Soft external skeletons are generally not well preserved, except in a few exceptional sites around the world. There is a wonderful place in the south of France, where the fossils of spiders that weaved a web were discovered 22.5 million years ago.
Scientists say they have identified why many soft-bodied creatures such as spiders, insects and fish are buried and preserved. With such details for this particular rock formation in Aix-en-Provence. Very favorable conditions include a substance produced by microalgae that would envelop the spider and promote a protective chemical change.
“Most life forms do not turn into fossils,” Alison Olcott, associate professor of geology and director of the University of Kansas Research Center, said in a statement.
“It’s hard to become a fossil. You have to die under very specific conditions, and one of the easiest ways to become a fossil is to have hard parts like bones, horns, and teeth. So, our record of soft-body life is incomplete, Olcott, lead author of the study published in the journal Communications Earth & Environment, said.
“But we have these exceptional periods of preservation where all the conditions were in harmony for the preservation to occur.”
Fluorescence provides clues
In the statement, Olcott said the discovery was made possible by the decision to examine the spider’s fossil under a fluorescent microscope. This type of observation is not part of the standard protocol for examining fossils, but part of the research The team thought this might help them discern more details about the fossilized spiders, which blended in with the surrounding rocks. Different parts of the rock absorb energy from the UV light in the microscope and return the light at different wavelengths.
“To our surprise, they were glowing, so we were very interested in the chemistry of these fossils that made them glow. If you look at the fossil on the rock, it’s almost indistinguishable from the rock itself, but it glows a different color under the fluorescent frame. ”
Not all geological samples self-lumines and glow, but when they do, they can be amazing and provide a lot of information, Olcott said. Microscopic aquatic algae detected by fluorescence microscopy are known as diatom fossils and when alive they secrete sulfur-rich substances that form algal mats.
“These microalgae form a sticky, sticky globe — and that’s how they stick together,” she said.
The authors suggested that this substance coated the spiders and activates a process called sulfur, which stabilizes and preserves the spiders’ fragile bodies.
“Basically, the chemistry of microalgae and the chemistry of spiders work together to achieve this unique conservation,” she said.
Olcott said the discovery could help geologists locate other notable fossils from this period in other parts of the world.
“If diatom mats help bring about this remarkable preservation of fossils, we should be able to explore more units of diatoms, the diatom-rich rocks currently found around the world, to look for more of these deposits.
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