The bottom burrowing animals were among the first to bounce back after the end of themian mass extinction.
In a new study published in the journal Science Advances, researchers from China, the U.S. and the UK show how life in the sea recovered from the event, which killed over 90 percent of species on Earth.
The end-Permian mass extinction wiped out life on the planet and took millions of years for it to return to pre- extinction levels. The international team was able to piece together the revival of sea life by looking at trails and burrows on the South China sea bed.
The end-Permian mass extinction and the recovery of life in the Early Triassic are well documented in South China.
We were able to look at trace fossils from 26 sections through the entire series of events, representing seven million years of time, and showing details at 400 sampling points.
The focus of the study was on burrows and trails. Soft-bodied animals in the sea can be found in trace fossils. The majority of these animals had no skeletons at all.
There are some amazing localities in South China where we find huge numbers of beautifully preserved trace fossils, and the details can show infaunal ecology, as well as their feedback effects on skeletonized animals.
The director of the study said that the trace fossils showed when and where soft-bodied, burrowing animals flourished.
It took about 3 million years for ecological recovery of soft-bodied animals to match the pre-extinction levels due to elevated temperatures and extended anoxia.
The breadth of ancient environments we could sample was one of the most remarkable aspects of the study.
The recovery of the hot Early ocean Triassic may have been aided by different responses to variable environmental controls.
The mass extinction reduced the ecological function of the surviving animals in the ocean.
Recovery began in deeper waters after only a few survivors were left. The full rebound of infaunal engineering activities took place at the same time that the recovery of nekton happened.
Deposit feeders such as worms and shrimps were the first animals to recover. It took a long time for the recovery of suspension feeders.
Some animals, such as corals, had vanished completely. Coral reefs did not come back right away.
The great mass extinctions of the geological past are important to understand.
The end-Permian crisis was caused by global warming and ocean acidification, but trace-making animals may be selected against by the environment.
Soft-bodied animals have resilience to high CO 2 and warming. It is possible that these engineers may have played a role in the recovery of the benthic ecosystems after mass extinctions.
More information: Resilience of infaunal ecosystems during the Early Triassic greenhouse Earth, Science Advances (2022). Journal information: Science Advances
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