The Central Paratethys Sea, a vast epicontinental sea that existed from the Eocene to the Pliocene, was a significant marine biodiversity hotspot during the Miocene Climate Optimum (MCO, ~17–14 Ma). This study presents a georeferenced dataset of 859 gastropod species from the Central Paratethys Sea, focusing on the periods from the Early to the Middle Miocene. The MCO, characterized by higher temperatures and sea levels, led to the formation of an archipelago-like landscape and the establishment of coral reefs, which increased habitat heterogeneity and species richness. However, the Middle Miocene Climate Transition (MMCT, ~14–13 Ma) caused a significant decline in biodiversity, with a 67% reduction in species numbers. The cooling and changing circulation patterns led to the loss of deep-water faunas and corallivorous gastropods, while surface waters experienced a zooplankton crisis. The study highlights the interplay between geodynamics and climate in shaping marine biodiversity, with the Central Paratethys Sea serving as a textbook example of how extrinsic factors influence the evolution of marine faunas.The Central Paratethys Sea, a vast epicontinental sea that existed from the Eocene to the Pliocene, was a significant marine biodiversity hotspot during the Miocene Climate Optimum (MCO, ~17–14 Ma). This study presents a georeferenced dataset of 859 gastropod species from the Central Paratethys Sea, focusing on the periods from the Early to the Middle Miocene. The MCO, characterized by higher temperatures and sea levels, led to the formation of an archipelago-like landscape and the establishment of coral reefs, which increased habitat heterogeneity and species richness. However, the Middle Miocene Climate Transition (MMCT, ~14–13 Ma) caused a significant decline in biodiversity, with a 67% reduction in species numbers. The cooling and changing circulation patterns led to the loss of deep-water faunas and corallivorous gastropods, while surface waters experienced a zooplankton crisis. The study highlights the interplay between geodynamics and climate in shaping marine biodiversity, with the Central Paratethys Sea serving as a textbook example of how extrinsic factors influence the evolution of marine faunas.