After the largest extinction on Earth, these animals were the first to recover

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The Permian-Triassic Extinction, which occurred approximately 252 million years ago, is colloquially known as the Great Dying because of the way it wiped out life on Earth—nearly ending it entirely. This is the most serious extinction in history.

However, life has bounced back, and new research shows that sediment-eating worms and shrimp — animals that feed on organic matter that has settled on the ocean floor — were the first to bounce back in terms of population and biodiversity.

Suspension feeders that snack on suspended organic matter appeared much later, according to detailed dating of trails and burrows on the bottom of the South China Sea. This analysis revealed many ichnofossils or trace fossils – not actual animal remains, but remnants of animal activity.

What the oceans might have looked like before (A) and after (BF) the extinction. (X.Feng/Z.-Q.Chen/MJ Benton/Y.Jiang)

“We were able to study 26-slice fossil tracks through a full series of events representing 7 million crucial years of time,” says palaeontologist Michael Benton of the University of Bristol in the UK.

“By displaying detail at 400 sampling points, we have finally reconstructed the recovery stages of all animals, including benthos, nekton, and also these soft-bodied burrowing animals in the ocean.”

Because soft-bodied animals don’t have skeletons to leave behind, fossil tracks are vital to figuring out 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 feeders were established.

“The crisis at the end of the Permian period, which was so devastating to life on Earth, was caused by global warming and ocean acidification, but the environment can select animals that leave traces, as opposed to skeletal organisms,” says paleoecologist Xueqian. Feng from China University of Geosciences.

“Our fossil footprint data shows the tolerance of soft-bodied animals to high levels of CO2.2 and warming. These ecosystem engineers may have played a role in the restoration of benthic ecosystems after severe mass extinctions, potentially, for example, causing evolutionary innovation and radiation in the early Triassic.”

When measuring recovery, the team looked at four different metrics: diversity (different types of animals), discrepancy (how different these different types were), how space was used (ecospace use), and how habitat was changed by animals (ecosystem). mechanical engineering).

First, life began to return to the deepest waters. After sediment feeders largely recovered, they were followed by suspension-feeding brachiopods, bryozoans, and bivalves, which are mostly sedentary and often root on the ocean floor, but much later.

Even later, the corals began to return. It took about 3 million years for the soft inhabitants of the sediments to return to pre-extinction levels.

“Maybe the sediment feeders made such a mess on the seafloor that the water was contaminated with silt, foamed mud prevented the sediment feeders from properly settling on the seafloor, or the muddy water produced by these sediment feeders just clogged the filter structures. weighed feeders and banned them from eating efficiently,” says geobiology graduate student Alison Cribb of the University of Southern California.

The Permian-Triassic extinction killed about 80 to 90 percent of the marine life on Earth, so it’s no surprise that recovery took a long time. By adding trace fossils to the data, along with body fossils, scientists can get a better picture of what happened next.

Climate change, global warming, declining oxygen levels, and increasing ocean acidity are considered to be the main causes of the mass extinction, and of course, this means that the results 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 we are going through and which species may be the most resilient.

The study was published in Scientific achievements.

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