Image: Nobu Tamura/Wikimedia Commons
Poison aside, frogs are generally weak and pathetic. Dinosaurs, meanwhile, range from weak and pathetic to huge and strong, so I'm going to say they're generally "not weak." But 70 million years ago, things were different. Extinct species of frogs like the Beelzebufo ampinga grew to be ten pounds in size. Maybe they even ate the weakest dinosaurs.
A team of British, Australian and American scientists realised that these days, frogs generally aren't known for their jaw strength. But one species of South American horned frogs, Ceratophrys cranwelli, is especially aggressive and can eat animals its own size. So, thought the researchers, using the C. cranwelli frog as a model, maybe they could estimate how strong of a bite the extinct Beelzebufo had. If you're not familiar with the Beelzebufo, or "devil frog," it lived in Madagascar around 65 to 70 million years ago, and it was huge, according to a Nat Geo fact sheet. Scientists already thought that it ate some crazy stuff based on its size, but quantifying the strength of its bite could give researchers a better understanding of its culinary preferences.
A South American horned frog Image: Kristopher Lappin
And indeed, the researchers learned that Beelzebufo's bite was strong. Very strong. "Our recovered scaling relationship suggests that exceptionally large... extinct giant frogs (Beelzebufo ampinga, Late Cretaceous of Madagascar) probably could bite with forces of 500 to 2200 [Newtons], comparable to medium to large-sized mammalian carnivores," they write in a paper published today in the journal Scientific Reports.
The researchers began by trying to understand the bite of their extant analogue to the extinct frog. They sampled eight C. cranwelli frogs ranging in mass from nine to 148 grams, and made the subjects bite a "force transducer," a fancy name for a pair of bars with soft leather on the ends that measured bite force. Here's a picture of that:
Image: Lappin et al, Sci. Rep (2017)
I like science a lot.
Anyway, the researchers had the frogs do a lot of biting, then compared the bite force to the frog's head width. They put that data into a computational model that spits out forces for a given head width, and found that a frog with a 154 millimetre (six inch)-wide head like the Beelzebufo would bite with a force of 2213.7 Newtons, almost 227kg of force. Wikipedia tells me that the average force of a human bite at the molar is about a third that number.
You probably want to know what these frogs ate -- the researchers had a guess. "Given that prey size is known to increase with body size in a variety of tetrapods, and that Beelzebufo clearly had the ability to bite with considerable force, large individuals would have been able to prey upon a variety of contemporaneous taxa, including small/juvenile crocodiles and non-avian dinosaurs."
This is, of course, simply an estimate of the frog's bite force. The paper points out that, well, the extinct Beelzebufo frog might have had a different jaw muscle setup and skull shape. "Therefore, our estimates of its bite-force performance should be received with caution, as should be the case with any such estimate." I've also passed the paper on to other researchers to see what they might have to say on the matter.
I consider myself thankful that I was born a human in the present age and not some other animal 70 million years ago. This frog does not seem like one I'd be interested in sharing a habitat with.