diagnostic character. Moreover, it is presumed that this structure also is a good phylogenetic character, and its study based on an extensive recent and fossil material might contribute to our present knowledge of the frog phylogeny.