Aspects of clavate borings in the type Maastrichtian (Upper Cretaceous) of the Netherlands and Belgium

We describe a collection of borings in carbonate and xylic substrates (Gastrochaenolites ispp., Teredolites longissimus Kelly & Bromley), some of them containing their producers, from the Maastricht and Houthem formations (late Maastrichtian and early Danian) in the type area of the Maastrichtian Stage, but mainly from the ENCI-Heidelberg Cement Group quarry, St. Pietersberg (southern Limburg, the Netherlands). Included are specimens of Gastrochaenolites dijugus Kelly & Bromley, showing different modes of formation of the figure-of-eight aperture, either as part of the lining, incorporating the substrate or both. Gastrochaenolites lapidicus Kelly & Bromley was produced by the gastrochaenid bivalve Gastrochaena, whereas G. orbicularis Kelly & Bromley is the trace of Jouannetia supracretacea (De Ryckholt). Bioglyph-like infills of G. orbicularis and G. torpedo Kelly & Bromley rather represent external moulds of the producing bivalves; they are termed pseudobioglyphs herein. Teredolites longissimus is preserved as clusters of in situ, parallel to sub-parallel tubes, although the woody substrate has decayed, and disarticulated fragments of calcareous tubes have been released from rotten wood. The latter include some specimens filled by flint and show good three-dimensional preservation. Some notes on the taxonomy of the producing bivalve taxa are added.