Fig. 2
From: Morphology of the snake spectacle reflects its evolutionary adaptation and development
Evolution of spectacle morphology, habitat type, and activity period in snakes. Plots show measured (tips) and reconstructed (internal branches) values of spectacle diameter (a), spectacle thickness (b), habitat type (c), and activity period (d) plotted on the phylogeny of snakes (Ma: million years). Internal branch values were reconstructed using linear parsimony in a and b, and maximum parsimony in c and d. Grey branches in c and d represent branches were it was not possible to resolve habitat and activity period