Spectacular fossil treasure trove pushes back origins of complex animals
image:
Reconstruction of Jiangchuan biota (~554-539 million years ago). Credit: Xiaodong Wang.
view moreCredit: Xiaodong Wang.
A newly discovered fossil site in southwest China has transformed our understanding of how complex animal life emerged on Earth, revealing that many key animal groups had already evolved before the start of the Cambrian Period. The study, led by researchers at Oxford University’s Museum of Natural History and Department of Earth Sciences as well as Yunnan University in China, has been published today (02 April) in Science.
One of the most transformative events in Earth’s history was the rapid diversification of animal life, resulting in a dramatic increase in complexity and diversity from simpler life forms. Up to now, this was thought to have occurred at the start of the Cambrian Period, in an event known as the Cambrian explosion, starting around 535 million years ago. The new study, however, shifts this timeframe back by at least 4 million years, to the end of the Ediacaran period.
Lead author Dr Gaorong Li (Yunnan University at the time of the study, now Museum of Natural History, Oxford University), said: “Our discovery closes a major gap in the earliest phases of animal diversification. For the first time, we demonstrate that many complex animals, normally only found in the Cambrian, were present in the Ediacaran period, meaning that they evolved much earlier than previously demonstrated by fossil evidence.”
The discovery comes from the Jiangchuan* Biota in Yunnan Province, southwest China, where more than 700 fossil specimens were recovered, aged between 554 and 539 million years old. The fossil site revealed a diverse community of Ediacaran organisms - both new, undescribed animal forms and groups known from the Cambrian period. Most strikingly, the international team identified fossils thought to be the oldest known relatives of deuterostomes – the broader group that today includes vertebrates such as humans and fish. The new fossils push the fossil record of deuterostomes back into the Ediacaran Period for the first time.
Among these fossil specimens were ancestors of modern starfish and their closest relatives, the acorn worms (the Ambulacraria**). These fossils have a U-shaped body and were attached to the seafloor with a stalk, with a pair of tentacles on their head used to catch food.
Co-author Dr Frankie Dunn (Museum of Natural History, Oxford University) said: “The presence of these ambulacrarians in the Ediacaran period is really exciting. We have already found fossils which are distant relatives of starfish and sea cucumbers and are looking for more. The discovery of ambulacrarian fossils in the Jiangchuan biota also means that the chordates – animals with a backbone – must also have existed at this time.”
Other ancestral groups among the fossils included worm-like bilaterian animals (having bilateral symmetry), some with complex feeding adaptations, alongside rare fossils interpreted as early comb jellies.
Many specimens showed novel combinations of anatomical features (such as tentacles, stalks, attachment discs, and feeding structures that can be turned inside out) that do not match any known Ediacaran or Cambrian species. “For instance, one specimen looks a lot like the sand worm from Dune!” Dr Dunn added.
Co-author Associate Professor Luke Parry (Department of Earth Sciences, Oxford University) added: “This discovery is extremely exciting because it reveals a transitional community: the weird world of the Ediacaran giving way to the Cambrian, the following time period where the animals are much easier to place in groups that are alive today. When we first saw these specimens, it was clear that this was something totally unique and unexpected.”
The new findings help to resolve a long-standing puzzle in evolutionary biology. While molecular studies and trace fossils suggested that animal lineages diversified well before the Cambrian explosion, up to now fossils of many of these groups of complex animals have been missing from the Ediacaran period.
Unlike most Ediacaran fossil sites, which preserve organisms mainly as impressions on sandstone surfaces, the Jiangchuan Biota fossils are preserved as carbonaceous films, a mode of preservation more typical of famous Cambrian sites such as the Burgess Shale in Canada. This exceptional preservation reveals anatomical details such as feeding structures, guts and locomotory organs.
Co-author Associate Professor Ross Anderson (Museum of Natural History, Oxford University) said: “Our results indicate that the apparent absence of these complex animal groups from other Ediacaran sites may reflect differences in preservation rather than true biological absence. Carbonaceous compressions like those at Jiangchuan are rare in rocks of this age, meaning that similar communities may simply not have been preserved elsewhere.”
The new fossils were discovered by a research group in Yunnan University, China, led by Professor Peiyun Cong and Associate Professor Fan Wei, who have spent nearly ten years looking for diverse Ediacaran animal fossils. The rocks from Eastern Yunnan were already known to contain fossils but previously had yielded only remains of algae and not animals.
Associate Professor Fan said: “After years of fieldwork, we finally found several sites with the right conditions where animal fossils are preserved together with the abundant algae.”
Professor Feng Tang from the Chinese Academy of Geological Science, Beijing, whose previous work on the site inspired the team’s decade-long fieldwork effort, said: “The new fossils provide the most compelling evidence for the presence of diverse bilaterian animals at the end of the Ediacaran, evidence people have searched for across decades.” *Pronounced ‘jing-choo-an.’
