Descripción de una nueva especie de bagre marino fósil (Teleostei, Siluriformes, Ariidae) del Mioceno de la provincia de Río Negro, Argentina

two fossil crania referable to the siluriform fish family ariidae are described. the specimens come from the early late miocene-lower middle miocene saladar member of the gran bajo del gualicho formation, located at salinas del gualicho, río negro province, argentina. the materials are referred to a new species of the recent genus genidens. the new taxon is distinguished from remaining living species in having a very short, broadened and rounded supraoccipital process, subrounded extrascapular and wide mesethmoid with a median notch, flat frontals, and straight lateral margins of the sphenotics. genidens ancestralis sp. nov. represents the oldest (and only known) fossil record for the genus, and constitutes a relatively small-sized species, very similar in general traits to living forms of genidens.