Despite its importance for making biologically meaningful conclusions in geometric morphometric analyses, landmark error is inconsistently assessed. We evaluate a set of 30 landmarks designed to capture shape variation among six major brain regions on endocasts of Euarchontoglires (Primates, Scandentia, Dermoptera, Lagomorpha, Rodentia). Seven trials were performed by three observers on virtual endocasts of three species: Alouatta palliata (Primates), Ochotona pallasi (Lagomorpha), and Octodon degus (Rodentia). Standard deviation for all landmarks was evaluated relative to mean inter-landmark distance, centroid size, and centroid radius. A Procrustes analysis of variance (ANOVA) was performed to assess inter- and intraobserver error. Results show that standard deviations in landmark placement across trials, species, and observers are low (≤ 1.5%). The Procrustes ANOVA found significant differences between observers, accounting for only a small portion of the variation (R² = 0.002, p ≤ 0.0001); most of the variation is attributed to species (R² = 0.993, p ≤ 0.0001). In a separate analysis, a landmark sampling evaluation curve (LaSEC) which included two additional curve semilandmark sets along the sagittal aspect of the neocortex and cerebellum was applied to 40 landmarked species spanning all five orders of Euarchontoglires. The LaSEC indicated that 99% of the variation is captured at by 30 landmarks. Morphological patterns previously thought to characterize these groups are replicated in a principal component analysis of landmark data for 40 species. Specifically, most variation relates to the relative scale of the neocortex and olfactory bulbs and the flexion of the basicranium. Overall, these landmarks are highly replicable and able to represent morphological patterns within a diverse group such as Euarchontoglires.

尽管它对于在几何形态测量分析中得出具有生物学意义的结论很重要，但对界标误差的评估却不一致。我们评估了一组 30 个标志物，旨在捕获 Euarchontoglires（灵长类动物、Scandentia、Dermoptera、Lagomorpha、Rodentia）内模上六个主要大脑区域之间的形状变化。三位观察者对三个物种的虚拟内铸进行了七项试验：Alouatta palliata（灵长类动物）、Ochotona pallasi（兔形目动物）和Octodon degus（啮齿目动物）。相对于平均地标间距离、质心大小和质心半径来评估所有地标的标准偏差。进行 Procrustes 方差分析 (ANOVA) 以评估观察者间和观察者内的误差。结果表明，试验、物种和观察者之间的标志物放置标准偏差较低（≤ 1.5%）。 Procrustes 方差分析发现观察者之间存在显着差异，仅占变异的一小部分（R ²  = 0.002，p ≤ 0.0001）；大部分变异归因于物种（R ²  = 0.993，p ≤ 0.0001）。在一项单独的分析中，将包括沿新皮质和小脑矢状面的两个附加曲线半地标集的地标采样评估曲线 (LaSEC) 应用于涵盖 Euarchontoglires 所有五个目的 40 个地标物种。 LaSEC 表明 99% 的变异是由 30 个地标捕获的。先前认为表征这些群体的形态模式在 40 个物种的标志性数据的主成分分析中得到了重复。具体来说，大多数变化与新皮质和嗅球的相对尺度以及基骨的弯曲有关。总体而言，这些地标具有高度可复制性，并且能够代表Euarchontoglires等不同群体的形态模式。