科学家发现古代南极青蛙

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When Thomas Mors looked at the small fossils from Antartica through his microscope, he found quite a surprise. They were hip and skull bones of a frog.

The fossils, some 40 million years old, were from a helmeted frog. About 4 centimeters long, this helmeted frog is closely related to five species of helmeted frogs that are native to Chile in South America. Helmeted frogs get their name from the shape of their heads.

Mors is a scientist at the Swedish Museum of Natural History and a lead author of the study that was published recently in the journal Scientific Reports.

Mors described the find as "a total unexpected discovery." He said, "I first found the hip bone, and I directly realized that I found an Antarctic frog – the first. And the first Antarctic amphibian for over 200 million years."

The discovery highlights how Antarctica, the land of ice and snow, was once home to forests and rivers that were full of life. Mors observed, "It tells us that whole ecosystems can be wiped out by global climate change, and that it might go fast."

Antarctica's climate at the time resembled the modern-day Valdivian rainforest in Chile. It was very wet with temperatures during the warmest months averaging about 14 degrees Celsius.

Until now, Antarctica's known prehistoric amphibians were members of extinct families. But the newly identified frog has plenty of living relatives.

South America's helmeted frogs are part of a group called Australobatrachia, or "southern frogs." That group also has members living in Australia and New Guinea.

Frogs first appeared roughly 250 million years ago, before the dinosaurs. They were found in all continents, except Antarctica.

With the discovery, Mors said, "now we know that they lived on all seven, before one of them froze."

I'm John Russell.

Will Dunham reported on this story for Reuters John Russell adapted it for Learning English. Hai Do was the editor.

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