The scientists have unearthed a 300-million-year-old fossilized fish from an age-old shallow lagoon, called Hamilton Quarry, in Kansas.
The newly discovered fossilized fish, which has been named Acanthodes bridgei, measured about 10 centimeters in length.
According to the scientists, the ancient fossilized fish was preserved in such a good condition that its rods and cones, together called photoreceptor cells, in the eyeballs can be clearly seen with the help of a scanning electron microscope.
The presence of the increasingly specialized cells clearly indicates that these age-old fish were able to see in color.
According to the scientists, the biological vision systems that comprises of light receptors and image-processing capability, have been in existence for at least 520 million years. But when the optical systems exactly developed the capacity to witness the ‘colorful’ world remained a big mystery.
There are two types of cells in the retina of the human eye. They are: rods and cones.
While rods are narrow, thin and more sensitive to light, the cones are specially designed in triangular shape so as to allow proper processing of color.
Both cells utilize pigment for the absorption of light. The researchers said that they found evidence of one of these melanin in the eye of the fish during a chemical analysis.
Lead study author George Tanaka, of Japan’s Kumamoto University, said that the fossils excavated from the lagoon are highly preserved as the sediments in the lagoon accelerated the pace of burying the living creatures.
The researchers said that the microbial activity assisted in the deposition of a film of phosphate over the eyes of the fish that probably led to the preservation process.
Tanaka hopes that the latest discovery could contribute immensely in shedding light on the evolution of many vertebrates, including birds and dinosaurs.
The study was published on Wednesday in the journal Nature Communications.
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