World’s Deadliest Frog… Ever!

Beezelbufo hunting a juvenile Masiakasaurus - artwork by Gustavo Monroy for Fossil Crates

 

Photo of Beelzebufo skeleton from Triebold Paleontology Inc., used with permission

As if small Late Cretaceous (70 mya) Madagascar animals didn’t have enough to worry about when trying to get a drink of water from the local pond, what with Mahajangasuchus, a fearsome crocodile relative, Masiakasaurus, a toothy bipedal dinosaur with bizarre teeth jutting from the tips of its jaws, and Majungasaurus, the apex predator “T. rex” of its day, add the world’s deadliest frog to the list of potential creatures that might eat it. 

Beelzebufo means “Devil toad,” so named because of its fearsome carnivorous capabilities and its overall similarities to certain toads of today.  This Madagascar titan weighed over 7 lbs and exceeded 9” snout-to-vent (=SVL, the measurement used by frog researchers to discuss body length).  The “top frog” on the island today, Mantidactylus guttulatus,  is only 4” long, relatively slender, and weighs mere ounces.

Though formally named in 2008 by a multidisciplinary team of scientists (Evans et al. 2008), the first of its bones was discovered in 1993 by Dr. David Krause and his team of paleontologists.  Its formal name is Beelzebufo ampinga, "Devil toad, shield," with Beel'zebul being a Greek term for a Devil and bufo meaning toad because it is thought to have resembled toads of today.  Ampinga means shield, named for the "cranial hyperossification" (I love that term!), which is paleontologist-speak for the thick, massive bones on its head.  It lived in the Maevarano Formation of Madagascar 70 million years ago.

Size

The table below shows how Beelzebufo stacks up in the length (SVL), weight, and skull width game against the largest frogs alive today.  Beelzebufo, at an estimated weight of 7 lbs, ties with the Goliath frog as the heaviest frog ever!  These two giants leapfrog by 40%, the next heaviest extant frogs, the Marine Toad at a tad under 6 lbs and the African Bullfrog at 5 lbs.  

Beelzebufo is related to the ceratophryines, aka the “horned frogs,” so named because some have large “horns” over their eyes.  They are more affectionately known as Pac-Man frogs and are some of the most dangerous predators alive today.  Why Pac-Man?  They can open their toothy maws astoundingly wide and swallow creatures half their size, resembling the yellow ‘80s dot-eater in the process!  

The Brazilian Horned Frog is the heaviest of the living “Pac-Men,” weighing 5 lbs.  Despite its comparative svelteness, these Pac-Man frogs have giant heads with cranial hyperossification, allowing them to bite far above their weight class, as you will soon see.

Taxon	SVL (in inches)	Weight (lbs)	Skull Width	Years lived
Goliath Frog -Conraua goliath	13”	7 lbs	Est 4”
African Bullfrog - Pyxicephalus adspersus	9.6”	5 lbs	Est 4”	16
Marine Toad - Rhinella marina	9.4”	5 lbs 13 oz	Est 4”	25
Beelzebufo ampinga UA 9629	9.2”	7 lbs	6”	16+?
Brazilian Horned Frog - Ceratophrys aurita	6.7”	5 lbs	5”	16

Let’s Talk About Bite, Baby!

Beelzebufo has the most powerful bite of any frog that has ever lived.  While most frogs have weak jaws and rely upon a long, sticky tongue to capture prey, the bones on Beelzebufo’s head are solid.  This, plus a few other neat skeletal adaptations, provide a devilish bite!  

Even more terrifying?  The Beelzebufo skull used in this study wasn’t fully grown!  Fully adult Pac-Man frogs today have strongly fused skulls. Beelzebufo's wasn’t completely fused, meaning it was still growing!  And the bigger the frog, the more powerful the bite.  

The researchers used alligators and crocodiles with heads approximately the same width as Beelzebufo, which is why they weighed so little. So they sought out ~6” wide skulls to compare reptile bite strengths at similar head widths.  The Common Snapping Turtle in the study also had a head ~6” wide.  My takeaway from the study is that nature is an incredibly excellent engineer!

