530m-year-old fossil has look of world’s oldest eye

Thu, 07/12/2017

The team, which included a researcher from the School of GeoSciences say that a 530-million-year-old fossil contains what could be the oldest eye ever discovered.

The remains of an extinct sea creature include an early form of the eye seen in many of today’s animals, including crabs, bees and dragonflies.  Scientists made the finding while examining the well-preserved fossil of a hard-shelled species – called a trilobite. These ancestors of spiders and crabs lived in coastal waters during the Palaeozoic era, between 541-251 million years ago. They found the ancient creature had a primitive form of compound eye – an optical organ that consists of arrays of tiny visual cells, called ommatidia, similar to those of present-day bees.

The right eye of the fossil – which was unearthed in Estonia – was partly worn away, giving researchers a clear view inside the organ. This revealed details of the eye’s structure and function, and how it differs from modern compound eyes.  Its eye consists of approximately 100 ommatidia, which are situated relatively far apart compared to contemporary compounds eyes.

The team also revealed that only a few million years later, improved compound eyes with higher resolution developed in another trilobite species from the present-day Baltic region.

Professor Euan Clarkson, of the University of Edinburgh’s School of GeoSciences, said:

“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.”

The study was carried out in collaboration with the University of Cologne, Germany, and Tallinn University of Technology, Estonia.

Further information

The paper Structure and function of a compound eye, more than half a billion years old is published in Proceedings of the National Academy of Sciences. B Schoenemann et al.

Close-up pf tribobite fossil's head.  Credit: Gennadi Baranov
Close-up pf tribobite fossil's head. Credit: Gennadi Baranov