Durham University scientists solve 500-million-year fossil mystery

Durham University

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-With images-

A peculiar spiny fossil, once thought to represent one of the earliest molluscs, has now been conclusively reclassified by scientists from Durham University and Yunnan University as something entirely different – a distant relative of sponge-like creatures known as chancelloriids.

This striking revelation is set to reshape our understanding of early animal evolution.

The fossil, named Shishania aculeata, hails from 500-million-year-old Cambrian deposits in Yunnan Province, southern China, a region world-renowned for its remarkably preserved snapshots of ancient life.

Initially interpreted as a primitive mollusc, potentially an ancestor of modern snails, slugs, and clams, Shishania was believed to display mollusc-like features including a muscular foot and specialised mineralised spines.

However, a new international study led by Durham University and published in Science paints a dramatically different picture.

The researchers said the new fossils show that Shishania doesn’t fit with molluscs at all, instead it closely resembles a group of ancient creatures called chancelloriids (bag-like animals covered in defensive spines, anchored to the Cambrian sea floor).

The researchers, using better-preserved specimens and advanced imaging techniques, discovered that many of the features previously thought to indicate molluscan affinity were in fact misleading artefacts of fossilisation.

For example, structures taken to be a ‘foot’ were revealed to be the result of distortion during the fossil’s preservation, a process described as a ‘taphonomic illusion’.

Study co-author, Dr Martin Smith of Durham University said: "These ancient fossils turned out to be masters of disguise. Shishania seemed to show all the hallmarks we might expect of an early mollusc ancestor.

“But as it dawned on us that the mollusc-like outlines of the fossil material represented a work of fossil origami, we were led to re-examine each other part of the interpretation in turn.

“The mystery started to unfurl once we found chancelloriids preserved in a very similar way in the same rock unit."

The reclassification is particularly significant because chancelloriids are an enigmatic group known only from Cambrian rocks, disappearing around 490 million years ago.

Though superficially resembling sponges, their bodies are adorned with star-shaped spicules whose intricate microstructure hints at possible connections to more complex animals.

With its extremely simple spines, Shishania suggests that chancelloriids developed their ornate spicules from scratch, rather than adapting them from pre-existing skeletal structures.

That tells something profound about how complex body plans evolved during the Cambrian explosion – the evolutionary burst that gave rise to all modern animal groups.

Dr Smith admitted the fossils initially seemed to confirm his own long-standing theories about early mollusc ancestors: “When Shishania was first described last year, I was thrilled – it seemed to match the early ‘slug-like’ animals I’d always imagined. But our Chinese colleagues’ new material forced me to re-evaluate everything.”

Further analysis revealed patterns once thought to reflect molluscan biology such as a ‘paintbrush-like’ arrangement in the spines were actually preservation artefacts, as the same patterning occurred randomly across the fossil.

Compression and deformation during fossilisation had also made the simple cylindrical animals appear more anatomically complex than they truly were.

This reinterpretation has implications not only for understanding chancelloriids, but also for identifying other ambiguous Cambrian fossils.

It reopens questions about early mollusc evolution and cautions against over-interpreting ambiguous fossil features.

At the same time, it helps solidify our picture of chancelloriid origins and gives us fresh insight into how evolutionary novelty emerged.

The study underscores the crucial role of China’s fossil-rich strata and exemplifies how international collaboration continues to transform our understanding of life’s earliest chapters.

ENDS

Media Information

Dr Martin Smith from Durham University is available for interview and can be contacted on martin.smith@durham.ac.uk or +44 (0)774 353 7510.

Alternatively, please contact Durham University Communications Office for interview requests on communications.team@durham.ac.uk or +44 (0)191 334 8623.

Source

‘Shishania is a chancelloriid and not a Cambrian mollusk’, (2025), Jie Yang et al., Science. www.doi.org/10.1126/science.adv4635.

An embargoed copy of the paper is included in the below dropbox link and available from Durham University Communications Office. Please email communications.team@durham.ac.uk.

