Fossils From a Single Quarry in China Reveal 91 Unknown Species From 512 Million Years Ago
More than 500 million years before humans walked the Earth, a catastrophic extinction event wiped out vast numbers of early animal species. Now, fossils pulled from a single quarry in southern China are revealing what life looked like in the aftermath — and the discovery is rewriting what scientists know about one of the earliest chapters in animal history.
Scientists have identified 91 previously unknown species among more than 150 species discovered at a fossil site in Hunan province, China, dating to approximately 512 million years ago. The creatures lived shortly after a mass extinction event known as the Sinsk event, which occurred approximately 513 million years ago and is associated with declining oxygen levels.
The findings were published in the journal Nature.
Over 50,000 Specimens From One Small Site
The fossils were collected between 2021 and 2024 from a single quarry measuring 12 meters high, 30 meters long and eight meters wide. Han Zeng of the Chinese Academy of Sciences described the site as “extraordinary,” telling AFP: “We have collected over 50,000 fossil specimens from a single quarry that is 12 meters high, 30 meters long and eight meters wide.”
In total, researchers uncovered more than 150 different species, 91 of which are new to science. The collection has been named the Huayuan biota after the county where it was found.
Han said there were “wonderful experiences when we realized that those animals were right there on the rock.”
Ancient Gills, Guts and Nerves still intact
One of the most striking aspects of the discovery is how well the ancient animals were preserved, right down to their softest features.
Han said: “Many fossils show soft parts including gills, guts, eyes and even nerves.”
That level of detail is exceptionally rare. Soft tissues decompose quickly after death and are far less likely to be preserved than hard structures like shells or bones. Finding gills, guts and nerves intact after more than half a billion years offers researchers an unusually vivid window into these creatures’ biology.
The species discovered include ancient relatives of worms, sponges and jellyfish. Researchers also identified numerous arthropods, including radiodonts, described as apex predators of the time.
According to Han, the fossils represent the first major discovery of soft-bodied organisms that lived directly after the Sinsk event. He said the fossils “open a new window into what happened.”
The Extinction That Ended the Cambrian Explosion
The fossils date to around 512 million years ago, shortly after the Sinsk event — a mass extinction associated with declining oxygen levels. The extinction event ended a period known as the Cambrian explosion, which began roughly 540 million years ago and marked a rapid diversification of animal life.
The Sinsk event is not classified among the “Big Five” mass extinctions in Earth’s history. Han said there is evidence of 18 or more mass extinctions over the past 540 million years, making the Sinsk event one of many devastating episodes that reshaped life on our planet.
Deep-Ocean Creatures May Have Fared Best
The discovery is providing clues about which animals survived the Sinsk event and why.
Michael Lee, an evolutionary biologist at the South Australian Museum who was not involved in the research, said: “the new fossils from China demonstrate that the Sinsk event affected shallow water forms most severely.”
Lee offered a vivid comparison. He told AFP: “The deep ocean is one of the most stable environments through geological time, in a similar way to how the cellar of a house is buffered from daily and seasonal changes and has less temperature fluctuations than the attic.”
He compared survival patterns to the coelacanth, a deep-water fish that survived the mass extinction that eliminated non-avian dinosaurs. Creatures living in deeper waters may have been insulated from the dramatic environmental changes that devastated species in shallower habitats.
A Link to Canada’s Famous Burgess Shale
The research also uncovered an unexpected connection between the Huayuan biota and one of the world’s most famous fossil sites thousands of miles away.
“It surprised us when we found the Huayuan biota shared various animals with the Burgess Shale, including the arthropods Helmetia and Surusicaris that were previously only known from the Burgess Shale,” Zeng told Reuters.
Canada’s Burgess Shale fossil site dates to an earlier phase of the Cambrian explosion. The researchers believe ocean currents may explain the connection.
“As larval stages are common in extant marine invertebrates, the best explanation of these shared taxa shall be that the larvae of early animals were capable of spreading by ocean currents since the early days of animals in the Cambrian,” Zeng told Reuters.
That finding suggests that even in the earliest ages of complex animal life, creatures were already dispersing across vast oceanic distances — a detail that reshapes the understanding of how ancient ecosystems were connected.
With 91 newly identified species, more than 50,000 individual fossil specimens and remarkably preserved soft tissues, the Huayuan biota offers an unprecedented look at life in the immediate aftermath of one of Earth’s earliest mass extinctions. The site is providing answers to questions that have long puzzled scientists about what happened after the Sinsk event brought the Cambrian explosion to a close.
As Han put it, these fossils “open a new window into what happened.”
Production of this article included the use of AI. It was reviewed and edited by a team of content specialists.
