An undersea menagerie buried under an avalanche of sediment some 518 million years ago is finally coming to light, revealing thousands of specimens for the first time—including many from entirely new species.
Paleontologists who found the fossil trove near Kunming, China, believe they’ve unearthed a Cambrian-era ‘paleonursery,’ according to their report in the journal Nature Ecology and Evolution, with more than half of the specimens juveniles.
There were preserved eggs, larvae, and specimens with appendages intact and internal soft tissues still visible.
The site, the Haiyan lagerstätte—from the German for ‘storage place’, it refers to a sedimentary deposit with extraordinarily well-preserved fossils—includes over 2,800 specimens from at least 118 species, including precursors to modern-day insects, worms, crustaceans, jellyfish, sponges and trilobites.
Some 17 of the species are previously unknown to science.
‘It’s just amazing to see all these juveniles in the fossil record,’ co-author Julien Kimmig, a paleontologist at Penn State University, said in a statement.
‘Juvenile fossils are something we hardly see, especially from soft-bodied invertebrates.’
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Paleontologists in Kunming, China, believe they’ve unearthed a Cambrian-era ‘paleonursery,’ featuring more than 2,800 fossilized specimens, half of which were juvenile
Running between 541 million and 485 million years ago, the Cambrian Period saw unimaginable climatic and biological changes, including the Cambrian explosion—the fastest and most widespread diversification of life in the planet’s history.
There is a thorough fossil record from that era, when life lived exclusively in the ocean, but little of it represents young creatures.
Each sediment layer in the lagerstätte represents a single ‘burial event,’ the researchers say, and while more recent strata have turned up some findings, none match the diversity of the lowest level.
It’s not clear what caused the burial event that killed off the specimens at that level.
The team theorizes it could have been a rapid change in oxygen levels or a storm causing muddy sludge ‘to flow down a slope and bury everything in its path.’
Being buried in the sludge kept the creatures so well-preserved they reveal body parts never before seen, including full three-dimensional eyes
The researchers have identified 118 species, including precursors to modern-day insects, worms, crustaceans, jellyfish, sponges and trilobites. Some 17 of the species are previously unknown to science
Pictured: early Cambrian stratigraphy of the Haiyan Lagerstätte
It might have killed them, but it kept them so well-preserved that they are revealing body parts never before seen, including full three-dimensional eyes.
The paleobiologists will use CT scans on those features to reconstruct the animals and extract even more information from the fossils, according to co-author Xianfeng Yang, a paleobiologist at China’s Yunnan University.
The sheer volume of juvenile specimens there suggests that, 518 million years ago, the deeper waters near the center of the Kunming Gulf offered offspring protection from ocean currents, predators and other hazards.
‘Could these worms and jellyfish and bugs have developed something as sophisticated as a paleonursery to raise their young?’ said Sara Kimmig, a professor at Penn State’s Earth and Environmental Systems Institute.
The fossils date to the Cambrian period, which saw unimaginable climatic and biological changes, including the fastest and most widespread diversification of life in the planet’s history
The sheer volume of eggs, larvae and juvenile specimens suggests that the deeper waters near the center of the Kunming Gulf offered offspring protection from ocean currents, predators and other hazards 518 million years ago
‘Whatever the case may be, it’s fascinating to be able to parallel this behavior to that of modern animals.’
Should their theory about the Haiyan lagerstätte being a Cambrian ‘daycare center’ be correct, Julien Kimming added, ‘it means that this type of animal behavior has not changed much in 518 million years.’
TICK, TICK, BOOM: WHAT WAS THE CAMBRIAN EXPLOSION?
Scientists have long speculated that a large oxygen spike during the ‘Cambrian Explosion’ was key to the development of many animal species.
The Cambrian Explosion, around 541 million years ago, was a period when a wide variety of animals burst onto the evolutionary scene.
Before about 580 million years ago, most organisms were simple, composed of individual cells occasionally organized into colonies.
Over the following 70 or 80 million years, the rate of evolution accelerated and the diversity of life began to resemble that of today.
It ended with the Cambrian-Ordovician extinction event, approximately 488 million years ago.