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The description of the representatives of the genus Labyrintholites is presented. The type species of the genus was published I. F. Sinzov in 1879. The considerable amount of the fossil material from the Santonian rocks found in the Saratov Volga Region has made it possible to substantiate the diagnosis of this genus within the order Hexactinosa and to present its taxonomic diversity within eight species. Among the Hexactinellids, the Labyrintholites are distinguished for their attachment to the substrate solid immobile elements.

Ammonite finds at the Miroshniki site, within the Albian-Cenomanian boundary interval, make it possible to identify the presence of the analogues of the Upper Albian zones Mortoniceras fallax (autochthonous burial within aleurolites) and Mortoniceras rostratum (allochthonous occurrence among phosphorite nodules). In this very section, an elasmobranchian assemblage has been isolated from the phosphorite interlayers; this is represented by 9 series and 13 genera. Small sand sharks Eostriatolamia subulata (Ag.) are dominant in its content.

The Albian-Cenomanian rocks compose a single complex of terrigenous deposits over the Volga Region. Delineation of the boundaries of the Cretaceous system units generally tends to cause difficulties, accounted for by rare finds of the fossils. In the northern part of the DonMedveditsa dislocations, natural outcrops of the Albian and the Cenomanian beds in the Burluk river valley have been examined since the 1950s. The authors have earlier made some case studies on the Gordienki, Krasny Yar, Melovatka and Moiseyevo sections.

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.

A first for the Volga region described two new species of echinoids and shows their stratigraphic position. Analyzed the relationship identified Maastrichtian sea urchins of the region coupled with synchronous complexes conjugate paleobiochores

Based on new finds of mandibular tooth plates of the chimaeroid Stoilodon aenigma Nessov &Averianov, 1996 (Holocephali, Chimaeroidei) from the Lower Cretaceous of central Russia, the diagnosis of the genus is modified and validity of the taxon is confirmed. New record of mandibular plate of the species from the Ryazanian regional stage (boreal Berriasian stage) of the Moscow Region has allowed us to expand stratigraphical distribution of the species within the whole early Cretaceous.

In the course of this work we cast the light on the state of research of the Late Cretaceous sea urchins in the Volga region as well as the development of ideas about their distribution in the rocks of the Upper Cretaceous in the region. Resources used in the research include studies about this group of invertebrates since the beginning of the XIX century up to the present day. It was estab­lished that the vast majority of publications consist of fragmentary information containing mentions of echinoderm remnants findings.

The level with anomalous high values of natural remanent magnetization and Koenigsberger ratios was identify in the Upper Maastrichtian of Vol’sk depression (Saratov Volga Region). The microprobe studies of samples from this layer registered elevated concentrations of microparticles of iron, nickel, intermetallics and magnetite spherules of cosmic genesis. Similar petromagnetic anomaly was detect in the uppermost of Maastrichtian in the South Cis-Caspian (Aktolagay Plateau, Kazakhstan).

The paper analyzes the stratigraphic distribution of elasmobranchs in the deposits of the Melovatka Formation (Cenomanian) from the right bank of the Volga (part of the Penza, Saratov and Volgograd regions).

Terminal layers of carbonate rocks of Maastrichtian and lower intervals of Paleocene aleurite-pelitic formations are accessible for investigation in Krasny Oktyabr and Bolshevik quarries (Volsk Depression). In the bottom of the Paleocene accumulation of skeletons of calcareous and siliceous sponges has been confirmed, mollusk and elasmobranch assemblage has been determined.