Fig. 5
From: Shell biomechanics suggests an aquatic palaeoecology at the dawn of turtle evolution
(a) Landmarks used to quantify shape variation in turtle shells (based on48 plotted on the 3D model of Proterochersis. (b) Morphospace plot based on the first two PCs representing shell shape variation in turtles. The positions of the models of Proganochelys quenstedtii and Proterochersis sp. are highlighted by squares. Landmark configurations representing shape extremes (black dots and lines) related to variation along the PC1 and PC2 axes superposed to the mean shape (grey dots and lines) are shown on the corners of each axis. Green and beige shaded areas represent the optima associated with aquatic and terrestrial taxa, respectively43.
