New discovery of 380 million year old giant fish fossil

The ginkgo tree, the nautilus (a mollusk), and the coelacanth are not biologically related, but part of their evolutionary history is strikingly similar: these creatures are known as 'living fossils.' In other words, they appear to have escaped the changes that normally occur over time, through evolution.

For the past 85 years, the coelacanth has been called a "living fossil" because it recalls the age of dinosaurs. These fish belong to the dorsal fin fish group , a group that also includes lungfish (fish with lungs) and tetrapods.

Few vertebrates arouse as much curiosity as the coelacanth, both because of the fascinating story of its discovery and because of its status as a "living fossil ". Moreover , only two species of coelacanth have survived this long evolutionary process , and they are now threatened with extinction.

The coelacanth Ngamugawi wirngarri in a Devonian coral reef habitat. (Photo: Katrina Kenny)

Big Discovery in Western Australia

Using the latest technological advances and innovative analytical methods available, scientists are working to better understand the evolution of these fascinating species, often referred to as 'living fossils,' and the 410 million-year evolutionary history of coelacanths.

The study, published in the journal Nature Communications, identified and described the fossil of a 380-million-year-old extinct coelacanth discovered in Western Australia.

These remarkably well-preserved fossils come from a crucial transitional period in the long evolutionary history of this fish and are the result of an international collaboration between researchers affiliated with institutions in Canada, Australia, Germany, the United Kingdom and Thailand.

Charles Darwin was the first to use the phrase 'living fossil' in his 1859 book On the Origin of Species, referring to living species that he considered 'unusual' compared to other species at the time. Although the concept was not clearly defined in Darwin's time, it has been adopted by hundreds of biologists since then. However, the term ' living fossil' remains a subject of debate within the scientific community.

More than 175 species of fossil coelacanths lived between the Lower Devonian period (419 to 411 million years ago) and the Late Cretaceous period (66 million years ago). In 1844, Swiss paleontologist Louis Agassiz identified a specific group of fossil fish, which he named the order Coelacanths.

For nearly a century, it was thought that the coelacanth went extinct at the end of the Cretaceous period, about 66 million years ago. During this time, nearly 75 percent of life on Earth became extinct, including most of the dinosaurs.

Then, on December 22, 1938, Marjorie Courtenay-Latimer, curator of the East London Museum in South Africa, received a call from a fisherman who had caught a rare and strange fish. She recognized it as an unknown species and contacted South African ichthyologist (fish biologist) JLB Smith, who confirmed that it was indeed the first living coelacanth ever observed.

In 1939, Smith named the species Latimeria chalumnae, also known as gombessa. Since then, the species, found along the east coast of Africa near the Comoros Islands, in the Mozambique Channel and off the coast of South Africa, has attracted considerable scientific interest.

In 1998, a second living species of coelacanth, Latimeria menadoensis (known as ikan raja laut, king of the sea, in Indonesian) , was discovered off the island of Sulawesi, Indonesia. The two species are the sole survivors of an ancient lineage that appears to have evolved very little in the last few million years.

After the discovery of Latimeria chalumnae, coelacanths were considered vertebrates whose body shape changed little over time, suggesting slow evolution.

To date, more than 50 species of fossil fish have been identified at Gogo. This diverse group of fish, along with marine invertebrates, lived together in the warm Devonian reef some 380 million years ago.

The latest research shows that coelacanths evolved rapidly early in their history , during the Devonian period, but this evolution slowed down thereafter. Evolutionary innovations virtually ceased after the Cretaceous period, suggesting that for some traits, coelacanths, such as Latimeria, appear to be frozen in time. The slow evolution of coelacanths suggests that they are not 'living fossils' but rather the result of a complex evolutionary process .