** Ambulacraria, from the latin ambulacrum, meaning "a walk planted with trees."
Notes to editors:
For media enquiries and interview requests, contact Caroline Wood: caroline.wood@admin.ox.ac.uk
The study ‘The dawn of the Phanerozoic: a transitional fauna from the late Ediacaran of Southwest China’ will be published in Science on 19:00 BST / 14:00 ET Thursday 02 April 2026, DOI 10.1126/science.adu2291. Advance copies of the paper may be obtained from the Science press package, SciPak, at https://www.eurekalert.org/press/scipak/ or by contacting scipak@aaas.org
Images relating to this release that can be used in articles can be found here: https://drive.google.com/drive/folders/1rhxNHeZ4Ct_09kq6SNO44OpKA3LpwXtH?usp=sharing These are for editorial purposes relating to this press release ONLY and MUST BE credited (see captions file in folder). They MUST NOT be sold on to third parties.
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Journal
Science
Article Title
The dawn of the Phanerozoic: a transitional fauna from the late Ediacaran of Southwest China
Article Publication Date
2-Apr-2026
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- Spectacular fossil treasure trove pushes back origins of complex animals
(University of Oxford)
The Haootia-like fossil (an early cnidarian – the phylum that includes jellyfish, sea anemones and corals) from the Jiangchuan Biota (~554-539 million years old). Scale bar: 2mm. Credit: Gaorong Li.
A deuterostome cambroernid fossil from the Jiangchuan Biota (~554-539 million years old), scale bar: 2mm. Credit: Gaorong Li.
A deuterostome cambroernid fossil from the Jiangchuan Biota (~554-539 million years old). Scale bar 2 mm. Credit: Gaorong Li.
A newly-discovered vermiform fossil from the Jiangchuan Biota (~554-539 million years old) with holdfast to anchor it to the ocean floor. Scale bar 5mm. Credit: Gaorong Li.
A deuterostome cambroernid fossil from the Jiangchuan Biota (~554-539 million years old) and artist’s reconstruction, scale bar: 2mm. Credit: Gaorong Li & Xiaodong Wang.
Engineering the bite of ancient marine predators
A new study compares the bite efficiency of fossil reptiles using advanced engineering simulations.
University of Liège
image:
Bite performance of North American mosasaurs and plesiosaurs, showing the bite performance as optimal (bright colours) or suboptimal (darker colours)
view moreCredit: University of Liège / EddyLab / F.Della Giustina
An international team of researchers, led by Palaeontologists of the University of Liège, has investigated the biting capabilities of extinct predatory marine reptiles, revealing how these formidable predators could coexist within the same ecosystem. This work sheds new light on the hunting strategies of long-extinct predators that dominated the seas during the Age of Dinosaurs.
How can we infer the hunting strategies of extinct predators? A multidisciplinary team of palaeontologists, biologists, and engineers from ULiège, now provides an answer to that question. By combining palaeontological data with cutting-edge 3D modeling and engineering simulations, the team recreated the biting behaviour of marine predators which inhabited an ancient sea that covered North America approximately 80 million years ago.
“Every ecosystem, even underwater, has a limited amount of food resources for predators,” explains Francesco Della Giustina, palaeontologist at the EDDy Lab. “The long-term co-occurrence of multiple large predators we see in North America during the Cretaceous suggests that they occupied subtly different ecological roles, targeting different types of prey rather than directly competing. While palaeontologists have long proposed such hypotheses, new technologies now allow us to test them quantitatively.”
The research team generated 3D models of the skulls and mandibles of coexisting marine reptiles: the plesiosaurs and the mosasaurs. The cranial musculature of each species was reconstructed, and the force of each muscle that closed the jaw was estimated. The team then applied a computational approach adapted from engineering, known as finite element analysis, to simulate the patterns of stress and strain on the bones during biting under realistic conditions. The researchers could then observe the mechanical behaviour of the jaws across many different species. The team identified clear differences in biting performance across predatory species, which can be translated into distinct capabilities and therefore, probably distinct behaviours. Some species likely occupied an apex predator niche (i.e. eating almost anything else on the food-chain) while other appear specialized to feed on smaller, softer, and more agile prey, such as small fish or cephalopods (e.g. squid).
“The mechanical performance of the skull provides key insights into the ecological roles of these animals,” adds Francesco Della Giustina. “We can now test, in a virtual environment, behaviours that would otherwise remain inaccessible in the fossil record. This opens new perspectives on how these predators lived, interacted, and evolved”.
In other words, by combining fossils with modern technologies, researchers are beginning to reconstruct how these ancient animals functioned as living organisms—bringing us closer than ever to understanding life in prehistoric oceans.
Journal
Palaeontology
Article Title
Distinct feeding biomechanics in Late Cretaceous marine reptiles from the Western Interior Seaway
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