Ancient relative of 'living fossil' fish reveals that geological activity supercharges evolution

Primeval fish that were thought to be "living fossils," largely unchanged since the time of the dinosaurs, are actually evolving dramatically — and they evolved faster when Earth's continents moved faster, fossils of a newly identified coelacanth species have revealed.

The findings suggest that the large-scale movement of continents may spur the evolution of life, the researchers reported Thursday (Sept. 12) in the journal Nature Communications.

Coelacanths are large fish that evolved 410 million years ago. Once known only from fossils, they were thought to be extinct until a fisher in South Africa hauled one up in 1938. Biologists dubbed the modern coelacanth a "living fossil" and believed it had not evolved much over millions of years.

The two coelacanth species alive today, Latimeria chalumnae and Latimeria menadoensis, are more closely related to other early fish, such as lungfish, than they are to today's modern ray-finned fish.

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But now, new "bridge" fossils reveal that coelacanths never stopped changing. The fossils, beautifully preserved in three dimensions, are one of the best anatomical looks yet at coelacanth history. Combined with other coelacanth fossils, the discovery reveals that the more geologically active the environment was, the more evolutionary change the fish underwent.

"Somewhat surprisingly, plate tectonic activity had a strong iNFLuence on rates of evolution of coelacanths throughout their 400 million-year History," said study first author Alice Clement, an evolutionary biologist at Flinders University in Australia.