A 300 million year old fish has been found in such a good state of preservation biologists weree able to examine the retina of it's eyes. They found the same rod and cone structure of all animals with good visual color perception.

The fish has not been completely examined, so more wonders may be revealed. Los Angeles Times A10, Saturday 27 Dec 2014 (dead tree edition).

Modern fish eyes are the same as they were 300 million years ago (except in some special cases such as cave fish).