Toothy Maw and Sticky Tongue

All that massive bite power was channeled into terrifying teeth!  Though all Pac-Man frogs lack teeth in their lower jaws, they don’t miss them.  Would you if you had ~150 teeth on the top of your mouth that look like this:

Fig 4. from Lappin et al. 2017 used under CC4.0

 

Beelzebufo skull looking at the top of the mouth to see ~150 teeth.  Figure 8f from Evans et al. 2008 used under CC4.0 modified by removing background

Those recurved, needle-sharp teeth slammed down with death-dealing force onto insects, fish, small vertebrates possibly including dinosaurs, and anything else that found themselves too near.  Beelzebufo was likely a see-food predator - it saw food and ate.  And everything was on the menu.  

One of the animals that may have been somewhat immune was the armored (and oh-so-cute) Simosuchus, a small, herbivorous, heavily-armored crocodile cousin.  Its armor might have withstood a bite (and broken more than a few teeth), but that’s about it.  Anything else was lunch!

Simosuchus illustrated by Metasuchus for Fossil Crates

Remembering that Beelzebufo is a frog, one may be wondering, what about its tongue?  Though we won’t be finding fossilized tongues anytime soon, we do have incredible videos of the tongues of modern Pac-Man frogs in action, thanks to work by Kleinteich and Gorb (2014).  They videotaped the tongues in action, and their videos make it apparent these tongues fire out when the bottom jaw lowers.  Check out the videos here!

One of the most astonishing aspects of the videos is how the tongue unfurls and grabs prey from its ventral surface.  What I always thought of as the top of the tongue is actually the bottom, folded back upon itself, tucked away until needed.  Watch the video a few times to see what I mean.  It turns out that as the lower jaw opens, it helps to propel the tongue outward, and the tongue is folded upon itself for storage in the mouth, but that unfurling helps to add to its thwack factor when it hits prey.  I always thought of frog tongues as precision weapons, with the tip of the tongue capturing the pesky fly.  In Pac-Man frogs, those tongues act as heavy weaponry, aiding to stun and stick prey so its chompers can come down and finish the job.

Lifestyle

Beelzebufo lived in an area with two seasons, one incredibly rainy, the other long, hot, and dry, just like Pac-Man frogs live in today.  Frogs that live in areas with long periods of dryness tend to have short limbs, a spherical shape, and thick, dry skin to help prevent moisture loss.  Pac-Man frogs have a neat trick to survive their harsh dry seasons; they dig burrows.

Pac-Man frogs use a special keratinized pad that sits atop the first metatarsal, which lets it dig a sizable hole to lay low in during the dry times.  We don’t (yet) have evidence of this specialized toe on Beelzebufo, but I’ll bet it shows up (or something similar) in a future discovery.

  Black arrow marks keratinized pad used to burrow (from Fabrezi 2011)

Another clue to Beelzebufo’s burrowing lifestyle is the loss of its tympanic membrane, aka its eardrum.  Burrowing frogs today tend not to have eardrums, as the need for hearing isn’t great when one spends so much time underground.  

Though we don’t have all of Beezlebufo’s limbs, we have enough to suspect that they moved like Pac-Man frogs, which walk more than they hop, thanks to their heavy heads.  They are ambush predators of the highest order, sitting patiently until the right moment to strike with that massive mouth, piercing prey with sharp teeth and giant tongues.  You can google “Pac-Man frog eating” and find dozens of videos of people feeding their pet Pac-Man various creatures.  I found the videos rather cruel and sad, but it does give one an idea of how incredibly voracious a massive Beelzebufo must have been.

 

If it moved like a Pac-Man frog, perhaps it engaged in pedal luring?  Modern ceratophrynids have been observed wiggling their toes to attract prey!  Check this video out here (watch for the moving toes towards the top of the screen).  I do wonder if this might attract the wrong attention, say from an adult Masiakasaurus or teen-aged Majungasaurus.

 

Why I Believe Beelzebufo is the Deadliest Frog Ever

Beelzebufo possesses the size, and bite strength, to qualify as the deadliest frog to have ever lived.  Yes, there are frogs covered in bufotoxins (“frog toxin,” an actual term!) that can kill animals, and such chemical-weaponed frogs have likely existed, with various toxicity levels, for millions of years.  However, these toxins accompany aposematic (warning coloration) skin and are for defensive purposes.  Think about the cute but incredibly toxic poison arrow frogs.  They are only deadly if they are harassed.  

