Several new species of coelacanths that lived at the end of the Triassic period, some 200 million years ago, have been identified from museum specimens unearthed over 150 years ago in the United Kingdom.
An artist’s reconstruction of a large mawsoniid coelacanth from the British Rhaetian. Image credit: Daniel Phillips.
Coelacanths are evolutionarily unique lobe-finned fishes that first appeared in the fossil record in the Early Devonian epoch, around 419 million years ago.
Over 175 fossil coelacanth species are known from throughout the Paleozoic and Mesozoic eras.
During the Mesozoic, they diversified significantly, with some species developing unusual body shapes.
However, at the end of the Cretaceous period, around 66 million years ago, they mysteriously disappeared from the fossil record.
It was presumed that coelacanths had been swept up as a casualty of the end-Cretaceous mass extinction event. But in 1938, the first specimen of the living species Latimeria chalumnae was caught fortuitously in South Africa.
“Our team realized that many fossils previously assigned to the small marine reptile Pachystropheus actually came from coelacanth fishes,” said University of Bristol’s Professor Mike Benton, senior author of the study.
“Many of the Pachystropheus and coelacanth fossils have uncanny similarities, but importantly, we then went off to look at collections around the country, and we found the same mistake had been made many times.”
“It is remarkable that some of these specimens had been sat in museum storage facilities, and even on public display, since the 1800s, and have seemingly been disregarded or identified as bones of lizards, mammals, and everything in-between,” said University of Bristol paleontologist Jacob Quinn, lead author of the study.
“From just four previous reports of coelacanths from the British Triassic, we now have over fifty.”
The paleontologists 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 one meter long, and suggesting a complex community at the time,” said Universidad de la República de Uruguay paleontologist Pablo Toriño, co-author of the study.
“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,” said co-author Dr. David Whiteside, a paleontologist at the University of Bristol.
“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.”
The study appears in the Journal of Vertebrate Paleontology.
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Jacob Quinn et al. 2025. Coelacanthiform fishes of the British Rhaetian. Journal of Vertebrate Paleontology 45: e2520921; doi: 10.1080/02724634.2025.2520921
