Nearly a hundred new animal species survived mass extinction half a billion years ago were discovered in a small quarry at Chinascientists revealed on Wednesday.
The trove of fossils offers a rare glimpse into a cataclysmic event that brought a sudden end to the greatest explosion of life in our planet’s history.
The site where the fossils were discovered in southern China’s Hunan province was “extraordinary”, Han Zeng of the Chinese Academy of Sciences told AFP.
“We collected more than 50,000 fossil specimens from a single quarry measuring 12 meters high, 30 meters long and eight meters wide,” added the lead author of the study. new study in the journal Nature.
In this small space, the Chinese team discovered more than 150 different species – including 91 new to science – between 2021 and 2024.
Han described “wonderful experiences when we realized these animals were there, on the rock.”
“Many fossils show soft parts, including gills, intestines, eyes and even nerves,” he added.
Han Zeng/handout via REUTERS 
Among the species discovered were ancient relatives of worms, sponges and jellyfish.
They also found many arthropods – a family that includes crabs and modern-day insects – including spiny, stalk-eyed creatures called radiodonts who were the apex predator of the time.
The discovery is particularly exciting for scientists because of the era in which these strange animals lived.
The big bang of evolution
Life appeared on Earth more than 3.5 billion years ago, but it was little more than a layer of slime for most of our planet’s history.
Then came the Cambrian explosion, known as the “big bang” of evolution, about 540 million years ago. Suddenly, most of the major groups of animals living today – including vertebrates, which would eventually include humans – evolved and began populating the world’s oceans.
This explosion of life is thought to have been caused by an increase in oxygen in Earth’s atmosphere.
However, this came to an abrupt end when almost half of all animals died out 513 million years ago. This mass extinction, known as the Sinsk Event, is believed to have been caused by falling oxygen levels.
The Chinese quarry animals, dated to around 512 million years ago, represent the first major discovery of soft-bodied fossils that lived directly after the Sinsk event, Han said.
That means the fossils – dubbed Huayuan biota after the county where they were found – “open a new window on what happened,” he added.
“It surprised us”
Michael Lee, an evolutionary biologist at the South Australian Museum not involved in the research, said “the new fossils from China demonstrate that the Sinsk event affected shallow water forms most severely.”
A deep-sea fish called coelacanth Likewise, they survived the mass extinction that wiped out all the dinosaurs that hadn’t evolved into birds, he pointed out.
“The deep ocean is one of the most stable environments over geological time, in the same way that the cellar of a house is protected from daily and seasonal changes and experiences fewer temperature fluctuations than the attic,” Lee told AFP.
Han said his team was also surprised that some of the animals from the quarry were also found in Canada. Burgess Shale site, which dates from an early period of the Cambrian explosion.
This suggests that these animals were already capable of traveling halfway around the world at this early stage, he added.
“It surprised us when we discovered that the Huayuan biota shared various animals with the Burgess Shale, including the Helmetia and Surusicaris arthropods that were previously only known from the Burgess Shale,” Zeng told Reuters. “As larval stages are common among extant marine invertebrates, the best explanation for these shared taxa would be that the larvae of early animals were capable of spreading by ocean currents since the earliest days of Cambrian animals.”
The Sinsk event is not considered one of the most famous “big five” mass extinctions in the history of our planet.
Han said there is evidence of at least 18 mass extinctions over the past 540 million years, calling for more attention to be given to immensely destructive events.
Scientists have long wondered whether dinosaurs were in decline before an asteroid hit the Earth 66 million years ago, causing a mass extinction. Recent research suggests that dinosaur populations were still booming in North America before the asteroid impact.
A research team in 2019 found that the steroid attack triggered a chaotic day of fires, earthquakes and tsunamis, which led to a prolonged period of global cooling.
