Eye cell analysis of a fossilized fish revealed that color vision has existed for the species since at least 300 million years ago.
Researchers at Kumamoto University in Japan analyzed a 300-million-year old fossil specimen of a fish called Acanthodes bridge found in Kansas. Scientists believe that it could be the last known common ancestor of modern jawed fishes such as barracudas and sharks.
The team, led by paleontologist Genko Tanaka, searched for rod and cone cells in the eyes of the specimen. Rod and cone cells are responsible for the sensitivity of the human eye to color and light. The researchers were surprised at the presence of rod and cone cells, suggesting that ancient fish had color vision.
The study is the first to prove that fish have rod and cone cells in their eyes. The researchers were surprised that these cells remained well-preserved after more than 300 years.
"Rods and cones are not usually preserved, because these soft tissues are more fragile," Tanaka told Live Science.
Further analysis showed that the fossil has granules that could be eumelanin, a pigment that allows one to see the colors black and brown. This finding contradicts an earlier belief that most fish are colorblind.
The researchers plan to use their findings for future research to identify the colors visible to extinct animals such as the dinosaurs.
This study was published in the Dec. 23 issue of Nature Communications.
