Rosa Rubicondior: How Science Works - Correcting A Mistake But Still Refuting Creationism

Visible to the naked eye, fossilized bacteria or algae were found in an ancient seabed that emerged in the current Brazilian state of Mato Grosso do Sul

Photo: Bruno Becker-Kerber/Harvard University

Microfossils interpreted as animal traces were actually algae and bacteria

A paper in Gondwana Research, recently highlighted in a FAPESP press release, helps illustrate one of the great strengths of science and one of the fatal weaknesses of creationism as a means of discovering the truth.

It reports the results of a reassessment of microscopic fossil evidence from the late Ediacaran, previously interpreted as evidence of burrowing, worm-like animals — possibly the earliest known meiofauna, a type of tiny animal life otherwise securely associated with the Cambrian fossil record.

The earlier interpretation also carried a secondary implication: that oxygen levels in those late Ediacaran marine environments may already have been high enough to support active, motile, multicellular animals. That conclusion now looks much less secure, because the structures appear not to be animal burrows at all, but fossilised communities of algae and bacteria.

That is where the real lesson lies. One of the attractions of creationism is that it offers a spurious sense of certainty to people who value certainty more than truth and accuracy — the so-called “certainty embracers”. To them, the fact that science sometimes corrects itself, and that scientists change their minds when new evidence becomes available, is misrepresented as a weakness. Creationism, by contrast, is treated as an unchanging, eternal truth precisely because it is protected from correction by refusing to submit itself to evidence.

Religion = unreasonable certainty
Science = Reasonable uncertainty

Religion offers unreasonable certainty; science works with reasonable uncertainty. The difference is that science is amenable to reason, evidence and correction, while creationism survives by rejecting them whenever they become inconvenient.

So creationists often seize on cases where one team of scientists re-evaluates evidence relied upon by an earlier team and concludes that the original interpretation was wrong. But this is not science failing; it is science working. It is exactly what makes science such a powerful tool for discovering what is true: it can change its collective mind when better evidence, better techniques and better analysis point in a different direction.

Sadly for creationists, however, this improved understanding rarely, if ever, turns out to support their beliefs. They may derive a few crumbs of comfort from the familiar refrain that “Darwinists got it wrong again”, but there can surely be little comfort in discovering that the structures in question were still made by living organisms some 540 million years before creationist dogma says Earth existed.

The corrected interpretation does not rescue creationism; it simply replaces one natural explanation with a better-supported natural explanation. The fossils are still ancient. They are still biological. They are still part of a deep-time history of life that creationism cannot accommodate without special pleading. The only thing that has changed is the identity of the organisms responsible for them.

The reassessment was led by Dr Bruno Becker-Kerber as part of his post-doctoral research at the Institute of Geosciences at the University of São Paulo (USP) and the Brazilian Center for Research in Energy and Materials (CNPEM), supported by a fellowship from FAPESP — Fundação de Amparo à Pesquisa do Estado de São Paulo, the São Paulo Research Foundation.

Body Fossils, Trace Fossils and Why the Difference Matters. Fossils do not always preserve the remains of an organism itself. Sometimes they preserve evidence of what an organism did. These are known as trace fossils, and include footprints, burrows, feeding marks, trails and other disturbances left in sediment.

A body fossil, by contrast, preserves part of the organism itself, such as a shell, bone, tooth, cell wall, filament, leaf, spore or other biological structure. In microscopic fossils, the distinction can be especially difficult, because tiny tubes, filaments or marks in ancient rock may look like animal burrows but could instead be the fossilised remains of microbial colonies, algae or bacteria.

That distinction matters because a burrow implies an animal capable of moving through sediment. In Ediacaran rocks, that would suggest the presence of tiny, active invertebrates before the Cambrian, and would also imply environmental conditions, including oxygen levels, capable of supporting such animals.

The fossils reassessed in the Gondwana Research paper had previously been interpreted as possible traces left by tiny worm-like animals. However, using more advanced techniques, including microtomography, nanotomography and Raman spectroscopy, the researchers found evidence more consistent with fossilised communities of algae and bacteria than with animal burrows.

So the fossils have not become less interesting. They have become more accurately understood. They still record life in the late Ediacaran, around 540 million years ago, but they no longer provide secure evidence for active, burrowing meiofaunal animals at that time.

This is how science progresses: not by defending an interpretation because it is comforting or traditional, but by testing it against new evidence and replacing it when a better explanation fits the facts.

