-snip- Such adaptations have kept frogs around for millions of years, but a recent checkup has scientists concerned. They fear a sudden mass extinction of amphibians on a scale and pace not experienced since the age of dinosaurs. Nearly a third of the world's 6,000 species of frogs, toads and salamanders are in danger of disappearing, according to the Global Amphibian Assessment. In the past 20 to 30 years, about 120 species of frogs are believed to have become extinct, the assessment found. Human destruction of habitat is one reason for the loss. But there is a new enemy for...