Graphics

Associated images are available via the following link: https://www.dropbox.com/scl/fo/x0n7m8awaa6nwpqiw0k77/AOpkPxio0yA5plw_qr03Cus?rlkey=hago2sy5miy337olnmpwgogrz&st=km5mvt6v&dl=0

003de3: Hollow triangular spines protrude from the margin of a Shishania specimen. Credit: Zhang Xiguang.

0219-Comb-2: The top end of a specimen of Shishania, showing the three-dimensionality of its spines and their arrangement around an apical orifice. Credit: Zhang Xiguang.

FigS3bb: Specimens of Shishania. A and B, specimen in different lighting conditions, showing how the uneven breakage of the specimen reveals the distinct upper and lower surfaces.  E-G, specimen showing three-dimensionality of its spines and their arrangement around an apical orifice.  H, two individual spines: on the left, preserved in top-down view, revealing the circular cross-section; on the right, preserved side-on. Credit: Zhang Xiguang.

About Durham University

Durham University is a globally outstanding centre of teaching and research based in historic Durham City in the UK.

We are a collegiate university committed to inspiring our people to do outstanding things at Durham and in the world.

We conduct research that improves lives globally and we are ranked as a world top 100 university with an international reputation in research and education (QS World University Rankings 2025).

We are a member of the Russell Group of leading research-intensive UK universities and we are consistently ranked as a top 10 university in national league tables (Times and Sunday Times Good University Guide, Guardian University Guide and The Complete University Guide).

For more information about Durham University visit: www.durham.ac.uk/about/

END OF MEDIA RELEASE – issued by Durham University Communications Office.

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Journal

Science

DOI

10.1126/science.adv4635. 

Article Title

Shishania is a chancelloriid and not a Cambrian mollusk

Article Publication Date

8-May-2025

 

Red alert for our closest relatives

New report shows drastic decline in endangered primates and calls for conservation measures

Deutsches Primatenzentrum (DPZ)/German Primate Center

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The smallest primate in the world, Madame Berthe's mouse lemur, is threatened with extinction.

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Credit: Manfred Eberle, Deutsches Primatenzentrum GmbH

An international team of primate researchers has published the 25 most endangered primate species in Asia, Africa, Madagascar and South America for the years 2023 to 2025. The publication, supported by the German Primate Center (DPZ) - Leibniz Institute for Primate Research in Göttingen, emphasizes how urgently global conservation measures need to be implemented now to save irreplaceable biodiversity.

"The situation is dramatic. If we don't act now, we will lose some of these species forever," warns Christian Roos, geneticist at the German Primate Center. “But there is hope - if science, politics and society take action together.” The report, compiled by leading primatologists and conservationists, underlines the urgent need for targeted conservation efforts to prevent the final extinction of these species.

The most important findings of the report

A group of experts comprising members of the conservation organizations International Union for Conservation of Nature (IUCN) and Conservation International (CI) as well as the International Primatological Society (IPS) has compiled a list of the 25 most endangered primate species in the world. Habitat destruction, hunting, climate change and illegal wildlife trade are the biggest threats to the animals.

The most endangered species include the Tapanuli orangutan (Pongo tapanuliensis) on Sumatra, with only around 800 individuals left. This makes it the most endangered ape species of all. It was only discovered in 2017 by DPZ scientists, among others. Its skull shape, dentition and genes are different from those of other orangutan species. This was revealed by extensive morphological and genetic analyses of orangutans, in which Christian Roos was also involved.

Many lemurs in Madagascar are also threatened with extinction, including Madame Berthe's mouse lemur (Microcebus berthae). The smallest primate in the world, weighing just 30 grams, was discovered in 1993 by DPZ scientists near the field station in the Forêt de Kirindy. Its population has declined significantly in the last three years. "This species has also disappeared from most of the remaining intact forests, which points to frightening consequences for possible conservation measures. This could be the first primate we lose forever in the 21st century, as there are no captive populations either," says Peter Kappeler, head of the field station in the Forêt de Kirindy.

