LONDON, UNITED KINGDOM: A 530-million-year-old fossil of an extinct sea creature contains what could be the oldest eye ever discovered, according to a study.
The remains include an early form of the eye seen in many of today’s animals, including crabs, bees and dragonflies, the researchers said.
Scientists, including those from the University of Edinburgh in the United Kingdom, made the finding while examining the well-preserved fossil of a hard-shelled species called trilobite.
These ancestors of spiders and crabs lived in coastal waters during the Paleozoic era, between 541-251 million years ago, the researchers said.
They discovered that the ancient creature had a primitive form of compound eye, an optical organ consisting of a series of tiny visual cells, called ommatidia, similar to those of today’s bees.
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The findings, published in the journal PNAS, suggest that compound eyes have changed little more than 500 million years.
The right eye of the fossil, which was unearthed in Estonia, was partially worn out, giving researchers a clear view inside the organ.
This revealed details of the structure and function of the eye, and how it differs from modern composite eyes.
The species had poor vision compared to many animals today, but could identify predators and obstacles in their path, the researchers said.
His eye consists of around 100 ommatidia, which are relatively separate compared to contemporary compound eyes, they said.
Unlike modern compound eyes, the fossil eye does not have a lens. This is likely because the primitive species, called Schmidtiellus reetae, lacked the shell parts necessary for lens formation.
The team also revealed that only a few million years later, improved compound eyes with higher resolution were developed in another trilobite species in the current Baltic region.
“This exceptional fossil shows us how early animals saw the world around them hundreds of millions of years ago,” said Professor Euan Clarkson of the University of Edinburgh.
“Surprisingly, it also reveals that the structure and function of compound eyes has barely changed in half a billion years,” Clarkson said.
“This may be the first example of eye that is possible to find,” said Professor Brigitte Schoenemann, of the University of Cologne in Germany.
“Older specimens in sediment layers beneath this fossil contain only traces of the original animals, which were too soft to be fossilized and have disintegrated over time,” said Schoenemann.