REFINEMENT OF TOOTH TRACE CRITERIA THROUGH EXPERIMENTATION AND LITERATURE REVIEW

Identifying the cause of bone perforations can be hard, and many are wrongly considered tooth traces. Much of this confusion stems from tooth trace classifications and descriptions that are too unclear or broad. As a result, tooth traces can be mistaken for other types of bone perforations such as excavation or collection marks, and natural bone morphologies. Identifying types of tooth traces (pit, puncture, score, or furrow) can also be hard for similar reasons. Inaccurate identification of perforations as tooth traces leads to wrong interpretations of animal behavior and interactions. Thus, more rigorous and detailed criteria for distinguishing tooth traces are needed.

From our study of the literature and first hand observations of tooth-traced fossil bones, we have developed revised definitions and criteria for the four basic types of tooth traces and for distinguishing tooth traces from other perforations. We then tested these criteria on dinosaur fossil bones from two separate institutions to determine if the criteria were useful for tooth trace identification. Forty-five bones were randomly selected from each collection. During the tests, each individual worked alone, searching in detail for perforations over every bone. Afterwards, we discussed our independent conclusions and compared results. We agreed on trace identification on average in 91% of cases when using the detailed tooth trace criteria. In order to refine our criteria to help researchers distinguish between tooth traces and tool marks, we performed an experiment in which we subjected five fossil bone fragments to different types of tools that are used in the field or in the lab. We found that with careful examination using our new criteria, the tool marks could be distinguished from tooth traces. Namely, compared to authentic tooth trace features, tool marks often left shallower depressions, uneven patterns for lines, and unusual flaking to even complete breakage of the bone.

Through using more rigorous tooth trace criteria, we found we were able to distinguish tooth traces from other bone perforations and to distinguish between different tooth trace types. Application of these revised criteria will be useful in correctly labeling bone perforations, which will help researchers avoid incorrect interpretations of animal biting behavior.