In a relatively short geological period during the Lower Miocene, global and local events influenced the development of two basin areas with different depositional histories: the Croatian Zagorje (HZB) and the North Croatian Basin (SHB). It is a common opinion that the Lower Miocene marine deposits in Croatia were only deposited in a small area in the HZB, which was part of the Central Paratethys since the beginning of the Miocene. At the same time, in the SHB, the development of the basin began with the formation of continental environments after a long-term emersion and marine sedimentation began in the lower Baden. The latest research documents an earlier transgression in the SHB area at the end of the Lower Miocene and points to the need to redefine the beginning of the transgression and reconstruct the paleoenvironment. Changes in the direction of circulation and different recharge characteristics of Miocene basins in Croatia resulted in changes in abiotic and biotic factors that determine different paleoenvironments. We will define paleoenvironments through space and time by connecting sedimentological, mineralogical, geochemical, and fossil data. We will concentrate on identifying global events that marked the Miocene time, and special attention will be focused on water temperatures in long-lived lakes and the sea, as well as average annual temperatures that were in line with changes in global temperature caused by fluctuations in the carbon dioxide content of the atmosphere. The research will be conducted within two work packages. By researching mineralogical, geochemical and sedimentological data and different groups of fossils (calcareous nanoplankton, palynomorphs, foraminifera, ostracods, otoliths of fish and molluscs), we will define the types of paleoenvironments and their mutual spatial and temporal relationship; make a paleoclimatic reconstruction of Miocene deposits; determine the paleobiogeographic movements of the most important fossil groups; determine the main zonal fossils and marker species of individual fossil groups and consider the correlation with the generally accepted zonation in the Paratethys and the Mediterranean. The main goal of the project is to connect the obtained research results with known global and regional Miocene events, such as the Miocene climatic optimum, the middle Miocene climatic transition, the Baden salinity crisis, fauna extinction events on the borders of Baden and Sarmatians and Sarmatians and Pannonian, the "washhouse" event in the upper Miocene, carbon isotope shift in the late Miocene, cooling in the upper Miocene and the Messinian salinity crisis.