One of paleontologists’ greatest challenges is to study the evolution of sight because soft tissue is usually the first to decay. Luck has it, a team of Japanese scientists discovered an approximately 300 million year-old fish fossil with well-preserved eye balls.
This discovery will shed new light on the evolution of color vision. Scientist believed that the ability to see in color evolved over millions of years. The discovery of this unique fossil can finally turn the hypothesis into a fact.
Eyesight is based on pigments’ ability to absorb light. These pigments can be found in cells known as “rods” and “cones”. These two types of cells function as photoreceptors, absorbing electromagnetic radiations (rays of visible light) and transforming them into information that the brain can process. So eyesight is enabled after the brain receives the needed information.
The rod and cone cells play different roles. While the first type is involved in deciphering color, details and quick changes occurring in one’s visual field the, the second form is responsible for sight in low light circumstances. The two work together thus providing human race with complex vision.
The 10 centimeters long creature discovered by paleontologists from the Kumamoto University in Japan is known as “myllokunmingia”, a member of the “spiny shark” family that preceded the dinosaurs. It is now the earliest form discovered to possess the ability to see in color. Scientists also discovered the fossilized fish has a backbone, thus becoming “the earliest known vertebrate to exist on the face of the Earth”.
The creature was discovered in the Hamilton Quarry situated in Kansas. The explanations to why the fossil was so well preserved are based on the fact that this region was once a lagoon. For millions of years, the fish lied buried under the quick changing sediments of the lagoon, remaining intact and completely impressioned.
Genko Tanaka, lead researcher in the study, explained how most components of the optical system are rarely preserved, as soft tissue usually decays within 64 days. He also described how the Hamilton Quarry “yields exceptionally well-preserved animal fossils in an estuarine depositional setting”.
Tanaka also mentioned that the fish’s gills and its pigments were also very well preserved. Because of their perfect conservation, the fossilized components can be examined under electron microscope.
Paleontologists believe that examining the myllokunmingia will help them in their research of birds, other species of prehistoric fish and even dinosaurs.
The findings were published on Dec.23 in the Nature Communications journal.
Image Source: IFL Science