Photos by renan_ozturk / Here's a snapshot of National Geographic's Lost World Expedition, a scientific "transect" of the Upper Paikwa River Basin—near Guyana’s northwestern border with Brazil and Venezuela—whose participants are looking for new species of amphibians and reptiles in one of the world’s richest and least explored hotspots of biodiversity. Words by m_synnott: Look hard enough and you can find frogs anywhere, from the Arctic to the Sahara. But nowhere are they more plentiful than in the rainforests that girdle South America’s equator. At last count, scientists like Bruce Means had cataloged about 1,000 species in the Amazon Basin. Of course, these are only the ones we know about; Means says there are likely ten times yet to be discovered. Sadly, we'll never know how many have already been lost to extinction. The reason for so much frog biodiversity in the Amazon is that speciation takes place over evolutionary time—and DNA analysis of tree frogs collected on past exped...