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Giant frog jumps continents

A giant frog fossil from Madagascar dubbed Beelzebufo or 'the frog from Hell' has been identified by scientists from University College London and Stony Brook University, New York. The discovery of the 70 million year-old fossil frog, of a kind once thought unique to South America, lends weight to a new theory that Madagascar, India and South America were linked until late in the Age of Dinosaurs.

The new frog resembles living Horned toads (ceratophryines or 'pac-man frogs') in having a squat body, huge head and wide mouth. With a body length (not counting the legs) of up to 40 cm -- longer than a rugby ball - and a weight of around four kilos (10 pounds), it is more than twice the size of its largest living relatives.

The fossil, published in the journal PNAS, enters the Malagasy history books alongside meat-eating dinosaurs, plant-eating crocodiles and giant snakes, all very different from the present day animals of Madagascar.

Professor Susan Evans of the UCL Department of Cell & Developmental Biology says: "This frog, a relative of today's Horned toads, would have been the size of a slightly squashed beach-ball, with short legs and a big mouth. If it shared the aggressive temperament and 'sit-and-wait' ambush tactics of living Horned toads, it would have been a formidable predator on small animals. Its diet would most likely have consisted of insects and small vertebrates like lizards, but it's not impossible that Beelzebufo might even have munched on hatchling or juvenile dinosaurs.

"Beelzebufo appears to be a very close relative of a group of South American frogs known as 'ceratophyrines,' or 'pac-man' frogs, because of their immense mouths," said Krause. The ceratophryines are known to camouflage themselves in their surroundings, then ambush predators.

"The finding presents a real puzzle biogeographically, particularly because of the poor fossil record of frogs on southern continents," said  Stony Brook University paleontologist David Krause, who led the research. "We're asking ourselves, 'What's a 'South American' frog doing half-way around the world, in Madagascar?'"

He said that because frogs "are not adept at dispersal across marine barriers, and since the few fossil frogs that are known from the Late Cretaceous in Africa are unrelated to Beelzebufo, one possibility is that there was a land connection between South America and Madagascar during that period."

Some geoscientists have suggested a lingering physical link between South America and Madagascar during the Late Cretaceous Period -- a link involving Antarctica. Antarctica in the Late Cretaceous was much warmer than it is today.

"The occurrence of this frog in Madagascar and its relatives' existence in South America provides strong evidence that the supercontinent Gondwana 'disassembled' during the latest part of the Cretaceous," said Richard Lane, program director in NSF's Division of Earth Sciences.

"Madagascar has a mainly endemic frog fauna whose history has generated intense debate, fuelled by recent phylogenetic studies and the near absence of a fossil record. Our discovery of a frog strikingly different from today's Madagascan frogs, and akin to the Horned toads previously considered endemic to South America, lends weight to the controversial paleobiogeographical model suggesting that Madagascar, the Indian subcontinent and South America were linked well into the Late Cretaceous. It also suggests that the initial spread of such beasts began earlier than that proposed by recent estimates."

University College London. February 2008.


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