New fossils from the Ediacaran Period show that some animal groups are older than we thought:
More than 539 million years ago, soft, clarinet-shaped animals anchored themselves to the seafloor on disc-shaped bases, swaying alongside stalked animals resembling worms and baskets. These woodwindlike creatures are just a few of those coming to life from a treasure trove of newly discovered fossils in southwestern China.
It’s surprising to see some of these weird creatures this far back in the fossil record, and their discovery is unearthing crucial new details about one of the most notable explosions in the diversity of animals in fossil history, researchers report April 2 in Science.
“This paper is absolutely fascinating,” says paleontologist Emily Mitchell at the University of Cambridge. “It provides vital insights into life around the end of the Ediacaran Period.”
The Ediacaran preceded a pivotal moment in animal prehistory called the Cambrian explosion, which started around 539 million years ago and marked a dramatic and rapid diversification, an “explosion” of physical forms and complexity. How that explosion happened isn’t clear. Fossils from the late Ediacaran Period, from 575 million to 539 million years ago, show this is when the first unambiguous animal fossils appear but don’t offer many details about the animals’ bodies or biology. Many of the Cambrian animal groups also do not appear in the Ediacaran record, suggesting that Cambrian animal diversity may have exploded from only a small number of species.
Now, a new trove of fossil specimens collected near Jiangcheng, China, is challenging that idea.
[...] Among the more eyebrow-raising findings were the animals with bilateral symmetry — similar features on the right and left sides. Fossilized bodies of bilaterians this early is rare, with only four species known from the Ediacaran until now. Li and the team found more than 180 bugle worm fossils, along with fossils of other bilaterial creatures, including those that looked like sausages on skewers, with feathery appendages around their mouth ends.
Emmy Smith, a paleontologist at Johns Hopkins University in Baltimore, was struck by the abundance and diversity of bilaterian fossil finds. Many of these show structures specialized for feeding. These weren’t simple progenitors of later lineages; these animals were already quite physically complex, she says. “That strengthens the view that major animal lineages were already diversifying before the Cambrian.”
The results suggest the explosion of animal diversity in the Cambrian didn’t appear out of nowhere, Li says. Instead, a gradual buildup of complex animal life was underway millions of years before.
Journal Reference: G Li et al. The dawn of the Phanerozoic: A transitional fauna from the late Ediacaran of Southwest China. Science. Published online: April 2, 2026. doi: 10.1126/science.adu2291
(Score: 3, Interesting) by khallow on Monday April 06, @03:14PM (1 child)
It's interesting how these changes fed on each other. sometimes literally. Plants grew faster from the availability of sea floor nutrients and released more oxygen. Animals with hard teeth had a wide variety of food sources to eat - not just the sea floor, but also other plants and animals. A stationary, soft animal couldn't just get by. It needed a trick: armor, motion, spikes and stingers, massive overreproduction. Something to protect it from getting eaten or to survive in large enough numbers even if it was eaten a lot. Basically, during the Cambrian explosion the last basic niches of Earth life were created. No diversification since has done the same (though some addition niches were later created such as relatively interactive niches like pollinators, fruit eaters, and rain forest plants). If one looks at the end of the dinosaurs, 66 million years ago, and the subsequent reoccupation of evolutionary niches dominated by mammal and flowering plants, the same basic niches are occupied as were the case in the Cambrian: plants at the base, herbivores, carnivores, parasites, recyclers, etc.
(Score: 4, Insightful) by HiThere on Monday April 06, @04:31PM
Things that didn't have mineralized skeletons essentially didn't fossilize. Things that only had partial skeletons left really incomplete and arguable traces.
So, yes, one should expect that LOTS of complex organisms lived long before we have any trace of such. And just because we find a trace in one particular area is absolutely NO sign that they and various equivalents didn't exist elsewhere. You only get the soft stuff when an area is very rapidly covered with a layer of very fine particulate stuff (clay usually) sufficiently to exclude the oxygen. That's RARE. So EXPECT that there was a lot of stuff that left no traces.
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