The fossil record of insect bone bioerosion: Insights from titanosaur remains at Lo Hueco (Late Cretaceous, Spain) and implications for continental ichnofacies

The fossil record of bone insect bioerosion in continental depositional settings is common and extends from the Middle Triassic until today. Many different examples of bioerosion structures associated with bone tissues of different organisms, from different ages and localities over the world, have been described. Regarding their possible tracemakers, different groups of necrophagous or osteophagous insects have been proposed. Among them, beetles (Coleoptera), particularly members of the family Dermestidae, are frequently proposed, but also termites (Isoptera), mayfly larvae (Asthenopodinae), fleas (Siphonaptera) or bees and wasps (Hymenoptera). The study of this particular fossil record from an ichnologic and taphonomic point of view becomes a very useful tool in order to obtain paleoecological, paleoethological and paleoenvironmental interpretations. Pouch-shaped borings (ascribed to the ichnogenus Cubiculum) found on titanosaurian bone remains from the Upper Cretaceous of Lo Hueco (Cuenca, central Spain) enlarge this bioerosion fossil record and in addition, the first occurrence of this ichnogenus on dinosaur osteoderms is documented. The abundance and exceptional preservation of Cubiculum specimens in Lo Hueco site allow the diagnosis of this ichnogenus to be clarified and emended. Continental Konzentrat-Lagerstätten preserving abundant remains of large vertebrates, such as Lo Hueco, may provide evidence of persistent carcass-supported ecosystems including insect bone bioeroders; for these cases, it is proposed the use of the Cubiculum ichnofacies.