taxonID	type	description	language	source
C73287DEFFCF036C2A95F93E84CAF9E7.taxon	description	A B shape shape Multivariate Multivariate 100 200 300 400 100 150 200 250 300 SCL SCL C D Orlitia borneensis shape shape Multivariate Multivariate 200 300 400 500 600 100 300 500 700 SCL SCL Fig. 3 Ontogenetic shell shape curves for selected species. Bivariate plots of multivariate shape against straight carapace length (SCL, in mm). A Chelus fimbriata, B Trachemys scripta, C Manouria emys, D Orlitia borneensis. The size-range for adult multivariate shape, based on our 85 % - adult shape threshold, is indicated by grey boxes. The red vertical line indicates the size threshold at which multivariate shape values reach 85 % of the shape of record-sized specimens, with corresponding female and male percentages of maximum SCL indicated at the top of the line. Datapoints are colour-coded according to their cluster assignments (‘ small’, ‘ intermediate’ or ‘ large’), and symbols represent sex. (X / Y %) values at largest datapoint indicates percentage of maximum female / male SCL recorded for the species. Solid lines are Gompertz curves fit across all data points. Dashed horizontal lines represent the lower 95 % interval at which the asymptotic multivariate shape value is reached according to the Gompertz functions ‘ large’ cluster category does not uniformly fall together with the 85 % shape thresholds or with the lower 5 % confidence intervals on shape asymptotes. Te 85 % shape thresholds nearly ubiquitously fall within the ‘ large’ cluster, indicating that the 85 % cut-off is quite conservative within the context of multivariate shape and absolute shell size. On the contrary, the lower 5 % confidence intervals on shape asymptotes usually fall within the ‘ intermediate’ cluster, highlighting the uncertainty of the asymptotic approach to generating size thresholds in the current dataset. Sexual shape dimorphism Allometric shape regressions with sex as a covariate show that sexual shape dimorphism is absent in many (N = 15) of the 21 tested turtles (Fig. 4 A; Supplementary Table 3). In only six species, we received a significant effect of sex (Fig. 4 A). In only two of these, the effect of sex is stronger than the effect of ontogeny, indicating that sex effect changes are less pronounced that ontogenetic shell shape changes (Fig. 4 A). Overall, size has a median effect-size of 2.8, and its effect is thus ~ 4.5 - fold the effect of sex, which has a median value of 0.6 (Fig. 4 B). Shape comparisons of two same-sized female and male specimens of the turtle in which we detected the largest relative sex effects, the geoemydid Leucocephalon yuwonoi, show that shape differences are minor (Fig. 4 C). Tese include a somewhat more elongated shell and more concave plastron in the male. However, these differences are minor when compared to ontogenetic shell shape differences in the species (Fig. 4 D), which include strong shell elongation, and also when compared to interspecific differences with the closely related Notochelys platynota (Fig. 4 E). Disparity analysis Our disparity analysis results lend support to our initial hypothesis of an increased extent of shell shape differentiation throughout ontogeny (Fig. 5). Both of our disparity metrics used (sum of ranges and Procrustes variances) return the same patterns. ‘ Small’ turtles exhibit significantly smaller morphological disparity in the shell than both ‘ intermediate’ and ‘ large’ - sized turtles (Tables 1, 2). However, we find no statistical difference between the disparity ranges of ‘ intermediate’ and ‘ large’ turtle individuals (Table 2; Fig. 5 B).	en	Hermanson, Guilherme, Evers, Serjoscha W. (2025): PG- 18: turtles reach adult shell shapes at about 65 % maximum carapace length. Swiss Journal of Palaeontology (47) 144 (1): 1-16, DOI: 10.1186/s13358-025-00395-0, URL: https://doi.org/10.1186/s13358-025-00395-0
