Frog Discovery Is "Once in a Century"

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Bossuyt said that other people may have seen Nasikabatrachus before, but none had bothered to examine it. Also, "this frog lives underground and it only comes out during the monsoon, about just two weeks per year, and then it is gone again," he said.

Frogs and Continents

Biju and Bossuyt conclude in Nature that the discovery of Nasikabatrachus and its relationship to sooglossids in the Seychelles helps paint a picture of how frogs evolved and spread around the world.

Scientists believe that the breakup and drift of continents influenced the evolution of advanced frogs. For example, India was once part of a large super-continent in the southern hemisphere known as Gondwana, along with South America, Africa, Madagascar, the Seychelles, Antarctica, and Australia.

According to one theory, the chunk that went on to form South America and Africa split from Gondwana about 160 million years ago. The Antarctica-Australia chunk split about 130 million years ago, followed by Madagascar about 90 million years ago and the Seychelles about 65 million years ago.

If this theory is correct, said Hedges, India would have continued on a northward trek isolated from the rest of the world for about 10 million years before it slammed into Asia 55 million years ago and formed the Himalaya.

On one hand, Hedges said "the fact that the new frog is related to something from the southern hemisphere is neat: it shows this geological connection."

On the other hand, Nasikabatrachus is so unique—so different from other frogs and only distantly related to the frogs in the Seychelles—that it supports the theory that India was isolated for millions of years before it rammed Asia, said Hedges.

This theory is contradicted by the fossil record, which shows closely related dinosaurs, lizards, frogs, and mammals in South America, Africa, and Asia. New models have been proposed that incorporate land bridges between these landmasses to explain the fossil record.

"When we find unique organisms it indicates they've been isolated for a lot of time like the giant Galápagos tortoises," said Hedges. "Having a unique frog in India [suggests India was] isolated a fairly long time and supports the model that India didn't have a firm connection with other continents."

The question remains, however, of why the fossil record of India indicates past land connections. "Perhaps those bridges were more like chains of islands that allowed some—but not all—groups to disperse," Hedges concludes in Nature.

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