(ORDO NEWS) — The Permian-Triassic extinction event, which occurred approximately 252 million years ago, is popularly referred to as the Great Dying Out because of the way it wiped out life on Earth, almost completely ending its existence. This is the worst extinction in history.
However, life did recover, and a new study shows that the first to recover in terms of population and biodiversity were deposited organisms such as worms and shrimp, animals that feed on organic matter that has settled on the ocean floor.
Suspension feeders, which feed on organic matter suspended in water, followed much later, according to a detailed analysis of trails and burrows on the bottom of the South China Sea. This analysis revealed many ichnofossils or trace fossils – not real animal remains, but traces of their life activity.
“We were able to view trace fossils from 26 sites across a series of events representing 7 million crucial years of time,” says palaeontologist Michael Benton of the University of Bristol in the UK.
“By showing details at 400 sampling points, we have finally reconstructed the recovery stages of all animals, including benthos, nekton, and these soft-bodied animals that burrow into the ocean.”
Because soft-bodied animals don’t have a skeleton to leave behind, trace fossils are critical to understanding how these creatures lived. The research team was also able to include body fossils in their study to see how other species began to recover after sediment-eating animals emerged.
“The end of the Permian crisis – so devastating to life on Earth – was caused by global warming and ocean acidification, but the animals that create the tracks may have been culled by the environment in a way that skeletal organisms were not,” says paleoecologist Xueqiang Feng of the China University of Geosciences. .
“Our trace fossil data suggests that soft-bodied animals are resilient to high CO2 concentrations and warming. These ecosystem engineers may have played a role in the restoration of benthic ecosystems after severe mass extinctions, which could, for example, have spurred evolutionary innovation and radiation in the early Triassic.”
The research team looked at four different metrics when evaluating recovery: diversity (different species of animals), disparities (how diverse those species were), space use (ecospace use), and habitat change by animals (ecosystem engineering).
Life began to return first in the deepest waters. After the sediment-eating organisms largely recovered, they were followed much later by suspension organisms such as brachiopods, bryozoans, and bivalves, which are mostly sedentary and often rooted on the ocean floor.
Even later, the corals began to return. It took about 3 million years for the soft-bodied inhabitants of sedimentary rocks to return to pre-extinction levels.
“It is possible that the deposited feeders were so fouling the seabed that the water became contaminated with silt, the agitated silt prevented the slurry feeders from properly settling on the seafloor, or the turbid water produced by these deposited feeders simply clogged the slurry feeders’ filter structures and prevented them from being fed effectively.” , says geobiology graduate student Alison Cribb of the University of Southern California.
As a result of the Permian-Triassic extinction, about 80-90 percent of the marine life on Earth died, so it is not surprising that recovery took a long time. By adding trace fossils to the data along with fossils of organisms, scientists can get a more complete picture of what happened next.
Climate change, global warming, oxygen depletion and ocean acidification are considered to be the main causes of the mass extinction – and of course, this means that the data obtained here can tell us more about what is happening in the modern era.
By understanding how some animals survived and recovered from the Great Dying, we can better understand how these creatures can survive the current warming period, and which species may be the most resilient.
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