A New Atoposaurid Crocodylomorph from the Upper Jurassic of the Owadów-Brzezinki Quarry

Atoposauridae are small-bodied Mesozoic crocodylomorphs with a broad, cosmopolitan distribution and a debated phylogenetic position, variously interpreted as basal Neosuchia or forms closely related to Eusuchia. Despite their predominantly European fossil record, occurrences from Central and Eastern Europe remain rare and are mostly restricted to Cretaceous deposits. A new, well-preserved atoposaurid specimen (ZPAL R.11/OB/ATT1) has been discovered in Late Jurassic (Tithonian) deposits of the Owadów–Brzezinki locality in central Poland. This find represents the first record of Atoposauridae from Poland and the easternmost Jurassic occurrence of the clade in Europe. The material, preserved in limestone, consists of a partially articulated skeleton dominated by cranial elements, including an intact posterior skull region, as well as postcranial elements such as vertebrae, ribs, a coracoid, a radiale, and osteoderms. The specimen was examined using computed tomography, enabling non-destructive analysis. Anatomical study revealed a previously undocumented mosaic of characters within Atoposauridae, together with distinct autapomorphic features, including strongly posteriorly projecting quadrate condyles, proportionally broad jugals, and a deep mandible bearing a triangular intermandibular fenestra. This combination of traits indicates clear taxonomic distinctiveness and supports the establishment of a new genus and species, Ewasuchus baryckae gen. et sp. nov. Comparative anatomical assessment suggests a mosaic of affinities, combining features shared with both Cretaceous atoposaurids and more classical Jurassic forms. Cranial and dental morphology, including indicators of strong musculature and feeding adaptations, suggests a predominantly terrestrial lifestyle. The Owadów–Brzezinki locality therefore offers an important Late Jurassic taphonomic window, providing new insights into the diversity and evolution of crocodylomorphs in Central and Eastern Europe.