The decapod fauna from the Badenian (middle Miocene) deposits of western Ukraine comprises in total 31 taxa: 20 species, 9 taxa left in open nomenclature, and 2 determined at family level. Thirteen of these taxa are reported for the first time from the territory of Ukraine. Among them are the first records of Trapezia glaessneri Müller, 1976 in the Fore-Carpathian Basin and Pachycheles sp. in Paratethys. One taxon (Petrolisthes sp. A) probably represents a new species. The occurrence of this significant decapod fauna is restricted almost exclusively to the Upper Badenian (i.e., early Serravallian) coralgal reefs of the Ternopil Beds. The taxonomic composition of the decapods indicates that the Late Badenian depositional environment was a shallow marine basin dominated by reefs that developed in warm-to-tropical waters of oceanic salinity. The decapod assemblage from the Ternopil Beds is similar in its taxonomic composition to numerous decapod faunules from fossil reefs of Eocene to Miocene age from the Mediterranean realm and of Miocene age from Paratethys. In contrast, decapod remains are very scarce in Badenian siliciclastic deposits (Mikolaiv Beds) and are represented by the most resistant skeletal elements, i.e., dactyli and fixed fingers. This scarcity was caused by the high-energy environment, with frequent episodes of redeposition, which disintegrated and abraded the decapod remains.

Over three thousand specimens representing the superfamily Trochoidea Rafinesque, 1815 [Trochidae Rafinesque, 1815 and Calliostomatidae Thiele, 1924 (1847)] from the upper Upper Badenian = Kosovian = lower Serravallian (middle Miocene) marine deposits of Ukraine, housed in the collections of the Polish Academy of Sciences Museum of the Earth in Warsaw (MZ), are studied herein. The abundant material has allowed for investigations of the intraspecific variation and revision of earlier determinations. As a result, 21 species belonging to 5 genera have been identified, described and illustrated, of which one is new [Clanculus (Clanculopsis) krachi sp. nov.] and one is left in open nomenclature. Granulifera O. Anistratenko, 2000 is considered a junior subjective synonym of Clanculopsis Monterosato, 1879; Granulifera pulla O. Anistratenko, 2000 is considered a junior subjective synonym of Monodonta tuberculata Eichwald, 1830; Gibbula sytovae Amitrov, 1961 is considered a junior subjective synonym of Trochus miocaenicus Mayer, 1853; Gibbula volhynica Friedberg, 1928 is considered a junior subjective synonym of Trochus novemcinctus von Buch, 1830; and Trochus buchii du Bois de Montpéreux, 1831 is suppressed in favour of the senior subjective synonym Trochus puschii Andrzejowski, 1830. The geographic distribution and stratigraphic ranges of the taxa are given. Six species are known only from the Polish-Ukrainian part of the Fore-Carpathian Basin. The protoconch features are systematically studied in the Trochidae and Calliostomatidae from this area for the first time.

The well-known Pleuronectia badensis Fontannes, 1882 (currently classified as Cristatopecten cristatus badense) is declared as a n omen protectum against the older synonym Pecten burdigalensis var. polonica Pusch, 1837 considered a nomen oblitum. It ranges from the early to the late Miocene (Burdigalian–Messinian) of the NE Atlantic and Mediterranean. In the Central Paratethys it appeared in the early Miocene (Karpatian, correlating with the latest Burdigalian) and became extinct in the middle Miocene (Late Badenian, correlating with the early Serravallian). In Poland – the northernmost part of Central Paratethys – the occurrence of this taxon is limited to the late Early Badenian (late Langhian).

For the first time, articulated shells of Anomia ephippium Linnæus, 1758, the bivalve species widely distributed in the Egerian–Late Badenian (latest early Oligocene to late middle Miocene) in the Central Paratethys, are described and illustrated. The most astonishing fact is the presence of a heavily calcified byssus that anchored the animal to hard substrates, which is still preserved inside the byssal notch. The investigated material derives from the Badenian (middle Miocene) Niskowa Formation in the Nowy Sącz Basin, a small intramontane basin situated in the Polish Outer Carpathians. Apart from articulated shells and left valves, the collected material contains some dozen of calcified byssi fixed to rigid substrate, SEM images of which are presented. Examination of the A. ephippium specimens stored in the Polish Academy of Sciences, Museum of the Earth in Warsaw revealed other Paratethyan records of anomiid calcified byssi attached to other specimens of A. ephippium. Finally, the paper provides an overview of the previous studies on the representatives of the genus Anomia Linnæus, 1758 from the Central Paratethys and its specific assignment.