Birds in a temperate climate filled with deciduous trees tend to be dull-colored, since that’s the best camouflage. But in jungles they blend in by being various bright shades of green, yellow, and red, like their surroundings. It might be reasonable to surmise that dinosaurs often blended with the prevalent colors of their habitat, and in some cases that might have meant bright green with bits of other colors, or mud-color, or the blue and turquoise of water. Look at the way the orange-and-white-and-black tiger blends perfectly with his habitat. It’s interesting to speculate. But you’re right that predators aren’t typically a color that makes them stand out to their prey. And vice versa.
I should have copied you in my post 31 as well. What you say is true ...as you move into tropical zones colors tend to get more vivid. Also, crazy bright colors are just as effective for both predators and prey as muted tuned-down coloring (e.g. compare the coloring of the Rhinocerous viper and that of the Puff Adder ....one is brightly colored, the other the color of earth, and both are virtually invisible in their respective environments until it is too late. Or, say, a comparison between a Lion’s coloring and a tiger’s. The animals are basically almost the same if you take out the skin ...they can even get fertile offspring ...but have totally different approaches to camouflage).