Borings occurring in fossil driftwood are described from the basal Upper Pliensbachian (Margaritatus Zone, Stokesi Subzone) of the northern foreland of the Harz Mountains (Northwestern Germany, Lower Saxony). They belong to the ichnotaxon Teredolites Leymerie, 1842 (T. longissimus Kelly & Bromley, 1984) and represent the hitherto worldwide stratigraphically oldest record of wood-borings produced by bivalves. A possible relationship between the appearance of wood-boring bivalves and the extinction of pseudoplanktic crinoids attached to driftwood is discussed, but seems unlikely.