Figure 8
From: First terror bird footprints reveal functionally didactyl posture
Geometric morphometric plots comparing Rionegrina pozosaladensis igen. et isp. nov. (Rz), with Aramayoichnus rheae (Ar, fossil rheid footprints), and footprints of extant Rhea americana (Ra), Rhea pennata (Rp), and Chunga burmeisteri (Ch) (n = 39). The numbered dots indicate the landmark locations in the mean shape of the sample; the sticks indicate the changes in the relative positions of the landmarks. (a) Multivariate regression of footprint shape onto size (as logarithm of centroid size) classified by (ichno)species. (b) Deformation grid reflecting shape changes. (c) Principal components plot of PC1 vs. PC2 of analysed footprints. The inset display the histogram of principal components. (d,e) Shape changes visualised by transformation grids at PC1 scores − 0.20 and 0.15. (f) Scatter plot showing the variation in shape of footprints of different ichno(species) along the first two canonical variate (CV1 and CV2) axes. The different ichno(species) represented by contrasting footprint shapes are clearly separated across CV1 (delimited by confidence ellipses). g-h, Shape changes, illustrated by the deformation grids, at CV1 scores -20 and 10, respectively.
