‘Ghost’ fossil discovery reveals plankton’s tolerance to past global warming events – Interested in that?
An international team of scientists has discovered a new type of fossil
UNIVERSITY OF LONDON
CREDIT: SM SLATER, P. BOWN / JOURNEY SCIENCE
An international team of scientists from UCL (University College London), the Swedish Museum of Natural History, the Natural History Museum (London) and the University of Florence have found a remarkable fossil that most as has been ignored so far.
The fossils are microscopic imprints, or “ghosts,” of single-celled plankton, known as coccolithophores, that lived in the seas millions of years ago, and whose discovery is now underway. changing our understanding of how plankton in the ocean is affected by climate change.
Parasite cells play an important role in today’s oceans, providing plenty of oxygen for us to breathe, supporting marine food webs and locking carbon in seafloor sediments. They are a type of microscopic plankton that surround their cells with hard limestone slabs, called broccoli, and these are the things that usually fossilize in rock.
The decline in the abundance of these fossils has been documented from many past global warming events, suggesting that these plankton have been severely affected by climate change and acidification. ocean chemistry. However, a study published today in the journal Science present new global records of abundant phantom fossils from three warming events during the Jurassic and Cretaceous (94, 120 and 183 million years ago), suggesting that coccyx cells are capable of more resilient to climate change in the past than previously thought.
Dr Sam Slater from the Swedish Museum of Natural History said: ‘The discovery of these stunning ghost fossils was completely unexpected. “We initially noticed they were preserved on the surface of fossil pollens, and quickly found that they were abundant during times when fossils on the coast would normally be rare or absent – This is a complete surprise!”
Despite their microscopic size, cocci may be abundant in the oceans today, visible from space in the form of cloud-like blooms. After death, their lime exoskeleton sinks to the seafloor, accumulating in large quantities, forming chalky rocks.
Professor Paul Bown (UCL) said: “The preservation of these ghostly nannofossils is truly remarkable. “Ghost fossils are extremely small – their length is approximately five thousandths of a millimeter, 15 times narrower than the width of a human hair! – but the details of the original plates are still perfectly visible, pressed tightly against the surface of the ancient organic matter, even though the plates themselves have disappeared”.
The ghostly fossils were formed while the sediment on the seabed was buried and turned into rock. As more slurry is gradually deposited on top, the resulting pressure squeezes the sheets of broccoli and other remaining organic matter together, and the stiff broccoli is pressed against the surface of the pollen, spores and other soft organic matter. Then, the acidic water in the voids in the rock dissolved the broccoli, leaving only their impressions – ghosts.
Professor Vivi Vajda (Swedish Museum of Natural History) explains: “Typically, paleontologists only look for broccoli fossils, and if they don’t find them, they often assume the communities This ancient plankton community has collapsed,” explains Professor Vivi Vajda (Swedish Museum of Natural History). “These spooky fossils show us that sometimes the fossil record fools us and that there are other ways to preserve these calcified plankton, which needs to be taken into account when trying to find them. understand past responses to climate change”.
Professor Silvia Danise (University of Florence) said: “Ghost nannofossils may be common in the fossil record, but they have been overlooked due to their small size and confusing way of preservation. We think this particular type of fossil will be useful in the future, especially when studying the geological intervals where the broccolis were originally missing from the fossil record.”
The study focused on the Toarcian Ocean Toxin Deficiency Event (T-OAE), a period of rapid global warming during the Early Jurassic (183 million years ago), caused by an increase in CO2-Atmospheric layers from large volcanoes in the Southern Hemisphere. The researchers found T-OAE-related ghost nannofossils from the UK, Germany, Japan and New Zealand, but also from two similar global warming events in the Cretaceous: The Ocean Anoxic Event. 1a (120 million years ago) from Sweden, and Ocean Anoxic Event 2 (94 million years ago) from Italy.
Professor Richard Twitchett (Natural History Museum, London) explains: “Ghost fossils show that plankton was abundant, diverse, and thrived during past warming events in the Jurassic period. and the Cretaceous, where previous records suggest that plankton collapsed due to ocean acidification.” “These fossils are rewriting our understanding of how calcareous plankton respond to warming events.”
Finally, Dr Sam Slater explains: “Our study shows that phytoplankton was abundant during previous warming events and contributed to the expansion of marine dead zones, where seafloor oxygen levels are too high. low enough for most species to survive. These conditions, along with plankton blooms and dead zones, could become more common across our globally warming oceans.”
JOURNEYS
Science
DOI
RESEARCH METHODS
Content analysis
RESEARCH SUBJECTS
Do not apply
ARTICLE TITLE
Global record of “ghost” nannofossils reveals plankton resilience to high CO and warming
ARTICLE PUBLICATION DATE
May 20, 2022
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