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Artist\u2019s reconstruction of the ancient ocean ecosystem preserved in the Jiangchuan biota<\/p>\n
Xiaodong Wang<\/p>\n<\/p>\n
A huge and beautifully preserved suite of fossils discovered in China has cast doubt on the idea that complex life flourished dramatically during a rapid burst of evolution known as the Cambrian explosion.<\/p>\n
This event, spanning roughly 541 million to 513 million years ago, is when most of the animal groups alive<\/a> today are thought to have first appeared, along with a bizarre array of evolutionary experiments<\/a> that later went extinct.<\/p>\n In the preceding period, known as the Ediacaran, it was thought that life was much less complex. But that is contradicted by the new fossil site in Yunnan province, known as the Jiangchuan biota, which includes more than 700 fossils dating from 554 to 537 million years ago.<\/p>\n \u201cThe discovery shows that Cambrian-type animal communities did not appear suddenly, but already had clear foundations and transitional forms by the end of the Ediacaran,\u201d says Gaorong Li<\/a> at Yunnan University in Kunming, China, who led the team behind the discovery.<\/p>\n Ross Anderson<\/a> at the University of Oxford, another member of the team, says the surprising complexity of the fossils has raised questions about whether the Cambrian explosion was more of a slow burn.<\/p>\n \u201cWe are certainly revealing a more complex picture about the beginnings of the explosion of animal diversity and when that happened,\u201d says Anderson.<\/p>\n When Li initially began looking at the site in mid-2022, all he was expecting to find was algae.<\/p>\n Instead, the researchers found a range of creatures known as bilaterians \u2013 animals with bilateral symmetry \u2013 of which only a few examples from the Ediacaran have been found before. They include two new species of deuterostomes \u2013 a major group that includes vertebrates \u2013 indicating that this group was already diverse in the Ediacaran period.<\/p>\n A cambroernid fossil from the Jiangchuan biota (left) and artist\u2019s reconstruction of the animal<\/p>\n Gaorong Li & Xiaodong Wang<\/p>\n<\/p>\n Some of the fossils have been identified as cambroernids, a group with coiled bodies and filamentous tentacles, that weren\u2019t known to exist before the Cambrian. There are also fossils similar to the Cambrian organism Margaretia, that resemble a tube with holes in the wall, \u201cmaking it look overall like an animal living inside a ventilation pipe\u201d, says Li.<\/p>\n He says the most common fossil the team found is an animal that anchored itself to the sea bed at one end and had a tubular appendage that could be extended outward at the other end, reminding the team of the sandworm from the science-fiction series Dune.<\/p>\n \u201cThis suggests an animal that lived attached to the seafloor and stretched out this structure to feed,\u201d says Li. \u201cAnother form is a sausage-shaped worm with a short, thick, curved body, clearly indicating the ability to move.\u201d<\/p>\n These animals are both strange and oddly familiar, he says, and may represent \u201cevolutionary experiments\u201d from a phase when life was exploring different body plans and ecological adaptations.<\/p>\n \u201cThey already possess key features seen in modern animals, such as a mouth, a gut and a proboscis or pharynx, but the way these structures are combined is unlike that of most animals living today,\u201d says Li. \u201cIn other words, although their overall appearance is strange, they still possess the basic body modules seen in modern animals.\u201d<\/p>\n![\"A](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/04\/SEI_291801828.jpg\")
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