Fig. 1: Facial variation across amniotes.
From: Sonic hedgehog and fibroblast growth factor 8 regulate the evolution of amniote facial proportions
Premaxilla bone (red), maxilla (blue) and nasal (yellow) highlighted to show variation in skeletal composition of the antorbital face. Skulls not to scale. Colored phylogenetic branches highlight the major amniote radiations: birds in orange, crocodilians in purple, chelonians in blue, squamates in yellow, and mammals in red. Species names and specimen numbers are provided in Table S1.
