One of the most common mistakes in painting dinosaurs is to make the skin texture equally prominent throughout the form.
In digital work, the appearance of overall equal texture can happen when a bumpy 2-D pattern is mapped equally over a form. The texture is rendered essentially the same way in the shadow as it is in the light, but in a reduced value or tone. Traditional painters are tempted to do the same. That way of doing texture doesn’t look real because it’s not how the eye sees it.
In fact, the textural relief is not equally apparent in the light and shadow. Texture is very difficult to see at all in the shadow region, and it’s only slightly more visible in the fully lit areas. The place to see texture is in the halflight.
The halflight is sometimes called the halftone or demi-teinte. This is the area where the form transitions from light into shadow. Astronomers looking at photos of the moon call this region the terminator. It’s the area where the raking light brings out the detail of the craters.
On this photo of a dinosaur model, I’ve marked the fully-lit areas with an L, the shadow with an S, and the halflight with an H.
Here’s another detail of a painting from Journey to Chandara, showing the halflight in comparison to the light and shadow. Note that the texture in the reflected light (RL) should also be downplayed compared to the halflight. With traditional opaque painting media, you can suggest halflight texture by dragging pigments over bumpy impastos, or in this case, canvas texture.
In more transparent media you can suggest halflight texture with a drybrush handling. This painting was also done in oil, but the paint is used more thinly.
Happy Thanksgiving. And remember, when you're eating a turkey, you're really eating an "avian dinosaur."