How chemical clues from prehistoric microbes rewrote the story of one of Earth’s biggest mass extinctions

How chemical clues from prehistoric microbes rewrote the story of one of Earth's biggest mass extinctions
Microbial mats in Shark Bay, Western Australia, similar to those that lived around 200 million years ago. Credit: Yalimay Jimenez Duarte WA-OIGC, Curtin University, Author provided

Chemical clues left behind by humble microbes have rewritten the timeline of one of the biggest mass extinction events in Earth’s history.


The so-called “end-Triassic mass extinction”, thought to have occurred just over 200 million years ago, wiped out swathes of prehistoric creatures both on land and in the oceans. It was prompted by the breakup of the supercontinent Pangea, which triggered massive volcanic activity that flooded the atmosphere with carbon dioxide and acidified the oceans.

But our new research, published in Proceedings of the National Academy of Sciences, suggests these cataclysmic events actually happened later than previously thought.

We made this discovery by examining molecular fossils—trace chemicals derived from microbial “mats” that bathed in prehistoric waters.

A likely story

Traditionally, scientists have placed the mass extinction event, and the volcanic upheaval that presaged it, at about 201 million years ago.

They came to this conclusion after studying rocks of that age from the Bristol Channel, UK, which show a distinctive chemical signature. The ratios of different isotopes of carbon within these rocks suggest this was the moment when the global atmosphere changed, as huge amounts of methane were pumped into the skies due to massive volcanic activity covering the central Atlantic, in turn altering the chemical composition of rocks that formed during this time.

How chemical clues from prehistoric microbes rewrote the story of one of Earth's biggest mass extinctions
The Bristol Channel is home to rock formations that give an insight into prehistoric life (and death) some 200 million years ago. Credit: Calum Peter Fox, Author provided

But we made a discovery that challenged this assumption. We found evidence of ancient microbial mats in the same region, at the same time. It was these flourishing communities of microbes that actually created the change in the chemical signature of the rocks, rather than a global volcanic event.

These microbial mats formed as the region’s waters changed from salty seawater to brackish or fresh water, and water levels dropped to puddle-like centimetre depths. This is another reason why scientists mistook this event for a mass extinction—marine creatures disappeared from the local fossil record at this time not because they had all died out, but because it was no longer marine.

Of course, the world’s marine creatures had only earned a relatively brief reprieve. We know the volcanic cataclysm did occur, but just not as long ago as previously assumed.

Still going strong

Remarkably, the microbial mats recorded in UK samples are similar to living microbial mats in Australia, such as in Western Australia’s Shark Bay. It’s amazing to think similar microbial communities are still living on Australia’s shorelines to this day.

Microbes have also been useful resources in research to learn about several other mass extinction events too, such as the “Great Dying” that marked the end of the Permian period roughly 252 million years ago, and the dramatic demise of the dinosaurs in a mass extinction some 66

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Scientists reveal new clues into how Earth got its oxygen

Scientists reveal new clues into how Earth got its oxygen
Earth’s thin shell of oxygen atmosphere keeps us alive, though we still don’t know exactly how it formed. A new study from the University of Chicago reveals clues in the role that iron had to play. Credit: NASA

For much of Earth’s four and a half billion years, the planet was barren and inhospitable; it wasn’t until the world acquired its blanket of oxygen that multicellular life could really get going. But scientists are still trying to understand exactly how—and why—our planet got this beautifully oxygenated atmosphere.


“If you think about it, this is the most important change that our planet experienced in its lifetime, and we are still not sure exactly how this happened,” said Nicolas Dauphas, the Louis Block Professor of Geophysical Sciences at the University of Chicago. “Any progress you can make toward answering this question is really important.”

In a new study published Oct. 23 in Science, UChicago graduate student Andy Heard, Dauphas and their colleagues used a pioneering technique to uncover new information about the role of oceanic iron in the rise of Earth’s atmosphere. The findings reveal more about Earth’s history, and can even shed light on the search for habitable planets in other star systems.

Scientists have painstakingly recreated a timeline of the ancient Earth by analyzing very ancient rocks; the chemical makeup of such rocks changes according to the conditions they formed under.

“The interesting thing about it is that prior to the permanent Great Oxygenation Event that happened 2.4 billion years ago, you see evidence in the timeline for these tantalizing little bursts of oxygen, where it looks like Earth was trying to set the stage for this atmosphere,” said Heard, the first author on the paper. “But the existing methods weren’t precise enough to tease out the information we needed.”

It all comes down to a puzzle.

As bridge engineers and car owners know, if there’s water around, oxygen and iron will form rust. “In the early days, the oceans were full of iron, which could have gobbled up any free oxygen that was hanging around,” Heard said. Theoretically, the formation of rust should consume any excess oxygen, leaving none to form an atmosphere.

Heard and Dauphas wanted to test a way to explain how oxygen could have accumulated despite this apparent problem: they knew that some of the iron in the oceans was actually combining with sulfur coming out of volcanoes to form pyrite (better known as fool’s gold). That process actually releases oxygen into the atmosphere. The question was which of these processes “wins.”

To test this, Heard used state-of-the-art facilities in Dauphas’ Origins Lab to develop a rigorous new technique to measure tiny variations in iron isotopes in order to find out which route the iron was taking. Collaborating with world experts at the University of Edinburgh, he also had to flesh out a fuller understanding of how the iron-to-pyrite pathway works. (“In order to make sulfide and run these experiments, you need understanding colleagues, because

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Scientists Think Beetle’s Armor Could Provide Clues To Stronger Buildings

NEW YORK (AP) — It’s a beetle that can withstand bird pecks, animal stomps and even being rolled over by a Toyota Camry. Now scientists are studying what the bug’s crush-resistant shell could teach them about designing stronger planes and buildings.

