Strange Magnetic Fossils Offer Peek Into Ancient Climate Change

Magnetic fossils of unknown organisms formed during past periods of global climate change are providing new clues about Earth’s ever-changing climate.

Electron microscope images of giant needles. Needles have a cylindrical shape and some taper toward one end of the crystal. (Credit: Courtney Wagner, Ioan Lascu and Kenneth Livi)

(CN) — Scientists announced Monday that they’ve come up with a new way to study rare magnetofossils without destroying them, allowing future researchers to carry on their work.

Discovered in marine sediments at Wilson Lake, New Jersey, these iron-based fossils are the remains of unknown bacteria that are only known to have occurred during periods of climactic upheaval — specifically warming oceans. 

They are microscopic in size, 1/1000th the width of a human hair to be precise, and researchers hope these fossils can help fill in pieces of the climate-change puzzle.

The team believes these magnetic fossils could align themselves along the Earth’s magnetic pole, helping them efficiently ferret their favorite nutrients out of the ocean like a foraging camper combing the countryside with a compass.

Scientists may not know who left these strange fossils behind, but they have a pretty good idea as to how they functioned. The team released their findings in a study published Monday in the scientific journal Proceedings of the National Academy of Sciences.

“It’s so fun to be a part of a discovery like this, something that can be used by other researchers studying magnetofossils and intervals of planetary change,” said lead author Courtney Wagner, a doctoral student in the Department of Geology and Geophysics at the University of Utah, in a statement. “This work can be used by many other scientists, within and outside our specialized community. This is very exciting and fulfilling.”

Originally formed in the early Eocene period between 34 and 56 million years ago, the larger version of these magnetofossils grew some 20 times bigger than the average type, and formed unique shapes like needles, bullets, spearheads and spindles. These magnetofossils can provide valuable clues about past climate conditions because they only formed during periods when ocean temperatures were on the rise.

“Giant magnetofossils are the preserved remains of iron biomineralizing organisms that have so far been identified only in sediments deposited during ancient greenhouse climates,” explain the authors in the study. “Giant magnetofossils have no modern analog, but their association with abrupt global warming events links them to environmental disturbances.”

Studying these rare fossils previously required crushing them into a fine powder for electron microscopy, which is expensive and time consuming. Thanks to new methods devised by the team, they can now analyze samples without destroying them, allowing later researchers a crack at this important puzzle.

By switching to an analysis technique called FORC (first order reversal curve) they were able to take high resolution magnetic measurements of the fossils, revealing a unique magnetic signature that can be applied to other sediment samples to reveal the presence of similar fossils.

“FORC measurements probe the reaction of magnetic particles to externally applied magnetic fields, enabling [us] to discriminate among different types of iron oxide particles without actually seeing them,” explained Ramon Egli, a researcher at the Central Institute for Meteorology and Geodynamics in Vienna, Austria.

Researchers are still trying to piece together what type of bacteria formed these unique fossils, as no known organisms are believed to create them today. Because magnetic fossils are thought to have only been formed during periods of climate change and ocean warming, the team hopes that finding and studying more of them will unlock new clues as to what prompted their formation at those specific times.

“The organisms that produced these giant magnetofossils are utterly mysterious, but this leaves exciting research avenues open for the future” said Ioan Lascu, a geologist at the Smithsonian Natural History Museum in Washington.

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