Beelzebufo ampinga faces off against the largest known living Malagasy frog, Mantydactylus ampinga.
When David Krause first discovered fossil bones from a frog that lived in Madagascar in the time of dinosaurs, he could not tell much except that it was big. He and his co-workers called it the “frog from hell.”
It took 15 years and another 75 incomplete fossils to put together enough the pieces to place the frog in the frog family tree and give it an official name: Beelzebufo ampinga. (That means “armored devil toad.”)
Dr. Krause, a professor of anatomical science at Stony Brook University, and his colleagues describe the giant frog in this week’s online edition of The Proceedings of the National Academy of Sciences.
Beelzebufo, which lived between 70 million and 65 million years ago, might be the largest frog ever, past or present. It may also have implications for geophysics, twisting the story of how the southern supercontinent of Gondwana broke apart into Africa, South America and Madagascar.
The goliath frog of West Africa is the largest of living frogs, grows more than a foot long, measured from snout to rear end, and can weigh more than seven pounds. The female Beelzebufo was a 16-inch, 10-pound behemoth. (The male was smaller.) Only another extinct frog, living about 20 million years in South America, may have been as large.
The largest frog living on Madagascar today is just over four inches long and would have made a nice hors d’oeuvre for Beelzebufo, Dr. Krause said.
Once Dr. Krause had dug up enough bones of Beelzebufo, he enlisted the help of Susan E. Evans and Marc E. H. Jones, two fossil frog experts at University College London.
The geophysical twist comes from Dr. Evans’s and Dr. Jones’s conclusions about Beelzeebufo’s genealogy. Its closest living relatives today live not in Madagascar or even Africa but in South America, a group known as Pac-Man frogs, because their wide mouths, big stomachs and voracious predatory appetites draw comparison to the 1980s video game.
The female Beelzebufos were “lady Pac-Man frogs, on steroids,” Dr. Krause said.
Geographically, that poses a puzzle, because Madagascar is a long way from South America and, according to the prehistoric maps, separated by much water. Madagascar detached from Africa 160 million years ago, and South America separated from Africa 100 million years ago. Further, no relatives of the Pac-Man frogs have been uncovered in Africa.
That raises the question: how did a relative of South American frogs get halfway around the world to Madagascar?
Dr. Krause suggests an alternate route, through Antarctica, which was at the bottom of the planet even then, but which had a much warmer climate where animals could thrive. South America was still connected to Antarctica as recently as 42 million years ago, but a land bridge between Madagascar and Antarctica is speculation.
“The geophysicists have not reconstructed the world quite that way,” Dr. Krause said. Such a connection would also explain why there are closely related members of other groups of animals, including dinosaurs, crocodiles and mammals, in both Madagascar and South America.
It was most likely a wait-and-lunge ambush predator like its South American relatives and perhaps even ate some small dinosaurs.
Ultimately, the Beelzebufo went the way of the dinosaurs, dying out at about the same time. The current frogs of Madagascar are not closely related and must have come from somewhere else.