Scientists say they have discovered a "staggering" mass of thousands of fossils on the river in China.
It is estimated that fossils are approximately 518 million years old and are particularly unusual because the soft tissues of many creatures, including the skin, eyes and internal organs, are "well-preserved" well preserved.
Paleontologists named the findings as "dying" – mainly because more than half of the fossils are previously undetected species.
Fossils, known as Qingjiang biot, were collected near the Danshui River in Hubei Province.
More than 20,000 specimens were collected, up to now, a total of 4,351 have been analyzed, including worms, jellyfish, marine windmills and algae.
They will become "a very important source when studying the early origin of the creature," said one of the field work leaders, Professor Xingliang Zhang of the Chinese University of Northwest.
Details of the findings were published in Science magazine on Friday.
The discovery is particularly surprising because "most of the creatures are soft organisms, such as jellyfish and worms, which usually do not have any chance of becoming fossilized," said prof. BBC.
Most of the fossils are heavy animals, because the harder substances, such as bones, are less likely to rot and decay.
Qingjiang biotechnology must be "rapidly buried in sediment" due to the storm, so that the soft tissues are so well preserved, says Professor Zhang.
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Scientists are particularly impressed by the fossils of jellyfish and marine windmills, which Professor Gaines describes as "unlike anything I've ever seen."
Meanwhile, paleontologist Allison Daley, who did not participate in the study but wrote an accompanying analysis in science, said that the BBC's science in action program was one of the most important in the last 100 years.
"I breathed in my mind – like a palaeontologist, I never thought I would witness the discovery of such an incredible site.
"For the first time we see the preservation of jellyfish – [when] think of jellyfish, today they are so soft, so sensitive, but they are incredibly well preserved here. "
The research team now documents the remaining samples and drills more in the region to learn more about the ancient local ecosystem and the process of fossilization.
Professor Zhang says he looks forward to studying "all this new kind of thing – I'm always excited to get something new."
Fossils originate from the Cambrian period, which began 541 million years ago and has experienced a rapid increase in animal diversity on Earth.
Professor Gaines hopes that his work will also attract modern readers.
Today, biodiversity is something we take for granted, although there are indications that extinction rates are increasing considerably.
"But most of the main animal species were created in a unique event in the history of life, a Cambrian explosion that has never been seen before or after.