Helenius

Helenius is a genus of large, extinct predatory fish that lived during the Devonian period. These ancient cartilaginous fishes are known for their distinctive, reinforced skulls, which may have served a defensive purpose or aided in their feeding habits. The most well-known species, Helenius antiquus, is characterized by a flattened body and a powerful jaw lined with sharp teeth. Fossil remains of Helenius have been found in various locations, primarily in Europe and North America, offering insights into the marine ecosystems of the Devonian.

These fish are classified within the Placodermi, an extinct class of armored fish that dominated the Devonian seas. Helenius, in particular, belongs to the order Arthrodira, a group of placoderms distinguished by a flexible joint between their head and shoulder armor. The exact diet and behavior of Helenius are subjects of ongoing scientific research, but its formidable dentition and robust build suggest it was an apex predator within its environment, likely preying on smaller fish and invertebrates. The discovery of Helenius fossils has been crucial for understanding the evolutionary history of jawed vertebrates and the diversification of early fish life.