[greensleeves (OP)]

Fish can see colour. So, I believe, can amphibians and reptiles, and of course birds also have good colour vision. However the vast majority of mammals cannot, it seems, detect colour, or have very limited colour vision (hence their largely uniform brown or gey appearance with differences only in shade). Yet primates including man, can distinguish colour easily. So what happened to colour vision in the evolution of mammals from reptiles, and how has it been 're-acquired' in primates? Has it really evolved for a second time independently of its evolution in other vertebrates, or did primates and other mammals evolve from two quite separate reptilian lines, one of which (primate ancestors) possessed colour vision, whilst the other did not? (This second option seems unlikely to me).