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Newly Discovered Coelacanth Fossil In Australia Shifts Our Understanding of Evolutionary Forces

Coelacanth off Pumula on the KwaZulu-Natal South Coast, South Africa.
Coelacanth off Pumula on the KwaZulu-Natal South Coast, South Africa. Image by Bruce A.S. Henderson, CC BY 4.0 https://creativecommons.org/licenses/by/4.0, via Wikimedia Commons

Coelacanths once thought to be extinct, have resurfaced in the modern world. Recently, researchers have uncovered the most pristine coelacanth fossil ever found, dating back hundreds of millions of years. And with it bubbled up new clues about how geological forces shape the creation of new species. 

The Rediscovery of Coelacanths

Sideview of most complete coelacanth fossil.
Sideview render of most complete coelacanth fossil. Screenshot from A Devonian coelacanth (Ngamugawi) skull reconstruction video Source: YouTube, Uploaded: Dr Alice Clement

Coelacanths are deep-sea fish that were thought to have disappeared from the Earth’s watery depths for millions of years. It wasn’t until 1938 that they resurfaced in a South African fisherman’s net when one was caught by accident. The fish’s reemergence was like discovering a live dinosaur in the present era which earned coelacanths the title of “living fossils.” 

Coelacanths Are Quite Boney

Petcoral fin of a Coelacanth (Latimeria chalumnae)
Petcoral fin of a Coelacanth (Latimeria chalumnae) from the Muséum national d’histoire naturelle (Paris, France). Image by © Citron via Wikimedia Commons

Coelacanths are a truly unique group of fish. They belong to a group of “lobe-finned” fish. This means their fins have a bone structure that’s surprisingly similar to human arms. In fact, they’re more closely related to tetrapods—four-limbed creatures like humans and frogs—than to most other fish! These living fossils have survived multiple mass extinctions, dating back over 410 million years. However, much of their ancient history remains shrouded in mystery due to fragmented fossil records.

Finding Prehistoric Nemo

Western Australia
Western Australia. Image by MODIS Land Rapid Response Team, NASA GSFC, Public domain, via Wikimedia Commons

This recent discovery in Western Australia has changed the current flow of coelacanths ancient history. The exceptionally well-preserved fossilized remains, found in the Gogo Formation, date back to the Devonian Period, approximately 380 million years ago. Named Ngamugawi wirngarri, the species was honored with a name in the local Gooniyandi language meaning  “ancient fish.” This fossil reveals new details about the anatomy and evolution of coelacanths.

City of Fish Diversity

Model-based reconstruction of life on an ancient seafloor during the Devonian Period
Model-based reconstruction of life on an ancient seafloor during the Devonian Period – the “Age of Fishes”. Image by James St. John, CC BY 2.0 https://creativecommons.org/licenses/by/2.0, via Wikimedia Commons

The fossil site where Ngamugawi wirngarri was found used to be a tropical reef home to a large fish society. More than 50 species of fish were citizens of these ancient waters! But this discovery tells us about how coelacanths in particular adapted to different environments in this ecosystem over millions of years.

Tectonically Driven Evolution

Tectonic plates movement
Tectonic plates movement. Image by USGS/Modified by Eurico Zimbres, Public domain, via Wikimedia Commons

It turns out, earthquakes might not just shake the ground – they could also shake up evolution! Researchers found that tectonic plate movements played a big role in the development of coelacanths. They say while factors like ocean temperature and oxygen levels were considered, they were less impactful. Instead, periods of heightened seismic activity appeared to coincide with the rise of new coelacanth species. Based on tectonic shift theory, evolutionary adaptations were prompted by changes in habitat caused by plate movements. No, not your dinner plate movements!

A Shaky Evolutionary Timeline

Top view of most complete coelacanth fossil.
Top view of most complete coelacanth fossil. Screenshot from A Devonian coelacanth (Ngamugawi) skull reconstruction video Source: YouTube, Uploaded: Dr Alice Clement

As the saying goes, slow and steady wins the race. For most of their 410-million-year history, coelacanths have evolved at a leisurely pace. But there were a few times when things got a little more exciting. These periods of rapid evolution often coincided with major geological events. The fossil record shows over 175 different coelacanth species, with new forms popping up during times of tectonic upheaval. I guess Earth just felt like shaking things up!

