(ORDO NEWS) — Studying the remains of the ancient single-celled algae coccolithophorids, scientists from Europe described a specific mechanism for the preservation of fossils, which had previously been almost ignored.
These are microscopic casts on the surface of pollen and other organics, which have perfectly preserved all the details of the surface of these cells, although nothing remains of them themselves.
Coccolithophorids are unicellular algae from a separate systematic group of haptophytes. Despite their very small size, coccolithophores are clearly visible even from space, as they form huge clusters and cause blooms in the seas. Their characteristic feature is considered to be calcareous plates on the surface of cells – coccoliths.
Now these algae are very important for the biosphere, since they actively release oxygen, serve as food for other organisms, and contribute to the conservation of carbon in sedimentary rocks at the bottom. At the same time, the paleontological record of the Earth has preserved many ancient species of coccolithophores.
In the distant past, these algae survived many global cataclysms, including episodes of warming of the Earth’s climate.
The number of their fossilized remains makes it possible to date such events, since coccolithophores are sensitive to temperature changes and ocean acidification. Similar processes are taking place on Earth even now, so the study of these microscopic algae is extremely important.
An article has been published in the new issue of the journal Science , which provides a detailed description of coccolithophores that lived during three episodes of global warming: 94, 120 and 183 million years ago, that is, in the Cretaceous and Jurassic periods of the Mesozoic era. The scientists concluded that coccolithophores were still more resistant to climate change than is commonly believed.
Of particular interest is the fact that the studied coccolithophores were preserved in sedimentary rocks due to a special mechanism, which had previously been almost ignored. These fossils are “ghosts”, i.e. imprints of the cell surface left on the surface of organic remains.
“The discovery of these wonderful “ghost” fossils came as a complete surprise to us,” says Dr. Sam Slater of the Swedish Museum of Natural History.
“At first we found them on the surface of fossilized pollen and soon realized that there were a lot of similar fossils dating back to that time, although there were almost no “ordinary” fossilized coccolithophores – this was a huge surprise.
“The preservation of these “ghostly” nanofossils (fossils up to several tens of micrometers in size.) is truly remarkable, adds Professor Paul Bown (Paul Bown) from University College London (UK).
“Ghost” fossils are very small – their length is approximately 0.005 millimeters, which is 15 times less than the thickness of a human hair.
Nevertheless, all the details of the original plates are perfectly distinguishable, since they were imprinted on the surface of ancient organic matter, even though these plates themselves have long since dissolved.”
Paleontologists are sure that the “ghostly” fossils were formed when the sediments at the bottom turned into rock.
As more and more layers of sediment accumulated at the bottom, the dead coccolithophores found themselves under increasing pressure, due to which they were pressed into the remains of organic matter and preserved in the form of a kind of “death mask” or bas-relief. Pollen, spores, and other soft remains could serve as the organics that preserve the “ghostly coccolithophores”.
The new study is a good reminder that scientists should not limit themselves to “under the lantern search”, that is, using familiar fossil sources, and not only them.
For years, paleontologists have been looking for coccolithophorids in the remains of carbonates, including chalk, but their numerous casts on organic matter have only now been noticed.
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