Glowing Spider Fossils Prompt Breakthrough Research on Treasure Trove of Amazingly Well-Preserved Specimens

Fluorescent Spider Fossil

Fossilized spider from the Aix-en-Provence Formation in France seen in hand pattern overlain with fluorescent microscopy picture of the identical fossil. Under regular lighting the spider fossil is difficult to distinguish from the encircling rock matrix, however when the fossil is happy by UV-illumination its chemical composition causes it to autofluorescence brightly, revealing further particulars of its preservation. Credit: Olcott et al.

Glowing spider fossils immediate breakthrough research of how they have been preserved at Aix-en-Provence.

A geologic formation close to Aix-en-Provence, France, is famend as one of the world’s most vital treasure troves of Cenozoic Era fossil species. Scientists have been uncovering exceptionally well-preserved fossilized vegetation and animals there for the reason that late 1700s.

“Most life doesn’t change into a fossil.” — Alison Olcott

The Aix-en-Provence formation is especially well-known for its fossilized terrestrial arthropods from the Oligocene Period (between roughly 23-34 million years in the past). Because arthropods — animals with exoskeletons like spiders — are not often fossilized, their abundance at Aix-en-Provence is astounding.

A brand new research printed within the journal Communications Earth & Environment on April 21, 2022, from researchers on the University of Kansas is the primary to ask: What are the distinctive chemical and geological processes at Aix-en-Provence that protect spiders from the Oligocene Period so exquisitely?

“Most life doesn’t change into a fossil,” stated lead creator Alison Olcott, affiliate professor of geology and director of the Center for Undergraduate Research at KU. “It’s arduous to change into a fossil. You need to die underneath very particular circumstances, and one of the simplest methods to change into a fossil is to have arduous components like bones, horns, and tooth. So, our document of soft-body life and terrestrial life, like spiders, is spotty — however we now have these durations of distinctive preservation when all circumstances have been harmonious for preservation to occur.”

Chemistry of Spider Fossil From Aix-en-Provence

Scanning electron picture of fossilized spider stomach revealing a black polymer on the fossil and the presence of two sorts of microalgae: a mat of straight diatoms on the fossil and dispersed centric diatoms within the surrounding matrix. This picture is overlain by chemical maps of sulfur (yellow) and silica (pink) revealing that whereas the microalgae are siliceous, the polymer protecting the fossil is sulfur-rich. Credit: Olcott et al.

Olcott and her KU co-authors Matthew Downen — then a doctoral candidate within the Department of Geology and now the assistant director at Center for Undergraduate Research — and Paul Selden, KU distinguished professor emeritus, together with James Schiffbauer of the University of Missouri, sought to find the precise processes at Aix-en-Provence that offered a pathway for preservation for the spider fossils.

“Matt was working on describing these fossils, and we determined — roughly on a whim — to stay them underneath the fluorescent microscope to see what occurred,” Olcott stated. “To our shock they glowed, and so we received very fascinated with what the chemistry of these fossils was that made them glow. If you simply have a look at the fossil on the rock, they’re virtually indistinguishable from the rock itself, however they glowed a distinct shade underneath the fluorescent scope. So, we began exploring the chemistry and found the fossils themselves comprise a black polymer made of carbon and sulfur that, underneath the microscope, seems to be just like the tar you see on the street. We additionally seen there have been simply hundreds and hundreds and hundreds of microalgae throughout the fossils and coating the fossils themselves.”

Aix-en-Provence Spider Fossil With Diatoms

Spider fossil from the Aix-en-Provence Formation with white field indicating location of scanning electron microscopy picture and chemical map of sulfur (yellow) and silica (pink) seen in higher left. Together these reveal a black sulfur-rich polymer on the fossil and the presence of two sorts of siliceous microalgae: a mat of straight diatoms on the fossil and dispersed centric diatoms within the surrounding matrix. Credit: Olcott et al.

Olcott and her colleagues hypothesize that the extracellular substance these microalgae, referred to as diatoms, are recognized to supply would have protected the spiders from oxygen and promoted sulfurization of the spiders, a chemical change that may clarify preservation of the fossils as carbonaceous movies over the hundreds of thousands of ensuing years.

“These microalgae make the sticky, viscous gloop — that’s how they stick collectively,” the KU researcher stated. “I hypothesized the chemistry of these microalgae, and the stuff they have been extruding, really made it doable for this chemical response to protect the spiders. Basically, the chemistry of the microalgae and the chemistry of the spiders work collectively to have this distinctive preservation occur.”

Indeed, this sulfurization phenomenon is similar as a standard industrial therapy used to protect rubber.

“Vulcanization is a naturally occurring course of — we do it ourselves to remedy rubber in a widely known course of,” Olcott stated. “Sulfurization takes carbon and cross-links it with sulfur and stabilizes the carbon, which is why we do it to rubber to make it last more. What I feel occurred right here chemically is the spider exoskeleton is chitin, which consists of lengthy polymers with carbon items close to one another, and it’s an ideal atmosphere to have the sulfur bridges are available and actually stabilize issues.”

Olcott stated the presence of diatomic mats might probably act as a information to search out extra deposits of well-preserved fossils sooner or later.

“The subsequent step is increasing these strategies to different deposits to see if preservation is tied to diatom mats,” she stated. “Of all the opposite distinctive fossil preservation websites on this planet within the Cenozoic Era, one thing like 80 % of them are present in affiliation with these microalgae. So, we’re questioning if this explains most of these fossil websites that we now have on this time — mainly from quickly after the dinosaurs went extinct till now. This mechanism may very well be answerable for giving us data to discover the evolution of bugs and different terrestrial life post-dinosaurs and to know local weather change, as a result of there’s a interval of fast local weather change and these terrestrial organisms assist us perceive what occurred to life final time local weather began shifting.”

Olcott and her colleagues are the primary to parse the chemistry of preservation at Aix-en-Provence, a truth she chalks up partly to challenges of finishing up science throughout COVID-19 restrictions.

“I truthfully assume this research is partially a end result of pandemic science,” she stated. “The first batch of these pictures confirmed up in May 2020. My lab was nonetheless closed; I used to be two months into my leg of 18 months at house with children on a regular basis — and so I needed to change how I used to be doing science. I spent loads of time with these pictures and these chemical maps and actually kind of explored them in a manner that they most likely wouldn’t have occurred if all of the labs have been open and we may have gone in and finished extra typical work.”

Reference: “The distinctive preservation of Aix-en-Provence spider fossils may have been facilitated by diatoms” by Alison N. Olcott, Matthew R. Downen, James D. Schiffbauer and Paul A. Selden, 21 April 2022, Communications Earth & Environment.
DOI: 10.1038/s43247-022-00424-7

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