Paleontologists working in Patagonia have unearthed the oldest-known fossil of a tadpole—and it was a whopper, measuring in at more than six inches long, the size of an adult human hand.

When they start their lives as tadpoles, they have gills like fish, but when they grow up, they develop lungs. And that’s not all. A frog’s skin is so thin that it can actually absorb oxygen ...

Through another series of experiments with tadpoles and green anole lizards ... also inherited their gill and ear structures from fish. In lizards, enhancer activity was in the ear canal, which ...