Figure 4.

Testing Psittacosaurus Countershading in Natural Conditions

(A–F) Gray colored cast without bristles attached, imaged under “closed habitat” conditions (A–C) and direct illumination (D–F). The model is shown as imaged in natural environment (A and D), masked (B and E), and in inverse color (C and F).

(G and H) Predicted boundaries of rapid transition from dark to light skin for countershading in the diffuse illumination of closed habitats (blue) and of direct lighting in a sunny open habitat (orange). Stippled lines indicate 95% confidence intervals.