There were complex ecosystems on Earth long before what was believed

About 250 million years ago, the Permian-Triassic mass extinction wiped out more than 80 percent of the planet’s species. It has been believed that life on Earth was dominated by a few species for the 10 million years that followed the catastrophe, and that only later could more complex ecosystems emerge.

Now, an international team of researchers, including scientists from McGill University and the University of Quebec in Montreal, both institutions in Canada, is challenging this widely accepted theory.

The traditional theory that the development of complex life after the mass extinction was not possible during those 10 million years is based on geochemical fingerprints of oceanic conditions at the time, which have been suggesting that marine life was too constrained to evolve due to to excessive heat and other hostile sea conditions that lasted for millions of years after the cataclysm.

Now, the discovery of fossils from 250.8 million years ago near China’s Guizhou region suggests complex ecosystems were already on Earth as little as a million years after the Permian-Triassic mass extinction, much sooner than thought.

Fossils from the Guizhou region reveal an oceanic ecosystem with diverse species that formed a complex food chain that included plants, fish, crabs, lobsters, shrimps, and mollusks. “In total, our team discovered 12 classes of organisms,” says Morgann Perrot, of McGill University and now Quebec University in Montreal.

Fish fossil photographed at the site where it was found during the paleontological excavations from which the new study has been nourished. (Photo: Xu Dai)

Previously, it was thought that a complex ecosystem would take between five and 10 million years to form evolutionarily after an extinction. However, the authors of the new study have found that specimens from the Guizhou region evolved much faster.

All this will force us to reconsider knowledge considered unquestionable, including the speed with which life can adapt to extreme crises. It will also force a reassessment of early Triassic ocean conditions.

The study is titled “A Mesozoic fossil lagerstätte from 250.8 million years ago shows a modern-type marine ecosystem”. And it has been published in the academic journal Science. (Fountain: NCYT by Amazings)