10-million-year-old fossil reveals the bite force of piranhas' giant ancestor

A jawbone approximately 10 million years old found in Argentina has provided remarkable new clues regarding the evolutionary history of piranhas. The fossil, unearthed in the Paraná geological region, shows that the giant species known as “Megapiranha paranensis” had a much more extraordinary profile than modern piranhas in terms of both tooth structure and jaw strength.

In the jawbone examined by Alberto Cione, an expert from the La Plata Museum, it was determined that three large teeth were arranged in a zigzag pattern. This structure points to a transition between the single row of teeth in carnivorous piranhas and the double row of teeth seen in their herbivorous relatives.

According to the researchers, the tooth arrangement in the fossil suggests that the teeth in the second row may have shifted toward the front row over time. This feature has led to the Megapiranha being considered an evolutionary bridge between pacu fish, known for their human-like teeth, and carnivorous piranhas.

Measurements revealed that the species could reach a length of approximately 1 meter. This size places the Megapiranha as a much larger and more effective predator in South America's prehistoric rivers compared to today's piranhas.

Calculations compared with jaw simulations performed on black piranhas indicate that the Megapiranha may have reached a bite force of over 4,700 newtons. When proportioned to its own body weight, this value points to a jaw strength comparable to that of giant great white sharks.

For scientists, this fossil is not only the remains of a powerful predator; it also serves as a rare record regarding the tooth arrangement, feeding habits, and evolutionary divergence of piranhas.