Measures to protect primates

The report calls urgently for the expansion of crucial area protection measures and the consistent enforcement of these measures in order to permanently preserve critical habitats. At the same time, the report emphasizes the importance of actively engaging indigenous and local communities and empowering them as stewards of their own regions. It also calls for comprehensive policy reform, in particular by tightening laws against illegal wildlife trade and ongoing deforestation. Finally, the report underlines the urgency of mobilizing sufficient financial resources to successfully implement long-term conservation programs. “Every primate species that we lose not only means an irreparable loss for nature, but also for us humans,” says Roos. “Because primates are not only fascinating animals - they are also key species of our ecosystems.” If a key species ceases to exist, no other species is able to occupy its ecological niche and the corresponding ecosystem changes radically.

The 25 most endangered primates in the world

Every two years, the 25 most endangered primate species in the world are announced at the meeting of the International Primatological Society in order to raise public awareness of the critical situation of primates. By listing the endangered primates, the researchers want to draw global attention to the fate of our closest relatives and raise funds for research and conservation measures. The report is based on the expertise of over 100 scientists worldwide.

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Method of Research

Meta-analysis

 

Renowned ecologist Diana Wall Gives back to the ecological community with a posthumous major donation to the Ecological Society of America

Ecological Society of America

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The Society is honored to announce a generous bequest from the late Dr. Diana Harrison Wall’s estate. She was a former Ecological Society of America (ESA) president (1999–2000) and an internationally respected figure in soil biodiversity and ecology. Wall, who passed away in March 2024, left a lasting legacy with a donation of $514,000 to ESA, making it one of the largest individual gifts in the Society's history.

Wall's exceptional contributions to ecological science spanned over five decades, during which she made groundbreaking discoveries in soil ecology, particularly in her studies of nematodes and soil biodiversity. A pioneer in her field, Wall’s work in Antarctica and her studies of soil nematodes were instrumental in advancing global understanding of soil ecosystems. As a scientist and leader, she emphasized the interconnectedness of environmental systems and the crucial role that soil organisms play in sustaining ecosystems.

“This extraordinary gift reflects Diana Wall’s deep dedication to the Ecological Society of America and to advancing the practice and application of ecological research,” said current ESA President Stephanie Hampton. “Diana was not only a brilliant scientist but also a passionate advocate for ecology as a critical tool for addressing global environmental challenges. On top of that, she was a role model and mentor to many, who can all attest to her infectious enthusiasm for science. This gift will help ensure that her contributions will continue to inspire future generations of ecologists and decision-makers.”

Wall's bequest will support ESA’s ongoing programs that further its mission of advancing the science and practice of ecology and supporting ecologists throughout their careers.

ESA Executive Director Catherine O'Riordan remarked, “We are deeply grateful for this major gift. Diana’s love for ESA was matched only by her dedication to science and to blazing a trail for others. This generous donation will allow us to expand our efforts to provide the next generation of ecologists with the tools, resources and opportunities they need to succeed.”

Throughout her career, Wall was a driving force behind many significant advances in soil biodiversity research. Her work in the McMurdo Dry Valleys of Antarctica demonstrated the vital role of nematodes in soil ecosystems and how they drive carbon cycling in extreme environments. Wall's fieldwork also uncovered the resilience of soil biota under climate change, making her a leader in the study of ecosystem functioning in both polar and desert ecosystems. She was instrumental in establishing the Global Soil Biodiversity Initiative, which produced the first comprehensive scientific assessment of global soil biodiversity. Wall’s contributions have profoundly shaped our understanding of soil ecology, ecosystem services and the impact of human activity on soil health.

In addition to her scientific endeavors, Wall was an advocate for women and minorities in science, and she contributed her tremendous leadership skills to many entities beyond ESA. Among her many leadership roles, she served as president of the Society of Nematologists, the American Institute of Biological Sciences and the Association of Ecosystem Research Centers. Wall’s numerous accolades include being named a fellow of the American Association for the Advancement of Science, election to membership in the American Academy of Arts and Sciences and the U.S. National Academy of Sciences and receiving the British Ecological Society's President's Medal. Her status as a major figure in Antarctic research is reflected in the USGS and ICSU Scientific Committee on Antarctic Research decision to name an Antarctic valley in her honor — Wall Valley.

Wall’s gift to ESA will ensure that her impact on the field of ecology continues for many years to come. It is a testament to her life’s work and her unwavering belief in the importance of ecological science.

