Pioneering research sheds new light on what shaped extinction pattern of prehistoric marine life – and size clearly mattered
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Image shows microscopic marine plankton, which are larger in size and went extinct.
view moreCredit: Brian Huber Smithsonian
Scientists have shown conclusively for the first time that tiny marine organisms in polar oceans survived the mass extinction event that wiped out prehistoric dinosaurs because they needed less energy and were more tolerant to darkness.
The study, led by the University of Bristol and published in the journal Nature, sought to solve a longstanding evolutionary enigma: what factors determined whether marine species would survive a mass extinction event known as the Cretaceous-Paleogene (K-Pg) boundary some 66 million years ago? Findings revealed that being small and accustomed to darkness proved to be the vital attributes.
Study lead author Dr Rui Ying said: “It’s an exciting breakthrough. For so many years scientists have been unable to test what actually decided whether a species prevailed or perished because the extinction event involves multiple environmental changes like ocean acidification and darkness.”
“It is difficult to understand the causality because of the lack of fossil data and environmental proxy data, especially at century timescale. Using a numerical model, I looked at the base of the food chain – plankton – which helped us to identify the most likely cause and the best survival strategies for plankton.”
The Cretaceous–Paleogene (K–Pg) boundary is an ancient and much-studied geological signature marking the mass extinction that wiped out non-avian dinosaurs, separating the Mesozoic Era (the age of reptiles) from the Cenozoic Era (the age of mammals). It is thought that the impact of an asteroid, called Chicxulub, caused the extinction of around 75% of species in the fossil record by triggering catastrophic environmental changes.
Despite decades of research, the mechanisms linking the environmental changes to the selective extinction patterns observed in the fossil record have until now been unresolved. But by creating and deploying a unique model which maps ecosystem traits globally, the scientists have been able to establish what attributes resulted in the marine plankton community’s survival.
Dr Ying, who is now a Senior Research Associate at the University of East Anglia, said: “The model is based on trades and the trade-off of how often they are eaten by predators and what they can eat against specific attributes, such as temperature, light level and body size.”
Study co-author Dr Fanny Monteiro, Associate Professor in Ocean Sciences at the University of Bristol, explained: “The body size and abundance of small plankton mean the organisms rely on less energy, increasing their likelihood of survival. An ability to deal with lower light and darkness and turbulent waters in higher latitudes also makes them more adaptable to polar regions. In contrast, species adapted to higher light and warmer waters were more vulnerable to this type of mass extinction.”
The model allowed the traits of millions of organisms to be analysed and quantified with unprecedented accuracy, providing important insights into the physical and chemical changes linked to diversity. Besides shining a light on the distant past of marine life, the research can also help inform forecasts of how ecosystems might respond in future.
Study co-author Professor Daniela Schmidt, Professor of Earth Sciences at the University of Bristol, said: “This study not only demonstrates how trait-based models can help us better understand biodiversity crises in ancient history, but it also has potential to indicate how less light and hotter environments, as a result of global warming, might impact current and future ecosystems.”
The research was funded by China Scholarship Council (CSC)-Bristol PhD Scholarship and NERC grants.
Study lead author Dr Rui Ying showing an example of the Cretaceous paleogeography/bathymetry model in the paper. On the right is the simulated ocean current with small arrows representing the direction of water movement.
Credit
University of Bristol
Journal
Nature
Subject of Research
Animals
Article Title
‘Darkness and body size shaped end-Cretaceous marine extinction patterns’
Article Publication Date
27-May-2026
Forgotten fossil helps rewrite part of animal evolution
An international study led by Flinders University has looked in places others haven’t before – and opened a new chapter to life on Earth.
Flinders University
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Flinders University's Thomas Turner (left) and Dr Russell Bicknell (right) with Turner's illustration of the 500-million-old anthropod Magnicornaspis garwoodi.
view moreCredit: Photograph: Flinders University
New research, to be published in BMC Biology at NOON GMT on 28 May, helps to fill in questions about the so-called “Furongian gap” from about 497 million to 485 million years ago, when palaeontologists previously thought there were far fewer fossils than periods before or after it.
“Palaeontologists have wondered whether this time of markedly less diversity of life could be linked to ocean chemistry, cooling climates or environmental instability,” says corresponding author Dr Russell Bicknell, from Flinders University’s College of Science and Engineering.
“But perhaps we haven’t been looking at the right sedimentary rocks or fossil-bearing deposits to get a clear picture of the kinds of soft-bodied organisms and early anthropods (animals with exoskeletons) which inhabited the planet at that time.”
An international team led by Flinders University research fellow Dr Bicknell and Dr Julien Kimmig from Germany’s Karlsruhe Institute of Technology (KIT) have described a new 500-million-old fossil anthropod related to the lineage which evolved into spiders and scorpions.
Named Magnicornaspis garwoodi, this enigmatic animal features broad head shields, segmented bodies and defensive spines that belong to the corcoraniids group.
Found near Québec in Canada and preserved within the Rivière-du-Loup Formation, the specimen was one of only a handful of species known from the Cambrian and Ordovician.
The researchers – who include Dr Aaron Goodman from the University of Illinois, Thomas Turner (Flinders University honours student and palaeoartist) and Dr Patrick Smith (Macquarie University) – say the fossil is important because it helps to fill blanks in fossil history. It joins a growing list of Furongian sites that challenge the notion of a barren late-Cambrian world.
Each new Furongian fossil discovery narrows this supposed gap and reveals increasingly sophisticated ecosystems thriving during the late Cambrian.
“Together, these discoveries increasingly suggest that Furongian ecosystems remained diverse and ecologically complex,” says ARC DECRA research fellow Dr Bicknell, who investigated the long-shelved museum specimen during his time at the American Museum of Natural History.
“Importantly, it comes from a geological setting not previously recognised for exceptional preservation.”
Research co-author Dr Kimmig says the discovery fits within a broader pattern emerging over the past two decades.
“The Furongian may not represent a true collapse in biodiversity, but rather a gap where scientists have looked and what kinds of rocks have been studied,” says Dr Kimmig, from the KIT Institute of Applied Geosciences and Head of Palaeontology and Evolution at Staatliches Museum für Naturkunde Karlsruhe.
The new fossil is named after Russell Garwood, a Manchester University palaeontologist who has spent his career understanding chelicerate evolution. The specimen was originally collected in 1962 during geological mapping near Québec and comes from black shales within the Rivière-du-Loup Formation, a unit deposited in relatively deep marine slope environments during the late Cambrian.
The specimen has been stored as part of the Smithsonian collections in Washington DC for decades.
“This highlights one of the most important aspects of palaeontology: major discoveries do not always emerge directly from fieldwork,” adds Dr Kimmig.
“Museum collections contain enormous quantities of under-studied material collected during geological surveys and expeditions over the past century.
“Revisiting these collections with modern techniques can fundamentally reshape understanding of ancient ecosystems.”
The article – “New exceptionally preserved arthropod from the Furongian of Canada” (2026) by Russell DC Bicknell), Julien Kimmig, Aaron Goodman (University of Illinois, US), Thomas Turner (Flinders) and Patrick M Smith (Macquarie University) – is published in BMC Biology. https://doi.org/10.1186/s12915-026-02617-4
Journal
BMC Biology
Method of Research
Observational study
Subject of Research
Not applicable
Article Title
New exceptionally preserved arthropod from the Furongian of Canada
Article Publication Date
28-May-2026
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