Sea life recovered from Permian-Triassic mass extinction faster than we thought

A diverse set of fossils from China indicates that a complex marine ecosystem existed 251 million years ago. This was shortly after a mass extinction wiped out the most complex life on Earth.

To Brian Owens

An exceptional assemblage of marine fossils from China seems to indicate a surprisingly rapid recovery of marine life after the largest mass extinction in Earth’s history.

The so-called Great Extinction at the end of the Permian about 252 million years ago is thought to have been caused by unusually high volcanic activity that led to ocean acidification and global warming. The disaster had a particularly severe impact on marine life, with more than 80% of sea life becoming extinct.

For a long time, paleontologists believed it would take about eight million years for marine ecosystems to recover from this recession and evolve into the modern form we know today.

Haijun Song and his colleagues at the China University of Geosciences in Wuhan studied the Guiyang biota. The Guiyang biota is a remarkably well-preserved group of marine fossils from southern China, dating to the beginning of the Triassic, he is 251 million years old. Contains at least 40 species of fish, clams, ammonites, and crustaceans such as shrimp and lobster.

Fossils include representatives of all levels of the food chain, from one-meter-long predatory coelacanths to small single-celled amoebas. While some major groups of organisms survived the mass extinction, many other previously abundant organisms, such as trilobites, were lost.

Song says the collection of species is very similar to what we see in modern oceans, except for the ill-fated ammonites, which went extinct along with the dinosaurs at the end of the Cretaceous period. This suggests that an unexpectedly diverse and complex marine ecosystem existed just one million years after the mass extinction. “In the history of geology, it’s rapid,” he says.

Paul Wignall of the University of Leeds, UK, says the fossil collection is full of exciting new discoveries, especially that shrimp and lobster were not seen in the Early Triassic. But he thinks the authors of the study have exaggerated the speed of recovery. He says he still has a long way to go.

David Bottjer of the University of Southern California, Los Angeles also says the fossils show the ecosystem is still in the early stages of recovery. “There are a lot of things going on in the ecosystem, but they are being done by a minimal crew,” he says.

Bottjer says this, along with the rest of the fossil record, indicates that recovery is likely patchy, with marine communities in some parts of the world recovering faster than others. . “This is the same thing we see in today’s environmental crisis,” he says. “Some places are more affected than others.”