Ichnotaxobases for bioerosion trace fossils in bones

Bioerosion trace fossils in bones are defined as biogenic structures that cut or destroy hard bone tissue as the result of mechanical and/or chemical processes. Under the premise that their paleoecological potential can completely be realized only through correct taxonomic assignment, this work focuses on the methodology for naming these biogenic structures. Thus, we propose the following ichnotaxobases in order to assist in naming trace fossils in bones: general morphology, bioglyphs, filling, branching, pattern of occurrence, and site of emplacement. The most common general morphologies are: pits and holes (borings); chambers; trails; tubes; channels (canals); grooves; striae; and furrows. The main types of bioglyphs are grooves and scratches, which may display different arrangements, such as parallel and opposing, or arcuate paired. The nature of the fill may help recognition of the origin, composition, and relationship with the surrounding sediment, as well as processes of destruction or consumption of bony tissue. The structure and layout of the filling, such as meniscate backfill or pelleted filling, offer information about the bioeroding processes. Branching structures on cortical bone are present in canals and furrows. Where the trace penetrates spongy bone, branching structures are forming tunnels that may connect internal chambers. The common patterns of occurrence are individual, paired, grouped, overlapping, lined, and arcuate. The site of emplacement may be in cortical bone, spongy bone, articular surfaces, internal bone microstructures, and external bone anatomical structures. The use of substrate as an ichnotaxobase is problematic, but as biological substrate, bone itself is a valuable source of information for paleoecologic and ethologic inferences. Given the paleontological importance of bioerosion trace fossils in bones, we underscore interactions between ichnology and other sciences, such as forensic entomology, archaeology, paleoecology, and taphonomy.