Silicified bony fish otoliths from the Vaals Formation (lower Campanian) of Vaals-Eschberg, the Netherlands

Abstract

The Vaals Formation in its type area, in southern Limburg, the Netherlands and adjoining Aachen area in Germany, comprises predominantly glauconitic sandy deposits that were laid down in a very shallow, nearshore environment. The early Campanian age assignment (c. 81 Ma) of the Vaals Formation is based primarily on ammonites (in particular Scaphites hippocrepis II–III) and belemnitellid coleoids. All aragonite has been dissolved in strata assigned to the Vaals Formation, and silicified macrofossil assemblages are found at certain levels. The silicification is thought to reflect temporary silica enrichment (by riverine input, or dissolution of sponge spicules or silicoflagellate tests). The most important and species-rich silicified assemblages are known from the so-called ‘Müller's Bed’, just below the Vaalsbroek Horizon and within the Gemmenich Member, in the lower part of the formation. Silicified molluscs, serpulids, scleractinian corals, bryozoans and echinoderms have been described in the past. Now, a temporary exposure (1987) of ‘Müller's Bed’ at Vaals-Eschberg has also produced silicified teleost otoliths. A total of 42 specimens have been recovered from this level, 20 of which could be identified and assigned to seven species, including three new ones; Centroberyx vaalsensis sp. nov. (Beryciformes, Berycidae), Protoholocentrus janjanssensi gen. et sp. nov. and Sillaginocentrus crispus sp. nov. (both Holocentriformes incertae sedis). The faunal composition differs distinctly from coeval otolith associations known from elsewhere in Europe and in North America. The putative holocentriform otoliths are the earliest known to date from the fossil record.