{"id":274893,"date":"2025-06-05T12:21:39","date_gmt":"2025-06-05T12:21:39","guid":{"rendered":"https:\/\/peraltafinancing.com\/aerospace\/these-tiny-beautiful-fossils-detail-the-history-of-the-ocean\/"},"modified":"2025-06-05T12:21:39","modified_gmt":"2025-06-05T12:21:39","slug":"these-tiny-beautiful-fossils-detail-the-history-of-the-ocean","status":"publish","type":"post","link":"https:\/\/fivemor.com\/?p=274893","title":{"rendered":"These Tiny, Beautiful Fossils Detail the History of the Ocean"},"content":{"rendered":"


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Bountiful remains of foraminifera reveal how organisms responded to climate disturbances of the past<\/h2>\n
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Tim Vernimmen, Knowable Magazine<\/a><\/p>\n

\n \"Foraminifera\"
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Studying foraminiferan fossils can help us understand how the climate may change in the future.
\n Paul Pearson \/ University College London<\/span>
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Climate change and declining biodiversity are the two biggest environmental crises facing humankind today, but predicting how they\u2019ll play out together is tricky. Ideally, scientists would study how life on Earth responded to previous periods of drastic climate change, but the fossil record for most species is spotty.<\/p>\n

The fossils of single-celled organisms known as foraminifera are an exception, however: They\u2019re everywhere.<\/p>\n

These marine organisms are encased in shells often built from calcium carbonate, the main ingredient of chalk (which derives from shells of foraminifera and other creatures that rain down on the seafloor when they die). Their name, derived from Latin, refers to the holes connecting the different chambers inside their often-beautiful shells. A fringe of extensions protruding around the shell allows them to find and collect food.<\/p>\n

\u201cWhen you look at a living foram, it\u2019s like a little grain of sand with a big sunburst of snotty tentacles around it,\u201d says paleoceanographer Chris Lowery<\/a> of the University of Texas at Austin.<\/p>\n

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\"Living

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This picture shows a living foraminiferan, on the right, of the species\u00a0Globigerinella calida<\/em>, fished out of the southwestern Indian Ocean with a plankton net in 2009. The tentacles it uses to feed and move are clearly visible, extending a significant distance from the shell.<\/p>\n

Tracy Aze \/ University of Plymouth<\/span><\/p>\n<\/figcaption><\/figure>\n

Most foraminiferan species reside on the seafloor, but paleontologists are particularly interested in planktonic species, which live suspended in open water. Because of their astonishing numbers and short lives, their fossils are found globally across the ocean floor.<\/p>\n

This has allowed researchers to reconstruct in detail which species flourished and which suffered when climate changed in the past, all by studying the shells and the chemical clues they contain. \u201cIf you do a little bit of chemistry on a foram shell, you can reconstruct things like the water temperature when it was growing,\u201d says micropaleontologist Andy Fraass<\/a> of the University of Victoria in Canada. \u201cSo they can tell us a lot about oceanic conditions.\u201d<\/p>\n

Researchers study the fossils by drilling into ocean sediment to reveal layer upon layer of the calcareous shells. The deeper they go, the further they look back in time. \u201cYou can pull up a tube of mud from the ocean floor, and take samples along its length, and they\u2019ll each contain thousands of forams: a detailed record of their local history,\u201d Lowery says.<\/p>\n

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\"Core

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Researchers on board a research vessel in 2022 in the western South Atlantic take samples along the length of sediment cores in search of marine fossils. The sediment being examined dates from the Paleocene-Eocene Thermal Maximum\u2014a warming event from 56 million years ago.<\/p>\n

Chris Lowery & IODP<\/span><\/p>\n<\/figcaption><\/figure>\n

Mass extinction<\/h2>\n

This kind of work has helped to reveal that planktonic foraminifera first showed up in the Jurassic period about 180 million years ago and experienced a major crisis when an asteroid hit the Earth some 66 million years ago<\/a>. \u201cEveryone talks about the dinosaurs going extinct at that time,\u201d says micropaleontologist Paul Pearson<\/a> of University College London, \u201cbut we know the details of what happened from foram fossils. First, there are many, then a distinct layer formed right after the impact, and [then there are] very few after.\u201d<\/p>\n

The impact vaporized rocks, releasing large quantities of sulfur and dust into the air. \u201cThat, and smoke from the many fires, blocked out sunlight for years,\u201d says Lowery, who was part of an ocean-drilling expedition in 2016 investigating the crater left by the asteroid. \u201cThis prevented the algae at the base of the marine food chain from doing photosynthesis and caused many ecosystems to collapse.\u201d Deep-seafloor-dwelling foraminifera, which were far away from the surface and were able to keep feeding on the remains of dead organisms, were mostly fine, but nine out of ten planktonic species went extinct.<\/p>\n

After this mass extinction, it took about ten million years for foraminiferan species diversity to recover<\/a>, Fraass and Lowery reported in 2019. \u201cWhen species go extinct, it\u2019s as if a big branch of their family tree breaks off,\u201d says Fraass. \u201cAnd it takes a lot of time to re-evolve enough diversity to regrow a branch.\u201d<\/p>\n

