The fossilized remains of an extinct sea creature contain what is believed to be the oldest intact eyes ever discovered. The find could help scientists understand how modern compound eyes developed.
Oldest Eyes Discovered On A Trilobite
While examining well-preserved fossils, scientists discovered that the remains contained intact eyes, making them the oldest eyes ever discovered at 530 million years old. Amazingly, they found that the eyes are actually an early form of the eyes of many modern creatures such as crabs, dragonflies, and bees.
They belonged to an extinct hard-shelled sea creature called a trilobite, which roamed around coastal areas during the Paleozoic period between 541 and 251 million years ago. The fossilized remains of the creature, which is an ancestor of modern spiders and crabs, were found at a site in Saviranna, northern Estonia.
Compound Eyes Development
If having discovered the oldest eyes isn't enough, the right eye of the trilobite was actually partially worn away, giving the researchers an opportunity to see the inside of the organ. Upon examination, researchers found that the creature had an ancient form of compound eye, a visual organ made up of tiny visual cells called ommatidia. These are the same kinds of eyes of some modern day bees and dragonflies.
The trilobite's eyes were made up of 100 ommatidia, which were located further apart compared to those of modern creatures. Although they surmised that the trilobite had relatively poorer eyesight compared to modern day creatures, it was able to identify predators in its path.
Perhaps the most striking difference between trilobite and modern compound eyes is that the trilobite eye had no lens. They believe that this is likely because the species did not yet have the capability to develop a lens. It is worth noting, however, that another trilobite species from the region developed higher-resolution eyes just a few million years later.
Based on their findings, researchers were amazed to see just little differences between the primitive and modern eyes despite the staggering amount of years in between them.
"This exceptional fossil shows us how early animals saw the world around them hundreds of millions of years ago. Remarkably, it also reveals that the structure and function of compound eyes has barely changed in half a billion years," said Professor Euan Clarkson of University of Edinburgh, coauthor of the study.
Their findings are published in the journal Proceedings of the National Academy of Sciences.