A new fossil discovery in China has given new insights into an apex predator from 425 million years ago.

The newly described bony fish, named Megamastax amblyodus, had weird clusters of teeth which uncover a critical step in the evolution of bony fish.

Dr Brian Choo, a Flinders University Postdoctoral Fellow in Vertebrate Palaeontology, says this long extinct predatory fish was an ancient forerunner of all animals with a skeleton and a backbone alive today.

“We believe this was the world’s oldest known vertebrate apex predator that lived at the top of the food chain in its environment,” he writes in The Conversation.

“Roughly 425 million years ago, in the warm seas over what is now southern China, there lived a metre-long bony fish with jaws full of clusters of spiky teeth.

“This fossil gives us an unprecedented view into the early evolution of bony fishes, and fills a key gap in our understanding of the evolution of vertebrate diversity seen on Earth today.”

The research published in Nature this week described the findings from a collection of fossils dating back to the Silurian period (around 444 to 419 million years ago).

Pre-Devonian (beyond around 419 million years ago) fossils are rare, and many early specimens are fragmented and incomplete. New fossil materials from two sites in southwestern China help to improve the understanding of the sequence of early evolutionary steps that shaped the osteichthyan lineage.

Bony fish are known as osteichthyans. They make up around 98% of all vertebrate species on Earth.

Researchers say the largest jaw of the Megamastax would have been 17cm long when complete, suggesting an animal roughly 1 metre long that was – and still is – the largest known jawed fish from the Silurian period.

While there were sharp, conventional teeth on the biting margins of the mouth, the inner surface of the lower jaw displayed a row of big semicircular “lumps” unlike anything seen before.

The new research, led by the Institute of Vertebrate Paleontology and Paleoanthropology in China, also includes descriptions of one of the oldest-known articulated bony fish, named Eosteus chongqingensis.

Acknowledgements: The Megamastax research was supported by the Open Research Program of the International Research Center of Big Data for Sustainable Development Goals (CBAS2023ORP01), the National Science Foundation of China (42130209, 92255301) as well as a Wallenberg Scholarship.