Potential biases in sampling design and interpretation of intra-tooth isotope analysis

An increasing number of studies dealing with environmental and dietary reconstruction involve measurement of intra-tooth variation of isotope ratios. The sampling procedure typically consists of collecting a sequence of horizontal bands perpendicular to the growth axis of the tooth. The objective is to obtain a temporal sequence of the changes recorded in dental tissues during and consequences for interpretation of the data. Time resolution is influenced by the pattern and duration of enamel mineralization, in a way that might, however, depend on the species and the tooth analysed. Although it may be impossible to sample discrete amounts of time, a chronological order seems to be respected, which should be well enough when the objective is to detect changes in isotope ratios with time. Absolute data must be interpreted with caution, applied to the compared specimens is consistent. A new sampling strategy is tested o modern goat teeth, involving drilling in an oblique direction. The results obtained from obliquely drilled is still needed to determine the value of alternative sampling strategies.