Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, Tennessee, United States of America.
PLoS One. 2013 Aug 6;8(8):e71428. doi: 10.1371/journal.pone.0071428. Print 2013.
The analysis of dental microwear is commonly used by paleontologists and anthropologists to clarify the diets of extinct species, including herbivorous and carnivorous mammals. Currently, there are numerous methods employed to quantify dental microwear, varying in the types of microscopes used, magnifications, and the characterization of wear in both two dimensions and three dimensions. Results from dental microwear studies utilizing different methods are not directly comparable and human quantification of wear features (e.g., pits and scratches) introduces interobserver error, with higher error being produced by less experienced individuals. Dental microwear texture analysis (DMTA), which analyzes microwear features in three dimensions, alleviates some of the problems surrounding two-dimensional microwear methods by reducing observer bias. Here, we assess the accuracy and comparability within and between 2D and 3D dental microwear analyses in herbivorous and carnivorous mammals at the same magnification. Specifically, we compare observer-generated 2D microwear data from photosimulations of the identical scanned areas of DMTA in extant African bovids and carnivorans using a scanning white light confocal microscope at 100x magnification. Using this magnification, dental microwear features quantified in 2D were able to separate grazing and frugivorous bovids using scratch frequency; however, DMTA variables were better able to discriminate between disparate dietary niches in both carnivorous and herbivorous mammals. Further, results demonstrate significant interobserver differences in 2D microwear data, with the microwear index remaining the least variable between experienced observers, consistent with prior research. Overall, our results highlight the importance of reducing observer error and analyzing dental microwear in three dimensions in order to consistently interpret diets accurately.
牙微磨损分析通常被古生物学家和人类学家用于阐明已灭绝物种的饮食，包括草食性和肉食性哺乳动物。目前，有许多方法可用于量化牙微磨损，这些方法在使用的显微镜类型、放大倍数以及二维和三维磨损特征的描述上有所不同。利用不同方法进行牙微磨损研究的结果无法直接比较，而且人类对磨损特征（例如凹坑和划痕）的量化会引入观察者误差，经验较少的观察者产生的误差更高。牙微磨损纹理分析（DMTA）可对三维牙微磨损特征进行分析，通过减少观察者偏差，缓解了二维牙微磨损方法所面临的一些问题。在这里，我们评估了在相同放大倍数下，草食性和肉食性哺乳动物的二维和三维牙微磨损分析的准确性和可比性。具体来说，我们比较了使用扫描白光共聚焦显微镜在 100 倍放大倍数下对现存非洲牛科动物和肉食动物的 DMTA 相同扫描区域的照片模拟生成的二维牙微磨损数据，以及观察者生成的二维牙微磨损数据。在这种放大倍数下，使用划痕频率可以将食草和杂食性牛科动物区分开来；然而，DMTA 变量能够更好地区分肉食性和草食性哺乳动物不同的饮食生态位。此外，结果表明，二维牙微磨损数据存在显著的观察者差异，微磨损指数在有经验的观察者之间变化最小，这与先前的研究一致。总体而言，我们的研究结果强调了减少观察者误差和在三维空间分析牙微磨损的重要性，以便准确地解释饮食。
