A large frog that lived 68 million years ago was capable of eating small dinosaurs and had a bite as powerful as a wolf or female tiger, researchers have found.
Scientists studying the bite force of a similar genus that lives today — the horned frog of South America — collaborated with a team of paleontologists to determine that the ancient Beelzebufo frog could have preyed on early crocodilians and small non-avian dinosaurs.
Their findings have been reported in a new study published in the journal Scientific Reports.
To figure out just how much power was in that extinct frog’s bite, lead author Kristopher Lappin, a professor of biological sciences at California State Polytechnic University in Pomona, Calif., examined horned frogs — sometimes known as Pac-Man frogs for their large, wide mouths and round shape.
Lappin and his team are interested in how things scale in the animal world, including the peculiar phenomenon behind the power of the bite.
“Other work out there — on rodents, crocodiles — has shown that as the animal gets bigger it bites harder than it should be predicted to based on size,” said Lappin in an interview with CBC News.
Two of his co-authors on this study, Susan Evans and Mark Jones, had published a 2014 paper on their findings about the Beelzebufo frog.
After compiling bone fragments collected over a decade, the two confirmed the frog’s lineage and its closest relative in modern times, the Pac-Man-like horned frog.
Lappin saw an opportunity to use empirical data from a living animal to help his colleagues learn more about the ferocious ancient frog, sometimes called “the devil frog” or “the frog from hell.”
So, working with horned frogs of various ages over a period of nearly 10 years, the scientists used a custom-made device consisting of two plates covered with leather to measure the force of the frogs’ bites.
They found that small horned frogs can bite with a force equivalent to 30 newtons, or about three kilograms. A scaling experiment then calculated that the largest horned frog living today — the kind about the size of a dinner plate — would have 500 newtons, or around 50 kilograms, behind its bite.
Using the same scaling relationship, the scientists estimated that the Beelzebufo had a bite force of up to 2,200 newtons, or 220 kilograms, which is comparable to formidable predators from the mammal world, such as wolves or female tigers.
‘This animal is a biter’
But to arrive at these findings, how did the scientists get the Pac-Mac frog to bite on command in a laboratory setting?
Lappin refers to famed Danish physiologist August Krogh to explain: “He said that for every research question, there’s a perfect animal. This animal is a biter. They often won’t let go. They’ll try to swallow your finger.”
Simply holding the measuring device — called a transducer — in one hand and the frog in the other and giving the frog a light tap on the mouth was all it took to prompt that vise-like bite, said Lappin.
“The bite of a large Beelzebufo would have been remarkable; definitely not something I would want to experience firsthand.”