I don't know how it would be possible to know what colors dinosaurs may have been able to see. Not sure how this is possible with real life animals either. As my dad pointed out, there doesn't seem to be any test to successfully prove what colors an animal, dead or alive, can see and which they could not.
Animal vision and color perception is a subject I am extremely interested in. I can't claim to know the exact methods scientists use to determine what colors an animal can see, but I have little (if any doubt) that there are successful ways of doing so. For instance, let's say you present a monkey with a set of differently colored buttons that would look identical to a colorblind animal, one of which deposits a treat when pressed. If the monkey is capable of distinguishing between the colors, it will quickly learn which button to press if it wants a snack.
Apparently, an animal's ability to perceive color is determined by the types of cone cells in its retina. Humans, for instance, have three different kinds of cones in their eyes, which allow us to see long, short, and medium wavelengths of colored light. Most other mammals have only one or two cone types (dogs, contrary to popular belief, are not completely colorblind). Birds, however, along with many reptiles, have three, four, or even five types of cone cells, allowing them to see a much broader range of wavelengths, including ultraviolet light. The theory is that because mammals spent virtually the entire Mesozoic Era as chiefly nocturnal creatures (for whom good color vision is more or less redundant), they lost most of their cone cell types, and that some of them only "re-evolved" color vision when they inherited the Earth from the non-avian dinosaurs.
One of my college science professors told me about a study involving sparrows (I think) with patches of feathers that reflect ultraviolet light such that they glow when the birds are placed under a UV lamp. The birds apparently live in a hierarchy dictated by the ultraviolet reflectivity of these feathers; the shinier the patches, the higher the bird's rank. When the researchers covered the UV-reflective feathers of high-ranking birds with paint or makeup of some sort, the birds' places in the pecking order dropped. I can't imagine the sparrows were too happy about it, but it's so fascinating (
I think so, anyway
), and somewhat relevant to the subject, that I couldn't help but mention it.
Anyway, because dinosaurs are fundamentally reptiles, and reptiles have good color vision, and birds are believed to be dinosaur descendants, and they have good color vision, there's good reason to believe that dinosaurs had good color vision too.
Holy cheese, how we've wandered from the original subject of this thread!
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