“This beetle is super tough,” said Purdue University civil engineer Pablo Zavattieri, who was among a group of researchers that ran over the insect with a car as part of a new study.

So, how does the seemingly indestructible insect do it? The species — aptly named diabolical ironclad beetle — owes its might to an unusual armor that is layered and pieced together like a jigsaw, according to the study by Zavattieri and his colleagues published in Nature on Wednesday. And its design, they say, could help inspire more durable structures and vehicles.

To understand what gives the inch-long beetle its strength, researchers first tested how much squishing it could take. The species, which can be found in Southern California’s woodlands, withstood compression of about 39,000 times its own weight.

For a 200-pound man, that would be like surviving a 7.8-million-pound crush.

Other local beetle species shattered under one-third as much pressure.

Researchers then used electron microscopes and CT scans to examine the beetle’s exoskeleton and figure out what made it so strong.

As is often the case for flightless beetles, the species’ elytra — a protective case that normally sheaths wings — had strengthened and toughened over time. Up close , scientists realized this cover also benefited from special, jigsaw-like bindings and a layered architecture.

When compressed, they found the structure fractured slowly instead of snapping all at once.

“When you pull them apart,” Zavattieri said, “it doesn’t break catastrophically. It just deforms a little bit. That’s crucial for the beetle.”

It could also be useful for engineers who design aircraft and other vehicles with a variety of materials such as steel, plastic and plaster. Currently, engineers rely on pins, bolts, welding and adhesives to hold everything together. But those techniques can be prone to degrading.

In the structure of the beetle’s shell, nature offers an “interesting and elegant” alternative, Zavattieri said.

Because the beetle-inspired design fractures in a gradual and predictable way, cracks could be more reliably inspected for safety, said Po-Yu Chen, an engineer at Taiwan’s National Tsing Hua University not involved in the research.

The beetle study is part of an $8 million project funded by the U.S. Air Force to explore how the biology of creatures such as mantis shrimp and bighorn sheep could help develop impact-resistant materials.

“We’re trying to go beyond what nature has done,” said study co-author David Kisailus, a materials scientist and engineer at the University of California, Irvine.

The research is the latest effort to borrow from the natural world to solve human problems, said Brown University evolutionary biologist Colin Donihue, who was not involved in the study. Velcro, for example, was inspired by the hook-like structure of plant burrs. Artificial adhesives took a page from super-clingy gecko

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Can’t crush this: Beetle armor gives clues to tougher planes

This 2016 photo provided by the University of California, Irvine, shows a diabolical ironclad beetle, which can withstand being crushed by forces almost 40,000 times its body weight and are native to desert habitats in Southern California. Scientists say the armor of the seemingly indestructible beetle could offer clues for designing stronger planes and buildings. In a study published Wednesday, Oct. 21, 2020, in the journal Nature, a group of scientists explains why the beetle is so squash-resistant. (Jesus Rivera, Kisailus Biomimetics and Nanostructured Materials Lab, University of California Irvine via AP)

This 2016 photo provided by the University of California, Irvine, shows a diabolical ironclad beetle, which can withstand being crushed by forces almost 40,000 times its body weight and are native to desert habitats in Southern California. Scientists say the armor of the seemingly indestructible beetle could offer clues for designing stronger planes and buildings. In a study published Wednesday, Oct. 21, 2020, in the journal Nature, a group of scientists explains why the beetle is so squash-resistant. (Jesus Rivera, Kisailus Biomimetics and Nanostructured Materials Lab, University of California Irvine via AP)

AP

It’s a beetle that can withstand bird pecks, animal stomps and even being rolled over by a Toyota Camry. Now scientists are studying what the bug’s crush-resistant shell could teach them about designing stronger planes and buildings.

“This beetle is super tough,” said Purdue University civil engineer Pablo Zavattieri, who was among a group of researchers that ran over the insect with a car as part of a new study.

So, how does the seemingly indestructible insect do it? The species — aptly named diabolical ironclad beetle — owes its might to an unusual armor that is layered and pieced together like a jigsaw, according to the study by Zavattieri and his colleagues published in Nature on Wednesday. And its design, they say, could help inspire more durable structures and vehicles.

To understand what gives the inch-long beetle its strength, researchers first tested how much squishing it could take. The species, which can be found in Southern California’s woodlands, withstood compression of about 39,000 times its own weight.

For a 200-pound man, that would be like surviving a 7.8-million-pound crush.

Other local beetle species shattered under one-third as much pressure.

Researchers then used electron microscopes and CT scans to examine the beetle’s exoskeleton and figure out what made it so strong.

As is often the case for flightless beetles, the species’ elytra — a protective case that normally sheaths wings — had strengthened and toughened over time. Up close , scientists realized this cover also benefited from special, jigsaw-like bindings and a layered architecture.

When compressed, they found the structure fractured slowly instead of snapping all at once.

“When you pull them apart,” Zavattieri said, “it doesn’t break catastrophically. It just deforms a little bit. That’s crucial for the beetle.”

It could also be useful for engineers who design aircraft and other vehicles with a variety of materials such as steel, plastic and plaster. Currently, engineers rely on pins, bolts, welding and adhesives to hold everything together. But those techniques can be prone to degrading.

In the structure of the beetle’s shell, nature offers an “interesting and elegant” alternative, Zavattieri said.

Because the beetle-inspired design fractures in a gradual and predictable way, cracks could be more reliably inspected for safety, said Po-Yu Chen, an engineer at Taiwan’s National Tsing Hua University not involved in the research.

The beetle study is part of an $8 million project funded by the U.S. Air Force to

Read more