Bored log-grounds by teredinid bivalves in marine deposits from the Monos Formation (Upper Cretaceous) in central Cuba

Borings of Apectoichnus longissimus and Teredolites clavatus are described from wood fragments preserved in sandstone deposits of the Maastrichtian (Upper Cretaceous) Monos Formation in central Cuba. In addition, palaeobiological, palaeoecological and taphonomic implications of these are inferred. The borings are interpreted as mainly produced by Teredinid marine bivalves, which inhabited driftwood substrates. The taphonomic features such as mode of occurrence, density and position of the borings within the relict log-grounds suggest: (i) post-burial compaction of the xylic substrates by the surrounding sediments during burial, (ii) different ontogenetic stages and colonization episodes of teredinids on the studied wood fragments and (iii) different residence time of the wood fragments floating or near the sediment–water interface. Furthermore, the accumulation of wood fragments with A. longissimus and T. clavatus in the shallow marine deposits of the Monos Formation was probably the result of a marine transgression event in these deposits, thus leaving them exposed to attack by teredinid larvae. This study explores the life histories and taphonomic histories of teredinid bivalves and wood fragments in the Monos Formation, adding to the literature on ichnofossils in this lithostratigraphic unit.