Applied and Analytical Palaeontology, Institute of Geosciences, Johannes Gutenberg University, 55128 Mainz, Germany;
Center of Natural History, University of Hamburg, 20146 Hamburg, Germany.
Proc Natl Acad Sci U S A. 2020 Sep 8;117(36):22264-22273. doi: 10.1073/pnas.2008149117. Epub 2020 Aug 24.
Food processing wears down teeth, thus affecting tooth functionality and evolutionary success. Other than intrinsic silica phytoliths, extrinsic mineral dust/grit adhering to plants causes tooth wear in mammalian herbivores. Dental microwear texture analysis (DMTA) is widely applied to infer diet from microscopic dental wear traces. The relationship between external abrasives and dental microwear texture (DMT) formation remains elusive. Feeding experiments with sheep have shown negligible effects of dust-laden grass and browse, suggesting that intrinsic properties of plants are more important. Here, we explore the effect of clay- to sand-sized mineral abrasives (quartz, volcanic ash, loess, kaolin) on DMT in a controlled feeding experiment with guinea pigs. By adding 1, 4, 5, or 8% mineral abrasives to a pelleted base diet, we test for the effect of particle size, shape, and amount on DMT. Wear by fine-grained quartz (>5/<50 µm), loess, and kaolin is not significantly different from the abrasive-free control diet. Fine silt-sized quartz (∼5 µm) results in higher surface anisotropy and lower roughness (polishing effect). Coarse-grained volcanic ash leads to significantly higher complexity, while fine sands (130 to 166 µm) result in significantly higher roughness. Complexity and roughness values exceed those from feeding experiments with guinea pigs who received plants with different phytolith content. Our results highlight that large (>95-µm) external silicate abrasives lead to distinct microscopic wear with higher roughness and complexity than caused by mineral abrasive-free herbivorous diets. Hence, high loads of mineral dust and grit in natural diets might be identified by DMTA, also in the fossil record.
食物加工会磨损牙齿，从而影响牙齿的功能和进化成功。除了内源性硅质植硅石外，附着在植物上的外源性矿物灰尘/沙砾也会导致哺乳动物食草动物的牙齿磨损。牙齿微观磨损纹理分析（DMTA）广泛应用于从微观牙齿磨损痕迹推断饮食。外源性磨料与牙齿微观磨损纹理（DMT）形成之间的关系仍不清楚。用绵羊进行的喂养实验表明，含有灰尘的草和树叶的影响可以忽略不计，这表明植物的内在特性更为重要。在这里，我们通过在豚鼠的控制喂养实验中探索粘土到沙粒大小的矿物磨料（石英、火山灰、黄土、高岭土）对 DMT 的影响来研究这个问题。通过在颗粒状基础饮食中添加 1%、4%、5%或 8%的矿物磨料，我们测试了粒径、形状和数量对 DMT 的影响。细粒石英（>5/<50 µm）、黄土和高岭土的磨损与无磨料的对照饮食没有明显区别。细砂级石英（~5 µm）导致表面各向异性更高，粗糙度更低（抛光效果）。粗粒火山灰导致复杂性显著增加，而细砂（130 至 166 µm）则导致粗糙度显著增加。复杂性和粗糙度值超过了那些从接受具有不同植硅石含量的植物的豚鼠喂养实验中获得的值。我们的研究结果表明，大粒径 (>95-µm) 的外源性硅酸盐磨料会导致明显的微观磨损，其粗糙度和复杂性均高于无矿物磨料的食草动物饮食。因此，DMTA 也可以在化石记录中识别出天然饮食中高负荷的矿物灰尘和沙砾。
