Measures of attachment or accommodation area on the skeleton are a popular means of rapidly generating estimates of muscle proportions and functional performance for use in large-scale macroevolutionary studies. Herein, we provide the first evaluation of the accuracy of these muscle area assessment (MAA) techniques for estimating muscle proportions, force outputs and bone loading in a comparative macroevolutionary context using the rodent masticatory system as a case study. We find that MAA approaches perform poorly, yielding large absolute errors in muscle properties, bite force and particularly bone stress. Perhaps more fundamentally, these methods regularly fail to correctly capture many qualitative differences between rodent morphotypes, particularly in stress patterns in finite-element models. Our findings cast doubts on the validity of these approaches as means to provide input data for biomechanical models applied to understand functional transitions in the fossil record, and perhaps even in taxon-rich statistical models that examine broad-scale macroevolutionary patterns. We suggest that future work should go back to the bones to test if correlations between attachment area and muscle size within homologous muscles across a large number of species yield strong predictive relationships that could be used to deliver more accurate predictions for macroevolutionary and functional studies.

骨骼上附着或调节区域的测量是快速生成肌肉比例和功能性能估计值的常用方法，可用于大规模宏观进化研究。在此，我们首次评估了这些肌肉面积评估 (MAA) 技术的准确性，以使用啮齿动物的咀嚼系统作为案例研究，在比较宏观进化背景下估计肌肉比例、力输出和骨骼负荷。我们发现 MAA 方法表现不佳，在肌肉特性、咬合力和特别是骨骼应力方面产生很大的绝对误差。也许更根本的是，这些方法经常无法正确捕捉啮齿动物形态类型之间的许多定性差异，特别是在有限元模型中的应力模式中。我们的研究结果对这些方法作为为生物力学模型提供输入数据的手段的有效性表示怀疑，这些模型应用于理解化石记录中的功能转变，甚至可能用于检查大规模宏观进化模式的富含分类群的统计模型。我们建议未来的工作应该回到骨骼来测试大量物种的同源肌肉内的附着区域和肌肉大小之间的相关性是否产生强大的预测关系，可用于为宏观进化和功能研究提供更准确的预测。