Found Here, There And Everywhere

Fossil of indeterminate Coelacanth from the Late Jurassic Fossil Lagerstätte of Painten
Fossil of indeterminate Coelacanth from the Late Jurassic Fossil Lagerstätte of Painten. Image by Dean Falk Schnabel, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons

Fossil evidence of coelacanths has been found worldwide. From Africa to Europe and even Antarctica, their global distribution shows just how adaptable coelacanths were. They could thrive in so many diverse environments. Unbothered by mass extinctions and drastic climate changes, they are one of the most resilient species in history. Despite their slow evolutionary rate, they managed to persist where many others perished. 

The End of Their Era

Preserved specimen of chalumnae
Preserved specimen of chalumnae, known as Coelacanth, in the Natural History Museum, Vienna, Austria. Image by Alberto Fernandez Fernandez, CC BY-SA 3.0 http://creativecommons.org/licenses/by-sa/3.0/, via Wikimedia Commons

By the end of the Cretaceous period, coelacanths seemingly vanished from the fossil record. We thought the disappearance was likely linked to the impact of the asteroid that wiped out the dinosaurs. Scientists long believed coelacanths were just another number amongst the body count. But then these fish had a surprising face reveal in the 20th century! Their sudden reappearance shows they were far more resilient than once thought.

Undead or Just a Living Fossil

Coelacanth off Pumula on the KwaZulu-Natal South Coast, South Africa.
Coelacanth off Pumula on the KwaZulu-Natal South Coast, South Africa. Image by Bruce A.S. Henderson, CC BY 4.0 https://creativecommons.org/licenses/by/4.0, via Wikimedia Commons

When you think of a “living fossil”, a creature stuck in a time warp, unchanged for millions of years, may come to mind.  But coelacanths are more than just relics of the past. While they’ve kept many of their ancient traits, they’re not the same as their prehistoric ancestors. Subtle differences in their DNA and body proportions show they are still evolving. Although it is happening at a snail’s pace.

The Modern-Day Coelacanths

Coelacanth scale pattern up close.
Coelacanth scale pattern up close. Screenshot from Coelacanths, Living Fossils of the Sea, Source: YouTube, Uploaded: Natural World Facts

Today, there are two living species of coelacanth: Latimeria chalumnae and Latimeria menadoensis. They are found off the coasts of Africa and Indonesia. Like a teenager compared to their grandma, these species only look similar to their ancient ancestors. When you look at a genetic analysis you’ll notice they have evolved in unique ways. These modern coelacanths offer a living window into an ancient lineage that helps scientists better understand their long evolutionary history as well as their future ahead.

Tectonic Plate Transformations

Volcanic Eruption.
Volcanic Eruption. Image by ISS Crew Earth Observations experiment and the Image Science & Analysis Group, Johnson Space Center., Public domain, via Wikimedia Commons

New species of coelacanths often appeared during times of high tectonic activity, such as earthquakes and volcanic eruptions. Maybe that’s why students transform into new Redbull-infused species during intense test periods! So looking at this study of coelacanths it’s likely our shifting landscape can drive evolutionary change for other species besides coelacanths as well. By understanding these connections it can help us see evolution beyond a biological process unaffected by the changes of Earth.

Future Fish Tales

Marjorie Courtenay-Latimer and coelacanth after its discovery in South Africa
Marjorie Courtenay-Latimer and coelacanth after its discovery in South Africa. Image by Public domain, via Wikimedia Commons

Ngamugawi Wirngarri has opened up a whole new chapter in the coelacanth saga. Scientists are now focusing on how geological events have shaped their evolution over millions of years. By exploring new fossil sites and revisiting old ones we may reveal even more about how these fascinating fish survived longer than dinos and most modern-day marriages.

In Short

Two foot long Coelacanth swimming along the South African coast.
Two foot long Coelacanth swimming along the South African coast. Screenshot from Coelacanths, Living Fossils of the Sea, Source: YouTube, Uploaded: Natural World Facts

Plate tectonics, the Earth’s shifting plates, have played a major role in shaping species. It’s like a giant game of species greeting Jenga! Coelacanths, both ancient, modern, and critically endangered, continue to surprise and inform us about the complex relationship between our planet’s geology and the evolution of life. But one has to wonder where these fish went into hiding. Tell me your guess in the comments.

YouTube video
A Devonian coelacanth (Ngamugawi) skull reconstruction video. Source: Youtube, Uploaded: Dr Alice Clement