Rosa Rubicondior: How Science Works - Expanding Our Knowledge of Coelacanth Evolution.

[Body]

Coelacanth, Latimeria chalumnae

Fraser, Michael D.; Henderson, Bruce A.S., et al (2020). CC BY 4.0, Link

Ancient fish was hiding in plain sight hundreds of years after its believed extinction, study shows - Taylor & Francis Newsroom

A recent re-examination of museum coelacanth fossils has shown that there was more than one taxon in the Late Triassic and that, where we believed there were just four specimens, there are actually more than fifty. These fossils were hiding in plain sight, mis-identified for decades in collections across Britain. This significantly expands the known diversity of coelacanths at that time and neatly illustrates how science continually refines and improves its understanding as new evidence and careful re-analysis emerge.

Coelacanths have long been a favourite talking-point for creationists, who seized on the 1938 discovery of living Latimeria — a lineage once known only from the fossil record and thought extinct — as supposed proof that evolution had somehow stalled. Because the modern species still carries the name “coelacanth”, they leap to the assumption that the fish has remained unchanged for over 200 million years, and therefore evolution must be false. I have even seen creationists claim that if coelacanths have “not evolved” in all that time, the Earth must therefore be only a few thousand years old. It’s an extraordinary logical contortion — and one born of misunderstanding both biology and evidence.

In reality, the modern coelacanth is not the same species as the ancient Triassic forms, nor is evolutionary change required to be dramatic or constant for every lineage. Species can remain broadly similar when their ecological niche remains stable — a concept perfectly consistent with evolutionary theory. What this study demonstrates, once again, is the iterative, self-correcting nature of science: questions are never closed, evidence is always open to re-examination, and conclusions adapt as new data emerges.

“Living Fossils” and Evolution — What Creationists Get Wrong. “Living fossil” is a casual term for species that appear broadly similar to ancient relatives in the fossil record — coelacanths, horseshoe crabs, gingko trees, etc. Creationists often claim these organisms “haven’t evolved”, and therefore evolution is false.

This argument fails for several reasons:

“Looks similar” ≠ “genetically identical” Morphology can remain stable even while genes, physiology, behaviour and ecology evolve. Coelacanths today are not carbon copies of their Triassic relatives — they are simply recognisably part of the same lineage.
Evolution is not a march to novelty Natural selection favours fitness, not change for its own sake. If an organism’s niche remains stable and its design works well, major alterations may not be favoured. Stability is sometimes the outcome of evolution, not a failure of it.
Extant species are not ancient species Modern “living fossils” are descendants, not time travellers. The original species went extinct; the lineage continued and diversified. Saying a coelacanth disproves evolution because it looks like an ancient coelacanth is like claiming modern crocodiles disprove mammals.
We see clear evolutionary history in the fossil record Coelacanth fossils alone show:

multiple extinct lineages
anatomical changes over time
branching diversification
long survival of the broader group

That’s exactly what evolutionary theory predicts.
“Living fossils” are evidence for evolution Long-lived lineages demonstrate:

evolutionary persistence under stable conditions
ecological success of certain forms
the deep time necessary for such persistence

In short:

A lineage surviving for millions of years does not refute evolution — it confirms it.

Creationists mistake conservation of form for absence of evolutionary change. Biology, fossils, and genetics all say otherwise.

The research, led by Jacob Quinn and colleagues from the University of Bristol and the University of the Republic in Montevideo, Uruguay, has just been published open access in the Journal of Vertebrate Palaeontology, accompanied by a news release from the journal’s publishers, Taylor & Francis.

Ancient fish was hiding in plain sight hundreds of years after its believed extinction, study shows
The modern coelacanth fish is a famous ‘living fossil’, long thought to have died out, but first fished out of deep waters in the Indian Ocean in 1938.
The modern coelacanth fish is a famous ‘living fossil’, long thought to have died out, but first fished out of deep waters in the Indian Ocean in 1938. Since then, dozens of examples have been found, but their fossil history is patchy. In a new study, published in the peer-reviewed Journal of Vertebrate Paleontology, Jacob Quinn and colleagues from the University of Bristol and University of Uruguay in Montevideo have identified coelacanths in museum collections that had been missed for 150 years.

