Inter-tooth comparison of d 13 C and d 18 O in ungulate tooth enamel from south-western Africa Julie Luyt * , Judith Sealy Department of Archaeology, University of Cape Town, South Africa article info Article history: Received 7 August 2017 Received in revised form 1 February 2018 Accepted 7 February 2018 Available online xxx Keywords: Carbon isotopes Oxygen isotopes Paleoenvironment Hydroxyapatite abstract This study explores variation in d 13 C and d 18 O in tooth enamel carbonate along the tooth-row of wild African ungulate fauna from southwestern Africa. The study includes seven species (six bovids and a suid), all indigenous wild mammals from game parks and nature reserves, i.e. relatively undisturbed natural environments. Three to six teeth from each of a total of 23 individuals were analysed. d 13 C and d 18 O in different teeth from the same individual showed ranges of up to 4.4 (excluding one outlier) and 6.2‰ respectively, with median values of 2.7 and 2.0‰. In three of the seven species studied, first molars tended to be depleted in d 13 C compared with second and third molars (although not all individuals showed this pattern), while in the remaining species they did not. First molars were not enriched in 18 O, as reported by some previous researchers. We conclude that there is no universal patterning in d 13 C and d 18 O along the tooth row. The amount of isotopic variation between teeth depends on the species’ life history and on the environment in which the animals lived. This is important in archaeological and palaeontological studies, which frequently and unavoidably rely on only small numbers of samples. © 2018 Elsevier Ltd and INQUA. All rights reserved. 1. Introduction Stable isotope analysis of animal tissues is now a major tool in ecological and environmental studies. In studies of contemporary environments a range of tissues can be analysed, including hair, feathers and dung which can be sampled without harming the animals. However, studies of past environments are usually based on calcified tissues, since soft tissues are generally not preserved. Tooth enamel is widely used for these studies, especially in research into more ancient time periods, because its density and the large size of the constituent crystals mean that it is generally resistant to post-depositional degradation (Ayliffe et al., 1994; Lee-Thorp, 2008). Researchers working on fossil assemblages are frequently constrained by limited numbers of teeth available for analysis. It is therefore important to know whether the isotopic composition of different teeth along the tooth-row of an individual animal is consistent, so that measurements of different teeth are directly comparable. Alternatively, if there are systematic differences be- tween teeth, we should establish whether we need to apply correction factors before making comparisons. This study was designed to address these questions by analysing three to six teeth from each of 23 ungulate individuals from southwestern South Africa. This is a larger sample size than most previous studies of isotopic variation along the tooth-row, and includes a wider range of animal species. Tooth formation takes place early in the life of most mammals. In species that do not have continuously growing teeth, dental tissue, and therefore the isotopic composition of teeth, reflects the diet consumed during the early part of an individual's life. Teeth start to form at the occlusal surface and proceed towards the root (Hillson, 2005). Enamel grows incrementally, a fact which is useful in studies that investigate patterns of seasonal variability during the time teeth were forming (Balasse et al., 2002; Tornero et al., 2016a). Enamel formation (amelogenesis) takes place in two stages: organic matrix secretion and mineralisation (Hillson, 2005). The initial enamel matrix comprises about one third protein, one third mineral and a third water. The first step in amelogenesis is the laying down of proteins by ameloblasts (Pasteris et al., 2008), fol- lowed by the addition of mineral to form hydroxyapatite (Passey and Cerling, 2002). As enamel matures, the protein and water is slowly removed until mature enamel contains less than 1% protein. Mature enamel crystallites are packed together, forming a dense, crystalline mass. The mineral content of enamel increases even * Corresponding author. Department of Archaeology, University of Cape Town, Private Bag X3, Rondebosch, 7701, South Africa. E-mail address: Julie.luyt@uct.ac.za (J. Luyt). Contents lists available at ScienceDirect Quaternary International journal homepage: www.elsevier.com/locate/quaint https://doi.org/10.1016/j.quaint.2018.02.009 1040-6182/© 2018 Elsevier Ltd and INQUA. All rights reserved. Quaternary International xxx (2018) 1e9 Please cite this article in press as: Luyt, J., Sealy, J., Inter-tooth comparison of d 13 C and d 18 O in ungulate tooth enamel from south-western Africa, Quaternary International (2018), https://doi.org/10.1016/j.quaint.2018.02.009