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\"Foraminifera

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Foraminiferan fossils allow researchers to plot foraminifera diversity through time. The catastrophic events marking the Cretaceous-Paleogene and Eocene-Oligocene boundaries caused dramatic drops in the number of species observed in the fossil record.<\/p>\n

Adapted from C.M. Lowery et al. \/ AR Earth and Planetary Sciences<\/em> 2020 \/ Knowable Magazine<\/span><\/p>\n<\/figcaption><\/figure>\n

Yet for those that survived the carnage, this created opportunities. \u201cWith so many species gone, there is less competition for previously rare resources, and even unusual individuals may have a shot, and perhaps be surprisingly successful,\u201d says marine ecologist Tracy Aze<\/a> of the University of Plymouth in the United Kingdom.<\/p>\n

Soon after the impact, a new type of foraminiferan appeared, says Pearson, \u201cstudded with spines that may have helped them to float as well as capture more food.\u201d<\/p>\n

Hot and cold<\/h2>\n

While the asteroid\u2019s sun-blocking fallout caused a period of severe cooling, the next big crisis sounds eerily more familiar: About 56 million years ago, the average temperature on the planet increased by up to 5 degrees Celsius (9 degrees Fahrenheit), possibly due to greenhouse gas emissions from volcanic activity.<\/p>\n

Seafloor foraminifera in deep waters were badly hit, likely because high levels of CO2 entering the ocean caused acidification that damaged their calcareous shells\u2014such effects are the greatest at large depths. But this time, few plankton species went extinct, in part because foraminifera escaped the warmth by moving to colder areas.<\/p>\n

\u201cIn the tropics, it may have become too hot for them to survive, with water temperatures up to 40 degrees C [104 degrees Fahrenheit],\u201d Aze says. \u201cBut we see many tropical species show up in more temperate areas\u2014while temperate species shifted polewards, as they are again doing today.\u201d Many foraminifera found refuge in or near the Southern Ocean around Antarctica<\/a>.<\/p>\n

Another mass extinction started around 33.9 million years ago, caused by a big dip in temperatures in a period called the Eocene-Oligocene transition. This foreshadowed a gradual cooling that would culminate in the most recent ice age<\/a>. \u201cWe jokingly refer to the Oligocene as the Uglyocene,\u201d says Aze. All the weird and wonderful planktonic foraminifera disappeared, and only some small unornamented ones remained. \u201cWe\u2019re not sure why.\u201d<\/p>\n

As before, that big crisis created big opportunities, and new species evolved with new habits and habitats. Currents originating at the poles caused increasing temperature differences between ocean layers that peaked near the equator. This created a wider range of conditions that supported a rich variety of species.<\/p>\n

In a 2023 study, Aze and others showed that around 15 million years ago, the global spread of foraminiferan diversity became roughly what it is now<\/a>\u2014greatest near the equator and gradually decreasing toward the poles.<\/p>\n

Uncertain future<\/h2>\n

What do these past events tell us about what we might expect for foraminiferan diversity\u2014and that of other species\u2014on a planet we are rapidly warming up today?<\/p>\n

In a 2023 study<\/a>, Pearson and colleagues used foraminifera fossil data to predict the fate of the ocean\u2019s twilight zone, a region roughly 650 feet to 3,250 feet below the surface. They estimated that the food supply reaching the middle of this zone will decline more than 20 percent in a mild warming scenario in which the average global surface temperature rise stays below 2 degrees Celsius (3.6 degrees Fahrenheit), and decline up to 70 percent in the unlikely event that temperatures rise 6 degrees Celsius (10.8 degrees Fahrenheit) by 2100. That\u2019s because warming increases the rate of decay of falling organic debris, so that less of it reaches the twilight zone.<\/p>\n

This would likely wreak havoc in this vast but understudied part of the world that provides crucial habitat to many marine animals that dive for prey<\/a> as well as to unique species like lanternfish that descend there during the day.<\/p>\n

Already, says Aze, organisms are shifting their ranges poleward in response to global warming, and, in step, scientists have noted a dip in diversity of foraminifera around the equator. \u201cThat will likely expand,\u201d she says.<\/p>\n

Though <\/strong>some species may find temporary refuge by moving toward the poles, the pace of climate change may be too rapid for many. A 2024 study of foraminifera trends<\/a> found that foraminiferan abundance has declined almost 25 percent over the past 80 years.<\/p>\n

That might be a bad sign for biodiversity in other groups of creatures, which often follow foraminiferan trends. Since foraminifera as a group bounced back from several mass extinctions, they are very unlikely to disappear, says Fraass. But recovery may take a long time, and humanity\u2019s involvement makes predicting the near future especially difficult. Or, as Lowery put it: \u201cAsk me again in a couple thousand years.\u201d<\/p>\n

\"Knowable\"<\/a><\/p>\n

Knowable Magazine<\/em> is an independent journalistic endeavor from Annual Reviews.<\/p>\n\n

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