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Megapiranha put T. rex’s bite to shame, says study

Tyrannosaurus rex and megalodon, a gigantic shark that preceded the great white, have nothing on the black piranha and the extinct megapiranha when it comes to chomping power. Researchers at George Washington University report that, relative to its size, the megapiranha bite was more powerful than T. Rex and history’s largest shark. According to the study published in Scientific Reports, the black piranha was determined to have a biting force behind its powerful teeth of up to 320 Newtons.

“Comparisons of body size-scaled bite forces to other apex predators reveal S. rhombeus and M. paranensis have among the most powerful bites estimated in carnivorous vertebrates. Our results functionally demonstrate the extraordinary bite of serrasalmid piranhas and provide a mechanistic rationale for their predatory dominance among past and present Amazonian ichthyofaunas,” the authors write in their study.

In 2010, Guillermo Ortí, the George Washington University Louis Weintraub Professor of Biology in the Columbian College of Arts and Sciences, and his colleagues journeyed to the Xingu and Iriri rivers in Amazonia to collect data on the piranhas.

Mr. Ortí and his colleagues argue that the piranhas’ aggressive nature, small body size and easy-to-access populations make them a great group of predatory vertebrates in which to examine the evolution of powerful chomping capabilities. Researchers believe that piranhas will attack and rip chunks of fins and flesh from prey regardless of size. Prior to this study, however, no data on the piranhas biting powers was available for researchers to use.

Researchers gathered the first bite-force measurements from wild specimens of the black piranha. Using these measurements, they were able to better understand the fundamental functional morphology of the jaws that gives the black piranha the ability to chomp down on its prey with a force that is more than 30 times greater than its weight. Researchers contend that this powerful biting force comes from the large muscle mass of the black piranha’s jaw and the deft transmission of its big contractile force through a modified jaw-closing lever.

Researchers believe that the ancient megapiranha shared a common trait with black piranhas: An extremely powerful bite. They reconstructed the bite force of the megapiranha and found that, despite its small body size, the chomping power of this extinct piranha was more powerful than that of megalodon.

“Bite simulations using a bronze-alloy metal replica of the M. paranensis jaw fossil were conducted to examine the potential for comminution of bony materials. These indentation trials tested the fossil teeth’s ability to penetrate ecologically relevant bony prey of varying thickness. Using the predicted bite force range, Megapiranhas teeth penetrated the thick cortical layer (5.94 mm) of a bovine femur in a primarily linear fashion generating piercing indentations from 1.0–2.3 mm deep. Further simulation tests on aquatic turtle carapace and dermal scales from armored catfishes repeatedly resulted in catastrophic punctures at much lower bite forces,” the researchers write.

The entire expedition was filmed by National Geographic. At the conclusion of the expedition, the National Geographic Channel aired a program called Megapiranha, in which the expedition and the extinct giant piranha were discussed.

“It was very exciting to participate in this project, travel one more time to the Amazon to be able to directly measure bite forces in the wild,” said Mr. Orti in a statement. “I learned a lot of biomechanics from my colleagues while collecting valuable specimens for my own research.”

The study’s findings are described in detail in a paper recently published in the journal Scientific Reports. The paper, entitled “Mega-Bites: Extreme Jaw Forces of Living and Extinct Piranhas,” explores the piranhas’ specialized jaw morphology, which helps them attack and take chunks of flesh out of much bigger prey.