A diverse Campanian biota from the Bozeș Formation (Petrești, Romania): Insights into the paleontology and paleoecology of a transitional sequence

Campanian estuarine deposits are rare across Europe, and the assemblages described herein represent a paleontologically significant exception. Systematic collection efforts conducted over the past eight years have resulted in the identification of 102 taxa spanning a broad spectrum of organisms, including calcareous nannoplankton, seeds, fruits, bivalves, gastropods, ammonites, corals, echinoids, asteroids, selachians, actinopterygians, anurans, squamates, crocodyliforms, and putative theropod dinosaurs, the latter inferred from eggshell fragments. Notably, a new percomorph fish taxon is described — Paraplesiopoma transylvanica n. gen. et n. sp. (Trif and Schwarzhans). In addition, amber — a rare occurrence in European Cretaceous strata — was recovered from the site. Sedimentological and paleontological evidence indicates a marked paleoenvironmental transition from fully marine to brackish, estuarine ecosystem. The presence of continental taxa within the assemblage offers valuable insights into the composition of the adjacent terrestrial ecosystems during the Campanian. This assemblage constitutes a unique mixture of autochthonous marine and aquatic elements with parautochthonous and allochtonous continental/terrestrial components, situated within the Alpine Tethyan realm, during the Late Cretaceous. Furthermore, it documents a diverse array of terrestrial organisms predating the well-known Maastrichtian vertebrate faunas of the so-called “Hațeg Island”, thereby providing an important window into the pre-Maastrichtian terrestrial biota of this region.