A new early diverging lepisosteid fish (Lepisosteiformes) from the Late Cretaceous of southeastern Brazil

The Bauru Group in Brazil is renowned for its rich and diverse fossil record from Late Cretaceous age, which includes a variety of vertebrates such as fishes, anurans, turtles, squamates, mesoeucrocodylians, and dinosaurs. In this study, we present compelling evidence for the existence of a distinct taxon of Lepisosteidae at a paleontological site bearing rocks of the Upper Cretaceous Adamantina Formation (Bauru Group). Based on several specimens, we erect a new genus and species of lepisosteiform fish: Britosteus amarildoi gen. et sp. nov. This discovery provides valuable insights into the anatomical features of this new form, contributing to our understanding of the diversity of Late Cretaceous fishes in Brazil. Historically, Lepisosteiformes had a broader geographic distribution than observed today, but our knowledge of their evolution and diversity remains limited. This is particularly true for the gaps in data between the Early and Late Cretaceous periods. The identification of Britosteus amarildoi gen. et sp. nov. contributes to fill this significant gap, establishing it as an early diverging member of Lepisosteidae and underscoring the complexity of its evolutionary history in South America. By illuminating the anatomical and taxonomic characteristics of this new taxon, we enhance our understanding of the evolutionary dynamics of lepisosteiform fishes during a crucial period in the continent's ancient past. •New genus and species of Lepisosteiform fish from Late Cretaceous Bauru Group.•It represents an early diverging lepisosteid.•It comes from continental settings, contributing to fill the temporal gap between Early and Late Cretaceous forms.•The new taxon is not included within the most common genera Lepisosteus and Atractosteus.