World's largest frog is the African Goliath frog (Conraua goliath) from central Africa: 13 in (33 cm) in body length (legs excluded), and weighs up to 7 lb (3 kg). But a newly discovered fossil frog from Madagascar dwarfed it: the armored amphibian had a body 16-inch (40 cm) long (and probably weighed around 5 kg (11 lb)! The fossil frog lived 65 million to 70 million years ago during the Cretaceous Period, during the last 5 million years of dinosaur existence.
The species, baptized Beelzebufo ("devil toad") ampinga, because of its size, scary look and predatory diet, had been described in an article published in the journal "Proceedings of the National Academy of Sciences" (PNAS).
"They are just these big round blobs, basically all mouth and stomach. They were sit-and-wait, ambush predators," lead researcher David Krause, paleontologist at Stony Brook University, told LiveScience.
Beelzebufo had rather short legs, thus it didn't hop much; it was rather a sit-and-wait ambush predator, expecting its prey (frogs, lizards or mice) to approach.
"When you consider its size, I don't think it's outside the realm of possibility that it could have consumed some hatchling dinosaurs," Krause said.
Today, the largest living Madagascar frog is just 4 in (10 cm) long.
But the real surprise for the researcher was to find that Beelzebufo was a close relative to a genus of living South American amphibians, Ceratophrys, called horned frogs or "pac-man", because of their huge mouths. There are 3 species of Ceratophrys, and they are quite big, the largest having half of the length of Beelzebufo and weighing 0.5 kg (1.1 lb).
"The finding presents a real puzzle biogeographically, particularly because of the poor fossil record of frogs on southern continents. We're asking ourselves, 'What's a South American frog doing half-way around the world, in Madagascar?" Krause said.
This is a direct proof that Madagascar, the large island off Africa's southeast coast, had once a connection to South America. Frogs cannot cross the sea as they die in saltwater.
"It's sort of impossible to believe that they rafted from South America to Madagascar," Krouse said.
More likely is that there was probably a bridge between South America and Madagascar, possibly made by Africa or Antarctica. But the frog fossils found in Africa are not related to those encountered in either South America or Madagascar, and Antarctic frog fossils are very scarce.
The connection between Madagascar and South America is proved also by many related fossils from the Dinosaur era, including dinosaurs, in both places. Majungatholus atopus, a 9 m (30 ft) long carnivorous dinosaur, with a forehead horn and pneumatic nasal fossae that lived in Madagascar 70-65 MA years ago resembles Carnotaurus sastrei from Argentina. But we do not have to go to fossils and dinosaur era: even today, the Madagascar fauna comprises iguana lizards and boa snakes closely related to the South American species.