Scientists say that a large, now extinct, frog called Beelzebufo that lived about 68 million years ago in Madagascar would have been capable of eating small dinosaurs.

The conclusion comes from a study of the bite force of South American horned frogs from the living genus Ceratophrys, known as Pacman frogs for their characteristic round shape and large mouth, similar to the video game character Pac-Man. Due to their attractive body colouring, voracious appetite, and comically huge heads, horned frogs are very popular in the international pet trade.

Published in the Nature journal Scientific Reports, the scientists from University of Adelaide, California State Polytechnic University  Pomona, University of California  Riverside and UCL, University College London found that living large South American horned frogs have similar bite forces to those of mammalian predators.

The study found that small horned frogs, with head width of about 4.5cm, can bite with a force of 30 newtons (N) or about 3 kg or 6.6 lbs. A scaling experiment, comparing bite force with head and body size, calculated that large horned frogs that are found in the tropical and subtropical moist lowland forests of South America, with a head width of up to 10 cm, would have a bite force of almost 500 N. This is comparable to reptiles and mammals with a similar head size.

Based on their scaling relationship, the scientists estimated the bite force of the giant extinct frog Beelzebufo which is in many ways similar to living horned frogs may have had a bite up to 2200 N, comparable to formidable mammalian predators such as wolves and female tigers.

The scientists measured bite force using a custom-made force transducer, a device which accurately measures the force applied to two plates covered with leather when an animal bites them.