The fossils identified in the new work date from the very end of the Triassic Period, some 200 million years ago, when the UK lay at more tropical latitudes.

During his Masters in Palaeobiology at Bristol, Jacob realised that many fossils previously assigned to the small marine reptile Pachystropheus actually came from coelacanth fishes. Many of the Pachystropheus and coelacanth fossils have uncanny similarities, but importantly, Jacob then went off to look at collections around the country, and he found the same mistake had been made many times.

Professor Michael J. Benton, corresponding author.
School of Earth Sciences
University of Bristol, Bristol, U.K.

It is remarkable that some of these specimens had been sat in museum storage facilities, and even on public display, since the late 1800s, and have seemingly been disregarded or identified as bones of lizards, mammals, and everything in-between, From just four previous reports of coelacanths from the British Triassic, we now have over fifty.

Jacob G. Quinn, lead author.
School of Earth Sciences
University of Bristol, Bristol, U.K.

Jacob made X-ray scans of many specimens to confirm the identifications. The specimens mostly belong to an extinct group of coelacanths, the Mawsoniidae, but closely related to the living fish.

Although the material we identify occurs as isolated specimens, we can see that they come from individuals of varying ages, sizes, and species, some of them up to 1 metre long, and suggesting a complex community at the time.

Pablo Toriño, co-author.
Instituto de Ciencias Geológicas
Departamento de Paleontología
Facultad de Ciencias,
Montevideo, Uruguay.

The coelacanth fossils all come from the area of Bristol and Mendip Hills, which in the Triassic was an archipelago of small islands in a shallow tropical sea, Like modern day coelacanths, these large fishes were likely opportunistic predators, lurking around the seafloor and eating anything they encountered, probably including these small Pachystropheus marine reptiles, which is ironic given their fossils have been confused with those of coelacanths for decades.

Dr David I. Whiteside, co-author
School of Earth Sciences
University of Bristol, Bristol, U.K.

Publication:
Quinn, J. G., Whiteside, D. I., Toriño, P., Matheau-Raven, E. R., & Benton, M. J. (2025).
Coelacanthiform fishes of the British Rhaetian.
Journal of Vertebrate Paleontology. e2520921 https://doi.org/10.1080/02724634.2025.2520921

ABSTRACT
Coelacanth fishes are well represented in the fossil record, ranging in age from the Early Devonian to the present day, though now represented by only two species of the genus Latimeria. After some diversification of form in the Early Devonian, the morphology of coelacanths remained relatively stable throughout the Mesozoic, with distinctive mawsoniid and latimeriid coelacanth morphologies established by the Late Jurassic. Coelacanth remains are well known from Paleozoic and Cretaceous rocks in Britain but poorly known from the Late Triassic. Recently, it was shown that many isolated coelacanth bones from the Rhaetian (latest Triassic) bonebeds had been misidentified as elements of the enigmatic thalattosaur Pachystropheus rhaeticus. We further identify a number of coelacanth bones, primarily from the skull, providing descriptions of each for the first time. For some bones, we describe numerous morphotypes, suggesting more than one taxon was present. Most specimens pertain to Mawsoniidae, while others may be assignable to Latimeriidae or are indeterminate coelacanths. We highlight taxonomic misidentifications to show that coelacanth specimens from the British Rhaetian have been confused as far back as the late 1800s. Numerous morphotypes of many bones in the sample hint at a complex community structure, with individuals of varying age, size, and likely several species, supported within the ecosystem. The fossil occurrences suggest these Triassic coelacanths preferred shallow water environments, matching our observation that many specimens pertain to Mawsoniidae, a clade elsewhere reported from brackish, near-shore conditions. In light of recent findings, the new specimens reinforce a European Triassic diversification for Mawsoniidae, which probably influenced their subsequent diversification and dispersion during the Jurassic.