Publication of the paper in Gondwana Research was accompanied by a press release from FAPESP via its news agency, Agência FAPESP:

Microfossils interpreted as animal traces were actually algae and bacteria
New evidence and a reanalysis of 540-million-year-old material using advanced imaging techniques rule out the idea they were from worms or small oceanic animals.
By André Julião | Agência FAPESP – A reexamination of microfossils found in the Brazilian state of Mato Grosso do Sul shows that the marks previously interpreted as traces of worms or other small oceanic animals are actually communities of fossilized microscopic bacteria and algae.

These findings imply that during the Ediacaran period, approximately 540 million years ago, there may not have been enough oxygen for the evolution of invertebrates that left traces in the substrate, as previously thought. The study was published in the journal Gondwana Research.

"Using microtomography and spectroscopy techniques, we observed that the microfossils have cellular structures – sometimes with preserved organic material – consistent with bacteria or algae that existed during that period. These aren't traces of animals that may have passed through the area," says Bruno Becker-Kerber, the first author of the study. He conducted the study as part of his postdoctoral research at the Institute of Geosciences at the University of São Paulo (USP) and at the Brazilian Center for Research in Energy and Materials (CNPEM), with a fellowship from FAPESP.

Currently conducting postdoctoral research at Harvard University in the United States, Becker-Kerber explains that if the records were marks left by animals, it would imply the existence of meiofauna – invertebrates less than one millimeter in length – that were already quite active during the Ediacaran period. These would be the oldest animals of this type ever recorded.

This period precedes the Cambrian explosion, when increased oxygen levels in the environment enabled the evolution of complex organisms and the diversification of animal species. The presence of meiofauna is confirmed in the Cambrian fossil record.

The study is part of the "Rio de la Plata Craton and Western Gondwana" project, which is supported by FAPESP and coordinated by Miguel Angelo Stipp Basei. Basei is a professor at IGc-USP and an author of the study.

Lucas Warren, a professor at the Institute of Geosciences and Exact Sciences at São Paulo State University (IGCE-UNESP) in Rio Claro, is also among the authors. He is supported by FAPESP.

The reanalyzed fossils were found in the municipality of Corumbá, and the newly analyzed fossils were found in a rock outcrop in Bonito, in the Serra da Bodoquena region. Both cities are in the current state of Mato Grosso do Sul, where the Tamengo geological formation is located.

The rocks formed in a marine environment on the continental shelf during the final stages of the formation of the supercontinent Gondwana, which later gave rise to Africa and South America.

In another study, the group described the first known lichen in the fossil record, which was also found in Mato Grosso do Sul and is younger than the recovered bacteria and algae (read more at agencia.fapesp.br/57029).

Tomography

The MOGNO beamline at Sirius, the CNPEM particle accelerator in Campinas, made it possible to precisely examine such tiny fossils, which range in size from a few micrometers to a few millimeters.

There, the samples underwent micro- and nanotomography, which produces images on the scale of micrometers (one-thousandth of a millimeter) and nanometers (one-billionth of a meter), respectively.

When you have a large sample and want to image a structure inside it, the resolution obtained is often insufficient. The MOGNO beamline is one of the few in the world that performs so-called zoom tomography, in which we focus on something inside the sample and analyze it at the nanoscale without destroying the sample.

Dr. Bruno Becker-Kerber, lead author
Now at: Department of Organismic & Evolutionary Biology and Museum of Comparative Zoology
Harvard University
Cambridge, MA, USA.

[Dr Becker-Kerber] points out that the study suggesting the fossils were animal traces did not have access to this technology.

Zoom tomography highlights what are likely bacteria or algae, specifically a possible sulfur-oxidizing bacterium, which is a type of the largest existing bacteria.
Photo: Bruno Becker-Kerber/Harvard University

Other, more accessible techniques, such as Raman spectroscopy, revealed the organic composition of the cell walls of the fossils, for example. This information was essential to corroborate the hypothesis that the marks were body fossils.

Some samples contain pyrite, a mineral composed of iron and sulfur. Therefore, based on the shape of some of the fossils, one hypothesis is that they contain remnants of sulfur-oxidizing bacteria, a group that uses sulfur as part of its metabolism.

This group of bacteria is surprising. Some of the largest ever recorded belong precisely to this category. Unlike the common image we have of microscopic bacteria, certain species can reach diameters larger than a strand of hair and are visible to the naked eye.

Dr. Bruno Becker-Kerber.

Visible to the naked eye, fossilized bacteria or algae were found in an ancient seabed that emerged in the current Brazilian state of Mato Grosso do Sul
photo: Bruno Becker-Kerber/Harvard University

However, there are no preserved parts that would allow for a more precise species distinction, such as reproductive structures. Nevertheless, the fossils exhibit preserved cells, cell wall divisions, and organic remnants at the different sites where they were collected. This would not be possible with traces of animals that merely passed through the sediment.

