A new discovery of spider fossils contained a surprising find: remnants of reflective eye tissue.
Although common today, spiders in the fossil record do not appear much, as their soft bodies are not well preserved, as published in the Journal of Systematic Palaeontology. This is the first time that a family of spiders outside of amber has been discovered, and the first time a spider's reflective eye tissue has been found in a fossil.
"It opens up a whole new world of how these things lived and how they caught their prey," said Paul Selden, one of the newspaper's authors and director of the Paleontological Institute of the University of Kansas, to Gizmodo.
A Korean high school and amateur fossil hunter named Kye-Soo Nam first found the fossils in a 112-million-year-old Cretaceous cliff, the Jinju Formation in South Korea. The formation has produced tons of other fossils, including plants, mollusks, fish and dinosaurs, as well as an unidentified fossil spider species.
In the new study, 10 spider samples were analyzed in dark gray slate and viewed under microscopes and measured. The scientists found that they represented seven different species. That alone is surprising and shows that there are probably many more extinct spider species that still need to be discovered.
Some of the fossils were from the spider family Lagonomegopidae. For the first time, such fossils were found outside of amber. However, if the spider is not conserved in amber but in stone, then they can see structures they had not seen before, such as those found in stone. B. the reflective eye tissue. This discovery allowed researchers to conclude much about the behavior of these spiders.
The samples showed a "rather remarkable preservation" of kanuförmigen reflecting tissue pieces in the eyes of the spiders, both of which are obviously visible in the fossil itself and were highlighted when the researchers analyzed the chemical composition of the fossil. They interpreted this reflective tissue as tapestry, which the eyes of some animals (but not of humans) use for seeing in low light. For this reason, pets and other mammals in flash photos often have bright, laser-like eyes.
You may wonder how the researchers found that they were looking at tapestry and nothing else. According to the paper, the spider tapetum, since it is formed from crystals of the molecule guanine, would be more conserved than other soft tissues. "Besides, the shape of the structure – clearly kanuförmig", they confirmed their suspicion, they write.
Each new fossil discovery adds more detail to the story of life on Earth – a story that may never be complete. In addition to learning more about ancient spiders, it's quite impressive to see the glow of 112-million-year-old, spidery eyes.