Template creation
The template consists of 900 landmarks: 101 fixed landmarks, 93 curves (271 semilandmarks), and 18 surfaces (528 semilandmarks) (Supplementary Figure 1). For the anatomical definitions of landmarks, please refer to Supplementary Table 1. The number of curve or surface semilandmarks was determined by the complexity of the curves or area covered. High density landmark and semilandmark configurations, ranging from 800 to more than 1000 landmarks, have been demonstrated empirically to successfully capture genuine biological signal (Cornette et al., 2013; Dumont et al., 2016; Goswami et al., 2019; Gunz & Mitteroecker, 2013; Segall et al., 2016; Watanabe et al., 2019; Weisbecker et al., 2019)
To ensure the repeatability of landmarking of the manually placed fixed landmarks, three morphologically close specimens were digitised at ten repetitions. Inter-repetition variation was much lower than inter-individual variation, confirming the good repeatability of the template used in this study (Supplementary Figure 2).