English: Figure 4

The Differing Pattern of Predicted Self-Shadowing in Sinosauropteryx

3D models of the abdomen of NIGP 127586 and NIGP 127587 imaged under different lighting conditions. “Model” represents the original photographs taken of the models to show how the self-shadows are cast across each, with and without synthetic fur added as a feather analog. “Prediction” shows how a gradient of pigment dorsoventrally would be expected to perfectly counterbalance the illumination gradient caused by self-shadowing.

(A and B) Direct sunlight at an altitude of around 30° on smooth and “feathered” models.

(C and D) Direct sunlight at an altitude of 90° on smooth and “feathered” models.

(E and F) Diffuse lighting under 100% cloud cover (which equates to a closed environment) on smooth and “feathered” models.

The ventral position and sharpness of the predicted countershading transition can be seen to be higher and sharper under overhead direct lighting, indicative of an open environment (C and D), whereas under diffuse lighting, representing a closed habitat, the transition is lower and more gradual (E and F).