Piranhas have a reputation for being the menaces of the fish world. The name itself conjures up an image of a small but lethal villain, swimming through tropical waters with huge, sharp chompers protruding up from their lower jaw. If the modern-day piranha doesn’t strike fear into your heart, the ancient one sure will. Justin Grubich, biologist at the American University of Cairo, worked with a team of researchers on a study that analyzed the primitive ancestor of today’s piranhas, Megapiranha paranensis. More specifically, the study looked at this monster’s powerful bite. Mega-piranha gets its name from its size: this fish weighed 20 to 30 pounds. It hunted South America’s waters between 6 and 10 milllion years ago, during the Miocene era, when many reptiles and other animals were larger-than-life sized. Grubich and colleagues set out to discover just how powerful mega-piranha’s bite really was. In order to do this, they used the existing black piranha’s bite to model jaw power. The team had black piranha specimens, native to the Amazon, bite down on an instrument that measured the force of their bite. They determined that these 2-pound fish bit down with a force of 72 pounds-force, more than 35 times their body weight. They then used the model of the living black piranha to infer about the ancient mega-piranha, adjusting for body size and jaw structure that was revealed from fossils. The result: mega-piranha bit down with a force of 279 and up to 1,067 pounds-force, around 50 times their body weight! This was probably because their jaw muscles, like those of modern piranhas, were connected all along the jaw. Scientists think mega-piranha probably died out as a result of the rise of the Andes Mountains, which disconnected their habitats and left them with few resources to maintain their large body size. With a bite that powerful, maybe it’s not such a bad thing Megapiranha paranensis isn’t still around today!

Discover more at www.livescience.com.

The study is in the journal Nature.

Published On: January 8, 2013

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