Structure of urostyle-sacral area in Pipidae (Amphibia, Anura)

摘要

A review of the structure of the urostyle-sacral area in recent and extinct Pipidae species and in the groups close to them is given based on the author's and reference data. There are contradictions in the morphological diagnosis of the sacrum structure in some forms. This fact was a cause for revision of the structure in recent representatives of the family. The results obtained permit us to affirm that the recent pipids have only one sacral vertebra which forms a wide transverse process with a hypertrophical edge. The following trends are observed in evolution of pipids: reducing the number of trunk segments, increasing the area of sacrum diapophysis and consolidation in the urostyle-sacral area. Nevertheless, there is no tendency to reducing the number of"functional" vertebrae by including presacral ones in the sacrum (increasing the number of sacral vertebrae). The presence of free posrsacral vertebrae in pipids is unlikely. Therefore, the extinct forms described by Nevo (Nevo. 1968) are either xenopoids froglings (shortly after metamorphosis) or not pipids.