A groundbreaking discovery of a well-preserved Devonian coelacanth fossil in Western Australia has shed new light on the evolutionary history of these enigmatic deep-sea fish. The study reveals the profound impact of tectonic plate activity on the diversification of coelacanths, challenging the notion of them being ‘living fossils’.
The Story of a Fossil Fish
Findings of a particular ancient primitive Devonian coelacanth fish, which is more intact than any other find known to date have significantly changed our perspective on coelacanth evolution and comes from the remote Western Australia site.
This new fossil, called Ngamugawi wirngarri, has been added to the extensive list of ancient fish and invertebrates found at the Gogo Formation, and this makes it one of the most diverse and well preserved assemblages on Earth.
This finding by an international team of researchers from Flinders University, Canada, Australia and Europe has addressed an important gap in the transition from primitive coelacanths to more ‘anatomically modern’ forms. Through collaboration with the Mimbi community, the researchers of the new species were given a felicituos name in Gooniyandi,
Tectonics, Isotropy and Evolutionary Rates
The most tantalizing discovery is the connection between tectonic plates and the rise of coelacanths. What the researchers found was that new coelacanth species were more likely to evolve in times when tectonic activity was intensified, because new habitats would be both created and separated.
It included the movements of the Earth crust which influenced the evolutionary pathways these ancient fish would follow. In response to changes in the geography and environments of our planet, coelacanths diversified and evolved into many of the unique species we find in the fossil record.
Strikingly, even the few exceptions are much slower than a teleost’s, and they average to 9 times slower or 3.5 times slower with Gras-seq coverage ranging from 1e4 to 1e10 (Pancera et al., manuscript submitted). That biological transformation contradicts the widespread idea unit coelacanths were ‘living fossils’ that had held up since long hundred thousands of years.
Conclusion
The well-preserved Ngamugawi wirngarri fossil found in Western Australia has given a new look of how coelacanths could have evolved. The study links tectonic plate activity to the diversification of these ancient fish and challenges the idea of coelacanths as ‘living fossils’ – relics isolated from the rest of Earth’s organisms for an incredible amount of time. As we gradually unlock the history of the Gogo Formation and many other fossil-bearing localities, we are also peeling away layers that will eventually reveal even more secrets about how our planet’s rock record help to shape life on Earth.
