primary colonies

Among Craticulariidae, the representatives of Postsporadopyle are peculiar for the skeleton intricate morphology determined by dichotomy and trichotomy of the primary modules. Besides the P. triloba known from the Santonian of the Volga region, two previously unknown here species are considered.

The morphological diversity of diosculumic sponges, known as Paracraticularia cylindrical, results from the fact that many fossils assigned to this species prove to be fragments of the apical segments of internodes (branches) from major colonies that are rarely encountered as totally preserved fossils. The structures of the branch apical segments and the oscula outlines reflect various manifestations of hexactinellida synchronous division conductive to morphological diversity of the descendants, the succeeding complicatedly structured colonial sponges.