The aim of our study was to carry out a detailed stratigraphic dissection of sections of the western territories of Kazakhstan using the remains of ichthyosaurs. Upper Jurassic and Lower Cretaceous ichthyosaurs were studied. Their collecting was carried out in the period of 2016–2023 from sections in the western Kazakhstan (the villages of Pogodayevo and Shchuchkino in the West Kazakhstan region, the village of Tushybek, Mangystau region (Central Mangyshlak Peninsula)) and the Middle Volga region (the village of Gorodishchi, Ulyanovsk region).

The article characterizes the reference sections of the Western region of the Republic of Kazakhstan with a description of the found remains of ichthyosaurs of the genera Kazakhstanosaurus, Nannopterygius, and Platypterygius. It has been established that fragments of their skeletons are found in the Upper Jurassic sediments of the sections near the villages of Pogodayevo and Shchuchkino in the West Kazakhstan territory, and in the village of Gorodishchi in the Ulyanovsk region, as well as in the sediments of the Lower Cretaceous of the Mangystau region. The species diversity of the genus Nannopterygius is noted.

Our study of the Upper Jurassic sections nearv. Pogodayevo, Shchuchkino and Gorodishchi, and the Lower Cretaceous section of nearv. Tushybek showed that the comparison of the identified Ichthyosaur genera with the Mesozoic scale complexes allowed accurate determination of the age of local stratons and the position of their boundaries.

The article presents the results of studies of a number of sections of Lower Cretaceous (Aptian) deposits in the Saratov Right Bank region (settlements Krasnyi Oktyabr’, Doktorovka, Kurdyum and Shirokoe), confined to the Yelshano-Kurdyum uplift. Oryctocenosis combines autochthonous (ichnofossils), subautochthonous (bivalves and gastropods) and allochthonous (ammonites, wood fragments) elements. Sedimentological and mineralogical indicators (ripple marks, desiccation cracks, wedge-shaped structures, cross-bedding, glauconite, and calcite veinlets), as well as fossil remains and features of their taphonomy, allow us to diagnose the coastal ecosystem of the epicontinental sea basin. In the ecosystem format, we see a variety of physico-geographical situations: areas of the bottom which are periodically actively bioturbated and hydrodynamically transformed into mature hardground; zones of active hydrodynamics with the formation of cross-bedding; and zones of subaerial surfaces with the possible development of stick soils. Reconstruction of the paleoecosystem is complicated by the presence of a number of natural facts that have not been unambiguously interpreted, images of which are given in the article. The studied sections are of interest from the standpoint of geoheritage. Selected natural facts are actively involved in the development of a number of geoscientific university museums.