An otolith fauna of 21 species was found in the lower part of the Rupelian clays. Five new genera are described: Parvicolliolus, Platyonos, Umbolota, Archilatilus and Serratidentex. Four new species are introduced: Platyonos limburgicus, Umbolota marina, Serratidentex sculptus and “Callionymus” pachyotus. Umbolota marina is a marine predecessor of Lota lota which is the only living freshwater cod species. Marine ancestors of the latter species have not been found before.

Mededelingen van de Werkgroep voor Tertiaire en Kwartaire Geologie

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Werkgroep voor Tertiaire en Kwartaire Geologie

Pieter A.M. Gaemers. (1985). Fish otoliths from the Rupelian of sand-pit Roelants at Heide-Boskant (municipality of Lubbeek, Belgium) and the stratigraphy of the Early Rupelian, 2. Systematic part. Mededelingen van de Werkgroep voor Tertiaire en Kwartaire Geologie, 22(4), 155–172.