INTRODUCTION
Coelacanth fishes are known from a range of fossils, as well as two living species of the genus Latimeria, the first discovered off the east coast of Africa in 1938, and the second in the western Pacific in 1998 (Clement et al., 2024; Forey, 1998, 2009). After some early divergence in form as the coelacanths split from other osteichthyans in the Early Devonian, the body plan of coelacanths remained relatively stable throughout the Mesozoic, especially from the Late Cretaceous onwards (e.g., Cavin et al., 2021; Clement et al., 2024; Ferrante & Cavin, 2023; Forey, 1998; Friedman & Coates, 2006; Toriño, et al., 2021.1a). Still, the living Latimeria is a popular classic example of a “living fossil” (e.g., Forey, 2009).

Morphological diversity peaked along with increased speciation in the Early Triassic (Cloutier, 1991a, 1991.1b; Cloutier & Forey, 1991.2; Forey, 1991.3, 1998; Toriño et al., 2021.1a; Wen et al. 2013), though it has been argued that coelacanths displayed little morphological disparity at that time (Schaeffer, 1952). After this peak, coelacanth diversity then declined through the Middle to Late Triassic before stabilizing (Clement et al., 2024; Ferrante & Cavin, 2023). From the Late Triassic to the Late Cretaceous, the dominant coelacanths were two lineages of Latimerioidae (Cavin et al., 2019, 2021): Latimeriidae, including the extant Latimeria, are regarded as marine, deep-water fish, while Mawsoniidae are considered to be brackish or freshwater fish (Cavin et al., 2021; Cupello et al., 2016).

In the U.K., coelacanths are well known from the Paleozoic and Cretaceous (Forey, 1998). Further, coelacanths are prominent in the Triassic of Europe, America, and China (Clement et al., 2024). Despite this rich fossil record, specimens of coelacanths are poorly known in the Late Triassic of Britain, being described from scant and isolated material, including four quadrate bones and a single gular plate of an indeterminate coelacanthiform (Allard et al., 2015; Duffin, 1978:fig. 7; Duffin, 1999:fig. 8; Hauser & Martill, 2013.1; Moreau et al., 2021.2). In a recent study of the enigmatic thalattosaur Pachystropheus rhaeticus, Quinn et al. (2024.1) recognized that some appendicular bones and the only cranial element of the reptile had been incorrectly identified, and instead belong to coelacanths. Here we describe these elements, including further materials rediscovered in collections, as well as those previously reported, to create a comprehensive description of all known coelacanth material from the British Rhaetian.

Quinn, J. G., Whiteside, D. I., Toriño, P., Matheau-Raven, E. R., & Benton, M. J. (2025).
Coelacanthiform fishes of the British Rhaetian.
Journal of Vertebrate Paleontology. e2520921 https://doi.org/10.1080/02724634.2025.2520921

Copyright: © 2025 The authors.
Published by Informa UK Ltd (Taylor & Francis Group). Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

What this discovery ultimately highlights is the strength of the scientific method. Even long-established assumptions are open to revision when new evidence emerges, and no conclusion is sacrosanct simply because it is familiar. That is why evolutionary biology has grown stronger over time, not weaker: it is grounded in testable evidence, not fixed dogma. The increasing diversity of known coelacanth fossils does not undermine evolution — it enriches our understanding of it.

By contrast, creationist arguments about “unchanged” species rely on a fundamental misunderstanding of how evolution works and a refusal to engage with evidence that does not fit a predetermined narrative. Mistaking a lineage for a species, equating superficial similarity with genetic stasis, and ignoring ecological context are not scientific critiques; they are symptoms of an argument built to defend belief, not uncover truth.

Coelacanths have survived because they were well adapted to their environments, not because time stopped for them. Their story is one of persistence, divergence and deep evolutionary history — a history written in stone long before anyone imagined trying to deny it. As long as fossils continue to be re-examined with fresh perspectives and rigorous methods, our picture of life’s past will only become clearer. And each such discovery reminds us that science progresses by questioning itself — something creationism has never been willing, or able, to do.

Advertisement

Amazon