Jacobsen, Aase Roland4; Bromley, Richard Granville3
1 Steno Museet, Faculty of Science, Aarhus University, Aarhus University2 Science Museums - The Steno Museum, Science Museums, Science and Technology, Aarhus University3 University of Copenhagen4 Science Museums - The Steno Museum, Science Museums, Science and Technology, Aarhus University
Research on tetrapod trace fossils has enjoyed a massive renaissance in the last couple of decades, which shows no signs of slowing down. This has resulted in the refinement of tetrapod tracks' ichnotaxobases and their constructional terminology and understanding of their palaeoecological significance. Strangely, however, the systematics of trace fossils resulting from bite traces and tooth scraping by tetrapods, especially on bone substrates, have been seriously neglected. Gnawing traces by modern mammals on bones have been well described, but only recently have a few papers been devoted to the naming of biting trace fossils in bone substrates. Study of tetrapod bite trace fossils has revealed feeding behaviour, jaw mechanism, face-biting behaviour, social behaviour etc., as well as palaeoenvironmental conditions. But should naming of scratches and holes produced by teeth be considered a worthless waste of time? Is naming of this group of trace fossils considered a productive move? We have extended this work, suggesting new ichnotaxa for bite traces to focus on their potential value for identifying the tracemaker and thereby feeding behaviour. Bite traces also have a great potential for indicating the co-existence of species in a palaeoenvironment. Trace fossils produced by biting and rasping by invertebrate animals have also been successfully used as palaeoenvironmental indicators. While the bite traces of invertebrates are usually based on the patterns of erosion caused by the dentition as a whole, as in Gnathichnus for echinoid bioerosion and Radulichnus for chiton and gastropod bioerosion, it is our conviction that tetrapod biting trace fossil nomenclature generally should be based on the damage caused by single teeth. Where several teeth have left traces as a group, this may be the result of a single bite, or several bites. These cases may be considered as compound trace fossils. This correlates with the use in tetrapod trackways of a single pes or manus, or one of each, as the suitable nominal basis for an ichnotaxon. A longer series of tracks constituting a trackway may be considered a compound trace fossil. Nevertheless, the ichnogenus Machichnus Mikula? et al., caused by rodents mining bone-material with their incisors and producing multiple subparallel grooves, is a recognizable pattern of successive bites that has received an ichnotaxon.