Beelzebufo has offensive capabilities unheard of among living frogs.  Every bit as long and heavy as the largest frogs today, a biteforce that would make a tiger envious, a mouth size that gives Samantha Ramsdell pause, and a possible temperament that views any living critter, regardless of size, as food (pics below!) gets my vote as the most deadly frog.

 

Here are three examples of modern Pac-Man frogs biting above their weight class.

Pac-Man frog successfully swallowed this lizard that was 2/3rd its snout-vent length! Figure from Chavez et al. 2011. Photo by J.P. Venegas.

Pac-Man frog trying to swallow a lizard longer than itself!  Figure from Chavez et al. 2011.

From Parsons published in Nature, August, 1932

The sheer bravado of these frogs to attack animals that are twice as long and heavy as them is incredible.  Remember that the Brazilian Horned Frog, Beelzebufo’s closest living relative, is 32% shorter, 40% lighter, and at least 20% smaller.   They are veritable dwarves compared to Beelzebufo!  Imagine how brazen it could be!  If it ate small dinosaurs in the Cretaceous, today Beelzebufo would count baby tapirs, giant anteaters and armadillos, maned wolves, and even jaguars on the menu!

Beelzebufo skull - photo compliments of Anthony Maltese of Triebold Paleontology, Inc.

Own your own skeletal cast today! 

Purchase a cast of Beelzebufo from Fossil Crates and we'll donate a percentage of the sale to the Ankizy Fund, a charity that saves the lives of children in remote Madagascar villages near the fossil localities by providing life-saving preventative measures (like toothbrushes and mosquito nets) and life-changing educations by funding 4 schools in the region.  Additionally, proceeds from a purchase will also go to the curation and collection of Madagascar fossils.  One Beelzebufo purchase improves (and saves!) the lives of children, and fossils.  Fossil Crates is proud to be part of helping Malagasy children thrive.

Additional Reading/Papers Used to Write This Blog

Báez and Perí 1990 Baurubatrachus pricei, nov. gen. et sp., un Anuro del Cretacico Superior de Minas Gerais, Brasil 

https://cdn.shopify.com/s/files/1/0274/6014/1133/files/baurbatrachus_holotype_baez.pdf?v=1679815006 

Chavez et al. 2011 Two new records in the diet of Ceratophrys cornuta Linnaeus, 1758 (Anura: Ceratophrydae)

https://corbidi.org/Investigacion/Publicaciones/Chavez_EtAl_2011_Ceratophrys_cornuta.pdf 

Christiansen and Wrote 2007 Bite Forces and Evolutionary Adaptations to Feeding Ecology in Carnivores

https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/0012-9658%282007%2988%5B347%3ABFAEAT%5D2.0.CO%3B2

Duellman and Lizana, 1994 Biology of a Sit-and-Wait Predator, the Leptodactylid Frog Ceratophrys cornuta

https://www.jstor.org/stable/3892875 

Evans et. al 2008 A giant frog with South American affinities from the Late Cretaceous of Madagascar

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2268566/

Evans et. al 2014 New Material of Beelzebufo, a Hyperossified Frog (Amphibia: Anura) from the Late Cretaceous of Madagascar https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3905036/#pone.0087236.s002 

Kleinteich and Gorb 2014 Tongue adhesion in the horned frog Ceratophrys sp.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5381498/

La Croix et. al 2011 Ontogeny of feeding performance and biomechanics in coyotes

https://zslpublications.onlinelibrary.wiley.com/doi/abs/10.1111/j.1469-7998.2011.00847.x

Lappin et. al 2017 Bite force in the horned frog (Ceratophrys cranwelli) with implications for extinct giant frogs https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5607344/#MOESM1

Paluh et. al 2020 Evolution of hyperossification expands skull diversity in frogs

https://www.pnas.org/doi/10.1073/pnas.2000872117

In herpetology the term frog and toad has no phylogenetic value.  In everyday use, toads are dry-skinned and bumpy, and frogs are smooth.  But there are dry-skinned frogs (like the Pac-Man frogs). When most people think of toads, they think of bufonids, which are not too far away from the Ceratophryids.

 

 

https://cdn.shopify.com/videos/c/o/v/0a9000a6c92a4252afc809b18c4c2fc1.mp4