For more information about Diana Wall, please read the Resolution of Respect in The Bulletin of the Ecological Society of America.

 

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Learn more about the upcoming ESA Annual Meeting, August 10–15, on the meeting website.

ESA invites press and institutional public information officers to attend for free. To register, please contact ESA Public Affairs Manager Mayda Nathan directly at mayda@esa.org.

 

The Ecological Society of America, founded in 1915, is the world’s largest community of professional ecologists and a trusted source of ecological knowledge, committed to advancing the understanding of life on Earth. The 8,000 member Society publishes six journals and a membership bulletin and broadly shares ecological information through policy, media outreach, and education initiatives. The Society’s Annual Meeting attracts 4,000 attendees and features the most recent advances in ecological science. Visit the ESA website at https://www.esa.org.

 

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FOREVER CHEMICALS

Health care workers, firefighters have increased PFAS levels, study finds

Researchers looked at PFAS serum concentrations in health care workers for the first time and were surprised by what they found

University of Arizona Health Sciences

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A study including researchers from the University of Arizona Health Sciences and published in the Journal of Exposure Science & Environmental Epidemiology found that firefighters had higher concentrations of certain per- and polyfluoroalkyl substances, or PFAS, and health care workers had moderate elevations of PFAS in their blood with significantly higher odds of two specific PFAS when compared with other essential workers.

“Our study reinforces previous research showing elevated PFAS levels among firefighters and suggests that health care workers may have unique sources of PFAS exposure as well,” said senior author Kate Ellingson, PhD, an associate professor at the Mel and Enid Zuckerman College of Public Health. “Our findings underscore the need to understand occupational exposure pathways for PFAS among different types of workers.”

PFAS are a class of synthetic chemicals used in a wide range of products because of their stain-, water- and flame-resistant properties. PFAS do not degrade easily over time and are highly stable in the environment, making them capable of contaminating our food, water and material products.

The study sought to assess the differences in blood concentrations of PFAS among a range of frontline workers in Arizona. It is the first to evaluate PFAS levels in individuals working in health care.

Among health care workers, researchers found moderate elevations of certain PFAS (PFHpS and PFUnA), along with notably higher odds of detecting Sb-PFOA and PFDoA compared with individuals in other professions.

Firefighters had the highest concentrations of PFAS in their blood samples, specifically concentrations of PFHxS, Sm-PFOS, n-PFOS and PFHpS. This aligns with previous studies and implies distinct sources of occupational PFAS exposure remain for firefighters in Arizona.

PFAS serum levels in other essential workers declined 6% to 17% per year over the three-year study period; however, there were still notable levels of PFAS in their blood samples.

PFAS data were available for 1,960 study participants, including 280 firefighters and 787 health care workers and 734 other essential workers. 

“Almost all adults in the U.S. have detectable levels of certain PFAS, and people in occupations with more frequent exposure to PFAS-containing materials have been shown to exhibit higher serum concentrations of some PFAS,” said co-author Jeff Burgess, MD, MPH, a professor, the director of the Center for Firefighter Health Collaborative Research at the Zuckerman College of Public Health and a BIO5 Institute member. “Research into occupational exposure to PFAS is vital to reduce the health risks associated with PFAS, including but not limited to increases in rates of certain cancers, increases in cholesterol levels, lower antibody response to certain immunizations, and increased rates of certain adverse reproductive outcomes.”

Firefighters are one of the more widely studied populations because of their frequent contact with sources of PFAS, including the protective gear worn while fighting fires and the foam used to extinguish fires. Other frontline workers, such as health care workers, are not as widely studied.

“To date, PFAS exposure in health care settings has not been widely studied, and the potential sources of exposure remain unclear,” Ellingson said, noting that single-use surgical masks, surgical gowns and X-ray film could be potential sources of PFAS exposure. “Therefore, it’s important to further examine specific exposure routes and health consequences for firefighters and health care workers.”

The study used data collected from July 2020 through April 2023 through the Arizona Healthcare, Emergency Response, and Other Essential Worker Surveillance Study, or AZ HEROES, at the U of A Health Sciences.

