lower Cretaceous

The offering paper covers the history of the Aptian stage stratigraphy and ammonites studies of the central part of the Northern Caucasus, which was subdivided by the author into five stages. The first (mid-to-late 19th century), second (1901–1951) and third (1952–1969) stages are reviewed. The first is associated with the beginning of research in the region, at this time the attempts of the stage and substage dividing were made.

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.

The representatives ofthe genusEpicheloniceras Casey, 1954fromthe Middle Aptian of Mangyshlak, Western and Southern Turkmenistan are described.

The article presents the study results of the ammonite subfamily Cheloniceratinae Spath, 1923 representatives (genera Cheloniceras Hyatt, 1900 and Epicheloniceras Casey, 1954) fromthe Lower and Middle Aptian of Mangyshlak, Western and Southern Turkmenistan. The diversity and stratigraphic distribution of species is assessed, intraspecific variability is identified and typified. Representatives of the genus Cheloniceras are described.