Figure 2.

Phylogenetic shape changes in gymnotiform neurocrania for 133 species. (a) Relative warp deformation grids from geometric morphometric analyses showing deformations of the first two principal components (PC). Note the heavy loading of variation in relative skull length (heterocephaly) on PC1. (b) Phylomorphospace analysis depicting the constrained colonization of gymnotiform skull shape. Note the multiple independent colonizations of brachycephalic (low PC1 values) and dolichocephalic skull shape