In addition to Ellingson and Burgess, co-authors from the University of Arizona Health Sciences include graduate student James Hollister, research manager Shawn Beitel, former graduate student Ferris Ramadan, Karen Lutrick, PhD, associate professor of family and community medicine at the College of Medicine – Tucson, and Julia Fisher, PhD, assistant research professor at the BIO5 Institute. Others who contributed to the research include first author Cedar Mitchell, PhD, an epidemiology field officer for the Centers for Disease Control and Prevention who previously served as an epidemic intelligence service officer with the Pima County Health Department, and Shawn O’Leary and Zhihua Tina Fan, PhD, both of the New Jersey Department of Health.

This research was supported by the Centers for Disease Control and Prevention’s National Center for Immunization and Respiratory Diseases under award no. 75D30120C08379 and the National Institute of Environmental Health Sciences, a division of the National Institutes of Health, under award nos. 5R21ES032680 and R21ES033598.

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Journal

Journal of Exposure Science & Environmental Epidemiology

DOI

10.1038/s41370-025-00753-7 

Method of Research

Randomized controlled/clinical trial

Subject of Research

People

Article Title

Differences in serum concentrations of per-and polyfluoroalkyl substances by occupation among firefighters, other first responders, healthcare workers, and other essential workers in Arizona, 2020–2023

Article Publication Date

6-Mar-2025

 

Generalist pests cause more damage, specialists kill more trees

Foundational insights for classifying pests by tree damage and mortality

USDA Forest Service ‑ Southern Research Station

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The hemlock woolly adelgid, a nonnative invasive insect and specialist, has killed millions of hemlock trees in the U.S., highlighting the potential threat and impact such pests can have on our forests.

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Credit: Steven Katovich, Bugwood.org

A recent study in the journal Forests highlights the critical need for understanding and managing nonnative forest specialist and generalist pests. 

“We classify pests for easier management; it’s just a matter of which we should focus on first, given limited labor and funding,” says Qinfeng Guo, a research ecologist with the USDA Forest Service and lead author of the study.

The hemlock woolly adelgid, introduced accidentally in the 1950s, remains a major tree-killer in the U.S. In Japan, its population is controlled by natural predators and host tree resistance, but in the eastern U.S., where it's invasive, these controls are absent, causing significant damage. The National Park Service reported a loss of 80-90% of eastern hemlocks at some sites. The hemlock woolly adelgid is one of 66 nonnative species analyzed by researchers in this study.

“Invasive insects are the biggest threat to forests. This study aims to shed light on the best methods for defining and confronting this vulnerability,” says Kevin Potter, second author of the study.

Specialist and generalist classifications are used frequently in the field of forest management. Specialist pests are those that consume one or very few host species, believed to take more of a toll on their hosts, while generalists usually infest more species and sometimes across multiple genera or even families.

The key finding of this study was that specialists caused more tree deaths than generalists. However, contrary to expectations, generalists inflicted more nonlethal damage due to their broader impact across multiple species. The study also found that newer nonnative pests caused more tree mortality than older ones, possibly because older pests have already killed the most vulnerable trees, spread to larger areas, and allowed host trees to adapt over time.

Guo and Potter stress the importance of better classification. As it is now, there is no standard approach to differentiating specialists from generalists, especially when it comes to assessing which is more damaging. Depending on the way the damage is measured, different conclusions can be drawn, leading to conflicting findings.

In their study, Guo and Potter analyze damage from 66 nonnative pest species, looking for differences between nonnative generalist and nonnative specialist pests. They do this using two approaches: the binary approach (each pest is either a generalist or a specialist) and the specialist-generalist continuum. 

Of the two approaches explored, the specialist-generalist continuum approach made for clearer findings given the limited data available.

“If you have enough species to form a gradient or continuum from specialists to generalists, you can examine host responses along the gradient in terms of infestation and impacts,” Guo comments, reiterating the importance of clear classifications and a need to fill the current gaps in data.

In order to understand current infestations and predict and prepare for future challenges, it’s important that we further efforts to understand the dynamics of invasive pest infestations and how to best manage them.

“Unfortunately, invasive pests are here to stay, and we need to understand how to manage them,” says Potter.

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Journal

Forests

DOI

10.3390/f16010127