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Fossil discovery suggests complex ecosystems existed on Earth much earlier than previously thought

news7g02/12/2023

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Watsonulus fish — **PICTURE DESCRIPTION: PICTURE OF WATSONULUS FISH CHEMICAL SCHOOL FROM GAOPO SECTION. / PICTURE DE TERRARY D’UN FOSSILE DE POISSON WATSONULUS (DE GAOPO PART).** see more
CREDIT: DAILY COINS

Discover challenges understanding how quickly life recovered from the largest mass extinction in Earth’s history

A peer-reviewed publication

MCGILL UNIVERSITY

About 250 million years ago, the Permian-Triassic mass extinction killed more than 80% of the planet’s species. Scientists then believed that life on Earth was dominated by simple species for 10 million years before more complex ecosystems could develop. Now, this age-old theory is being challenged by an international team of researchers – including scientists from McGill University and the Universidad Québec à Montréal.

A fossil ocean ecosystem

Until now, scientists have long hypothesized that scorching ocean conditions caused by catastrophic climate change prevented the development of complex life following the mass extinction event. This idea is based on geochemical evidence of ocean conditions at the time. Now, the discovery of fossils dating back 250.8 million years near China’s Guizhou region shows that complex ecosystems were present on Earth just a million years after the mass extinction. Permian-Triassic, much earlier than previously thought.

“The fossils of the Guizhou region show an ocean ecosystem with diverse species that make up a complex food chain that includes plant life, bony fish, ray-finned fish, crabs, lobsters, shrimp and molluscs. In total, our team discovered 12 types of organisms and even found fossilized feces, revealing clues to the diets of these ancient animals,” said Morgann Perrot, former graduate student Postdoctoral fellow at McGill University, now working at the University of Québec à Montréal, said.

Challenging an age-old theory

Previously, it was thought that complex ecosystems would need 5 to 10 million years to evolve after extinction. However, the researchers found that specimens in the Guizhou region evolved much faster than that by using radiometry to date the rocks where the fossils were discovered. .

“All of this has implications for our understanding of how quickly life can respond to severe crises. It also requires a reassessment of ocean conditions early in the Triassic,” said Perrot, whose research focuses on earth science and geochronology.

about research

“A Mesozoic fossil lagerstätte from 250.8 million years ago reveals a modern-type marine ecosystem” by Xu Dai, Joshua Davies, Zhiwei Yuan, Arnaud Brayard, Maria Ovtcharova, Guanghui Xu, Xiaokang Liu, Christopher Smith, Carrie Schweitzer, Mingtao Li, Morgann Perrot, Shouyi Jiang, Luyi Miao, Yiran Cao, Jia Yan, Ruoyu Bai, Fengyu Wang, Wei Guo, Huyue Song, Li Tian, Jacobo Dal Corso, Yuting Liu, Daoliang Chu, and Haijun Song were published in Science.