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A new species of coelacanth fish from western Australia challenges the notion that they are the oldest living fossils.
A live recreation of the Ngamugawi wirngarri coelacanth in its natural habitat. Credit: Illustration Katrina Kenny (courtesy of Flinders University)
Asteroids and climate change have been linked to animal origin and extinctions in the past, and plate tectonics also now seems to play a role in evolution, a new study suggests.
The study, published in the journal Nature Communications, described an amazingly well-preserved primitive Devonian coelacanth fish from remote western Australia linked to heightened tectonic activity.
New fossil specimen
The study was led by Flinders University and experts from Australia, Canada and Europe. The fossil from the Gogo Formation in WA has been named Ngamugawi wirngarri, and helps to fill gaps in a transition period in coelacanth history between its most primitive forms and more modern forms.
“We are thrilled to work with people of the Mimbi community to grace this beautiful new fish with the first name taken from the Gooniyandi language,” said first author Dr Alice Clement, an evolutionary biologist and palaeontologist from Flinders University. “Our analyses found that tectonic plate activity had a profound influence on rates of coelacanth evolution. Namely that new species of coelacanth were more likely to evolve during periods of heightened tectonic activity as new habitats were divided and created.”
The study confirms that the Gogo Formation is one of the richest and best-preserved assemblages of fossil invertebrates and fishes in the world.
Ngamugawi wirngarri coelacanth skull bones. Credit: J Long (Flinders University)
Flinders University’s Strategic Professor of Palaeontology John Long said the specimen, dating from the Devonian Period 359-419 million years ago, “provides us with some great insight into the early anatomy of this lineage that eventually led to humans. For more than 35 years, we have found several perfectly preserved 3D fish fossils from Gogo sites which have yielded many significant discoveries, including mineralised soft tissues and the origins of complex sexual reproduction in vertebrates. Our study of this new species led us to analyse the evolutionary history of all known coelacanths.”
Parts of human anatomy originated during the Early Palaeozoic, 540-350 million years ago when jaws, teeth, chambered hearts and paired lungs among others all appeared within early fishes.
“While now covered in dry rocky outcrops, the Gogo Formation on Gooniyandi Country in the Kimberley region of northern Western Australia was part of an ancient tropical reef teeming with more than 50 species of fish about 380 million years ago. We calculated the rates of evolution across their 410 million-year history. This revealed that coelacanth evolution has slowed down drastically since the time of the dinosaurs but with a few intriguing exceptions.” Said the team.
Modern lives of coelacanth
Today the coelacanth is a deep-sea fish which lives off the coast of eastern Africa and Indonesia and can grow to be 2 metres long. They are ‘lobe finned’ fish, meaning they have robust bones in their fins. Because of this, they are considered to be more closely related to lungfish and tetrapods than other fish.
175 species of coelacanths have been discovered over the last 410 million years. During the Mesozoic Era coelacanths diversified significantly, with some developing unusual body shapes. Though, at the end of the Cretaceous Period around 66 million years ago coelacanths disappeared from the fossil record.
The End Cretaceous mass extinction event, triggered by an asteroid impact, killed 75% of all life on the planet. So, it was thought that coelacanths were another victim of this event. But in 1938, people fishing off South Africa caught a large, strange looking fish from the depths, a coelacanth.
Senior co-author and vertebrate palaeontologist Professor Richard Cloutier from the University of Quebec says that this new study will challenge the idea that coelacanths are the oldest living fossils.
“They first appear in the geological record more than 410 million years ago, with fragmentary fossils known from places like China and Australia. However, most of the early forms remain poorly known, making Ngamugawi wirngarri the best-known Devonian coelacanth.” Said Professor Cloutier. “As we slowly fill in the gaps, we can start to understand how living coelacanth species of Latimeria, which commonly are considered to be ‘living fossils,’ actually are continuing to evolve and might not deserve such an enigmatic title.”
Source of the news:
Clement, A.M., Cloutier, R., Michael, L., King, B., Vanhaesebroucke, O., Corey, Dutel, H., Trinajstic, K. and Long, J.A. (2024). A Late Devonian coelacanth reconfigures actinistian phylogeny, disparity, and evolutionary dynamics. Nature Communications, [online] 15(1), pp.1–13.
doi:https://doi.org/10.1038/s41467-024-51238-4.