There are concave and convex partitions, coiled filaments, cells without sediment but containing organic matter. This evidence is much closer to bacteria or algae than to mere marks of disturbance caused by animals.

Dr. Bruno Becker-Kerber.

Furthermore, the distribution of the fossils in the material indicates three distinct size categories, which suggests that they represent different species that may have lived in a microbial consortium. The larger population shares similarities with green or red algae, while the smaller populations may be algae, cyanobacteria, or sulfur-oxidizing bacteria.

These findings help paint a more accurate picture of the period leading up to the Cambrian explosion and provide further evidence that may help us better understand the conditions surrounding the event that transformed life on Earth.

Publication:
Becker-Kerber, Bruno; Archilha, Nathaly Lopes; Knoll, Andrew; et al.
Proposed Ediacaran meiofaunal burrows from Brazil are pyritized algal/microbial consortia
Gondwana Research (2026); 154, 335-347. DOI: https://doi.org/10.1016/j.gr.2026.01.011

Highlights

The oldest purported meiofauna are reinterpreted as pyritized filamentous organisms.
U–Pb radiometric dating chronologically links the fossiliferous horizons.
Cell morphology indicates a composite microbiota of eukaryotic algae and bacteria.

Abstract
The Ediacaran Period marks the first appearance of animal body fossils in the rock record. While the metazoan affinities of many late Ediacaran macrofossils are well established, their precise placement in the phylogenetic tree remains debated. Meiofaunal trace fossils potentially provide an alternative line of evidence for the presence of early branching bilaterian lineages, but their interpretation is complicated by their similarity with a range of different geological and biological structures. Here, we examine the oldest putative meiofaunal traces from the late Ediacaran (541 Ma) Tamengo Formation, Corumbá Group, Brazil, combining new material and a suite of analytical techniques to assess their morphology, spatial distribution, and preservation. Additionally, we report a newly discovered locality for these fossils, chronologically correlated with the classical outcrops in the Corumbá area through U-Pb radiometric dating of tuff zircons. Concordia ages obtained for the new locality are 544 ± 2.6 (LA-MC-ICP-MS) and 539.03 ± 2.27 Ma (LA-ICP-MS). Fossils from multiple localities exhibit features such as preserved cells, cell wall divisions, organic remains at cell walls, shared alignment, extreme diameter variations, and a lack of cross-cutting relationships. These characteristics are inconsistent with burrow-like trace fossils but are fully consistent with the interpretation as remains of pyritized filamentous organisms. The multimodal size distribution, with at least three distinct size classes, and their partial in-situ preservation further suggest that they represent different species, possibly living in a microbial consortium. While their exact biological affinities remain uncertain, the largest populations share similarities with benthic red or green algae, while the smallest populations could be algal, cyanobacterial or large sulfur-oxidizing bacteria. The preservation of these remains suggests that bioturbation, macrofaunal or meiofaunal, was limited or absent where and when these fossils formed.

Graphical abstract

Becker-Kerber, Bruno; Archilha, Nathaly Lopes; Knoll, Andrew; et al.
Proposed Ediacaran meiofaunal burrows from Brazil are pyritized algal/microbial consortia
Gondwana Research (2026); 154, 335-347. DOI: https://doi.org/10.1016/j.gr.2026.01.011

© 2026 Elsevier B.V.
Reprinted under the terms of s60 of the Copyright, Designs and Patents Act 1988.

Creationists may, of course, try to present this reassessment as another example of science being unreliable, but that only reveals how little they understand the process they are criticising. The earlier interpretation was not protected as dogma; it was tested. New techniques were applied, the evidence was re-examined, and a better-supported explanation replaced the old one. That is not a failure of science. It is exactly why science works.

What creationism offers, by contrast, is not a method for discovering truth but a mechanism for defending a conclusion already decided in advance. No fossil, no dating method, no microscopic structure and no chemical signature is allowed to mean what the evidence says it means if it conflicts with creationist dogma. In that sense, creationism cannot be corrected because it was never genuinely open to correction in the first place.

And yet, even this corrected interpretation still leaves creationism exactly where it was before — contradicted by the evidence. These were not animal burrows after all, but they were still biological structures produced by living organisms in rocks around 540 million years old. The conclusion has changed in detail, but not in the direction creationists would need. The fossils still belong to a world hundreds of millions of years older than creationist mythology allows.

So this is not a story about science being embarrassed by a mistake. It is a story about science doing what creationism cannot do: recognising uncertainty, revisiting evidence, using better tools, and improving its explanations. The result is not less knowledge, but more reliable knowledge — and another reminder that reality is not discovered by clinging to certainty, but by having the courage to change our minds when the evidence requires it.

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