Researchers examining decades-old X-rays of a 390-million-year-old trilobite fossil found that it has a truly unique eye structure consisting of 200 large lenses in each eye.
Phacops-Geesops, a trilobite of the suborder Phacopina, lived in the Devonian about 390 million years ago.
At least six facets are arranged under each optical lens in each extinct arthropod’s eye, which all together again form a small compound eye,” explains zoologist Brigitte Schönemann of the Institute for Didactics of Biology at the University of Cologne. said in a statement.
“So we have about 200 compound eyes — one under each lens — in one eye.”
While this discovery was originally made by amateur paleontologist Wilhelm Stürmer in the 1970s, Stürmer’s results were not officially confirmed until Schoenemann and his team recently went back and re-evaluated the x-rays – and confirmed them with a CT scan.
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The eyes of the geesops Phacops, a trilobite from the Devonian Period, each had 200 lenses that included six tiny facets. Each facet forms a different individual eye
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Stürmer, a radiologist at German technology company Siemens, was an enthusiastic paleontologist for decades and drove his VW bus with an X-ray station to the mines in central Germany’s Hunsrück in search of fossils.
When he saw the x-ray of p. Gosh, he was sure they showed a petrified optic nerve with multiple lenses.
However, at the time, the findings of the attackers were rejected by experts.
“The consensus is that only bones and teeth, the hard parts of living things, can be seen in fossils, but not in soft parts like intestines or nerves,” Schoenemann said.
X-rays from the 1970s originally included p. geesops had this unique optical network, but experts at the time rejected the idea. Photo: A phacopid schizocroal eye exhibits greater distance between the lenses than most compound eyes
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In a new study published in Scientific report, Schoenemann and an international team of researchers verified Stürmer’s lay analysis.
They found that the trilobites of the suborder Phacopina had an optical network unique to the animal kingdom.
Each of his two eyes has 200 lenses, each measuring up to one millimeter in size.
Their subfaces are arranged in a ring or two, including a “foam-like nest,” says Schoenemann, which is likely the local neural network used to directly process information from the hypereye.
Recent CT scans of trilobite fossils (above) confirm 50-year-old findings from amateur paleontologist Wilhelm Stürmer of a compound eye type.
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They also discovered the optic nerve that would carry information from the trilobite eye to the brain, as Stürmer theorized.
Schoenemann even found markings on Stürmer’s X-ray images that labeled the six subfaces.
“A negative X-ray shows an arrow with a red pen pointing to the bottom six-sided structure under the main lens,” he said.
“This may indicate that Striker already recognized the hyper-compound eye.”
The team confirmed Stürmer’s findings with modern CT technology that was not available 40 years ago.
Trilobites dominated the world’s oceans from the beginning of Cambodia about 540 million years ago to the end of Permian about 250 million years ago.
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Trilobites dominated the world’s oceans from the beginning of Cambodia about 540 million years ago to the end of Permian about 250 million years ago.
Most trilobites had compound eyes similar to those found in insects today – a large number of hexagonal faces that make up the eyes, with eight photoreceptors under each facet.
For example, drone bees have 8,600 facets, while dragonflies have up to 10,000 facets.
To produce a coherent image, these aspects must be very close together.
However, in the trilobite suborder Phacopinae, the externally visible compound eye lenses are much larger and further apart.
It only added to when Schönemann examined 50-year-old Stürmer’s X-ray and found that he was looking at hyper-compound eyes.
The “supereye” may be an evolutionary adaptation to seeing in low light, he said.
This may be a thing. Geesops’ hypereye was designed to help it see in low light, the researchers said. Photo: trilobite rendering from the 1880s
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With its highly complex visual system, it may be much more sensitive to light than normal trilobites.
“It’s also possible that each component of the eye fulfills a different function — for example, to increase contrast or allow different color perception,” says Schoeneman.
When Stürmer died in the mid-1980s, his legacy donated his archives to the university, but researchers did not thoroughly examine them until recently.
In 2017, paleontologists in Estonia discovered a 530 million-year-old “remarkable” trilobite fossil that may contain the oldest eye ever found.
The fossil’s right eye is partially worn out, giving researchers a clear view of the inside of the organ, including details of its structure and function.
Unlike Phacops-Geesops, this more primitive species, Schmidtiellus reetae, has no lenses.
Its eyes are made up of about 100 optical units, or ommatidia, which are relatively far apart when compared to contemporary compound eyes, the team said in a study published in the journal Proceedings of the National Academy of Sciences.
This is likely because the species lost part of the shell required for lens formation.
“This extraordinary fossil shows us how ancient animals saw the world around them hundreds of millions of years ago,” said geologist Euan Clarkson, who co-authored the report. said then.
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